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The Renewal Epidemic-Type Aftershock Sequence (RETAS) model is a recently proposed point process model that can fit event sequences such as earthquakes better than preexisting models. Evaluating the log-likelihood function and directly maximizing it has been shown to be a viable approach to obtain the maximum likelihood estimator (MLE) of the RETAS model. However, the direct likelihood maximization suffers from numerical issues such as premature termination of parameter searching and sensitivity to the initial value. In this work, we propose to use the Expectation-Maximization (EM) algorithm as a numerically more stable alternative to obtain the MLE of the RETAS model. We propose two choices of the latent variables, leading to two variants of the EM algorithm. As well as deriving the conditional distribution of the latent variables given the observed data required in the E-step of each EM-cycle, we propose an approximation approach to speed up the E-step. The resulting approximate EM algorithms can obtain the MLE much faster without compromising on the accuracy of the solution. These newly developed EM algorithms are shown to perform well in simulation studies and are applied to an Italian earthquake catalog. for this article are available online. [ABSTRACT FROM AUTHOR]

The Kaikōura Earthquake ruptured a complex network of at least 20 faults in the northeastern South Island, with variable geometries, slip and slip rates. Ground shaking and surface fault rupture generated a tsunami, thousands of landslides, and many dammed rivers. The earthquake damaged farmland, buildings and infrastructure in the northeastern South Island and Wellington regions, closing critical transport networks for over a year. This special issue presents a collection of 12 papers on the earthquake. These papers cover a range of topics, including, the geometries and paleoearthquake histories of faults that ruptured, seismic hazards, the tsunami and coastal geomorphology, together with the societal impact and communication of the earthquake. They incorporate our understanding of the earthquake 5–6 years since it occurred. Despite an unprecedented amount of data and thousands of published papers referring to the earthquake, many key questions remain. These include: is the Hikurangi subduction interface capable of producing great earthquakes beneath the northeastern South Island? Why did the Hope Fault not accommodate significant slip in the earthquake? Has the earthquake changed the seismic hazard in central Aotearoa New Zealand? Addressing these questions will improve understanding of seismic processes and hazards helping to build resilience to future earthquakes. [ABSTRACT FROM AUTHOR]

The north-striking sinistral reverse Papatea Fault ruptured with a very large (up to 12 m) oblique slip as part of the 2016 MW 7.8 Kaikōura earthquake in the northeastern South Island. Paleoseismic studies were undertaken at three sites along the Papatea Fault, named Murray's roadcut, Jacqui's Gully (both on the main strand), and Wharekiri trench (western strand). These sites provide evidence for up to three Late Holocene paleoearthquakes prior to 2016 (=E0) on this previously unmapped active fault, with preferred OxCal-modelled timings of 98–149 (E1), 546–645 cal yr BP (E2), and >738 cal yr BP (E3). Event correlations between the sites are generally consistent across these past events, implying that the two strands of the Papatea Fault link at depth and rupture together co-seismically as in 2016. Comparisons of its paleoseismic record with the Kekerengu Fault and uplift data from Waipapa Bay and Kaikōura, suggest that the Papatea Fault may have three distinct rupture modes: (i) Kaikōura-type multi-fault ruptures with multi-metre, anelastic block displacements and associated major landscape change; (ii) multi-fault earthquake ruptures with other regional fault combinations; and (iii) single-fault Papatea ruptures with metre-scale displacement. OxCal models offer the possibility that the E1 fault rupture occurred in 1855 CE. [ABSTRACT FROM AUTHOR]

The Mw 7.8 Kaikōura earthquake of November 14th, 2016 provided rare opportunities to evaluate ground deformation during a large strike-slip earthquake. Following the earthquake, both halves of a displaced paleoseismic trench were re-excavated and extended to test, refine, and extend the known late Holocene chronology of surface rupturing earthquakes on the Kekerengu Fault. 28 organic-bearing samples were collected during these excavations. Of these, six samples provided new 14C ages that could be superimposed on the preferred age model of (Little VDR, Kearse J, Norton K, Benson A, Wang N. 2018. Kekerengu fault, New Zealand: Timing and size of Late Holocene surface ruptures. Bulletin of the Seismological Society of America. 108(3B):1556–1572) to derive an expanded, updated age model of earthquake events on the fault that is now based on 16 dated samples. Including the 2016 earthquake, we recognise six surface rupturing earthquakes on the Kekerengu Fault since ∼2000 cal. B.P. Based on the last five events, our analysis yields an updated estimate of the mean recurrence interval for surface rupturing on the fault of 375 ± 32 yrs (1σ) since ∼1650 cal. B.P. An older, sixth event (E5) was not included in the preferred age model due to uncertainties in interpretation; however, incorporating this event into an alternative, six-event age model would adjust the recurrence interval estimate to 433 ± 22 yrs (1σ) since ∼2000 cal. B.P. [ABSTRACT FROM AUTHOR]

During the Kaikōura earthquake, a paleoseismic trench was dextrally displaced ∼9 m and shortened by 1.3 ± 0.4 m – the largest globally recorded displacement of a trench. Analysis showed that two processes accommodated subequal amounts of slip at the surface: (1) discrete dextral-slip on two steeply-dipping faults bounding a <3.5 m wide central deformation zone; and (2) coseismic clockwise rotation of turf rafts and pervasive sediment deformation in that zone. The second (successive) process resulted in upward (<1 m) and outward (<2 m) bulging along low-angle thrusts, creating horizontal fault-perpendicular shortening that exceeds the heave (∼1.3 m). This discrepancy results from coseismic rotation of rafts, that shorten upon approaching perpendicularity with the fault – creating extra apparent shortening (in fault-orthogonal view). Comparison of pre- and post-earthquake trench logs indicates that strike-slip ruptures at the same site can be expressed differently over time; fault strands carrying major displacement in 2016 were not the locus of deformation in the previous earthquake(s), suggesting temporal unpredictability is important in defining fault zones. The last several paleoearthquakes at the trench produced cm-dm scale normal-sense dip separations across faults; however, the 2016 earthquake created compressive structures including up-bulging and low-angle reverse faulting, as well as fissuring. This contrast in deformation style likely resulted from an >8° clockwise rotation of the local slip vector in 2016 (becoming transpressive), highlighting that small changes in slip kinematics may affect rupture zone structures. [ABSTRACT FROM AUTHOR]

For much of Russia's fractious history, the earth's stability at least could be taken for granted. The imperial heartland was situated deep on the Eurasian tectonic plate, rarely experiencing fatal seismic activity. As the empire expanded, however, it acquired several of Eurasia's most earthquake-prone regions. This interplay between colonization and seismic landscapes produced a novel entity: the 'seismic colony'. With its occasional earthquakes and perpetual risks, the seismic colony posed a significant challenge to Russian rule, particularly in Turkestan. Earthquakes devastated infrastructure, gave lie to the civilizing mission and fostered social disorder, thereby undercutting the technologies of rule that the empire relied on to exploit the region. Engaging analytical tools from the history of environment and technology, this article details this threat and the developments it prompted from Russian experts and settlers, including first-response efforts, reconfigured construction practices, and the concretization of seismology as a science and infrastructure. [ABSTRACT FROM AUTHOR]

Brittle punching failures can occur in slab–column connections due to earthquake-induced unbalanced moments. The performance of undamaged specimens and various repair/strengthening techniques have been studied in the past. This paper investigates a less studied scenario, in which a flat slab–column connection severely damaged by an earthquake is subjected to another earthquake without undergoing repair. The performance under this special loading protocol is analysed. It is shown that the drift capacity was not significantly impaired, but both the lateral and bending stiffness were reduced. Other relevant observations regarding the post-earthquake life of slab–column connections are brought to attention. [ABSTRACT FROM AUTHOR]

Part of North-Western Himalaya particularly Uttarakhand has been identified by several eminent seismologists as gap area where large size earthquake (greater than magnitude 7) is expected. The region has witnessed two earthquakes having a magnitude greater than 6 in last 25 years (March 28, 1999 Chamoli earthquake and October 20, 1991 Uttarkashi earthquake) both having an epicenter in Gharwal region of Uttarakhand. Several studies have shown that a future large earthquake in central Himalayas can generate severe ground motion in the National capital region of Delhi, which is about 300 km from this expected source. Several densely populated cities and villages having total population of several millions are located between Delhi and Uttarakhand. These towns/cities will be severely affected by a large earthquake having an epicenter in this region. Using advancements in communication technology and real-time seismology, a project to have an earthquake early warning system for Northern India is under progress at Indian Institute of Technology, Roorkee. In this project, a dense network of 84 accelerometers has been installed covering an area of about 100 × 40 km in Garhwal region. This network has an average station to station distance of less than 10 km and all the sensors are streaming data, which is being processed in real time at central server stationed at Roorkee. This paper describes details of the network, sensors, present status of development, performance of instrumentation during recent events, and processing details. [ABSTRACT FROM AUTHOR]

The damages done by earthquakes in the human history can't be denied in any sense as the phenomenon is responsible for bringing catastrophes both socially and economically. It is known that Pakistan is located in one of the seismically active regions of the world. The Quetta earthquake which occurred in 1935, the Ziarat earthquake of 2008, the Kashmir earthquake in 2005 and the Dallbaandin earthquake in 2011 bear the testimony of active seismicity in Pakistan. The Building code of Pakistan (BCP) 2007 has placed Peshawar in seismic zone 2B with a PGA range of 0.16–0.24. However, this is not in line with the historical data and available ground motion records. Therefore, in this research, a probabilistic seismic hazard assessment technique was used to estimate the strong ground motion parameters for a grid of 11 km by 11 km, covering all the active faults within and around the Peshawar region and having significant effect on the seismicity of Peshawar. Moreover, PGA along with spectral acceleration values are required by modern building codes (IBC 2009 and ASCE-7) for the estimation of seismic loads, is calculated. From seismic hazard analysis, it was found that Peshawar lies in seismic Zone 1 with a PGA value of 0.06. The estimated PGA value was also validated and in line with the PGA values obtained from the ground motion records of Peshawar Meteorological Department. [ABSTRACT FROM AUTHOR]

A strident focus on atmospheric carbons and on climate change as its distinguishing feature has seen much debate and research surrounding the Anthropocene stray from its conceptual grounding in geology. Yet new research argues that hallmarks of the Anthropocene such as sea-level rise, melting ice sheets, and environmental engineering projects designed to mitigate chronic shortages of potable water all increase the potential of seismic activity, placing geological forces back at the center of conversations on planetary futures. Following calls to consider the political dimensions of environmental change in the Anthropocene, this article examines the multiple layerings of natural hazards, political crises and transformations, and mega-urbanization through the lens of catastrophic geological events, drawing evidence from an ongoing longitudinal study of the devastating Mexico City earthquakes of 1985 and 2017. This case suggests that such events intersect with contemporary political economy in a variety of ways, from the disruption of urban investment patterns and the initiation of processes of mass abandonment or of creative destruction and gentrification to the exacerbation of political crises at scales from the submunicipal to the supranational, the facilitation of social movement formation, and the acceleration of political revolutions such as Mexico's democratic transition of 2000. These insights offer productive avenues for engaging with the political economies of geological events and processes and the prescriptive powers of geology as a field of knowledge production and political power that increasingly demand attention across an urbanizing planet. [ABSTRACT FROM AUTHOR]

The 14th November 2016 Kaikōura earthquake was one of the most complex crustal earthquakes recorded in the modern era. The rupture propagated northward for more than 170 km along both mapped and unmapped faults causing widespread damage across central New Zealand. Field, Satellite Radar and GPS observations revealed ground displacements of up to 6 m (fault offsets of ∼12 m), extensive coastal uplift and large scale anelastic deformation including the ∼10 m uplift of a fault-bounded block.In the aftermath of the earthquake, slip models have estimated as much as 25 m of slip at depth along with the potential co-seismic rupture of the southern Hikurangi subduction interface. From the complex network of faults, exhibiting a variety of slip kinematics, to the large co-seismic slip, this earthquake has challenged our assumptions about fault segmentation in multi fault ruptures with important implications for seismic hazard. Following the earthquake, studies from multiple national and international groups have started to unravel some of the earthquakes complexities. Here I will present a broad overview of the current findings and discuss some of the ongoing debates and questions which have yet to be resolved. [ABSTRACT FROM AUTHOR]

In the nineteenth century, Ernst Chladni's acoustic figures provided productive new experimental techniques for investigating natural phenomena. The movement of invisible forces, such as light, electricity, magnetism, and heat, were hard for natural philosophers to examine. But Chladni's use of vibrating glass plates and sand to reveal the wave motions of sound offered an experimental framework through which to make natural phenomena visible. In Britain, it was Michael Faraday and Charles Wheatstone in the 1820s and 1830s who made best use of these practices and apparatus. Sound waves also provided new ways of thinking about earthquakes and seismic phenomena. This article explores how Robert Mallet, the first self-styled "seismologist", examined earthquakes, drawing on broader philosophical work surrounding vibrations and acoustic waves. Mallet was keen to draw parallels between the movement of seismic shock waves and the movement of musical sounds, including those from a piano moving through a room. He was not alone in this respect. Charles Darwin, among others, noticed comparisons between the sonorous and the seismic. By contextualising Victorian seismology within the context of Victorian acoustic science, this article argues that the two disciplines were deeply connected. [ABSTRACT FROM AUTHOR]

This paper deals with artificial neural networks (ANN) for post-quake structural damages evaluation. Two groups of governing parameters are considered: the structural components group and the secondary components group. The adequate ANN requests the analysis of: the best combination of the components' damages which governs the global damage of a building; the neural network parameters, i.e. number of hidden layers and neurons as well as the activation functions. A set of 3614 damaged buildings is extracted from a database collected during a post-quake survey by trained staff (Boumerdes, Algeria: Mw = 6.8; May 21, 2003 earthquake). The comparison between predicted and observed damages shows that the best ANN corresponds to: one hidden layer with a number of neurons equal to the number of main building components (i.e. 4 or 8 components), and the "hyperbolic tangent" function as activation function. For the collected database, the ANN's predictions and the observed global damages are in accordance for: 70% of the considered buildings when the global damage is assumed to be influenced only by the secondary (non-structural) elements group, 80% of the considered buildings when the global damage is assumed to be influenced only by the structural group, 87% of the considered buildings when the global damage is assumed to be influenced by both building components groups, i.e. structural and secondary components. [ABSTRACT FROM AUTHOR]

Shake-table studies were conducted on a ¼-scale, 2-span bridge model incorporating a newly-developed concept of replaceable plastic hinges and columns that can be easily assembled and disassembled. The plastic hinges incorporate novel materials that mitigate column damage and permanent drift, allowing the bridge to undergo intense seismic shaking and remain operational when most conventional bridges would warrant demolition. Designed to be disassembled, the column components have the potential to be reused, which is intended to help mitigate the environmental impact from material extraction and manufacture. The concept feasibility was demonstrated by assembling, testing, and disassembling the same bridge model twice. [ABSTRACT FROM AUTHOR]

Prediction of earthquakes has been long of interest of scientists to create a timely warning to save lives and reduce the damage. During the last few decades, scientists could record and classify the earthquakes' effective parameters through careful studies. Precursor, as one of the most important parameters, presents the variation in the concentration of radon gas in the earth's crust released by faults. Measuring and comparing this precursor requires the installation of appropriate hardware in the vicinity of the faults. The extraction of this gas and its lead ions will create additional precursors in the atmosphere layers. Through intelligent analyzing such historical meteorological data sets which are being measured and recorded in most parts of the world, the earthquakes can be predicted. In order to predict the magnitude and number of the earthquakes in this study, the particle filter-based and support vector regression is used. To evaluate the validity of the proposed method, the results are compared with multi layered perceptron neural network and support vector regression. The proposed method indicated the relationship between climatic data and the occurrence of earthquake leading to a precision of 96% for predicting the mean magnitude of earthquakes and a high accuracy of 78% for the expected earthquake count in a month. The accuracy of the method was measured by the correlation coefficient index. [ABSTRACT FROM AUTHOR]

A c. AD 1620 West Coast earthquake has been attributed to the northern and central segments of the Alpine Fault but does not match well with paleoseismic indicators or the currently understood recurrence interval of Alpine Fault ruptures. We model the landsliding and resulting river aggradation from a Mw 7.6 earthquake on a modelled reverse fault located between the central Alpine Fault and the main divide of the Southern Alps. The Waiho-Callery and Whataroa catchments are significantly more impacted by coseismic landsliding from this Southern Alps earthquake than from an Alpine Fault earthquake. The modelling suggests that the c. AD 1620 earthquake was not an Alpine Fault event, and that large earthquakes on subsidiary faults (or fault systems) can have larger localised impacts on river behaviour west of the Southern Alps than an Alpine Fault earthquake. [ABSTRACT FROM AUTHOR]

Paleoseismology has been making an important contribution to understanding the Alpine Fault and the hazard it poses to society. However, evidence of past earthquakes comes from a wide variety of sources and publication of the evidence has been somewhat fragmented. Here, we review physical evidence for past large to great earthquakes on the Alpine Fault to summarise current understanding, illustrate progress and highlight future directions. Paleoseismic evidence has been derived from tree disturbance, landscape features and trenches across the fault. These records have been supplemented and extended back in time with sedimentary evidence of Alpine Fault earthquakes from fault-proximal lakes and wetlands. In this review, we update radiocarbon analyses using recent calibration curves and modern Bayesian statistical methods where necessary to enable comparison between on-fault, fault-proximal and off-fault earthquake records. Over recent decades, Alpine Fault paleoseismology has progressed from playing an important role in demonstrating that large surface-rupturing earthquakes occur, to enabling estimates of earthquake recurrence behaviour, shaking intensities, rupture extents, landscape response durations and likelihood of the next earthquake. [ABSTRACT FROM AUTHOR]

The surface displacement amplitudes excited by out-of-plane SH waves on and around a semi-parabolic canyon had solution that was introduced over twenty years ago. In 2015, such solution was updated to much (5 times) higher frequencies, using a transformation involving the Wronskian. The same excitations also introduce rotations on and around the parabolic canyon. This article is the first of two that discuss the torsional component of rotations, with the rocking components discussed in the subsequent article. The rotational amplitudes of motions, as much as the displacement amplitudes, play an important role in studying the surface responses of structures, and can lead to a better understanding of the behavior of surface topographies in the event of seismic excitation. [ABSTRACT FROM PUBLISHER]

This paper discusses simulated ground motion intensity, and its underlying modelling assumptions, for great earthquakes on the Alpine Fault. The simulations utilise the latest understanding of wave propagation physics, kinematic earthquake rupture descriptions and the three-dimensional nature of the Earth's crust in the South Island of New Zealand. The effect of hypocentre location is explicitly examined, which is found to lead to significant differences in ground motion intensities (quantified in the form of peak ground velocity, PGV) over the northern half and southwest of the South Island. Comparison with previously adopted empirical ground motion models also illustrates that the simulations, which explicitly model rupture directivity and basin-generated surface waves, lead to notably larger PGV amplitudes than the empirical predictions in the northern half of the South Island and Canterbury. The simulations performed in this paper have been adopted, as one possible ground motion prediction, in the ‘Project AF8’ Civil Defence Emergency Management exercise scenario. The similarity of the modelled ground motion features with those observed in recent worldwide earthquakes as well as similar simulations in other regions, and the notably higher simulated amplitudes than those from empirical predictions, may warrant a re-examination of regional impact assessments for major Alpine Fault earthquakes. [ABSTRACT FROM PUBLISHER]

The dominant high-frequency component of ground motion for most seismic events in Australia comes from the crustal Lg phase that can commonly propagate efficiently to considerable distances across the continent. Using results from recent tomography for the attenuation of Lg, we are able to build the pattern of transmission of ground motion from events within the continent. The effects are readily displayed in terms of a distribution of effective magnitude. The same approach can also be used to look at the cumulative effects across the continent from 1840 to date as a useful complement to other ways of assessing earthquake potential. [ABSTRACT FROM PUBLISHER]

This study is aimed at verifying a strain-based post-earthquake serviceability verification method for steel bridge piers installed with three types of seismic dampers. All the dampers are designed to ensure the maximum response strain meet the requirement of the strain-based method according to performance Level 2 of Japanese specifications, and then the displacement-based verification method is employed to verify whether the requirement to the same performance level can be satisfied. Results indicate that the proposed strain-based verification method is more conservative than the displacement-based verification method in evaluating post-earthquake serviceability, and seismic performance of the retrofitted steel bridge piers is also significantly improved. [ABSTRACT FROM AUTHOR]

The 7.8 Mw Gorkha earthquake struck the east of Lamjung in Nepal, followed by a sequence of powerful aftershocks. Chinese Team Six including the authors inspected the seismic damage to civil structures along 10 paths in densely populated areas with a seismic intensity of VII to IX, 40 days after the main shock. The damage was categorized according to structure types and described in detail. Several conclusions are made: powerful aftershocks can significantly affect the failure patterns; geological conditions, structure types, and height have great influence on the level of damage; and the local risky retrofitting technique needs improvement badly. [ABSTRACT FROM AUTHOR]

Elastomeric pad bearings are widely applied in short- to medium-span girder bridges in China, with the superstructure restrained by reinforced concrete (RC) shear keys in the transverse direction. Field investigations after the 2008 Wenchuan earthquake reveal that bearing systems had suffered the most serious damage, such as span falling, bearing displaced, and shear key failure, while the piers and foundations underwent minor damage. As part of a major study on damage mechanism and displacement control method for short- to medium-span bridges suffered in Wenchuan earthquake, a 1:4 scale, two-span bridge model supported on elastomeric pad bearings were recently tested on shake tables at Tongji University, Shanghai. The bridge model was subjected to increasing levels of four seismic excitations possessing different spectral characteristics. Two restraint systems with and without the restraint of RC shear keys were tested. A comprehensive analytical modeling of the test systems was also performed using OpenSees. The experimental results confirmed that for the typical bridges on elastomeric pad bearings without RC shear keys, the sliding effect of the elastomeric pad bearings plays an important role in isolation of ground motions and, however, lead to lager bearing displacement that consequently increases the seismic risk of fall of span, especially under earthquakes that contain significant mid-period contents or velocity pulse components. It is suggested from the test results that RC shear keys should be elaborately designed in order to achieve a balance between isolation efficiency and bearing displacement. Good correlation between the analytical and the experimental data indicates that the analytical models for the bearing and RC shear key as well as other modeling assumptions were appropriate. [ABSTRACT FROM AUTHOR]

Palaeoseismological and archaeoseismological studies in the Kurai fault zone, along which the Kurai Range is thrust onto Cenozoic deposits of the Chuya intramontane basin, led to the identification of a long reverse fault scarp 8.0 m high. The scarp segments are primary seismic deformations of large ancient earthquakes. The scarp’s morphology, results of trenching investigations, and deformations of Neogene deposits indicate a thrusting of the piedmont plain onto the Kurai Range, which is unique for the Gorny Altai. Similarly for Northern Tien Shan, we explain this by the formation of both a thrust transporting the mountain range onto the depression and a branching thrust dislocation that forms the detected fault scarp. In a trench made in one of the scarp segments, we identified the parameters of the seismogenic fault – a thrust with a 30° dipping plane. The reconstructed displacement along the fault plane is 4.8 m and the vertical displacement is 2.4 m, which indicates a 7.2–7.6 magnitude of the ancient earthquake. The14C age of the humus-rich loamy sand from the lower part of the colluvial wedge constrains the age of the earthquake at 3403–3059 years BP. Younger than 2500 years seismogenic displacements along the fault scarp are indicated by deformations of cairn structures of the Turalu–Dzhyurt-III burial mound, which was previously dated as iron age between the second half of I BC and I AD. [ABSTRACT FROM PUBLISHER]

The Manyas fault zone (MFZ) is a splay fault of the Yenice Gönen Fault, which is located on the southern branch of the North Anatolian Fault System. The MFZ is a 38 km long, WNW--ESE-trending and normal fault zone comprised of three en-echelon segments. On 6 October 1964, an earthquake (Ms = 6.9) occurred on the Salur segment. In this study, paleoseismic trench studies were performed along the Salur segment. Based on these paleoseismic trench studies, at least three earthquakes resulting in a surface rupture within the last 4000 years, including the 1964 earthquake have been identified and dated. The penultimate event can be correlated with the AD 1323 earthquake. There is no archaeological and/or historical record that can be associated with the oldest earthquake dated between BP 3800 ± 600 and BP 2300 ± 200 years. Additionally, the trench study performed to the north of the Salur segment demonstrates paleoliquefaction structures crossing each other. The surface deformation that occurred during the 1964 earthquake is determined primarily to be the consequence of liquefaction. According to the fault plane slip data, the MFZ is a purely normal fault demonstrating a listric geometry with a dip of 64°--74° to the NNE. [ABSTRACT FROM AUTHOR]

At the eastern boundary of the south Taupo Rift, the NE-striking, rift-bounding Rangipo and the ENE-striking Wahianoa active normal faults intersect. We investigate their intersection at the Upper Waikato Stream to understand the kinematics of a rift termination in an active volcanic area. The Upper Waikato Stream Fault is a previously unrecognised seismogenic source also at the eastern boundary, capable of producing aMW6.5 and up toMW7.1 earthquake if it ruptures in conjunction with the Rangipo or Wahianoa faults. We found a minimum of 12 surface-rupturing earthquakes in the last 45.16 ka on the Upper Waikato Stream Fault (mean slip-rate c. 0.5 mm/yr), and a minimum of nine surface-rupturing earthquakes in the last 133 ka on the Wahianoa Fault (mean slip-rate c. 0.2 mm/yr). Periods of highest slip-rate on these faults may coincide in time with Taupo, Ruapehu or Tongariro eruptions, but, despite their intersection, movement was not coincident across all faults. The Upper Waikato Stream Fault responded to a major Taupo Volcano eruption, the Wahianoa to a major eruptive sequence from Mt Tongariro and the Rangipo to major explosive events from Mt Ruapehu. [ABSTRACT FROM PUBLISHER]

The Edremit Fault Zone (EFZ) forms one of the southern segments of the North Anatolian Fault Zone (NAFZ) at the northern margin of the Edremit Gulf (Biga Peninsula, South Marmara Region, Turkey). Stratigraphic, structural and kinematic results indicate that basinward younging of the fault zone, in terms of a rolling-hinge mechanism, has resulted in at least three discrete Miocene to Holocene deformational phases: the oldest one (Phase 1) directly related to the inactive Kazdağ Detachment Fault, which was formed under N–S trending pure extension; Phase 2 is characterised by a strike-slip stress condition, probably related to the progression of the NAFZ towards the Edremit area in the Plio–Quaternary; and Phase 3 is represented by the high-angle normal faulting, which is directly interrelated with the last movement of the EFZ. Our palaeoseismic studies on the EFZ revealed the occurrence of three past surface rupture events; the first one occurred before 13178 BC, a penultimate event that may correspond to either the 160 AD or 253 AD historical earthquakes, and the youngest one can be associated with the 6 October 1944 earthquake (Mw = 6.8). These palaeoseismic data indicate that there is no systematic earthquake recurrence period on the EFZ. [ABSTRACT FROM PUBLISHER]

The identification of historical events by geological and archaeological evidence is often ambiguous and conflicting, undermining the enormous potential for sub-annual precision in dating. The ruin of one of the largest pottery factories in the Middle East during Byzantine times, recently excavated in Yavneh (central Israel), exemplifies this: aligned fallen walls and columns and a kiln that collapsed while still in operation, with dozens of ceramic storage jars in articulation. Archaeological dating, which limits the time of the collapse to the seventh century CE, cannot distinguish between two large documented earthquakes that occurred during this century. By using pollen grains trapped by the collapse, we were able to distinguish, for the first time, between the two candidate earthquakes: September 634 CE and early June 659 CE. The pollen was extracted from the dust captured on the floor of the kiln during the cooling process of the vessels. The dust was collected only from below in situ whole vessels, and based on our reconstruction had been accumulated for about several days (after the heating process ended and before the collapse). Since the palynological assemblages included spring-blooming plants (such as Olea europaea and Sarcopoterium spinosum) and no common regional autumn bloomers (e.g. Artemisia), it is proposed that the kiln went out of use due to the early June 659 CE earthquake. We also propose that the recovery of the Yavneh workshops was no longer economically worthwhile, maybe in part due to changes in economic and political conditions in the region following the Muslim conquest. [ABSTRACT FROM AUTHOR]

The 18 September 2011 Sikkim Himalaya earthquake of Mw 6.9 (focal depth 50 km, NEIC report) with maximum intensity of VII on MM scale (www.usgs.gov) occurred in the Himalayan seismic belt (HSB), to the north of the main central thrust. Neither this thrust nor theplane of detachmentenvisaged in the HSB model, however, caused this strong devastating earthquake. The Engdahl–Hilst–Buland (EHB) relocated past earthquakes recorded during 1965–2007 and the available global centroid moment tensor) solutions are critically examined to identify the source zone and stress regime of the September 2011 earthquake. The depth section plot of these earthquakes shows that a deeper (10–50 km) vertical fault zone caused the main shock in the Sikkim Himalaya. The NW (North-West) and NE (North-East) trending transverse fault zones cutting across the eastern Himalaya are the source zones of the earthquakes. Stress inversion shows that the region is dominated by horizontal NNW-SSE (North of North-West-South of South-East) compressional stress and low angle or near horizontal ENE-WSW (East of North-East-West of South-West) tensional stress; this stress regime is conducive for strike-slip faulting earthquakes in Sikkim Himalaya and its vicinity. The Coulomb stress transfer analysis indicates positive values of Coulomb stress changefor failure in the intersecting deeper fault zone that produced the four immediate felt aftershocks (M≥ 4.0). [ABSTRACT FROM PUBLISHER]

The aim of the present study is to analyze the occurrences of future earthquakes using forecasting techniques from past seismicity in northeast India (latitude 20°N–31°N and longitude 87°E–97°E). The present study applies two types of retrospective binary forecasting. The first one is the pattern informatics (PI) method and the other is the Relative Intensity (RI) method. These techniques quantify the spatio-temporal seismicity rate changes in the historic seismicity of the study region. For this purpose, a uniform and complete earthquake catalogue in moment magnitude (Mw > 3) is prepared. The resulting binary forecasts are evaluated with the relative operating characteristics (ROC) diagram. The ROC diagram quantifies the results in terms of a hit rate (fraction of events that are successfully forecasted) versus a false alarm rate (no event occurs in a hotspot box). Evaluation of forecasting results using ROC diagram is more protective than maximum likelihood tests. The result gives a regional seismogenic map where earthquakes are likely to occur during a specified period in the future. The recent India–Nepal border earthquake of 18 September 2011 occurred in one of the forecasted regions. These techniques have been applied for the first time to the Indian subcontinent. [ABSTRACT FROM AUTHOR]

An analytical expression of a gravity retaining wall's seismic stability against sliding and overturning is proposed in this article. The derivation, aiming at the cohesionless soil with inclined backfill surface and nonvertical wall back, is based on limit equilibrium analysis and the pseudo-dynamic method. The variations of the sliding and overturning stability safe factors with the horizontal seismic acceleration are investigated for different seismic amplification factors, soil friction angles, wall friction angles, vertical seismic acceleration coefficients, wall back inclination angles, and backfill surface inclination angles. The results indicate that the soil friction and horizontal seismic action significantly impact the seismic stability. The increase of vertical earthquake action changes the curvature of stability factor curves. The wall friction and back inclination strengthen the gravity retaining wall's resistance to sliding and overturning failure while the backfill surface inclination plays a negative role in the seismic stability. We also found that the seismic stability safe factors calculated by the proposed method are larger but more reasonable than those by the Mononobe-Okabe method. [ABSTRACT FROM PUBLISHER]

Foraminiferal faunas in 29 short cores (maximum depth 7 m) of estuarine and coastal wetland sediment were used to reconstruct the middle–late Holocene (last 7 ka) elevational history on the southern shores of Poverty Bay, North Island, New Zealand. This coast is on the southwest side of a rapidly subsiding area beneath western Poverty Bay. Modern Analogue Technique paleo-elevation estimates based on fossil foraminiferal faunas indicate that the four study areas have gradual late Holocene (<3.5 ka) subsidence rates that increase from the southwest (mean c. 0.5 m ka–1) to northeast (mean c. 1.0 m ka–1). Only two rapid, possibly co-seismic, vertical displacement events are recognised: (1) c. 1.2 m of subsidence at 5.7 ± 0.4 ka (cal yr BP), which may have been generated by a subduction interface earthquake centred offshore and recorded in other published studies in northern Hawkes Bay, c. 35 km to the south; and (2) c. 1 m of uplift (relative sea-level fall) at c. 4.5 ± 0.3 ka, which might have been generated by rupture on an offshore upper plate fault that also uplifted coastal terraces at Pakarae and Mahia, 40 km to the north and south of the study area, or by rupture on the subduction interface penetrating beneath Poverty Bay. No sudden displacement events are recognised during the last 4 ka although subsidence, possibly aseismic, has continued. [ABSTRACT FROM AUTHOR]

A next generation ground motion model for the prediction of spectral accelerations both in the fore-arc and back-arc regions of the Carpathians Mountains is developed in this research for the Vrancea intermediate depth seismic source in Romania. This ground motion prediction equation (GMPE) is an updated version of the model given in Vacareanuet al.[2014] and is applicable in both the fore-arc and the back-arc regions. The strong ground motion database from which the prediction model is derived consists of over 700 triaxial accelerograms from Vrancea subcrustal seismic events, as well as from other intermediate-depth earthquakes produced in other seismically active regions in the world. The applicability of this ground motion prediction model in both the fore-arc and the back-arc region is tested using the analysis of residuals. Moreover, the appropriateness of this GMPE for soil classes B and C defined in EN 1998-1, as well as for average soil conditions is investigated. All results suggest that this model is an improvement of the previous versions of ground motion prediction equations for Vrancea intermediate-depth seismic source and its use in both the fore-arc and the back-arc regions make it a reliable candidate for more accurate seismic hazard studies of Romania. [ABSTRACT FROM AUTHOR]

The Aegean region and its surrounding area of Western Turkey is one of the most seismically active and rapidly deforming regions in the world. The study area, Izmir, is located between 26° 15′–28° 20′ E longitude and 37° 45′–39° 15′ N latitude in the Aegean region of Western Anatolia. The Tuzla Fault passes through Izmir, which is the third largest city in Turkey. In this study, we approach the problem of estimating and investigating the vertical displacements along the Tuzla Fault using a network of high precision levelling line. We established a levelling route with eight benchmarks, along the fault line. Six precise levelling campaigns were performed between 2009 and 2012, and the collected data in the surveying campaigns were processed by using the least-squares adjustment method and global testing in order to evaluate the vertical displacement. The results of the precise levelling indicated that the vertical displacements in the study area are not as significant in this period as were expected. However, compared with previous studies conducted in the same area, this study is different not only from the technique applied, but also it is carried out for the first time. [ABSTRACT FROM AUTHOR]

The impact of seismogenic ionosphere non-uniformity is considered on the Schumann resonance (SR) signals observed both in the vertical electric and two orthogonal horizontal magnetic field components. The model is able to interpret the anomalous signals observed in Japan in possible association with the earthquakes (EQs) in Taiwan. Changes in the SR intensity arise from a localized reduction of the ionosphere over the EQ epicentre. Signals in the regular Earth–ionosphere cavity are described by using the knee model of vertical conductivity profile. It is suggested that pre-seismic and seismic activity lowers the knee altitude by 20 km at the centre of disturbance, and the perturbation has the Gaussian radial dependence in the 1 Mm zone. The diffraction problem in the cavity with a localized disturbance is resolved by using the Stratton–Chu integral equation. The data of Optical Transient Detector are used to model the source distribution. A pronounced modification is obtained in the intensity around the fourth mode frequency in a form of abrupt spectral changes. The model data are found to be similar to observations, and properties of the model seismic anomalies are discussed. [ABSTRACT FROM PUBLISHER]

The August 30, 1986 (MW = 7.1) and May 30, 1990 (MW = 6.9) Vrancea intermediate-depth earthquakes, despite their almost similar magnitudes, have produced very different spectral contents as shown by the strong ground motions recorded in Bucharest and its surroundings. The differences can be attributed to different epicentral distances and to different values of the stress drop. The characteristics of the seismic ground motions recorded in Bucharest area in the 1986 and 1990 seismic events are discussed in the context of (a) the source characteristics of the two earthquakes and (b) the local soil conditions in Bucharest. Furthermore, an attempt is made to determine the soil factorsSdefined in EN 1998-1 for the Bucharest area, based on the strong ground motion dataset recorded during the two seismic events. [ABSTRACT FROM AUTHOR]

The goal of this article is to select those real (or recorded) ground motions capable of exposing the low- and mid-rise reinforced concrete frame structures to an extreme limit state. By performing correlation analyses, two optimal intensity measures are first selected to represent the ground motion damage potential. Then based on each record's damage potential, four subsets of strong ground motions, referred to as the most unfavorable ground motions, are identified and preliminarily confirmed to be applicable to the low- and mid-rise RC frame structures. [ABSTRACT FROM AUTHOR]

The horizontal pullout capacity of vertical anchors embedded in sand in the presence of pseudo static horizontal earthquake body forces has been determined by using the lower bound finite element limit analysis. The variation of the pullout factor Fγwith changes in embedment ratio of the anchor plate for different values of horizontal earthquake acceleration coefficient (αh) has been established. The effect of the anchor-soil interface friction angle on the results has also been examined. The pullout capacity decreases quite significantly with an increase in αh. The pullout capacity becomes higher for greater values of embedment ratio and interface friction angle. The normal pressure distribution along the front surface of the anchor plate and the development of failure patterns have also been examined. [ABSTRACT FROM PUBLISHER]

On 28 March 1970, an unexpected and destructive earthquake (Ms = 7.2) originated along the Erdoğmuş fault (EF), which forms the southern margin of the modern Erdoğmuş–Yenigediz graben in the central part of the Akşehir–Simav fault system. The EF is a N-dipping normal fault, ∼12 km long, generally E–W-trending, and characterized by a minor right-lateral strike–slip component. To determine its past activity, a palaeoseismological exploratory trenching study was conducted. Two trenches (EFT-1 and EFT-2) were excavated on the ground surface rupture of the 1970 Gediz earthquake near Erdoğmuş village. Based on the relative displacement between units observed and mapped in EFT-1, at least three events were identified. Two events were also identified in EFT-2. Only one of the events in EFT-1 can be dated via14C. The estimated recurrence interval on the EF is ∼910 ± 40 years. [ABSTRACT FROM AUTHOR]

Estimated source parameters, path characteristics, and site parameters are used to simulate earthquake shaking waveforms in Vietnam. We used recorded accelerograms and point-source stochastic methodologies and included in our analysis empirical relationships between the duration of ground motion, seismic moment, and magnitude, and also those between corner-frequency, high-cut-off frequency, and moment-magnitude derived from earthquakes recorded in Vietnam and adjacent regions. Local site effects were estimated using horizontal-to-vertical spectral ratio methods. Simulated times series are compared with observed accelerograms from the5.3 Dienbien earthquake in 2001, the first strong earthquake event to be recorded in Vietnam. Our synthetic time series of strong ground motion agrees well with both the observed waveforms and the response spectra, but suggests that PGA values obtained using current Vietnam codes may underestimate probable accelerations by 10–30%. [ABSTRACT FROM AUTHOR]

Incremental Dynamic Analysis (IDA) was used to evaluate the seismic response of straight, continuous 4-span bridges with different sub-structure configurations. Three different record sets were chosen to represent three different earthquake types which can occur for a site such as Vancouver (i.e., crustal, subduction interface, and subduction inslab earthquakes). Seventy eight records were considered in each set (i.e., a total of 234 records) and the capacities of the bridges were evaluated using a fast IDA algorithm. A simplified method to account for the effects of spectral shapes was used. Different subsets of the records with specific characteristics were also used in the IDA. The bridges were designed and evaluated for two different design force modification factors and bridges with different degrees of irregularity were studied. Comparisons of the IDA results obtained indicated that in most of the cases the interface record sets resulted in lower median collapse capacities and hence were the most critical of the ground motions studied. [ABSTRACT FROM AUTHOR]

Here, using three statistical models, namely, Gamma, lognormal and the Brownian Passage Time (BPT), we investigate the earthquake recurrence intervals by the use of instrumental and historical data for 15 seismogenic sources in the Iranian plateau. The renewal model parameters have been estimated using the maximum likelihood method. Also, the conditional probabilities of the occurrences of strong earthquakes during a specified interval of time have been estimated on the basis of the various statistical models. The logarithmic of likelihood function (ln L) has been used to compare the suitability of models and it was found that the lognormal model represents the best results in regions with intermittent occurrence characteristics. [ABSTRACT FROM AUTHOR]

In order to design a structure according to Eurocode EN 1990, a uniform “reliability index” must be defined for all design parameters (strengths, loadings, etc.) that present an “uncertainty.” However, Design Earthquakes constitute exception of the above parameters; thus, the present article covers this gap. For various values of reliability index and using an ideal, fictitious, Standard Normal Probability Density Function, new Peak Ground Acceleration functions of the mean return period of the design earthquakes are proposed. As a pilot scheme, we chose the 82 most important seismic records of the last 40 years for the seismic area of Greece. [ABSTRACT FROM PUBLISHER]

Although Australia has been the subject of a wide range of seismological studies, these have concentrated on specific features of the continent at crustal scales and on the broad-scale features in the mantle. The Australian Seismological Reference Model (AuSREM) is designed to bring together the existing information and provide a synthesis in the form of a 3-D model that can provide the basis for future refinement from more detailed studies. The model is grid based with a 0.5° sampling in latitude and longitude and is designed to be fully interpolable, so that properties can be extracted at any point. The crustal component makes use of prior compilations of sediment thicknesses, with cross-checks against recent reflection profiling, and provides P and S wavespeed distributions through the crust. The primary information for P wavespeed comes from refraction profiles, for S wavespeed from receiver function studies, and we are able to use the results of ambient noise tomography to link the point observations into national coverage. Density values are derived using results from gravity interpretations. AuSREM is able to build on a new map of depth to Moho, which has been created using all available information including Moho picks from over 10 000 km of full crustal profiling across the continent. In the upper mantle, the primary source of information comes from seismic surface wave tomography and a representative model has been developed to capture the features of a range of studies. Body-wave studies and regional tomography provide useful constraints on the relationship between P and S wavespeeds. The mantle model extends beyond the continent and so covers a larger area than for the crust. Below 350 km and in the surrounding area, AuSREM is linked to the S40RTS model. Potential applications of the AuSREM model come through the delineation of major structural features in the crust and mantle, and consequent improvements in, for example, earthquake location within the continent and at the nearby plate boundaries. [ABSTRACT FROM AUTHOR]

This article highlights soil-structure interaction (SSI) effects on the seismic structural response accounting for uncertainties in the model parameters and input ground motions. A probabilistic Monte Carlo methodology was used to conduct approximately six million dynamic time-history simulations using an established rheological soil-shallow foundation-structure model. Considering the results yields outcomes that contradict prevailing views of the always beneficial role of SSI. In other words, the likelihood of having amplification in structural response due to SSI is large enough that it cannot be readily ignored. This research provides a significant first step towards reliability-based seismic design procedures incorporating foundation flexibility. [ABSTRACT FROM AUTHOR]

Performance-based earthquake engineering methodologies often require a probabilistic model of structural demand. Since observations masking the probability distribution of the majority of the data are frequently found, robust estimation methods are proposed to estimate the probabilistic model parameters (i.e., central value and dispersion). The performance of thirty-three robust dispersion estimators is evaluated, for different sample sizes, using the chord rotation, curvature, shear force, and inter-story drift demands obtained after analyzing five reinforced concrete structures under real earthquake records scaled to several intensities. Based on the results, combinations involving dispersion and central value (defined in a companion article) estimators are proposed. [ABSTRACT FROM AUTHOR]

In this article, site response analyses for 124 sites collected in Korea were performed to evaluate earthquake ground motions in regions of shallow bedrock in Korea. Based on the results, a new two-parameter site classification system was developed for use in regions of shallow bedrock. The system incorporates depth to bedrock and mean VS of soil above bedrock as parameters for site classification instead of VS30. Soil sites were divided into seven site classes and the corresponding site coefficients were proposed for each site category. Some verification work demonstrates the superiority of the proposed system over the current seismic codes. [ABSTRACT FROM AUTHOR]

The noise level of the Romanian broadband stations operating since 2006 has been studied in order to identify the variations in background seismic noise as a function of time of day, season, and particular conditions at the stations. Power spectral densities and their corresponding probability density functions are used in this paper to characterize the background seismic noise. At high frequencies (> 1 Hz), seismic noise seems to have cultural origin, since significant variations (up to 55 dB) between daytime and nighttime noise levels are observed at almost all of the stations. However, this variability appears not to influence the detection capabilities of the Romanian Seismic Network in case of intermediate-depth earthquakes and earthquakes with magnitude over 3.0. For smaller magnitude events (Mw < 3), we showed that the number of stations detecting an event decreases during daytime. We studied the seasonal variation of the seismic noise for primary and secondary microseisms (with emphasize for the latter) and we demonstrated that the noise levels are higher in winter than in summer. We also observed a shift of the double-frequency peak from lower periods in summer to longer periods in winter. The polarization analysis indicated that the main sources of secondary microseisms for stations close to the Black Sea are coming from the Black Sea, while for the others the main sources are found in the Mediterranean Sea and Atlantic Ocean. Finally, the analysis of the probability density functions for stations located in different geologic conditions has pointed out that the noise level is higher for stations sited on softer formations than those sited on hard rocks. [ABSTRACT FROM AUTHOR]

A temporary seismic network deployed in northwestern Australia between October 2005 and March 2008 recorded 28 earthquakes ranging in magnitude between M L 2.0 and M L 5.3. Twenty-three of these events occurred in areas underlain by continental crust previously affected by Mesozoic continental rifting (Carnarvon and Perth basins), with five occurring within the area underlain by the Precambrian craton. Focal mechanisms for 26 of the earthquakes show dominantly strike-slip solutions, regardless of the type of underlying crust (craton or extended margin). Geomorphological investigations in the Gascoyne region have identified several youthful fault scarps, especially along the Mt. Narryer fault zone in west-central Western Australia. This fault zone lies in the epicentral region of the 1941M L 6.8 to 7.3 Meeberrie earthquake, the largest historical earthquake to have affected Australia. The 120 km-long north-trending Mt Narryer fault zone comprises five left-stepping en echelon segments. The two southern segments display west-side-up reverse displacements across the Roderick and Sanford river alluvial channels, and have captured and diverted active stream flow, formed sag ponds, and impounded Lake Wooleen. The geomorphic expression of the northern three segments, and the en echelon stepping nature of the fault zone as a whole, suggests a component of strike-slip deformation, which is consistent with the sense of faulting determined from the focal mechanism solutions in our seismicity analyses. The higher proportion of events recorded along the extended continental margin compared with the craton suggests that the dense network of late Mesozoic rift-related faults along thecontinental margin may be reactivating and responding to far-field stress conditions. However, the presence of the Mt Narryer fault system indicates that structures within the craton also accommodate some of the regional stress and can be sources of future large magnitude earthquakes, such as the1941 Meeberrie event. The differences in activity rates between the extended margin and cratonic provinces may reflect the differences in crustal architecture, and the way that faults in these two different terranes respond to far-field stresses. [ABSTRACT FROM AUTHOR]

Significant damage has been caused by past earthquakes to pile supported wharves, nevertheless a rigorous analytical vulnerability and risk analysis of pile-supported wharves has not yet been performed. Efforts so far are mainly based on pushover analyses, which do not capture dynamic phenomena during the earthquake excitation. Moreover, most methods for dynamic analyses of pile foundations focus on soil nonlinearities, but not also on the nonlinear structural response of the pile (formation of plastic hinges), which is inevitable as a mode of failure in the case of pile-supported wharves. The primary objective of this research is to propose a methodology for performance-based fragility analysis of pile-supported wharves on the basis of nonlinear dynamic analysis. A model which accounts both for soil and pile nonlinear response was investigated. A wharf section of representative geometry was subjected to parametric analysis, for which variables are input motion, its intensity, and soil properties. A two-parameter lognormal distribution was implemented for the preliminary definition of fragility curves for pile-supported wharves. Increasing the number of analyses will allow for a more refined definition of fragility curves for pile-supported wharves, in the future, that can be used for cost-efficient management of pile-supported wharves against losses due to seismic excitation. [ABSTRACT FROM AUTHOR]