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On 26th May 2021, an earthquake with a moment magnitude Mw 5.1 hit the densely populated cities of Gisenyi (Rwanda) and Goma (D.R. Congo) which sit on the active East African Rift System. It was one of the largest earthquakes associated with the 2021 Mount Nyiragongo eruption. Although of moderate magnitude, the earthquake substantially damaged manmade structures. This paper presents field observations on the geotechnical impact, building damage, and factors contributing to the heightened destruction caused by this moderate earthquake. The damage pattern observed in the field indicates that masonry structures with inadequate seismic detailing were the most damaged buildings. In addition, the statistical analysis of the damaged buildings indicates most of the damaged structures were located in plains covered by volcanic soil. The intensity of the waves was estimated using the building damage data based on the European Macroseismic Scale (EMS-98). An intensity distribution map was generated for the surveyed area, suggesting EMS-98 intensity of VIII or IX along the eastern basin boundary fault and VII around the cities of Goma and Gisenyi where the land is composed of black cotton soil of volcanic origin. The higher intensity values along the eastern basin-bounding fault indicate that a reevaluation of the seismic hazard for the region is necessary. Since this is the first-ever such damage survey for the region, the developed intensity map can be used to understand the correlation between the intensity of the ground motion and damage severity which contributed to the seismic hazard assessment of the study area. [ABSTRACT FROM AUTHOR]

Post-earthquake scientific investigation is considered as one of the pillars supporting earthquake engineering. On the 6th of February, 2023, two deadly strong earthquakes, which magnitudes were Mw7.8 and Mw7.5, respectively, shook Southern-Central Turkiye, caused significantly large casualties and tremendous economy loss. Through on-site field survey, liquefaction phenomena and liquefaction-induced damage to buildings were observed. The observations are: (1) the consequences of soil liquefaction included sandboils, lateral spreading, ground subsidence and ground failure caused by loss of bearing capacity; (2) in two liquefied areas, lateral spreading was investigated and the spreading displacement ranged from several centimeters to meters, resulting in damage or demolishing of buildings; (3) in Golbasi town, many 6 to 10-story buildings significantly subsided and tilted due to liquefaction-induced loss of ground bearing capacity. Buildings subsided by tens of centimeters to 2 ~ 3 m, and tilted by several degrees to tens of degrees; (4) ground subsidence of tens of centimeters with respect to adjacent buildings was detected. The liquefaction phenomena were compared with those triggered by the 2008 Wenchuan, China, earthquake which maintained similar in magnitude and focal depth. The findings and lessons learnt will enhance the understanding of liquefaction hazard, challenge the current liquefaction countermeasures, and eventually facilitate to improve liquefaction mitigation techniques. [ABSTRACT FROM AUTHOR]

This paper analyzed the quality of the xBD image-training dataset for identifying building damage across a variety of natural hazards using deep learning convolutional neural networks. Specifically, we evaluated the pros and cons of combining training datasets across multiple natural hazards and provided recommendations on using the provided training dataset to optimize classification accuracy for building damage detection. The xBD dataset was rebalanced, using random over-sampling and under-sampling methods. Random over-sampling randomly duplicates the minority class, while random under-sampling randomly cuts-off the majority class. With the balanced dataset, we used the xBD baseline architecture as a starting point in the classification and find that it overfit to the no damage class; therefore, we improved the base classification algorithm by modifying the top layers of ResNet50. We found that not all classes (destroyed, major damage, minor damage, and no damage) were uniformly identifiable across natural hazards; therefore, we retrained the weights from ImageNet, adding five new convolution, batch normalization, and max pooling layers on top of ResNet50. One dropout layer, with a rate of 0.5 was also added in-between the fully connected layers to reduce overfitting and improve performance. We also evaluate the identifiability of the four damage classes in the xbd dataset. Because classification performance was significantly higher for the "no damage" class as compared to "minor", "major", and "destroyed" classes, we evaluated merging classes. We kept the "no damage" class and created a second merged class ("damaged") representing "minor damage," "major damage," and "destroyed." We used the same architecture for the multiclass classification and the binary classification but without the ImageNet weights. Based on this work, we recommend that users be aware of performance differences across natural hazards and across damage classes. Earthquake building damage is extremely limited in the training data and, as a result, application of the trained algorithm on earthquake data cannot be evaluated given the xBD dataset. Building damage due to volcano and tsunami are also poorly represented in the training data, and do not have sufficient data for model validation (especially within all damage classes). Wind hazards are well-represented and therefore application of the algorithm trained using either the wind-only data or the multi-hazard dataset is reliable. The multi-class algorithm trained with wind hazard specific data slightly outperforms a multihazard trained multiclass model (F1 score 0.70 vs. 0.67). Both models have similar performance across all four classes (F1 > 0.5). For flood, fire, and tsunami hazards, we recommend using the binary damage classes as identifiability is low for at least two of the classes in each hazard. For flood building damage, binary classification performance resulted in a significantly higher F1 score when trained with the flood specific dataset versus the multihazard data (0.72 vs. 0.54). On the other hand, for fire building damage, classification performance is slightly higher when the model is trained on multi-hazard data, rather than trained using a fire specific dataset (F1 score 0.46 vs. 0.42). [ABSTRACT FROM AUTHOR]

The development of a damage scenario following an earthquake swarm event in high-risk areas, such as the inland Sea of Galilee (SoG) in Israel, is critical for significantly increasing public awareness in preparation for a strong earthquake event. Following the earthquake swarms in 2013 and 2020 that occurred near the Dead Sea Fault (DSF) system in the SoG, the present study adopts a conservative approach to damage scenario development, maintaining that these events should be treated as precursory swarms. Accordingly, different damage and loss scenarios were developed using the 2020 Federal Emergency Management Agency software program Hazus and new in-house spatial analysis and postprocessing tools. The results of the scenario analyses confirm that the most intensive damage is expected to be concentrated around the SoG, especially in the adjacent city, Tiberias, if a moderate earthquake (Mw ∼ 6) occurred soon thereafter along the DSF system. In contrast, if a stronger earthquake (Mw ∼ 7) was to occur, the damage may spread to distant cities, such as Beit She'an and Haifa (distances of more than 50 km). Considering the potentially high number of casualties, intensive damage to buildings and essential facilities, high economic loss, blockages of main roads due to slope failures, and weight of debris expected to accumulate near the SoG, we stress the importance of immediate action on the part of civil protection agencies based on the present scenarios to promote the readiness of the population and significantly reduce the anticipated disaster magnitude. [ABSTRACT FROM AUTHOR]

On October 5, 2021, a landslide-debris flow disaster chain occurred suddenly in Hanping village, Shaanxi Province, China. This catastrophic disaster chain damaged 7 houses, 41.9 hectares of arable land and 3 roads and resulted in 1 death. Based on a detailed field investigation of the disaster site, we analyzed the dynamic evolution of the disaster chain by using experimental analysis, unmanned aerial vehicle photogrammetry, satellite remote sensing interpretation and the SBAS-InSAR technique and then preliminarily revealed the movement process and causal mechanism of the disaster chain. The results suggested that the first landslide initiated in the upper part of Canger cliff, which is the result of the combined effects of slope structure, earthquake damage, engineering disturbance, and rainfall infiltration. Among them, extreme rainfall events are the primary factors that induce landslides. Before the landslide, InSAR results showed that deformations had already appeared in the source area, and the deformation rate had a strong correlation with precipitation. Then, the potential-to-kinetic transformation effect and air cushion effects generated by the landslide movement in the narrow and steep section of Canger cliff led to the disintegration of the sliding body. With replenished surface runoff, the clastic flow gradually transformed into debris flow. Moreover, due to the dam-breaching effects at bayonets and bends and the entrainment effect of the high-density debris flow along the gully, the scale of debris flow increases gradually, resulting in catastrophic damage during the movement. The findings of this study provide a significant reference and guidance for understanding the chain-generation mechanism of landslide-debris flow disaster chains, as well as informing disaster prevention and mitigation strategies. [ABSTRACT FROM AUTHOR]

United Nations SDGs-11 focuses on safe, resilient, sustainable cities and human settlement. Importance given to implement the Disaster Risk Reduction strategy where the number of death and economic loss to be reduced. Seismic disaster risk reduction is one of the major task in SDGs., The occurrence of earthquake in the Himalayan region is continuous and infrastructures are highly affected. The study aims to suggest a suitable seismic retrofitting technique for infrastructures in Sikkim Himalayan region by In-situ and laboratory based analysis. In the lab environment, geoinformatic based geospatial databases have been generated to understand the seismological characteristics of the study area and a seismic retrofitting experiment has been conducted with the help of plaster of Paris column wrapping with glass fiber to test the strengthening of the column specimen. Also, In-situ field observation data has been collected and analyzed to recognize the vulnerable infrastructures which have the probability to get damaged during an earthquake and relevant seismic retrofitting technique has been suggested for vulnerable infrastructures by incorporating with lab based structural analysis. The experimental result shows that the first crack is developed in the Specimen-I without wrapping while the applied load is 320N, deflectometer reading is 555 mm. At a load of 640N, the column developed crack. The complete failure of the column has also been recognized from this specimen while the applied load is 832N and deflectometer reading is 924 mm. In the fiber wrapped specimen (Specimen- II), it is observed that the crack is not developed in the specimen-II column till it has been completely uprooted from the base when the load reached 320N the corresponding deflection was found to be 350 mm which is very much less than Specimen I. The experimental result indicates that the glass fiber wrapped specimen appears stronger with an increasing load than without wrapped specimen. It can be inferred that the seismic retrofitting technique using GFRP wrap in concrete structure can improve the strength of the buildings in the study region. The proposed technique is suggested for different concrete infrastructures in the study region to improve the strength of the columns and beams for protecting infrastructures. [ABSTRACT FROM AUTHOR]

Assessing or predicting seismic damage in buildings is an essential and challenging component of seismic risk studies. Machine learning methods offer new perspectives for damage characterization, taking advantage of available data on the characteristics of built environments. In this study, we aim (1) to characterize seismic damage using a classification model trained and tested on damage survey data from earthquakes in Nepal, Haiti, Serbia and Italy and (2) to test how well a model trained on a given region (host) can predict damage in another region (target). The strategy adopted considers only simple data characterizing the building (number of stories and building age), seismic ground motion (macroseismic intensity) and a traffic-light-based damage classification model (green, yellow, red categories). The study confirms that the extreme gradient boosting classification model (XGBC) with oversampling predicts damage with 60% accuracy. However, the quality of the survey is a key issue for model performance. Furthermore, the host-to-target test suggests that the model's applicability may be limited to regions with similar contextual environments (e.g., socio-economic conditions). Our results show that a model from one region can only be applied to another region under certain conditions. We expect our model to serve as a starting point for further analysis in host-to-target region adjustment and confirm the need for additional post-earthquake surveys in other regions with different tectonic, urban fabric and socio-economic contexts. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to present the damage features of masonry structures and engineering seismology studies after the 19–22 November 2021 Köprüköy earthquakes (Mw 5.1 and Mw 4.7). The masonry structures damaged near the epicenter have been examined. Damages have been detected that such as vertical cracks in the walls of the masonry structures, out-of-plane bending of the walls, splits in the joints of the walls, and separation of the floors from the elements such as walls and roofs. The fact that the structures in the region do not receive an engineering service and that they are constructed without complying with the relevant earthquake regulations are thought to cause such damage. The damage in Topçu village of Köprüköy district in Erzurum is more than in other settlements. Microtremor measurements have been applied in Topçu Village to investigate dynamic soil features. The soil amplification factor and soil predominant period have been obtained ~ 6.8 and ~ 1.3 s for the first measurement and ~ 9.4 and ~ 1.3 s for second location, respectively. Also, Vs30, bedrock depth, vulnerability index, and shear strain parameters have been calculated using some empirical relations. High bedrock depth and low Vs30 values are obtained for both measurements. The vulnerability index and shear strain values also indicate that the vulnerability of the soil is high. In order to remain in the safe zone for structures in a possible future earthquake, it has been suggested that it should comply with the earthquake-soil-structure relationship and should be designed in accordance with the earthquake regulation standard. [ABSTRACT FROM AUTHOR]

This study develops a novel approach for identifying buildings that were damaged in the aftermath of the Kahramanmaraş earthquakes on February 6, 2023, which were among the most devastating in the history of Türkiye. The approach involves using two pre-event and one post-event Sentinel-1 and Sentinel-2 images to detect changes in the varying-sized and shaped buildings following the earthquakes. The approach is based on the hypothesis that the radiometric characteristics of building pixels should change after an earthquake, and these changes can be detected by analysing the spectral distance between the building pixel vectors before and after the earthquake. The proposed approach examines the changes in building pixel vectors on pre-event and post-event Sentinel-2 MultiSpectral Instrument images. It also incorporates the backscattering features of Sentinel-1 Synthetic Aperture Radar images, as well as the variance image, a feature that is derived from a Grey-Level Co-occurrence Matrix, and the Normalized Difference Built-up Index image, which were derived from the optical data. The approach was tested on three sites, two of which were in Kahramanmaraş and the third in Hatay city. The results showed that the proposed method was able to accurately identify damaged and undamaged buildings with an overall accuracy of 75%, 84.4%, and 73.8% in test sites 1, 2, and 3, respectively. These findings demonstrate the potential of the proposed approach to effectively identify damaged buildings in post-disaster situations. [ABSTRACT FROM AUTHOR]

Landslides are a major cause of earthquake damage, and the ability to anticipate seismically triggered landslide displacement is critical for seismic hazard assessment. The necessity for efficient measures for preventing and minimizing the damage caused by co-seismic landslides has prompted the development of innovative approaches for assessing areas exposed to seismically induced landslides at a regional scale. Uttarakhand is highly seismically active, and major geological formations of this region are heavily jointed or fractured. Landslides are common in this area, and the risk of earthquake-induced landslides is particularly significant due to the region's strong seismicity. The present study incorporated a combination of a probabilistic approach and modified Newmark's method to obtain seismically induced landslide susceptibility maps. Firstly, a well-established probabilistic seismic hazard assessment method was utilized to calculate the probability of occurrence for various levels of earthquake shaking in terms of Arias intensity for different time intervals. Then by using an empirical equation based on Newmark's displacement model, the slope strength demand was evaluated. The resulting slope strength demand values represent the minimal value of resistance required by a slope to maintain the probability of triggering an earthquake-induced landslide below a predetermined threshold. Finally, the spatial distribution of slope strength demand was compared with in-situ critical acceleration values computed using a modified Newmark method to determine slope failure probability. The obtained map presents a detailed demarcation of areas that will be affected by co-seismic landslide hazards in the future. [ABSTRACT FROM AUTHOR]

In Turkey, the İzmir earthquake with Mw = 6.9 moment magnitude with the epicenter of 17.26 km off the Seferihisar (İzmir) coast in the Aegean Sea occurred in October 30, 2020, at Turkish time 14.51. According to the acceleration records of İzmir earthquake, the recorded peak ground acceleration (PGA) was approximately 0.182 g, and 117 deaths occurred in this earthquake, while 1032 people were injured. In this study, the structural damages that occurred on the buildings due to the İzmir earthquake were examined and discussed in detail according to the current and former Turkish regulations. Moreover, a RC building constructed in 1998 and survived the earthquake without any permanent damage (a 5-story building designed as 3-story in the existing static project but added two more floors without any in situ strengthening) was subjected to pushover analysis, linear analyses considering regulations and nonlinear time-history pushover analysis according to the acceleration records of İzmir earthquake. The obtained structural results were compared and discussed according to the current and former regulations. [ABSTRACT FROM AUTHOR]

A probabilistic methodology is presented for assessing cascading multi-hazard risk for ground shaking and post-earthquake fires at a regional scale. The proposed methodology focuses on direct economic losses to buildings caused by the combined effect of ground shaking and post-earthquake fires and evaluates the exceedance probability of the regional shaking–fire losses in a predefined future time period by comprehensively considering the effects of various uncertain factors on the losses via Monte Carlo simulations. Probabilistic seismic risk assessments are extended by integrating post-earthquake fire models with seismic activity models, ground motion prediction equations, and seismic fragility functions. The fire models include post-earthquake ignition models, a weather model, a physics-based urban fire spread model, and a fire brigade response model. This integrated modeling enables the incorporation of the following uncertain factors with causal relationships into the assessments: earthquake occurrence, ground motion intensity distribution, damage to buildings resulting from ground shaking, post-earthquake ignition occurrence and occupant firefighting, weather condition, fire brigade response time including time to detection, and damage to buildings resulting from post-earthquake urban fire spread. To demonstrate the methodology, a realistic case study is conducted for a historical urban area with closely spaced wooden buildings in Kyoto, Japan, focusing on possible large earthquakes along major active faults. Contrary to conventional single-hazard approaches, the results highlight the impact of multi-hazard consideration on risk assessments. This indicates that the methodology can be a useful tool for more appropriately understanding earthquake risk and promoting risk-informed decision-making in urban communities for risk reduction. [ABSTRACT FROM AUTHOR]

The eastern Mediterranean region is characterized by high seismicity which has been documented by instrumental data and historical reporting. Strong submarine or coastal earthquakes often are associated by tsunami waves. We improve the earthquake and tsunami historical documentation in the eastern Mediterranean, including the Sinai sub-plate, with the study of two Greek documents that remained little-known to the seismological community. The first document is the Historia chronike written by the Byzantine chronicler John (Ioannis) of Antioch during the AD seventh century. The second is the book Epitome of Holly and Secular History of Sinai, written by Patriarch Nektarios during the seventeenth century. Both documents provide new information about earthquakes, tsunamis, one volcanic eruption and comets observed in the eastern Mediterranean region in various time periods. New evidence is presented about the puzzling earthquake and tsunami that caused destruction in Phoenicia in 138/135 BC, the AD 634 Palestine damaging earthquake, the tephra fall which was associated with a small volcanic eruption in NW Arabia in AD 639/640, the AD mid-eighth century destructive earthquakes in Palestine and Jordan and an associated destructive tsunami in the coast of Phoenicia. New information is revealed about the very little-known earthquakes of AD 1091 and the damaging seismic sequence of AD 1212 (or 1312) in St. Catherine's Monastery in Sinai. The synchronization of some earthquake events with astronomical phenomena, like the apparition of comets and sun eclipses, supported dating the events more precisely. [ABSTRACT FROM AUTHOR]

The local site conditions have great impact on the characteristics of input motions propagating along the soil deposits. This eventually contributes to the damages of earthquake events to urban areas. This study reports the local site effect during the 08.11.2021 earthquake event occurred near the Konya city. For this, five input ground motions of the earthquake event recorded at five different stations are investigated. The stations are positioned at varied soil classes of A, B and C, and no recording is available on the class D site. In addition, site response analyses are conducted using five soil profiles from the site of Konya city. The soil profiles are simulated in the Deepsoil programme adapting equivalent linear approach in frequency domain. The spectral accelerations of the recorded input ground motions reflect obviously the influence of the local site conditions. When the soil site (where the earthquake is recorded) gets softer, the spectral peaks appear to shift to the longer periods. The site response analyses at the sites in the Konya city also imply such effect. The analysis of the soft soil deposit with the Vs of 175 m/s expresses de-amplification of the spectral accelerations at the shorter periods and amplifications at the longer periods. Moreover, the site response analyses tend to express good indication of the spectral amplification factors for different soil classes. These suggest that the local site conditions in the studied area, in addition to the peak ground acceleration level of the earthquake event, can increase the level of building damages. Overall, the study highlights the impact of local site conditions on the spectral accelerations of input motions and potential of site response analysis to speculate that effect. [ABSTRACT FROM AUTHOR]

Many cities are built on or near active faults, which pose seismic hazard and risk to the urban population. This risk is exacerbated by city expansion, which may obscure signs of active faulting. Here, we estimate the risk to Bishkek city, Kyrgyzstan, due to realistic earthquake scenarios based on historic earthquakes in the region and an improved knowledge of the active fault sources. We use previous literature and fault mapping, combined with new high-resolution digital elevation models to identify and characterise faults that pose a risk to Bishkek. We then estimate the hazard (ground shaking), damage to residential buildings and distribution of losses (economical cost and fatalities) using the Global Earthquake Model OpenQuake engine. We model historical events and hypothetical events on a variety of faults that could plausibly host significant earthquakes. This includes proximal, recognised, faults as well as a fault under folding in the north of the city that we identify using satellite DEMs. We find that potential earthquakes on faults nearest to Bishkek—Issyk Ata, Shamsi Tunduk, Chonkurchak and the northern fault—would cause the most damage to the city. An Mw 7.5 earthquake on the Issyk Ata fault could potentially cause 7900 ± 2600 completely damaged buildings, a further 16,400 ± 2000 damaged buildings and 2400 ± 1500 fatalities. It is vital to properly identify, characterise and model active faults near cities to reduce uncertainty as modelling the northern fault as a Mw 6.5 instead of Mw 6.0 would result in 37% more completely damaged buildings and 48% more fatalities. [ABSTRACT FROM AUTHOR]

The Genç District is located on the Bingöl Seismic Gap (BSG) of the Eastern Anatolian Fault Zone (EAFZ) with its ~ 34.000 residents. The Karlıova Triple Junction, where the EAFZ, the North Anatolian Fault Zone, and the Varto Fault Zone meet, is only 80 km NE of the Genç District. To make an earthquake disaster damage prediction of the Genç District, carrying a high risk of disaster, we have (1) prepared a new geological map, and (2) conducted a single-station microtremor survey. We defined that three SW-NE trending active faults of the sinistral Genç Fault Zone are cutting through the District. We have obtained dominant period (T) as < 0.2 s, the amplification factor (A) between 8 and 10, the average shear wave velocity for the first 30 m (Vs30) as < 300 m/s, and the seismic vulnerability index (Kg) as > 20, in the central part of the Genç District. We have also prepared damage prediction maps for three bedrock acceleration values (0.25, 0.50, 0.75 g). Our earthquake damage prediction scenarios evidenced that as the bedrock acceleration values increase, the area of soil plastic behavior expands linearly. Here we report that if the average expected peak ground acceleration value (0.55–0.625 g) is exceeded during an earthquake, significant damage would be inevitable for the central part of the Genç District where most of the schools, mosques, public buildings, and hospitals are settled-down. [ABSTRACT FROM AUTHOR]

The western Makran subduction zone is capable of producing considerable tsunami run-up heights that penetrate up to 5 km inland. In this study, we show how climate change has affected urbanization along the tsunami-prone Makran coastline during the past 35 years. To address this issue, we have employed climate data, satellite altimeter radar, geomorphology and historical shoreline changes in order to shed light on the factors leading to a decline in access to freshwater resources and also rapid urbanization. We furthermore consider the interactions between environmental changes and human-induced coastal and catchment modifications in increasing socioeconomic vulnerabilities of littoral areas. The results of this study show that agricultural and freshwater management methods along the Chabahar coastal plain date back to at least 1808 CE, when wetter climate conditions characterized the area. Severe climate changes have been pronounced since 2000. Within this context, the majority of agricultural lands have been abandoned due to increasing drought intensity and duration. Decreasing cultivation and limited access to freshwater resources have led to extensive urbanization particularly for the two cities of Konarak and Chabahar. Enhanced soil erosion, increasing summer monsoon wind speed, sea-level rise and the growing number of strong storm events are some of the climate change-related hazards for high to very high socially vulnerable zones. In addition to environmental risks, poor urban planning has increased damage to coastal infrastructures such as ports and desalination plants. Furthermore, industrial and urban growth in the northwest of the Makran could further enhance socioeconomic damage by earthquakes and tsunamis. [ABSTRACT FROM AUTHOR]

An earthquake with a magnitude ranging from Mw = 6.9 (KOERI) to Mw = 7.0 (USGS) struck Samos Island in the Aegean Sea on October 30, 2020, with an epicentre 70 kms from the İzmir city centre in Turkey. The earthquake took place at 14:51 local time (11:51 UTC). The peak ground acceleration (PGA) of this earthquake was recorded to be 0.179 g at the epicentre of the earthquake. This earthquake occurred at a depth of 17.26 km (AFAD (2020) İzmir Earthquake Report, (In Turkish)) and lasted 16 s. The main shock from the earthquake triggered a tsunami that hit the building stocks built near the coast. During the gradual deregulation of COVID-19 pandemic regulations, various events caused considerable damage to the building stock, particularly in the Izmir Seferihisar and Bayraklı regions and resulted in a massive disruption of daily habits. The main shock caused 117 deaths in both Turkey and Greece, and 1632 people were also injured in Turkey. Moreover, several injuries occurred in Greece. A total of 103 buildings collapsed, 700 were severely damaged, 814 buildings were moderately damaged, and 7889 were slightly damaged. The basic aim of this paper is to briefly present the past and present seismotectonic characteristics of the region, present building stock, and former structural conditions before the earthquake, assess structural performance and classify distinguished earthquake-induced failures and damage due to the basin effect. [ABSTRACT FROM AUTHOR]

Major earthquakes in a given location are unpredictable, infrequent, and often fatal. Using data from a previous earthquake disaster, this study explores the relationship between certain characteristics of the physical environment and the type and extent of building damage by using spatial statistical analyses and principal component analysis. The results show that a specified set of physical environmental features, including landslide-prone areas and proximity to a fault, are associated with greater degrees of building damage. The results also show, as evidenced by cases in which buildings constructed according to standards of earthquake-resistant design still collapsed, a sole concern with buildings is insufficient for community safety. Policy implications include that although building design, quality construction, and governmental inspection of new developments are important as adaptation measures to earthquakes, they may be of secondary importance compared to prohibiting future development in earthquake-prone areas possessing the physical features identified herein. [ABSTRACT FROM AUTHOR]

An earthquake of magnitude 6.9 hit the city of Izmir (Turkey) on 30 October 2020, resulting in 117 deaths (in Turkey) and considerable economic losses. The earthquake also triggered a tsunami. Following the earthquake, field surveys are being conducted in a Covid-secure way to study and document the damages caused. The earthquake caused significant damages to residential buildings mainly located in the district of Bayrakli and Bornova. However, no damages were observed in railway and roadway bridges or tunnels and that helped the rescue operations. The damages were mainly structural which included the so-called pancake collapse (where the entire building collapsed) and soft storey type collapse (weak storey characterised with weak columns collapsed), and in some cases, only the ground floor completely collapsed. Due to the proximity of the epicentre and the geology of the area, it seemed that the ground motions were amplified. This technical note provides a summary of the seismological and recorded ground characteristics of the earthquake together with the lessons learnt. [ABSTRACT FROM AUTHOR]

There have been damaging hurricanes and earthquakes throughout the history of the Caribbean. However, the intensity and frequency of these natural events have increased. The Caribbean is comprised of territories with dependencies on developed countries, as well as territories that are sovereign states. In September 2017, Hurricane Maria impacted the island of Dominica resulting in damage equivalent to 226% of the Gross Domestic Product. There were 65 fatalities, 1.37 billion US$ in damage, and a recovery period of approximately 5 years. In August 2018, a significant earthquake occurred near Trinidad, the larger of the twin-island state of Trinidad and Tobago, which provides critical support to the Caribbean Community. There were no fatalities or significant injuries, and approximately 12 million US$ in damage, which with some exceptions, was not sufficient for major disruption. In this paper, the results of rapid visual assessment of the buildings after these events are reported with an emphasis on damage in terms of actual versus expected performance. The following are considered: (1) causes of excessive damage; (2) existing approaches that may be used for adequately improving performance, and (3) possible research ideas for the cases where cost-effective approaches to improving performance do not exist at this time. It was concluded that: (i) the main cause of the damage due to the hurricane is an underestimation of the expected wind speed and that adequate performance is possible if building codes are enforced and (ii) the earthquake damage was excessive relative to the extent of ground shaking. Given the general similarity of construction between Trinidad and the rest of the Caribbean, it was also concluded that the Caribbean as a whole has inadequate buildings as regards earthquake resistance and an extensive retrofit effort is required. [ABSTRACT FROM AUTHOR]

A 6.8-magnitude earthquake that occurred on January 24, 2020, has been effective in Turkey's eastern regions. The earthquake, with recorded peak ground acceleration (PGA) value of 0.292 g, caused the destruction or heavy damage of buildings, especially in the city center of Elazığ province. The purpose of this paper was to share the results of detailed investigation in the earthquake-stricken area. Additionally, the causes of damages and failures observed in the buildings were compared to those that had occurred in previous earthquakes in Turkey. In this study, the damages observed in especially RC buildings as well as in masonry and rural buildings were summarized, the lessons learned were evaluated, and the results were interpreted with reference to Turkish earthquake codes. In the study, it was particularly emphasized why the building stock underwent such damage even though the buildings were exposed to earthquake acceleration well below the design acceleration values. [ABSTRACT FROM AUTHOR]

The island of Ischia, located in the Gulf of Naples, represents an unusual case of resurgent caldera where small-to-moderate magnitude volcano-tectonic earthquakes generate large damage and catastrophic effects, as in the case of 4 March 1881 (Imax-VIII-IXMCS) and 28 July 1883 (Imax X-XI MCS) historical earthquakes, and of the recent 21 August 2017 MW = 3.9, event. All these earthquakes struck the northern area of the island. With about 65,000 inhabitants, Ischia is a popular touristic destination for thermals baths, hosting more than 3,000,000 visitors per year, thus representing a high seismic risk area. Assessing its seismic potential appears a fundamental goal and, to this end, the estimate of the magnitude of significant historical events and the characterization of their source are crucial. We report here a reassessment of historical data of damage of 1881 and 1883 earthquakes to evaluate the main source parameters of these events (obtained with the BOXER and EXISM software) and quantitatively compare, for the first time, the results with the source characteristics, obtained from instrumental data, of the recent 2017 earthquake. The results allowed us to assess the location, as well as the possible dimension and the related maximum magnitude, of the seismogenic structure responsible for such damaging earthquakes. Our results also provide an additional framework to define the mechanisms leading to earthquakes associated with the dynamics of calderas. [ABSTRACT FROM AUTHOR]

After the major Mexican earthquakes that took place in September 7 (8.2 Mw) and 19 (7.1 Mw), 2017, damage was assessed in the communities of Motozintla and Unión Juárez in the state of Chiapas, Huexca in Morelos, and Jolalpan in Puebla, Mexico. In these communities, as part of a previous research, the structural vulnerability was assessed before the occurrence of these two earthquakes. In this work, we validate the vulnerability maps previously generated by comparing them with the spatial distribution of the damaged houses. Our results indicate that the structural vulnerability maps identified some of the areas where most of the damage was concentrated. However, other regions not previously considered also registered a high number of damaged houses. We believe that the physical location of houses is another main factor that conditions the level of earthquake damage. Based on these findings, we updated the structural vulnerability maps developed for the four studied communities. We believe that these new maps provide a more accurate assessment of the vulnerable areas, where the high vulnerability zones are regions where most damage will take place. However, in the low vulnerability zones, where the expected damage is low, a small percentage of moderate and high damage can also occur. Our findings provide valuable additional elements for the development of integral comprehensive measures for reducing earthquake vulnerability and risk and for strengthening the local civil protection plans including retrofitting of structures, earthquake response plans, and disaster education. [ABSTRACT FROM AUTHOR]

The earthquake in Sivrice, the district of Elazığ, took place at 20:55 (with local time, GMT+3) on January 24, 2020, with a magnitude of 6.8 in Turkey. This earthquake was felt in some districts and villages of Malatya as well as Elazig province and caused loss of life and property. After the earthquake, on-site investigations were carried out in the earthquake area. It was observed that liquefaction and lateral spreading occurred in alluvium soil deposits that are considered to be close to surface at lake shores and reservoir of the dams, but no soil-induced damage was observed in the city center. It is understood that extensive geotechnical investigations should be carried out in order to prevent damage to the structures due to soil problems in case of larger earthquakes. The common observed structural damages in the reinforced concrete (RC) buildings occurred due to short column effect, large and heavy overhangs, beam discontinuity, workmanship defects, and lack of control. Along with the masonry buildings in Elazig center and villages, damages that occurred in traditional stone masonry houses at the villages of Elazığ and Malatya had been examined, and causes had been investigated. Different levels of damage occurred widely in masonry minarets that did not meet adequate engineering service. In this study, geotechnical and structural damages have been investigated, and suggestions have been presented for the preparation of the region in question on active faults for possible earthquakes. [ABSTRACT FROM AUTHOR]

Empirical vulnerability models are fundamental tools to assess the impact of future earthquakes on urban settlements and communities. Generally, they consist of sets of fragility curves that are derived from georeferenced post-earthquake damage data. Following the 2015 Nepal earthquake sequence, the World Bank, through the Global Program for Safer Schools, conducted a Structural Integrity and Damage Assessment (SIDA) of about 18,000 school buildings in the earthquake-affected area. In this work, the database is utilized to identify the main structural characteristics of the Nepalese school building stock. For the first time, extended SIDA school damage data is processed to derive fragility curves for the main structural typologies. Data sets for each structural typology are used for a Bayesian updating of existing fragilities to obtain regional models for Nepalese schools. These fragility estimates can be adopted to assess potential seismic losses of the school infrastructure in Nepal. Additionally, they can be used for calibrating loss assessment studies in the wider Himalayan region where the structural typologies are similar. [ABSTRACT FROM AUTHOR]

The seismically induced ground failure is defined as any earthquake-generated process that leads to deformations within a soil medium, which in turn results in permanent horizontal or vertical displacements of the ground surface. As a result, relative movements occur on the ground and structures affected by these movements and thus they may be damaged. Determining earthquake-induced ground failure areas is important to carry out damage assessment studies more quickly and reliably and to prevent more destructive damages. Large earthquake-induced ground failure areas or limited access to the areas due to earthquake causes costly and unsafe fieldwork. Using satellite photographs, earthquake-induced ground failure areas can be easily and reliably detected and the fieldwork can be planned quickly. This study aimed at determining the postearthquake-induced ground failure areas and buildings or structures partially ruined (damaged) by using a deep learning-based object detection method, using Google Earth satellite images after an earthquake. The data set obtained after the earthquake occurred in the 2018 Palu region of Indonesia was used. This data set is divided into two parts for training and test areas. A descriptive approach is considered for detecting the earthquake-induced ground failure areas and damaged structures from collected images from Google Earth software using satellite photographs, using a pretrained Faster R-CNN. To demonstrate the effectiveness of the proposed method, the data set was first created with Google Earth Pro software and it was generated with 392 images for the earthquake-induced ground failure area and 223 images for the damaged area with a resolution of 1024 × 600 pixels. The analyses were carried out by taking into account different image scales. As a result of the analyses, it was concluded that the earthquake-induced ground failure effects (liquefied soil) and damaged structures can be detected to a large extent by using object detection-based deep learning methods. [ABSTRACT FROM AUTHOR]

In the past couple of decades, Operational Earthquake Forecasting (OEF) has been proposed as a way of mitigating earthquake risk. In particular, it has the potential to reduce human losses (injuries and deaths) by triggering actions such as reinforcing earthquake drills and preventing access to vulnerable structures during a period of increased seismic hazard. Despite the dramatic increases in seismic hazard in the immediate period before a mainshock (of up to 1000 times has been observed), the probability of a potentially damaging earthquake occurring in the coming days or weeks remains small (generally less than 5%). Therefore, it is necessary to balance the definite cost of taking an action against the uncertain chance that it will mitigate earthquake losses. In this article, parametric cost–benefit analyses using a recent seismic hazard model for Europe and a wide range of inputs are conducted to assess when potential actions for short-term OEF are cost–beneficial prior to a severe mainshock. Ninety-six maps for various combinations of input parameters are presented. These maps show that low-cost actions (costing less than 1% of the mitigated losses) are cost–beneficial within the context of OEF for areas of moderate to high seismicity in the Mediterranean region. The actions triggered by OEF in northern areas of the continent are, however, unlikely to be cost–beneficial unless very large increases in seismicity are observed or very low-cost actions are possible. [ABSTRACT FROM AUTHOR]

Building damage probabilities are invaluable for assessing short-term losses from natural hazards. In many countries however, the individual building level data required for assessing reliable damage are usually unavailable. This paper shows how the post-processing of aggregate HAZUS earthquake damage assessments can yield building-level damage probabilities. On the basis of three plausible scenarios for Northern Israel, we generate and visualize a building-level combined damage probability index. We use the tools of exploratory spatial data analysis to purge any causal influences in the spatial pattern of these calculated damage probabilities. The costs and benefits of our approach are discussed. [ABSTRACT FROM AUTHOR]

Delhi, National Capital Region (NCR) of India, falls in the seismic Zone IV (Zone factor 0.24) on the seismic zoning map prepared by the Bureau of Indian Standards (BIS), and this region may experience devastating intensities in case of plausible moderate to the major earthquake in the vicinity. The strategic geological, geomorphological, and geographic characteristics make this seat of administrative power more vulnerable toward the earthquake disaster right from the ancient periods. Therefore, we study the impact of the M 6.0 earthquake sourced at Sohna fault in the neighborhood of the capital region by generating synthetic accelerograms through semiempirical envelop technique. The observed accelerograms of November 25, 2007 ( M w 4.7) earthquake have been modeled to utilize the reliability of the semiempirical approach. To analyze the actual scenario, the ground motions at the surface have been generated after the incorporation of the site effects because different soil conditions of NCR fascinate different degrees of damage in case of a destructive earthquake. As a result, the obtained peak ground acceleration (PGA) varies between 100 and 600 cm/s2, and some of the sites exhibit even higher PGA values being situated on the sediments of river-oriented plain areas and proximity of the source. The spatial distribution of estimated values of PGA and spectral accelerations at different periods show that sites in NCR like Delhi (600 cm/s2), Sonipat (633 cm/s2), Gurgaon (461 cm/s2), and Faridabad (300 cm/s2) exhibit high to severe seismic hazard in case of M 6.0 at Sohna fault and it is suggested that a population of about 4.78 million along with the infrastructure of this region is exposed to high risk. The estimated seismic exposure of the population is important to utilize the resources properly before the destructive earthquake incidence. The hazard maps for PGA and different structural periods in the NCR region reveal the level of seismic hazard and risk of the study region. These hazard maps are very helpful for administrators, stakeholders, and civil engineers to construct earthquake-resistant structures to minimize the risk generated by the future impending earthquakes. The exponential growth of the buildings, industries, businesses, etc., attracts the attention of urban area planners because of high seismic risk due to the damaging earthquakes, and its severity must be understood to save the life and property to mitigate the natural disaster like an earthquake by proper disaster mitigation plans, especially in the metropolitan cities like Delhi NCR. [ABSTRACT FROM AUTHOR]

The 2011 Great East Japan earthquake and tsunami remind us once again that these types of cascade event can occur and cause considerable damage. The scientific community realizes the need for rapid theoretical and practical progress on cascade events to provide field teams with the necessary tools and information for action during these types of events. The earthquake damage scenario for Martinique and Guadeloupe islands (French West Indies) has already been performed within the framework of French governmental projects, but these areas, in the vicinity of the French West Indies subduction zone, are also subject to tsunami events. In this study, we propose to perform a combined scenario in which an earthquake is followed by a tsunami, as it could arrive one day, considering the seismic characteristics and potential of such a subduction zone. The vulnerability of the buildings is defined considering local specific information based on several years of field inventories and inspections and is later classified into one of the 36 model building types of HAZUS. The calculation of the damages due to tsunamis follows the HAZUS methodologies. The main novelty of our study is the calculation of damage due to the two phenomena occurring one after the other, not in parallel, as is calculated in the existing literature. Therefore, for the calculation of the damages due to the second event (i.e. the tsunami), the vulnerability characteristics of the initial structure are reduced, considering the damage state of the construction after the first event (i.e. the earthquake). Hence, in our case, this calculation approach allows us to update the number of exposed elements and their changed vulnerabilities considering the damages due to the earthquake, since certain structures are already damaged by the earthquake before the arrival of the tsunami wave. The results coming from our study and our manner of treating the cascading hazards are putting into perspective with the Hazus method for combining damages coming from earthquake and the damages coming from consequently tsunami. The results expressed as the sum of the damages in both most damaged states, Extensive and Complete, are more or less in the same range of values for both studies (our study and HAZUS 2017). However, a trend of having more percentage of complete damages (and hence, less the Extensive damages) with our method than the ones obtained with the Hazus combination can be important information for crisis managing. This is a first result for the French West Indies territory, but anyway, more studies should be carried out in order to check this trend and eventually to confirm and validate this issue for others territories with others bathymetries, vulnerabilities and seismological features. [ABSTRACT FROM AUTHOR]

Seismic damage estimation is an important key ingredient of seismic loss modeling, risk mitigation and disaster management. It is a problem involving inherent uncertainties and complexities. Thus, it is important to employ robust approaches which will handle the problem accurately. In this study, classification and regression tree approach is applied on damage data sets collected from reinforced concrete frame buildings after major previous earthquakes in Turkey. Four damage states ranging from None to Severe are used, while five structural parameters are employed as damage identifiers. For validation, results of classification analyses are compared against observed damage states. Results in terms of well-known classification performance measures indicate that when the size of the database is larger, the correct classification rates are higher. Performance measures computed for Test data set indicate similar success to that of Train data set. The approach is found to be effective in classifying randomly selected damage data. [ABSTRACT FROM AUTHOR]

High-quality waveforms of the vertical and horizontal components of 1356 seismic events recorded from 2013 to 2016 by the Dominican Republic's seismic network, were analyzed to study the local spatial distribution of the coda frequency-dependent attenuation Qc(f)−1. Qc(f) was estimated at central frequencies of 1.5 (± 0.5), 3.0 (± 1.0), 6.0 (± 2.0), and 12.0 (± 4.0) Hz and interpreted by considering the single backscattering model. Our results of the attenuation of coda waves may explain why some regions of the Dominican Republic (DR) are more prone to suffer damage due to earthquakes than other areas. The majority of the cities and towns in the DR that were severely damaged by earthquakes in the past are located in zones of low and very low coda wave attenuation. In contrast, cities located in zones of high Qc(f)−1 tend to suffer less damage. Our findings identify regions with low seismic attenuation that reflect zones with soft soils that could be impacted by future large events in the DR. These results can be used as a tool for planning seismic hazard mitigation and emergency response as well as for land use regulations. [ABSTRACT FROM AUTHOR]

In this study, Dempster–Shafer theory (DST) is integrated into a geographic information system to model vulnerability of the land surface to earthquake events in northwestern Kermanshah Province, Iran, to predict where damage is most likely to occur. DST has never been used to spatially model earthquake vulnerability. To achieve this, data layers for several environmental attributes—aspect, elevation, lithology, slope angle, land use, distance from river courses, distance from roads, and distance from faults—were compiled in ArcGIS 10.2.2 software. Using membership functions, fuzzy maps were generated for each parameter. These fuzzy maps provided input data for the DST model. The predicted values were analyzed and compared at three confidence levels to determine the effectiveness of the model. The results are that 11.14%, 14.14%, and 17.18% (95%, 99%, and 99.5% confidence levels, respectively) of the study area are predicted to be susceptible to earthquakes based on receiver operating characteristic curves. The results also show that, according to the area under the curve (AUC) values (0.967, 0.828, and 0.849 for 95%, 99%, and 99.5% confidence levels, respectively), DST model generates earthquake zoning maps with high accuracy. Therefore, this model can be used for generating earthquake zoning maps with confidence levels that best suit the economic conditions and significance of the region. [ABSTRACT FROM AUTHOR]

Urban gas pipelines network as one of the most vital lifelines plays an important role in the level of vulnerability and earthquake damage. Iran is located on the Alpide earthquake belt, which is one of the highly earthquake-prone zones of the world. The first earthquake effect, which can damage pipelines, is the transient ground deformation caused by wave propagation. The second one is the permanent ground deformation, which refers to liquefaction, landslide, and ground failure. With the failure of the gas pipelines, a fire may also occur, and consequently, the indirect damage caused by the earthquake may even further increase. This paper investigates the seismic risk of the Asaluyeh city urban gas distribution network by regarding the all geo-seismic hazard using HAZUS methodology. The post-earthquake ignition is evaluated using fault tree method, and the consequences of the design earthquake are assessed using PHAST package. Finally, the network physical damage risk, human risk, and direct economic risk are all evaluated. The results show that three possible failures may happen in the Asaluyeh gas distribution network. While the probability of an ignition occurrence is 35% for leakage and 32% for breaking, the post-earthquake ignition can affect around 30 people. [ABSTRACT FROM AUTHOR]

Karachi is Pakistan's largest city with population exceeding 18 million and is amongst the top five most congested cities in the world. Karachi has experienced no earthquake related damage in the recorded history of past ~ 175 years. Yet, Karachi is located in a seismically active tectonic setting often compared to Los Angeles with active plate boundary faults and triple junctions within a radius of ~ 150 km. This discrepancy in earthquake history and seismotectonic setting has led to diverse seismic hazard assessments for Karachi ranging from assignment of seismic hazard zones I (least severe) to IV (most severe). Recent assessment adopted in Building Code of Pakistan (2007) assigns an intermediate seismic hazard value of 0.16–0.24 g (Zone IIB) to Karachi, which is broadly accepted but sometimes criticized to be an underestimation (e.g. Bilham et al. Seismol Res Lett 78(6):601–631, 2007). The present study based on a new active faults compilation and seismic sources definition together with incorporation of maximum possible information on historical earthquakes (up to 893AD) has led to a re-assessment of seismic hazard for Karachi using probabilistic and deterministic seismic hazard assessment approaches. According to this study, Karachi is assessed to be prone to ground motions ~ 0.25 g with metropolitan areas having hazard values between 0.21 and 0.25 g for 10% probability of exceedance in 50 years (475-year return period). The deterministic seismic hazard analysis suggest maximum that peak ground acceleration (PGA) varies from 0.19 to 0.99 g in Karachi and its higher values are concentrated around the Nagar Parker fault that is controlling and hazardous for Karachi. [ABSTRACT FROM AUTHOR]

Destructive megathrust earthquakes, such as the 2015 Mw 8.3 Illapel event, frequently affect Chile. In this study, we assess the damage of the 2015 Illapel Earthquake in the Coquimbo Region (North-Central Chile) using the MSK-64 macroseismic intensity scale, adapted to Chilean civil structures. We complement these observations with the analysis of strong motion records and geophysical data of 29 seismic stations, including average shear wave velocities in the upper 30 m, Vs30, and horizontal-to-vertical spectral ratios. The calculated MSK intensities indicate that the damage was lower than expected for such megathrust earthquake, which can be attributable to the high Vs30 and the low predominant vibration periods of the sites. Nevertheless, few sites have shown systematic high intensities during comparable earthquakes most likely due to local site effects. The intensities of the 2015 Illapel earthquake are lower than the reported for the 1997 Mw 7.1 Punitaqui intraplate intermediate-depth earthquake, despite the larger magnitude of the recent event. [ABSTRACT FROM AUTHOR]

On the basis of data obtained from China Earthquake Administration and China National Statistics Bureau, this paper focuses on the earthquake disaster loss characteristics in 31 provinces or municipalities of China from 1993 to 2016. The trends of direct economic losses, casualties and affected population are also analyzed by constructing two relative earthquake loss indexes (losses/GDP and losses/E) and employing gray correlation theory. Results show that during the 24 years, without taking Wenchuan Ms8.0 earthquake into account, the direct economic losses exhibit a significant increasing trend while losses/GDP also increases but is not significant. Meanwhile, the injuries and affected population both witness a decline trend but the fatalities show the opposite. According to the correlational degree of each year, 8 years (1995, 1996, 1998, 2003, 2008, 2010, 2013 and 2014) suffered losses of equal or above moderate grade. Regionally, the western China suffered the most accumulative direct economic losses and losses/GDP. However, the ranking results of losses/E demonstrate that the central China is the most vulnerable when confronting with the same earthquake. Specifically, Sichuan and Yunnan suffered losses of extra-large grade, Qinghai of large grade and Tibet, Xinjiang and Guangdong of moderate grade. These discoveries are helpful for earthquake mitigation and preparedness as well as earthquake loss evaluation in China. [ABSTRACT FROM AUTHOR]

The Indo-Gangetic Plains which lies between the Himalayan mountain ranges and peninsular India is considered to be the region of great concern due to its thick sediments and proximity to the seismically most active zone of India, the Himalayan collision zone. No earthquake loss estimation studies have been taken up previously in central Indo-Gangetic Plains (CIGP) so far. The goal of this paper is to compute the social and economic loss in CIGP region which will raise the awareness of the general public, policymakers and structural engineers about seismic risk in CIGP so that necessary mitigation measures will be taken up in advance. Further, the relative contribution of six input parameters to the overall uncertainty is ascertained from sensitivity analysis. Earthquake loss estimation reveals that Allahabad district, even though demarcated as zone II in IS 1893:2002, has expected economic losses around 9-13 billion dollars and the highest number of homeless and uninhabitable dwellings. Also, model building class (MBC) MMB (mud mortar bricks with temporary roof), comprising of 16.48% of total households in CIGP region, has high collapse rate when compared to other MBCs, due to the fact that those buildings have temporary roof made of wood, bamboo, polythene, plastic, thatch, mud and others. Further, for a scenario magnitude range of Mw 7.5-8.5, the expected human casualties vary between 0.14 and 1.7 lakhs, and the economic losses vary from 18 to 140 billion dollars, respectively. These results may not be unrealistic, as the region happens to be in the seismic bypass of 1905 Kangra and 1934 Bihar-Nepal earthquakes, with an anticipated catastrophic earthquake of Mw > 8.0. The poor quality and low seismic resilience of buildings in CIGP region are the principal reasons for the corresponding huge casualties and economic losses. Finally, from the sensitivity analysis, we found that the most sensitive parameter is magnitude followed by GMPE and source location, respectively. [ABSTRACT FROM AUTHOR]

This article presents a sensitivity analysis investigating the impact of using high-resolution site conditions databases in portfolio earthquake loss estimation. This article also estimates the effects of variability in the site condition databases on probabilistic earthquake loss ratios and their geographical pattern with respect to structural characteristics of different building types. To perform the earthquake loss estimation here, the OpenQuake software developed by Global Earthquake Model is implemented in Clemson University’s supercomputer. The probabilistic event-based risk analysis is employed considering several notional portfolios of different building types in the San Francisco area as the inventory exposure. This analysis produces the stochastic event sets worth for 10,000 years including almost 8000 synthetically simulated earthquakes. Then, the ground motion prediction equations are used to calculate the ground motion per event and incorporate the effect of five site conditions, on amplifying or de-amplifying the ground motions on notional building exposure locations. Notional buildings are used to account for various building characteristics in conformance with the building taxonomy represented in HAZUS software. The HAZUS damage functions are applied to model the vulnerability of various structural types of buildings. Finally, the 50-year average mean loss and probabilistic loss for multiple values for probability of exceedance (2, 10, 20, and 40%) in 50 years are calculated, and the impact of different site condition databases on portfolio loss ratios is investigated for different structural types and heights of buildings. The results show the aggregated and geographical variation of loss and loss ratio throughout the region for various site conditions. Comparing the aggregated loss and loss ratio, while considering different databases, represents normalized differences that are limited to 6% for all building taxonomy with various heights and for all PoEs. However, site-specific loss ratio errors are significantly greater and in some cases are more than 20%. [ABSTRACT FROM AUTHOR]

The transformation of Rome during the Late Antiquity and the Early Middle Ages has been investigated by archaeologists and historians. Social and political changes are the main aspects which led to a progressive modification of the urban framework; abandonment, spoliation and transformation of buildings are quite diffused as documented by the archaeological literature. The consequence of these practices is a higher vulnerability of the buildings which, from the seismological point of view, played a main role in increasing the effects of seismic shaking. A number of earthquakes have struck Rome during the period of investigation (fifth to ninth century A.D.), known from historical sources: 443, 484-508, 618, 801, 847; in some cases (443, 484-508, 801) damage has been documented. In contrast, the archaeological sources characterise collapse layers and evidence of destruction at different sites with changing and not always conclusive chronological constraints. Consequently, collapse and destruction have been alternatively attributed to the above-mentioned earthquakes. Through a geoarchaeological and stratigraphic analysis of potentially coseismic collapse units, we want (1) to describe the archaeoseismic evidence derived from recent excavations and from the available literature (e.g. Piazza Madonna di Loreto, Piazza Venezia, Palazzo Valentini Crypta Balbi, Colosseo, Basilica Hilariana, Basilica di Santa Petronilla, Santa Maria Antiqua,…); (2) to discuss the chronological problems and the uncertainty of attribution of the collapse units to known historical earthquakes; (3) to discuss the earthquake damage exaggeration due to erroneous attribution of seismic origin to the evidence of destruction derived from archaeological data. Finally, we will infer the role that earthquakes may have had on the development of the urban landscape in the fifth to ninth century A.D. [ABSTRACT FROM AUTHOR]

Tsunami hazard in coastal areas susceptible to flooding, although reduced (in terms of probability of occurrence), may pose a high risk. Therefore, in these areas, a detailed evacuation planning of the affected population is required as a risk mitigation measure. The knowledge and enforcement of evacuation routes may reduce the population vulnerability, making it more resilient and reducing risk. This paper presents a GIS approach for modelling evacuation routes based on the optimal path search problem, of the graph theory, which is implemented on ArcCasper tool. The methodology proposed considers the elements involved in the evacuation process, the worst credible tsunami inundation scenario (hazard extent and travel time), the number of people that needs to be evacuated in different time scenarios, the safe areas or destination points of the evacuation routes, the roads network characteristics and finally the time available to evacuate. The knowledge of those elements allows predicting some possible outcomes of the evacuation, such as the arrival time of the evacuees to a shelter and the identification of congestion hot spots resulting from the application of a flocking model which simulates the path to be used by evacuees avoiding obstacles. The municipality of Cascais was used to test the methodology proposed in this study. Cascais is one of the largest urban centres located about 25 km west of Lisbon, Portugal, with a high density of infrastructure along the coastline whereby most of the population and economic activities are exposed to a tsunami. The results, presented in the form of maps, allow identifying the optimal evacuation routes as well as the unfeasible routes. This crucial information could be used to the evacuation optimization regarding the location of meeting points and vertical shelters as well as to improve the accessibility of the areas to be evacuated. [ABSTRACT FROM AUTHOR]

The January 25, 2016, Mw 6.3 Alborán Sea earthquake shook the autonomous city of Melilla (Spain) with a macro-seismic intensity of VI (EMS-98). In spite of this low intensity, significant non-structural damages were reported, whose cost was estimated in more than 13 million euros. The damages were concentrated in the modernist district, which is considered the most important and valuable part of the city. This scenario is not new in Melilla, since historical and instrumental seismicity studies based on intensities felt in Melilla have revealed that earthquakes with intensities of V-VI have a return period of approximately 25 years. However, seismic microzonation studies have not been carried out so far. In this paper, we present a seismic microzonation study based on seismic noise measurements and the foreshock, mainshock and aftershock records of the January 25, 2016, earthquake. The seismic signals were processed using the horizontal-to-vertical spectral ratio (HVSR) technique. The frequency amplification results were correlated with geological formations, and after that they were correlated with the distribution of damages. The lagoon and the recent alluvial deposits show the maximum number of damaged buildings and maximum frequency amplifications of 2-8 between 2 and 7 Hz. In the coastal deposits, some amplification in the same frequency range has been observed, but other formations show a minimum number of damaged buildings and a flat spectral response ratio. Two important factors in this damage pattern are the high vulnerability of ornamental facades characteristics (non-structural elements) of the modern architecture buildings and their location on the lagoon and the recent alluvial deposits where maximum site amplification is reached. [ABSTRACT FROM AUTHOR]

Given the recent historical disastrous tsunamis and the knowledge that the Arabian Gulf (AG) is tectonically active, this study aimed to evaluate tsunami hazards in Kuwait from both submarine earthquakes and subaerial landslides. Despite the low or unknown tsunami risks that impose potential threats to the coastal area’s infrastructures and population of Kuwait, such an investigation is important to sustain the economy and safety of life. This study focused on tsunamis generated by submarine earthquakes with earthquake magnitudes (Mw) of 8.3-9.0 along the Makran Subduction Zone (MSZ) and subaerial landslides with volumes of 0.75-2.0 km3 from six sources along the Iranian coast inside the AG and one source at the Gulf entrance in Oman. The level of tsunami hazards associated with these tsunamigenic sources was evaluated using numerical modeling. Tsunami model was applied to conduct a numerical tsunami simulation and predict tsunami propagation. For landslide sources, a two-layer model was proposed to solve nonlinear longwave equations within two interfacing layers with appropriate kinematic and dynamic boundary conditions. Threat level maps along the coasts of the AG and Kuwait were developed to illustrate the impacts of potential tsunamis triggered by submarine earthquakes of different scales and subaerial landslides at different sources. GEBCO 30 arc-second grid data and others were used as bathymetry and topography data for numerical modeling. Earthquakes of Mw 8.3 and Mw 8.6 along the MSZ had low and considerable impacts, respectively, at the Gulf entrance, but negligible impacts on Kuwait. An earthquake of Mw 9.0 had a remarkable impact for the entire Gulf region and generated a maximum tsunami amplitude of up to 0.5 m along the Kuwaiti coastline 12 h after the earthquake. In the case of landslides inside the AG, the majority impact occurred locally near the sources. The landslide source opposite to Kuwait Bay generated the maximum tsunami amplitudes reaching 0.3 m inside Kuwait Bay and 1.8 m along the southern coasts of Kuwait. [ABSTRACT FROM AUTHOR]

Among the activities developed under the framework of the Global Earthquake Model, the development of a global consequences database was included. This was defined with the objective of serving as public repository of damages and losses, occurred on different types of elements because of a selected list of earthquakes with epicentres at varying locations around the globe, but also to be used as a benchmark for the development of vulnerability models that capture specific characteristics of the building typologies in each country. The online earthquakes consequences’ database has information on 71 events where 16 of them occurred in the Latin America and the Caribbean Region. A complete and comprehensive review and data gathering process were developed for these selected earthquakes accounting for different aspects and dimensions that were considered of interest, besides the physical damage, such as casualties, socio-economic implications, damages and disruptions in critical facilities and infrastructures, together with the occurrence of secondary events triggered by the ground shaking such as landslides and tsunamis. When possible, the damage and casualties were geo-located using a standardized approach and included in the database. The contributions of the Latin America and Caribbean Region to the database were at the same time a challenge and an opportunity to collect, review, put together and standardize, up to a certain point, damage data of previous earthquakes additionally of being a step forward in the field of open data. [ABSTRACT FROM AUTHOR]

Through this paper we propose and test a GIS framework that addresses the issue of seismic risk due to urban road network failure. The approach relies on full GIS integration, on Monte Carlo simulations for generating potentially disrupted network configurations, considering also the damage probability due to direct earthquake implications, and on traffic considerations (both in typical and post-earthquake situations). The damage probability can be obtained using fragility functions for critical structures like bridges and tunnels or by determining empirically the possibility of affected buildings to generate debris leading to road obstruction. Multiple performance indicators such as travel time and distance under various conditions are combined, in order to quantify the risks inflicted by dysfunctionalities in the emergency intervention process. The framework considers at the same time temporal and spatial dimensions, being able to cope with traffic dynamics or reconfigurable network configurations. The ArcGIS Network Analyst Module is used for model integration, and full city scale analysis is performed in order to test the capabilities. Bucharest (capital of Romania) is selected for the case study; this 2 million inhabitant city is one of the most endangered in Europe, due to earthquakes that occur in the Vrancea Area, at intermediate depth, with moment magnitudes > 7, but also due to the vulnerable building stock. Beside this, it is one of Europe’s top cities when it comes to traffic congestion. The results of the study provide initial insights on the deficiencies of the city’s road network and connectivity limitations, showing the high impact of road obstructions and traffic congestion on intervention times, for ambulances and firefighters, in case of an earthquake. [ABSTRACT FROM AUTHOR]

Participation of local people during any disaster is enormous. They possess better knowledge and information about their own community than anyone else from the outside. This study proposes Participatory Vulnerability Reduction (PVR), a community-based approach for disaster management. The concept of PVR was applied to an urban community of Dhaka city (Ward no. 06 of Dhaka North City Corporation) which has been identified by the Comprehensive Disaster Management Programme as one of the most vulnerable areas of the city for earthquake. PVR consists three steps, and in each step, different participatory urban appraisal tools were used. In the first step, the community people assessed the earthquake vulnerability. It was found that some certain parts of the study area are highly vulnerable due to lack of accessibility to the critical facilities, inadequacy of open space, poor construction practice and unsuitable soil condition for building construction. This was followed by analyzing the root causes and effects of these problems. Structural fragility of the buildings, construction of settlements by filling the low-lying areas and development of slums beside taller buildings are the three major causes behind the above vulnerable issues. In the second step, capacity of the community was assessed in terms of resources and their organizational structure. In the final step, local people developed the strategies to overcome the vulnerability and a community-based organizational set up was proposed to coordinate the collective actions. Although developed in local context, application of PVR is not limited for earthquake and it can be replicated for other communities as well. [ABSTRACT FROM AUTHOR]

We apply the general concept of seismic risk analysis based on morphostructural analysis of the territory, pattern recognition of earthquake-prone nodes, and the Unified Scaling Law for Earthquakes, USLE, in another seismic region of Russia to the west from Lake Baikal, i.e., Altai-Sayan Region. The USLE generalizes the empirical Gutenberg-Richter relationship making use of apparently fractal distribution of earthquake sources of different size: log10NM,L=A+B·5-M+C·log10L, where N (M, L) is the expected annual number of earthquakes of a certain magnitude M within an seismically prone area of linear dimension L. The local estimates of A, B, and C allow determination of the expected maximum credible magnitude in a given time interval and the associated spread around ground shaking parameters (e.g., peak ground acceleration, PGA, or macroseismic intensity, I0). Compilation of the corresponding seismic hazard map of Altai-Sayan Region and its rigorous testing against the available seismic evidences in the past is used to model regional maps of specific earthquake risks for population, cities, and infrastructures. [ABSTRACT FROM AUTHOR]

Earthquake risk can be quantified in terms of the estimated numbers of human casualties and of damaged buildings as well as the monetary losses. The information required for the assessment of earthquake risk in a given region includes the expected level of ground shaking intensity (i.e., the seismic hazard), inventory data for building stock at risk, identification of predominant building typologies and of their vulnerability characteristics, and spatial distribution of number of inhabitants. This study presents an indicative assessment of earthquake risk associated with the building stock in Muscat, the capital city of the Sultanate of Oman. For this purpose, building inventory and demographic data for the city are compiled in GIS environment. The buildings are classified to identify their damageability/vulnerability characteristics, and predominant building typologies are determined. For the estimation of casualties, Muscat population data are further analyzed to calculate number of occupants in the exposed building stock. Spectral acceleration-displacement based damage estimation methodology is implemented for risk calculations. Site-specific ground motions in terms spectral accelerations obtained from the probabilistic seismic hazard assessment for 475- and 2475-year return periods are considered for the representation of earthquake demand in damage analyses. Assessment of damage to buildings and estimation of casualties are obtained using analytical fragility relationships and building damage related casualty-vulnerability models, respectively. Earthquake risk maps illustrating the spatial distribution of number of damaged buildings at different damage states are presented for the considered levels of seismic hazard. [ABSTRACT FROM AUTHOR]

Worldwide, earthquakes and related disasters have persistently had severe negative impacts on human livelihoods and have caused widespread socioeconomic and environmental damage. The severity of these disasters has prompted recognition of the need for comprehensive and effective disaster and emergency management (DEM) efforts, which are required to plan, respond to and develop risk mitigation strategies. In this regard, recently developed methods, known as multi-criteria decision analysis (MCDA), have been widely used in DEM domains by emergency managers to greatly improve the quality of the decision-making process, making it more participatory, explicit, rational and efficient. In this study, MCDA techniques of the Analytical Hierarchical Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), integrated with GIS, were used to produce earthquake hazard and risk maps for earthquake disaster monitoring and analysis for a case study region of Küçükçekmece in Istanbul, Turkey. The five main criteria that have the strongest influence on the impact of earthquakes on the study region were determined: topography, distance to epicentre, soil classification, liquefaction and fault/focal mechanism. AHP was used to determine the weights of these parameters, which were also used as input into the TOPSIS method and GIS (ESRI ArcGIS) for simulating these outputs to produce earthquake hazard maps. The resulting earthquake hazard maps created by both the AHP and TOPSIS models were compared, showing high correlation and compatibility. To estimate the elements at risk, population and building data were used with the AHP and TOPSIS hazard maps for potential loss assessment; thus, we demonstrated the potential of integrating GIS with AHP and TOPSIS in generating hazard maps for effective earthquake disaster and risk management. [ABSTRACT FROM AUTHOR]