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In this paper a novel passive device defined as the tuned mass damper inerter (TMDI) is studied to control the response of a base-isolated nuclear power plant containment (BI-NPPC) structures under stochastic horizontal ground motions. A new method of connecting TMDI to the isolation foundation is proposed. Recently, the TMDI has been introduced as a generalization of the classical TMD to achieve enhanced performance. Consider the case of a base-isolated structure equipped with a TMDI device, which is served as a base-isolated nuclear power plant containment. A particular arrangement of mechanical gearings (inerter) attached to TMD is set, optimum parameters of this system are found based on a simplified two degree of freedom model that reflects the dynamic properties of both the isolation structure and the TMDI. A straightforward numerical approach is developed for the optimal design of this device considering a white noise ground excitation, and a simplified analytical solution for the optimal design of TMDI parameters are introduced and compared with the numerical results in terms of the optimum frequency ratio, the optimum damping ratio and enhanced performance. Within a probabilistic framework, the influence of soil conditions is investigated by modeling the seismic ground motion as a filtered Gaussian random process. Different filter parameters are considered that may be associated with firm, medium or soil conditions depending on the frequency content of the power spectral density function. Several natural recorded accelerograms are also selected to scrutinize the effectiveness of the TMDI isolated-base structure via time-domain analyses. Properties of the BIS are considered in respect of its damping and stiffness. It can be concluded that higher control performances are achieved when lower values of base isolation sub-system damping ratio are used, however, the control performances of the TMDI are basically not affected by small variation of the natural frequency of the isolated-base structure. [ABSTRACT FROM AUTHOR]

Models belonging to the ionosphere that is directly affected by factors such as solar activity, geomagnetic storm, earthquake, seasonal changes, and geographical location need to be considered altogether. In this sense, the cause of the ionospheric anomalies should be meticulously distinguished from each other. Ionospheric anomalies that occur before or (and) after an earthquake have a serious place in earthquake prediction studies. Total electron content (TEC) is one of the significant parameters to be able to discuss the anomalies of the ionosphere. This essay investigates ionospheric anomalies before and after the Mw 6.5 Samar, Philippines (12.025° N, 125.416° E and November 18, 2003, at 17:14 UT) earthquake. The paper analyzes anomalies with the aid of the TEC (TECU) map. In the paper, the time-domain TEC variables are transferred to the frequency-domain for observing some clues-peaks by short-term Fourier transformation spectral analysis. The discussion handles the effect of the solar activity with the F10.7 (sfu) index and the effect of geomagnetic storms with Bz (nT), v (km/s), P (nPa), E (mV/m), Kp (nT), and Dst (nT) parameters (index). The lower and upper boundaries of the TEC map obtained from the International Reference Ionosphere (IRI-2016) are calculated with the help of median and standard deviation. The boundary-setting process is named statistical analysis. TEC data exceeding the boundaries are marked as anomaly data. According to the paper, 11-day anomalies (9-day of which belong to pre-earthquake) are detected. Probably, the anomalies observed on November 6, 7, and 12 belong to the Samar earthquake. [ABSTRACT FROM AUTHOR]

Phenomenology is the unity of principles and methods employed for investigating the essence of things. The present paper is a brief review of the series of publications that these authors carried out over the past decade. The general thrust of these publications consists in the idea that phenomenological ideas of physics are used to analyze earthquakes. One conspicuous example of a phenomenological theory is thermodynamics. Maxwell's electrodynamics is also a perfect example of a phenomenological theory. The phenomenology of earthquakes is still far from reaching that high level of excellence. A look at the rational knowledge of geodynamics shows that we have so far reached a preliminary stage where we are aware of the subject-matter, methods, and problems faced by the future phenomenological theory of earthquakes. Nevertheless, we already clearly see that our approach to the construction of such a theory has promise. We are using concrete examples to show that phenomenological concepts of general physics are helpful in the search for the principles of the theory, in the processing and analysis of concrete manifestations of seismicity. [ABSTRACT FROM AUTHOR]

On February 6, 2023, an Mw7.8 earthquake hit the south of Kahramanmaras prefecture, Turkey, followed by another Mw7.5 earthquake after nine hours in the middle region of the Kahramanmaras prefecture. More than 84,000 buildings collapsed or were severely damaged, and more than 50,000 lives were lost in Turkey and Syria. Some of the authors, as members of Chinese rescue team, entered Antakya, Hatay prefecture, and investigated the damaged buildings. This paper first summarizes the damage patterns of buildings and provides three reasons for the massive number of collapsed buildings; i.e., the lack of seismic measures for better ductility, site effects such as liquefaction and surface rupture, and pronounced low-frequency components of the ground motions. Next, the seismic responses of two typical buildings are calculated based on the geometric data estimated by visual inspection. The results imply that the resonance of the whole structure and the poorer ductility of key members resulted in the collapse of buildings. Finally, some conclusions are drawn. Note that although a large number of buildings were seriously damaged to collapse, the majority of buildings in the areas of extreme shaking were lightly or moderately damaged, which implies that well designed and constructed buildings were able to survive and protect human lives even in over-design earthquakes. [ABSTRACT FROM AUTHOR]

Load reduction methods (LRMs) for the deeply buried structure such as a high-filled cut-and-cover tunnels (HFCCTs) under seismic loads are complex when compared with cases under static loads. The soil arching effect (SAE) for load reduction mechanisms is ambiguous. Unfortunately, very limited related research focused on these LRMs subjected to earthquake loads. This paper mainly focused on investigating the SAE induced by different LRMs under dynamic loads. Parametric studies were conducted using FLAC3D to assess the effectiveness of these LRM based on the variations of the SAE in soils under three different seismic waves. Several proven effective LRMs such as the inclusion of expanded polystyrene (EPS) and combined with concrete wedges were analyzed. Considering the variations of vertical soil pressure (VSP) and lateral soil pressure (LSP), the results show that the SAE is significantly related to the height and thickness of the soil arching zone (SAZ) that develops, which in turn affects the soils pressure distribution (SPD) around the CCT's structures. In addition, the use of EPS above and on both sides of a CCT to reduce both VSP and LSP simultaneously was found to resist seismic loads more effectively. [ABSTRACT FROM AUTHOR]

The paper presents the studies of the Khuvsgul earthquake on January 11, 2021 at 21:32 UTC (January 12, 2021 at 05:32 local time), MW = 6.7, ML = 6.9, and the seismicity structure in the aftershock period for the Altai-Sayan mountain region and the Baikal rift zone, where the epicenter of this earthquake was located. Two faults are seismically activated, diverging from the southern end of the aftershock area at an acute angle: one in the northeast and one in the northwest direction, as well as transverse faults between them. According to the epicenter position and studies of the source area by other authors, the main event corresponds to the northeastern fault, and large aftershocks occurred at the junction of the northwestern fault with transverse faults feathering from the east. The main event was immediately followed by a series of large aftershocks, the strongest of which occurred on March 31, 2021 with ML = 6.2 and on May 3, 2021 with ML = 6.4. Spatial changes in the seismic regime of the aftershock region led to the predominant activity of its southern end. The junction area of the collisional structures of the Altai–Sayan folded zone and the rift structures of the Baikal depressions system is distinguished in seismicity as a block structure with increased seismicity near the block boundaries. First of all, these are the Tuva-Mongolian block and the eastern part of the Sayano-Tuva block. After the Khuvsgul earthquake of 2021, a block structure with the activation of the epicentral zones of the 1991 Busingol earthquake, the 2011–2012 Tuva earthquakes, and other structures seismically active until 2021 has increased seismic activity. It is proved that the 2014 Khuvsgul earthquake occurred under the basin of the same name and is associated with other faults than the 2021 earthquake and is not a direct precursor of the 2021–2022 activation. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of a study showing that anomalies in the seismic regime parameters before earthquakes of various magnitudes occur in stages. The occurrence in stages means the correlation between the times of formation and development of anomalies in various seismic regime parameters. Earthquakes in regions with two general types of tectonics are selected for analysis: in the subduction zone (Kamchatka and Japan) and in the rift zone (Iceland). The selection of regions is primarily based on the availability and quality of regional seismic catalogs. GR b-value and the composite parameter known as the RTL are used as the seismic regime parameters. The detection of spatiotemporal anomalies before the selected earthquakes is based on the known "precursory patterns" of the seismic regime parameters. Comparing the durations of the detected anomalies shows that the anomalies of b-value generally occur earlier than the RTL anomalies. Possible reasons why the anomalies occur in stages are suggested. In the vicinity of the studied earthquakes, a change in the seismogenic rupture concentration parameter within the corresponding seismic cycles is also estimated. Comparing the times at which the detected seismic regime anomalies occur with the values of the seismogenic rupture concentration parameter corresponding to these times shows that the formation of seismic regime anomalies occurs at a stage when the system of seismogenic ruptures accumulated during the seismic cycle has almost reached its critical value. [ABSTRACT FROM AUTHOR]

The paper is devoted to the assessment and forecast of the occurrence of submarine landslides on the shelf of southeastern Vietnam. The prediction is based on the analysis of the existence of slip tendency on known faults, studying the magnitude of possible relative vertical and horizontal displacements in the Earth's crust, considering the slope steepness of bottom relief and surface of landslide deposits, as well as assessing the probability of reactivation of faults and likely earthquake zones. The results of the study allow making decisions on combating submarine landslides, reducing damage to people and property in coastal areas. Based on the information obtained, not only submarine landslides but also other geological hazards in areas of the Vietnamese continental shelf can be predicted. [ABSTRACT FROM AUTHOR]

This paper discusses continuum models for simulating earthquake sequences on faults governed by rate-and-state dependent friction. Through detailed numerical analysis of a conventional strike-slip fault, new observations regarding the use of various continuum earthquake models are presented. We update a recently proposed plasticity-based model using a consistently linearized formulation, show its agreement with discrete fault models for fault thicknesses of hundreds of meters, and demonstrate mesh objectivity for slip-related variables. To obtain a fully regularized fault width description with an internal length scale, we study the performance and mesh convergence of a plasticity-based model complemented by a Kelvin viscosity term and the phase-field approach to cohesive fracture. The Kelvin viscoplasticity-based model can introduce an internal length scale and a mesh-objective response. However, on grid sizes down to meters, this only holds for very high Kelvin viscosities that inhibit seismic slip rates, which renders this approach impractical for simulating earthquake sequences. On the other hand, our phase-field implementation for earthquake sequences provides a numerically robust framework that agrees with a discrete reference solution, is mesh objective, and reaches seismic slip rates. The model, unsurprisingly, requires highly refined grids around the fault zones to reproduce results close to a discrete model. Following this line, the effect of an internal length scale parameter on the phase-field predictions and mesh convergence are discussed. [ABSTRACT FROM AUTHOR]

The estimation of seismic damages and debris at the urban scale—at a building-by-building level- is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to estimate at the same time the quantity of debris generated per building according to its damage level and the distribution of the debris (extent and height) around buildings. Finally, the lack of comprehensive data on the building stock and the relevant building properties and their taxonomy further increases the complexity of assessing possible earthquake consequences at an urban scale. This paper addresses these challenges and proposes improvements to the assessment of seismic damages and debris from building-level simulations, along with the development of a 3D building model based on satellite images and heterogeneous data. These developments, applied to the city of Beirut, Lebanon, highlight the control of the site effects on the seismic damage's spatial distribution throughout the city and the large volume and extent of debris to be expected in the city for a strong earthquake. [ABSTRACT FROM AUTHOR]

On December 29, 2020, nine months after the March Mw 5.4 Zagreb earthquake and amidst the COVID-19 lockdown, a devastating Mw 6.4 earthquake struck near the town of Petrinja, about 50 km SE from the country's capital Zagreb. It was preceded by the Mw 4.9 foreshock from the day before. The main shock claimed 7 fatalities and caused widespread damage. Historical centers of nearby cities with invaluable heritage buildings were significantly affected as were the many residential buildings, built mainly of unreinforced masonry. Damage was observed as far as 60 km from the epicenter. This paper summarizes the seismological aspects of the Mw 6.4 Petrinja earthquake, the emergency response and the main impacts to people and buildings. The description and findings are based on the field observations and a series of post-earthquake activities led by the team of the Faculty of Civil Engineering, University of Zagreb. Typical damage to buildings and usability data are presented with examples based on 50,000 inspection results. By far the most affected were the unreinforced masonry buildings, followed by confined masonry, whereas reinforced concrete buildings were the least affected. The total direct and indirect losses are estimated to 4.8 billion EUR. The provided information represents a useful basis and impetus for improving emergency action and long-term disaster reduction plans in other regions with similar building exposure and seismotectonic settings. [ABSTRACT FROM AUTHOR]

Predicting individual large earthquakes (EQs)' locations, magnitudes, and timing remains unreachable. The author's prior study shows that individual large EQs have unique signatures obtained from multi-layered data transformations. Via spatio-temporal convolutions, decades-long EQ catalog data are transformed into pseudo-physics quantities (e.g., energy, power, vorticity, and Laplacian), which turn into surface-like information via Gauss curvatures. Using these new features, a rule-learning machine learning approach unravels promising prediction rules. This paper suggests further data transformation via Fourier transformation (FT). Results show that FT-based new feature can help sharpen the prediction rules. Feasibility tests of large EQs ( M ≥ 6.5) over the past 40 years in the western U.S. show promise, shedding light on data-driven prediction of individual large EQs. The handshake among ML methods, Fourier, and Gauss may help answer the long-standing enigma of seismogenesis. [ABSTRACT FROM AUTHOR]

Soil plug formation in open-ended piles due to pile driving is a widely studied phenomenon in onshore applications. The narrow diameters of traditional onshore piles ranging from 0.5 to 1.5 m facilitate plug generation during installation and transfer of enhanced confining stresses across the whole body of the soil plug. Offshore wind monopiles with larger diameters and smaller aspect ratios may not enhance confining stress within the soil plug as effectively as their onshore counterparts. Monopiles are currently the most widespread foundation in the offshore wind sector including in seismic areas. Earthquake shaking can lead to accumulation of excess pore pressure and subsequent liquefaction of the soil retained inside the plug. This research investigates the influence of monopile diameter and confining stress on the development of earthquake-induced excess pore pressure within the soil plug using fully coupled time domain Finite Element Analysis. The results presented in this paper reveal lower accumulation of earthquake-induced excess pore pressure in soil plugs subjected to confining stress. However, the influence of additional horizontal stress caused by monopile driving on the generation of excess pore pressure within the soil plug diminishes as the monopile diameter is progressively increased. [ABSTRACT FROM AUTHOR]

This paper addresses how residents can safely access shelters from their buildings. Firstly, we investigated Xiaying Village, a typical community with severe buildings damage at the epicentre of the Ms5.0 magnitude earthquake in Tonghai that occurred on August 13, 2018, and found that the injured residents when escaping resulted from the damage to masonry buildings. Secondly, a probabilistic approach combining response spectrum and allowable maximum acceleration is proposed to estimate the damage risk of masonry buildings with inadequate seismic performance in old communities. Thirdly, three models are proposed to assess the risk of the escape path, which include all scenarios of the escape of residents to shelters. Finally, an accessibility analysis of the paths that residents may choose to escape to the shelter is presented. The results of the community escape case study in the Tonghai earthquake show that the probabilistic approach to estimating the escape risk is feasible, and the number of damaged buildings in the escape path dictates the accessibility of residents to the shelter. The proposed method is important for guiding old community residents to escape when a strong earthquake strikes, and it is an effective way to improve community disaster resilience. [ABSTRACT FROM AUTHOR]

The tectonic setting of Lebanon in the eastern Mediterranean region is a restraining bend along the Dead Sea Transform Fault, which is the plate boundary between Arabia and Africa. Within the Lebanese Restraining Bend, the plate boundary splays into several fault branches that are mapped onshore Lebanon and known to have contributed to the evolution of the Lebanese structural framework. Different models have been proposed about the geological structures offshore Lebanon, and how those structures could relate to the onshore tectonics. Based on 2D seismic reflection data, a previously interpreted thrust fault system offshore Lebanon referred to as "Mount Lebanon thrust" was suggested to be responsible for the 9 July 551 M 7.2 earthquake, which was one of the most destructive in the history of the Levant. This thrust system has been accepted as the main structure behind the offshore seismic activity. The objective of this paper is to use current 3D seismic reflection data in order to interpret the main tectonic structures offshore Lebanon, and to differentiate features formed by tectonic activity from others caused by different mechanisms such as subsurface salt movement. Such information is very useful in understanding the tectonic framework of the region from the earthquake geology perspective. A bathymetric map of the Lebanese offshore area was generated and used to delineate the seafloor features. Major and minor faults were interpreted and used to identify and understand the behavior of potential tsunami-generating structures. After careful investigation of the offshore area using the available 3D seismic data, the authors were not able to confirm the existence of Mount Lebanon thrust. Instead, they propose that the Latakia ridge that lies between Lebanon and Cyprus is a major and prominent structure that can trigger high-magnitude tsunamigenic earthquakes. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the identification of potential seismic damage in an area called Tanah Patah, Bengkulu City, Indonesia. This study is initiated by conducting site investigation and geophysical measurements. Ground motion prediction is conducted to estimate peak ground acceleration which is then used to estimate the damage intensity level during a large earthquake. A spectral matching method to generate ground motion at investigated sites is conducted. Seismic ground response analysis to observe ground response and soil behaviour is performed. The results show that peak ground acceleration in the study area is about 0.255–0.342 g during a large earthquake. IX is this area's Modified Mercalli Intensity (MMI) level scale. Since sandy soils dominate the study area, several sites could be more vulnerable to undergoing liquefaction. The thickness of potentially liquefiable soils is about 8.6–12.8 m. The results could help local governments develop spatial plans in the study area. [ABSTRACT FROM AUTHOR]

This paper provides an overview and introduction to the development of non-ergodic ground-motion models, GMMs. It is intended for a reader who is familiar with the standard approach for developing ergodic GMMs. It starts with a brief summary of the development of ergodic GMMs and then describes different methods that are used in the development of non-ergodic GMMs with an emphasis on Gaussian process (GP) regression, as that is currently the method preferred by most researchers contributing to this special issue. Non-ergodic modeling requires the definition of locations for the source and site characterizing the systematic source and site effects; the non-ergodic domain is divided into cells for describing the systematic path effects. Modeling the cell-specific anelastic attenuation as a GP, and considerations on constraints for extrapolation of the non-ergodic GMMs are also discussed. An updated unifying notation for non-ergodic GMMs is also presented, which has been adopted by the authors of this issue. [ABSTRACT FROM AUTHOR]

Slow-moving landslide-prone areas (SLAs) are unstable objects on the terrestrial surface that can collapse rapidly when provoked by earthquakes, leading to infrastructure damage. It is critical to identify SLAs prior to earthquake events and assess their hazard-causing probabilities when triggered. An assessment approach of earthquake-triggered geohazards is proposed in this paper by combining interferometric synthetic aperture radar (InSAR) derived SLAs and geological and geomorphological factors. Taking the Ms6.8 Luding earthquake, which occurred in the Sichuan Province of southwestern China on September 5, 2022, as an example, 1320 scenes of Sentinel-1 SAR data in western Sichuan were processed using the small baseline subset (SBAS) InSAR technique before the earthquake. After the earthquake, hazard probability assessment was performed in real-time by filtering the SLAs using a spatial analysis technique with geological and geomorphological factors, e.g., real-time peak ground acceleration (PGA), slope, distance to fault (DTF), and distance to the river (DTR) data. The results show that 11 SLAs were classified into high-risk zones. As verified by the Luding co-seismic landslide dataset from visual interpretation of optical remote sensing images, 142 coseismic landslides were triggered by the earthquake in these high-risk regions. In these areas, an ancient landslide, with high pre-earthquake displacement rates (−50 mm/year) on the scarp was reactivated under the Luding earthquake forces. This method can provide a scientific tool for disaster mitigation and rapid response emergency management. [ABSTRACT FROM AUTHOR]

When lakes are dammed by earthquake-induced landslides, they can pose a significant threat to communities and infrastructure both downstream and upstream. To improve means for disaster prevention and mitigation, a field investigation together with the DEM-SPH numerical method was utilized to study a landslide-dammed lake disaster in the Baoxing River after the 2022 Lushan earthquake. The simulation results agreed well with those of the field investigation; the simulated landslide dam and dammed lake were similar to the field observations. The whole process of the formation of the landslide-dammed lake, including the formation of the natural dam, the blocking of the river, and overtopping, was well described. The maximum average velocity and sliding distance of the causative Xinhua landslide were 6.55 m/s and 318 m, respectively. The limit storage capacity of the dammed lake was 513,317 m3; the water level increased under the impoundment, and the maximum river depth was 22.56 m. The fluid pressure increased with river flow direction, and the maximum fluid pressure was 1.81 × 105 Pa. The process of the river blocking disaster was divided into three stages: the impoundment stage, discharge stage, and balanced stage. In the event of a heavy rainfall, the submerged area could increase by 20.8% compared with the current state. The coupled numerical investigation presented in this paper provides new insights into the research and risk assessment of landslide-dammed lakes. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the effect of the preparation of the Chuya earthquake on September 27, 2003, the strongest event in the Altai-Sayan folded region for the entire instrumental period of seismological observations, on meteorological characteristics (temperature, relative humidity, atmospheric chemical potential correction, latent heat of evaporation, and the mean and dispersion values of these data) and their spectral characteristics in the Gorny Altai region. The meteorological and spectral characteristics are shown to change for a certain time before the main shock. The spectral characteristics distinctly change both during the preparation of the main shock and during the aftershock process. [ABSTRACT FROM AUTHOR]

Using the gravity/GNSS data of 318 stations observed in 2020, this paper optimizes the Bouguer and free-air gravity anomalies around the 2021 Yangbi Ms 6.4 Earthquake, inverses the litho-spheric density structure of the focal area, and obtains the distribution of isostatic additional force borne by the lithosphere. The results show that the Bouguer gravity anomaly in western Yunnan varies from -120 to -360 mGal. As a whole the anomalies are large in the north and small in the south, and the value in the source area of the 2021 Yangbi Ms 6.4 Earthquake is about -260 mGal. Significant lateral differences indicates that the crust around the great earthquake does not belong to a solid and stable tectonic unit. The lithosphere in the source area is basically in equilibrium, indicating that the occurrence of the great event is not relative to the lithospheric equilibrium, but to the differential movement of the crust in the horizontal direction. In addition, we obtain the teleseismic SKS phases of 51 stations. As a whole, the polarization direction of fast wave in western Yunnan is approximately vertical to the maximum gradient change direction of regional Bouguer gravity anomaly that reflects the change of Moho. [ABSTRACT FROM AUTHOR]

The seismic response of monopile foundations is a growing area of research as the offshore wind industry expands worldwide, including in earthquake prone regions of the world. This paper presents dynamic centrifuge tests aimed at investigating the dynamic response of monopiles in both dry and saturated sandy soils. The latter case includes soil liquefaction under strong input motions, with measured excess pore pressures indicating liquefaction. The natural frequency of the monopile-soil system is experimentally determined by measuring the response to a sine sweep motion. Strong earthquakes are then applied at this frequency and its harmonics. This paper discusses the response of the monopile in terms of the peak accelerations observed in the dry and saturated tests, as well as using response spectra and amplification ratios. The dynamic bending moments along the pile are also measured to infer the bending moment profile with depth. Finally, two identical monopiles are pushed-over in each of the centrifuge tests to establish the pre and post-earthquake monotonic response, including the lateral stiffness and capacity, which are compared for the dry model tests and the saturated case. [ABSTRACT FROM AUTHOR]

Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage. [ABSTRACT FROM AUTHOR]

The October 30, 2020 Earthquake caused unexpectedly significant damage in İzmir considering its distance to the city. This paper evaluates the recorded ground motions, summarizes the performance of structures affected from the earthquake with emphasis on the reasons of damage. A detailed damage assessment was carried out by the Earthquake Engineering Research Center of Middle East Technical University to compile data on the damage of RC and masonry buildings. It was observed that majority of the damage was concentrated in the Bayraklı district due to its peculiar soil properties where many 7–10 story mid-rise RC buildings suffered heavy damage and collapse. The level of amplified ground motions combined with deficiencies of apparently non-code compliant buildings exacerbated the damage. The main reasons of damage were mainly attributed to the presence of soft stories, lack of proper detailing, poor construction quality, presence of heavy overhangs, and hence significant lack of code-compliance in essence. The influence of infill walls on seismic performance of deficient and inadequate buildings was clearly seen in this earthquake. This paper also discusses seismic code requirements in effect and their influence on the observed building performance. The recorded ground motions were compared with the code spectra to evaluate the performance of the buildings. The code response spectra were found to be well above the recorded ground motion spectra at the sites where significant damage was observed. [ABSTRACT FROM AUTHOR]

Soil liquefaction on 28 September 2018 in Palu, Indonesia, included one of the largest soil movements ever, where objects on the ground surface moved hundreds of meters away and settlements sank into the mud. Some preliminary studies show that in addition to a strong earthquake, there are strong indications that a confined aquifer in the Palu valley worsened the liquefaction. The role of the confined aquifer can be recognized early on from one of various signs, namely the presence of massive surface inundations suspected due to groundwater expulsion which is thought to originate mostly from the confined aquifer. This paper describes the mechanism of the soil liquefaction in Palu from the perspective of earthquake hydrogeology, focusing on the groundwater expelled from an unconfined aquifer and especially from the underlying confined aquifer through hydraulic inter-connection between the two, which is possible due to simultaneous interaction of excess pore pressure dissipation and enhanced permeability driven by an earthquake in the near field. If this hypothesis proves to be strong, there are implications for engineering practices because the evaluation of potential soil liquefaction carried out currently in the geotechnical engineering field generally only involves the role of shallow groundwater and/or the unconfined aquifer and the role of soil layers not deeper than 30 m from the ground surface. It may be necessary to complement current evaluation practice with an evaluation of the deep groundwater response to earthquakes, especially if the deep groundwater is artesian and productive, with a relatively thin confining layer. [ABSTRACT FROM AUTHOR]

This paper documents performance of cast-in-place reinforced concrete (RC) buildings in the Durrës municipality during Albania earthquake of November 26, 2019 (MW 6.4). Both mid- and high-rise RC buildings were affected by the earthquake, experiencing structural and/or non-structural damage and even collapse in some cases. The authors performed a reconnaissance study after the earthquake and were involved in seismic assessment of buildings in the affected area. Besides the observations related to physical damage of RC buildings, the paper also presents results of a statistical analysis of damaged RC buildings in the Durrës municipality. The discussion in the paper is focused on damage patterns and failure mechanisms that are relevant for the seismic response of RC structures. Most common damage pattern observed after the earthquakes was related to masonry infill walls, which experienced damage and failure in some cases, and affected the performance of adjacent RC columns due to the infill/frame interaction. Taller RC framed buildings (10 storeys and higher) were expected to have RC shear walls; however, these walls were reportedly absent in the damaged buildings of this type. In some cases, masonry infill walls (instead of RC shear walls) were used in the elevator shaft areas, which resulted in inadequate seismic performance. A case study has been presented to illustrate seismic behaviour of mid-rise and high-rise cast-in-place RC buildings in the November 2019 earthquake, and is based on post-earthquake field observations and a detailed seismic assessment of two earthquake-damaged buildings. Finally, relevant lessons and recommendations are presented in light of the observed performance of RC buildings. [ABSTRACT FROM AUTHOR]

This paper reports on two sets of centrifuge model tests of wind turbines in dry sand and saturated sand subjected to earthquake sequences. The wind turbine system is composed of a single pile foundation and a wind turbine. All tests were applied with liquefaction experiments and analysis projects (LEAP) waves to simplify the analysis. The objectives of the tests are to investigate: (1) the influence of earthquake history on the seismic response of wind turbines; (2) the influence of earthquake history on the dynamic pile-soil interaction; and (3) the influence of two different foundation types on the seismic response of wind turbines. The tests indicated that earthquake history has a significant influence on the natural frequency of the pile and the soil around the pile in the saturated sand, but has no obvious influence on the dry sand. The shear modulus of the soil and the acceleration amplification factor of the pile top in both tests increased and the maximum bending moment envelope of the single pile foundation shrunk. The stiffness of the p-y curve in saturated sand was increased by the earthquake history, while that in dry sand was not significantly affected. [ABSTRACT FROM AUTHOR]

Earthquake-induced landslides are complex dynamic processes, a better understanding of which can be achieved by studying the entire dynamic process, including the propagation of seismic waves, cracking, instability, movement, and deposition. This paper explores the entire dynamic process in combination with the propagation of seismic waves and crack developing process of the slope under earthquake actions, while taking into account the strength attenuation, the major factor that causes the high-speed and long-runout movement. In this study, a simulation analysis tool called discontinuous deformation analysis (DDA) was used and improved by incorporating a seismic input method based on a viscous boundary and the free-field theory, virtual and real joints, and a shear strength attenuation criterion, to conduct a unified simulation analysis of the whole dynamic process of earthquake-induced landslide, and to analyze the influence of the dynamic response law on the instability and motion of landslide. Based on these improvements, the Donghekou landslide caused by the Wenchuan earthquake in 2008 was simulated. The dynamic characteristics of the slope showed an obvious amplification effect. At places with strong dynamic responses, cracks initiated rapidly. The progressive crack developing process of the landslide was represented. Owing to the low-friction effect, the speed increased sharply after the landslide began, promoting its high speed and long runout. From the crack propagation in the slope and the formation process of the sliding surface, it is evident that the Donghekou landslide was a typical tension-cracking and shearing sliding landslide. Highlights: The entire dynamic process analysis landslide method, from continuous to discontinuous, was established. The influence of the site dynamic response to the formation of a landslide was considered. The instability mechanism of a landslide was analyzed based on the fragmentation process. [ABSTRACT FROM AUTHOR]

This paper discusses and compares two recently developed methodologies for the prediction of damage accumulation in structures subjected to multiple earthquakes within their lifetime, one based on a regression model and one based on a Markov-chain based approach. A stochastic earthquake hazard model is considered for generating sample sequences of ground motion records that are then used to estimate the probabilistic distribution of the damage accumulated during the time interval of interest using the various methodologies. A simulation-based approach provides a reference solution against which the other methodologies are compared. Besides assessing the effectiveness and accuracy of the two methodologies, some improvements of the regression model are proposed and evaluated. The comparison between the methodologies is carried out by examining a reinforced concrete (RC) bridge pier model and using the Park–Ang damage index to describe the damage accumulation. The study results demonstrate the importance of considering the possibility of occurrence of multiple shocks in estimating the life-cycle performance of structures and highlight strengths and drawbacks of the investigated methodologies. [ABSTRACT FROM AUTHOR]

The response of a two-storey RC school building in the town of Argostoli, Cephalonia Island, Greece, during the seismic sequence of January and February 2014, is examined. The structure was built following an older generation of seismic codes dating from the 1950s, which provide limited strength and ductility against lateral loads. Despite the severity of ground shaking and the two successive events, the building suffered relatively minor damage, like most of the RC buildings in the town. Following a short presentation of some basic seismological, structural and geotechnical aspects of the seismic sequence, the paper focuses on the seismic performance of the structure at hand. To this end, a series of detailed non-linear static and time-history dynamic analyses are reported, which highlight the interplay of soil, foundation and superstructure in modifying the seismic demand. It is demonstrated that SSI had an unexpectedly important (detrimental) role in the behaviour of the structure, increasing its natural period by about 25% and aggravating ductility demand in almost all columns, despite the moderately soft soil conditions (average VS = 180 m/s). The results shed light on the seismic performance of the building and help drawing conclusions on the engineering effects of the 2014 Cephalonia earthquake sequence. [ABSTRACT FROM AUTHOR]

Seismic losses due to earthquakes have been shown to have significant economic, social and environmental consequences. Over recent years, research to predict potential economic and social impact due to seismic risk has been increasing. Recognizing that the traditional philosophy of life safety design can lead to extensive damage and demolition which has a large environmental cost, incorporating environmental impacts associated with the expected seismic damage over a building's life is a key step as the building industry moves towards both sustainable and seismically resilient design. This paper introduces a framework that uses environmental indicators quantifying losses from seismic response that can then be used to advocate for a change in seismic performance objectives. First, existing literature and previously developed approaches for quantifying potential environmental impact due to seismic damage are summarized. Next, performance based earthquake engineering concepts are used to demonstrate a probabilistic approach to quantify potential environmental impacts using a range of environmental and resource use indicators over the life span of a case study building. In addition, a case study is presented to compare different environmental indicators between a Code Minimum building and the same building redesigned for a higher seismic performance. The majority of the composition of the environmental indicator values are from the inclusion of the non-repairable scenario, and from the repair activities, the majority of the impacts are from damage to drift sensitive components including curtains walls, partitions and elevators. For the Code Minimum building the non-repairable scenario contributes to between 8 to 11% the total seismic cost. For the Stronger Stiffer building, the non-repairable scenario contributes around 3% of the initial impact. Neglecting non-repairable scenarios does significantly reduce the potential environmental impacts when analyzing buildings designed for current code minimum structural standards. [ABSTRACT FROM AUTHOR]

In this paper, an automatic aftershock forecasting system for China is presented. Based on a parameter-free historical analogy method, this system can produce short-term aftershock forecast, including seismic sequence types and the magnitude of the largest aftershock, within a few minutes after a major earthquake and can further provide scientists and government agencies with a set of background information for consultation purposes. First, the system construction concept and operation framework are described, and an evaluation of the forecast performance of the system is then conducted considering earthquakes from 2019 to 2021 in mainland China. The results indicate that the sequence type classification precision reaches 83.5%, and the magnitude of more than 90% of the aftershocks is smaller than that of upper range forecast. This system is fast and easy to control, and all the reports and maps can be produced approximately 5 min after earthquake occurrence. Practical use verifies that the application of this system has greatly improved the efficiency of post-earthquake consultation in mainland China. [ABSTRACT FROM AUTHOR]

This paper reports results of mathematical modeling applied to the stress and strain in epicentral zones before and after the large earthquakes that occurred on June 22, 2002 in the Qazvin Province, northwestern Iran (Mw = 6.4) and the Gujarat, India earthquake of January 26, 2001 (M = 6.9). The modeling relied on a method for calculating stress and strain in a blocky elastic isotropic heterogeneous medium disturbed by a set of faults that are due to an external tectonic stress field. The boundary conditions were specified based on geological and seismological data. It has been shown that the epicenters of large crustal earthquakes occur in zones of high stress concentration at the ends of tectonic faults. Rupture occurs when the relationship between acting tectonic stresses satisfies the requirement σyy/σxx >3, thus connecting zones of high stress. The evolution of the aftershock process is controlled by the stress drop caused by a new rupture, while the resulting aftershock clusters are in spatial correlation with the stress drop zone. The new rupture propagates in the direction of dominant tectonic fault orientation in the region. We show a relationship to exist between rupture length and the possible retrospectively predicted location and magnitude of the earthquake depending on the elastic energy buildup and its possible release under specified structural tectonic conditions. [ABSTRACT FROM AUTHOR]

One of the primary tasks for effective disaster relief after a catastrophic earthquake is robust communication. In this paper, we propose a simple logistic method based on two-parameter sets of geology and building structure for the failure prediction of the base stations in post-earthquake. Using the post-earthquake base station data in Sichuan, China, the prediction results are 96.7% and 90% for the two-parameter sets and all parameter sets, respectively, and 93.3% for the neural network method sets. The results show that the two-parameter method outweighs the whole parameter set logistic method and the neural network prediction and can effectively improve the accuracy of the prediction. The weight parameters of two-parameter set by the actual field data significantly show that the failure of base stations after earthquake is mainly due to the geological differences where the base stations are located. It can be envisioned that if the geological distribution between the earthquake source and the base station is parameterized, the multi-parameter sets logistic method can not only effectively solve the failure prediction after earthquakes and the evaluation of communication base stations under complex conditions, but also provide site selection evaluation for the construction of civil buildings and power grid towers in earthquake-prone areas. [ABSTRACT FROM AUTHOR]

Abstract—According to the paradox of seismicity, earthquakes that rupture by the mechanism of ordinary brittle failure cannot occur at depths greater than a few dozens of km. Several models have been proposed to explain deeper earthquakes, but these models have not been, however, convincingly supported by the depth variation data of earthquake source parameters. This paper presents the examples of seismicity cutoff at the depth level of the Earth's crust despite the undoubted continuation of similar fault displacements at greater depths. Based on the worldwide data, the changes in a number of average earthquake parameters with depth are shown. The pattern of these changes is consistent with the expected differences in the physical mechanisms of the earthquakes with depth and substantially refines the accepted classification of earthquakes into shallow, intermediate, and deep. The difference in the physical mechanisms of the earthquakes implies a probable difference in the patterns of their precursors. The analysis of the hourly ionograms from the vertical ionospheric sounding station "Tokyo" for 1957–2020 has shown the different pattern of seismoionospheric effect for the earthquakes (more than 300 events) that occurred at different depths and presumably had different dominant seismogenesis mechanisms. The average amplitude of variations in the critical frequency foF2, which provides the observed anomalies, is estimated to be only 2–3% of foF2. The differentiation of the earthquakes by depth has increased the statistical significance of the observed seismoionospheric effect. [ABSTRACT FROM AUTHOR]

This paper presents the findings of an experimental investigation of the efficiency of several low-cost frictional geotechnical seismic isolation methods on a rigid building model. A total of eleven different aseismic layers were considered. One layer was made of stone pebbles only, whereas the remaining ten layers were composites containing combinations of stone pebbles with different types and positions of "sliding" elements/materials (geogrid, geomembrane, and limestone sand layers). All the samples were exposed to four earthquake accelerograms of different durations and predominant periods, with three levels of peak ground acceleration (PGA): 0.2, 0.4, and 0.6 g. The test results confirm that the composite aseismic layers can significantly reduce the inertial/earthquake forces of the rigid building model relative to the stone pebble layer, depending on the type of earthquake and PGA. The need for further research on this issue on real building models is highlighted. [ABSTRACT FROM AUTHOR]

The motivation of this study stems from a retaining wall made of waste tires. The wall did not suffer any earthquake or tsunami-induced damage during the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan. This paper deals with a case study on this tire retaining wall. Results from a series of field and laboratory investigations are first described. A numerical simulation is also described in which whole tires were used as protective layers in an embankment. The results show that confining effect of each tire, friction between the tires, ductility, and damping inherent in tires contribute towards the excellent performance of the retaining wall during the earthquake loading. The case study also reveals that it is the isolation mechanism due to the vibration absorption capability of rubber particles in tires, which could protect tire retaining structure during the earthquake. [ABSTRACT FROM AUTHOR]

Summary: The aim of this paper is to demonstrate the efficiency of a low-cost and sustainable timber-based energy dissipation system with recentering ability, which can be used as a seismic isolation system or a tuned mass damper for the seismic protection of structures in developing or developed countries. The system, defined as Dovetail with SPrings (Dove-SP), utilizes the attractive properties of timber to store CO2, thus reducing the carbon footprint of the existing energy dissipation systems: It comprises two timber slabs that are designed to slide against each other in a motion that is restrained by a dovetail sliding joint. Two sliding interfaces that allow this sliding motion at an attractively low friction coefficient are experimentally investigated: A PVC sand-wich (PVC-s) sliding interface, comprising a thin layer of sand that is sand-wiched between two PVC layers and a timber sand-wich sliding interface consisting of a thin layer of sand encapsulated between two beech timber surfaces. A set of low-cost steel springs is designed and installed on both sides of the dovetail joint to recenter the structure back to its original position after the end of an earthquake ground motion excitation. A novel, low-cost and deformable wood material fabricated from delignified balsa wood is used to reduce the pounding effects before the activation of the steel springs. The seismic behavior and the recentering ability of the novel timber-based energy dissipation system subjected to an ensemble of recorded earthquake ground motion excitations was experimentally investigated through a large-scale shaking table investigation at ETH Zurich. [ABSTRACT FROM AUTHOR]

This paper reports the comparison results obtained for temporal variations in atmospheric pressure and soil radon concentration measured in loose sediments at three monitoring stations in the Baikal region for the period of three relatively strong earthquakes such as Bystrinskii (September 21, 2020, K = 14.6), Kudarinskii (December 9, 2020, K = 14.0), and Khubsugulskii (January 11, 2021, K = 16.0). According to the emanation monitoring data, radon release is controlled in this region by variations in atmospheric pressure. As first identified by the formalized statistical analysis, this relationship is subjected to irregularities in the course of each seismic activation studied. They are related to the earthquake preparation processes. Upon expanding the monitoring network, this discovery opens up real opportunities for developing the emanation approach to medium-term forecasting. [ABSTRACT FROM AUTHOR]

Large-magnitude earthquakes in northern Chile and southern Peru occur every 108 years on average. It should be noted that over 143 years since the catastrophic earthquake of May 9, 1877, any similar events were completely absent. In 2007, a 7.7 Mw earthquake occurred near Tocopilla, and in 2014 a catastrophic M = 8.1 earthquake hit Pisagua. It is believed that only part of the energy accumulated over 143 years has been released during those events, while most of it is yet to be released. Thus, we can conclude that a serious tsunami hazard exists for all coastal cities of southern Peru and northern Chile. In this paper, on the basis of the available historical data and geodynamic studies, numerical simulation of the historical catastrophic earthquake and tsunami of May 9, 1877 is carried out assuming the blockwise earthquake source configurations. We implemented 23 simulation scenarios for different kinematic behavior patterns of such a source, sequentially updating the source fragmentation to reduce the misfit between the simulated and observed wave height data. Using the proposed methodology, for each scenario, the generation of a tsunami source is simulated and the computation of wave fields up to the 5-m isobath is carried out. The results obtained are compared with historical data. Analysis of the entire set of simulated earthquake scenarios makes it possible to choose a tsunamigenic earthquake scenario with the most adequate characteristics of tsunami waves in the coastal zone. [ABSTRACT FROM AUTHOR]

This paper proposes a rapid strengthening method for severely earthquake-damaged RC piers. In this strengthening method, high-strength steel bars (HSSB) HTRB600 were used as vertical and horizontal planting rebars anchored into pier footing and pier shaft, and ultra-high-strength concrete (UHPC) was used as grout material. Meanwhile, the UHPC was used to strengthen the damaged plastic hinge region to form the enlarged section to realize the mechanical integrity of the strengthening piers. Utilizing the early strength property of UHPC, the proposed rapid strengthening method can realize the rapid recovery of vertical bearing capacity of severely damaged RC piers, thus ensuring the rapid passage and emergency rescue of bridges after earthquakes. Four severely damaged RC piers under cyclic tests were strengthened and reloaded, and the seismic performance of strengthening and original RC piers was compared, including lateral bearing capacity, lateral stiffness, deformability and hysteretic dissipated energy. Research results show that, for RC piers with only bar buckling but no bar fracture in original specimen, the UHPC enlarged section over strengthens the damaged plastic hinge region, resulting in the plastic hinge of the strengthening piers being relocated to the upper part of enlarged strengthening section. The strengthening pier presents better seismic performance, including lateral bearing capacity, deformability and energy dissipation capacity than original piers. For RC piers with partial longitudinal reinforcement facture, two kinds of strengthening methods, with or without using horizontal planting rebars, were adopted. When using horizontal planting rebars, in spite of presenting asymmetric failure due to the asymmetric damage of original piers, the strengthening RC piers still present comparable seismic performance with original piers. However, the strengthening pier without using horizontal planting rebars presents more distinct pinching effect, lower deformability and hysteretic dissipated energy than original pier. Therefore, the horizontal planting rebars can enhance the force integrity between UHPC enlarged section and pier shaft, and then ensure the seismic performance of strengthening RC piers. Overall, the proposed rapid strengthening method with horizontal planting rebars can not only fulfill the post-earthquake rapid passage demand in short time for the severely earthquake-damaged RC piers, but also ensure the long-term service of strengthening bridge piers by restoring their seismic performance. [ABSTRACT FROM AUTHOR]

The paper addresses the investigation of the dynamic characteristics of a case study, the Egyptian church of Abu serga. To this aim some in situ investigations have been conducted and related results are discussed. The paper presents interesting and innovative aspects, mainly related to the characteristics of the church investigated, covering a lack of knowledge in the scientific literature due to the typology of the church. The integrated geotechnical and geophysical investigation techniques assessed the level of seismic and other geo-environmental risks that Abu serga church suffers from. It suffers multiple Geo-environmental hazards. The main objectives of this pilot study are as follows: (1) Identifying the shear velocity Vs analysis profile of the subsoil and also the resonant frequency of soil and the historical building of Abu serga church using ambient noise recordings (microtremors) to assess the level of seismic and other geo-environmental hazards. (2) Understanding the damage to the historic building caused by the recent earthquakes. (3) Offering technical support and advice on intervention retrofitting for the historic damaged structure. In this study, ambient noise recordings have been processed through horizontal to vertical spectral ratios to examine the main frequencies and to examine whether the building has its main frequency close to that of the soil in order to identify potential resonance phenomena. Numerous ambient noise recordings were recorded on the soil, in the basement, and at each floor of the buildings. This study suggests moderate level of earthquake activity at Abu serga church and is in a good agreement with the fact that "Egypt is a part of the stable African Shield", but the existence of old structures such as the Abu serga church may reduce the ability to resist any earthquake shaking. [ABSTRACT FROM AUTHOR]

The earthquake cycle of stress accumulation and release is associated with the elastic rebound hypothesis proposed by H.F. Reid following the M7.9 San Francisco earthquake of 1906. However, observing details of the actual values of time- and space-dependent tectonic stress is not possible at the present time. In two previous papers, we have proposed methods to image the earthquake cycle in California by means of proxy variables. These variables are based on correlations in patterns of small earthquakes that occur nearly continuously in time. The purpose of the present paper is to compare these two methods by evaluating their information content using decision thresholds and Receiver Operating Characteristic methods together with Shannon information entropy. Using seismic data from 1940 to present in California, we find that both methods provide nearly equivalent information on the rise and fall of earthquake correlations associated with major earthquakes in the region. We conclude that the resulting timeseries can be viewed as proxies for the cycle of stress accumulation and release associated with major tectonic activity. Article Highlights: The current state of the earthquake cycle of tectonic stress accumulation and release is unobservable We review two methods for visualizing the current state of the earthquake cycle from correlation in small earthquake patterns Machine learning techniques indicate that signals in a correlation time series corresponding to future large earthquakes can be detected [ABSTRACT FROM AUTHOR]

This paper presents a topology optimization approach for the seismic design of multiple-rocking self-centering concentrically braced frames (SC-CBFs). SC-CBFs have been recently developed as damage-free seismic lateral load-resisting systems. In these systems, rocking sections are potentially designed in several locations over the height due to several modes. The design of multiple-rocking SC-CBFs is a demanding task due to their highly non-linear behavior. The vertical irregularity, caused by the non-continuous stiffness over the height of these systems, makes the prediction of their behavior a challenging task, especially when subjected to dynamic ground accelerations. In this paper, an efficient and general design approach for these systems is developed utilizing gradient-based topology optimization. An optimization problem is formulated such that the construction cost of the SC-CBF is minimized while simultaneously considering the topology of the frame, cables, energy dissipation (ED) material, and the location of the rocking sections. The performance of the building is limited to acceptable limits by formulating the constraints of the optimization problem based on the results obtained from non-linear time history analysis (NLTHA). An efficient numerical integration scheme based on the mixed lagrangian formalism (MLF) was adopted to conduct the NLTHA. The proposed method was used for the design of 5- and 10-story buildings. The results show that efficient designs could be achieved with a reasonable number of iterations using a personal computer. This makes the proposed approach desirable for the design of multiple-rocking SC-CBFs by researchers and engineers. [ABSTRACT FROM AUTHOR]

Alexandria is one of the Mediterranean UNESCO World Heritage sites at risk from coastal flooding and Earthquakes. Nowadays, the safety of archaeological underground structures draws more and more attention. After many catastrophic events, the study of anti-seismic for underground structures has also become an important problem to be solved. Based on the typical underground structure seismic damage phenomenon, this paper summarizes the seismic characteristics, research methods and design methods of underground structures to offer a guide for engineers and conservators, where the polymer anti-seismic piling to protect the underground monumental structures against strong earthquakes is presented and validated in numerical analysis. In this paper, typical damages of archaeological underground structures are firstly presented, followed by the FEM analysis using the PLAXIS 2D code for the seismic response of Catacombs of Kom El-Shoqafa in Alexandria, Egypt with and without the anti-seismic polymer pilling techniques. Results of this work underline the high potential of these low-cost anti seismic technique, confirming the possibility of achieving a significant improvement of the seismic performance of archaeological underground structures by using the low-cost and easy to manufacture it. [ABSTRACT FROM AUTHOR]

This paper describes the methods and results of the strong ground motion simulations for three earthquakes from the 2016 Kumamoto earthquake sequence using corrected empirical Green's functions. The target earthquakes were an aftershock (Mw 5.5), the largest foreshock of the sequence (Mw 6.1), and the mainshock (Mw 7.1). The corrected empirical Green's function method was used in the simulations. This simulation method combines simple source and path factors with empirical site amplification and phase factors to generate realistic site-specific strong motions. Simulations were originally conducted to participate in blind prediction exercises in ESG6. Although the simulations performed in this study were based on the models submitted to the blind prediction committee, several modifications were made after the blind prediction exercise. First, the observed records at the target site of the blind prediction called KUMA were used to compare observed and synthetic strong ground motions. In addition, a regional spectral inversion was conducted to obtain a more appropriate Q-value and site amplification factor. Synthetic strong motions were found to explain the observed strong ground motions at KUMA and other stations. Comparisons with predictions by other methods and the sensitivity to the rupture scenario were also discussed. These results provide useful information for applying the corrected Green's function method to strong ground motion simulations. [ABSTRACT FROM AUTHOR]

This paper contributes to the existing literature on the explanation of housing prices. First, our proposed methodology accounts for cross-sectional dependence, both locally and globally, using individual data of more than 200,000 transactions in the three most northern provinces of the Netherlands over the period 1993–2014. Second, the selection of houses within each focal house's sub-market is not only based on distance and time, but also on their degree of similarity. Third, global cross-sectional dependence is not modeled by time-fixed effects, as in previous studies, but by cross-sectional price averages. Fourth, we accumulate the strength and frequency with which earthquakes affect each focal house before it was sold into one single measure using a seismological model and then subdivide it into different bins to account for nonlinear effects and to determine a threshold below which earthquakes have no effect. This way we are able to investigate the propagation of the detrimental impact of earthquakes on housing prices over space and time without the need to select a reference area in advance, which potentially might also have been affected by earthquakes. [ABSTRACT FROM AUTHOR]

We performed the spectral inversion to separate the source, path, and site effects using strong ground motion records from essential facilities such as powerhouses and hydroelectric dams, distributed all over Costa Rica. The spectral inversion technique was adapted to a sparsely observed strong motion data set. We used the results to estimate strong ground motions at sites where there were no observation records in and around the intensity anomaly that appeared during the 2012 Sámara earthquake of Mw 7.6. To ensure the quality, we incorporated a broadband station to estimate levels of acceleration source spectra for six events 5.3 ≤ Mw ≤ 6.5, using them as the reference events for the spectral inversion. In this paper, we introduced two consistency checks: confirmation of the correctness of the input data, and verification of the output using synthetic spectra. We used them as an iterative implementation of sequences of elimination of suspicious data and inversions. We regulated the source spectra of the reference events for the final inversion, considering the estimate of site effect for one-dimensional SH wave propagation at the site of the lowest site amplification. We obtained the frequency-dependent quality factor Q = 179f0.5598 for the northern and central parts of Costa Rica. From the output of the spectral inversion, we reproduced the acceleration spectra of earthquakes in the sites where the event was not recorded. We applied this formulation using the earthquake mentioned above. The resulting synthetic spectra are consistent with the anomalous intensity distribution reported at that time. [ABSTRACT FROM AUTHOR]

With the overwhelming number of older reinforced concrete buildings that need to be assessed for seismic vulnerability in a city, local governments face the question of how to assess their building inventory. By leveraging engineering drawings that are stored in a digital format, a well-established method for classification reinforced concrete buildings with respect to seismic vulnerability, and machine learning techniques, we have developed a technique to automatically extract quantitative information from the drawings to classify vulnerability. Using this technique, stakeholders will be able to rapidly classify buildings according to their seismic vulnerability and have access to information they need to prioritize a large building inventory. The approach has the potential to have significant impact on our ability to rapidly make decisions related to retrofit and improvements in our communities. In the Los Angeles County alone it is estimated that several thousand buildings of this type exist. The Hassan index is adopted here as the method for automation due to its simple application during the classification of the vulnerable reinforced concrete buildings. This paper will present the technique used for automating information extraction to compute the Hassan index for a large building inventory. [ABSTRACT FROM AUTHOR]

Computer vision-based inspection methods show promise for automating post-earthquake building inspections. These methods survey a building with unmanned aerial vehicles and automatically detect damage in the collected images. Nevertheless, assessing the damage's impact on structural safety requires localizing damage to specific building components with known design and function. This paper proposes a BIM-based automated inspection framework to provide context for visual surveys. A deep learning-based semantic segmentation algorithm is trained to automatically identify damage in images. The BIM automatically associates any identified damage with specific building components. Then, components are classified into damage states consistent with component fragility models for integration with a structural analysis. To demonstrate the framework, methods are developed to photorealistically simulate severe structural damage in a synthetic computer graphics environment. A graphics model of a real building in Urbana, Illinois, is generated to test the framework; the model is integrated with a structural analysis to apply earthquake damage in a physically realistic manner. A simulated UAV survey is flown of the graphics model and the framework is applied. The method achieves high accuracy in assigning damage states to visible structural components. This assignment enables integration with a performance-based earthquake assessment to classify building safety. [ABSTRACT FROM AUTHOR]