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The presence of seamount on the subducting interface of oceanic and continental tectonic plates has potential to alter the characteristics of ground motion due interface earthquakes. In this study, we address the influence of seamount presence on offshore wind turbine response, through a finite element simulation of earthquake and subsequently applying the recorded shaking from earthquake simulation as input to offshore wind turbines. The wind turbine response is computing by incremental dynamic analysis and fragility curves are derived for serviceability and ultimate limits of wind turbines. The effect of hypocenter being above or below the seamount, on the offshore wind turbine fragility is also addressed.

Indonesia is a country located in the convergence of small plates and large plates. Furthermore, this causes Indonesia to be high potentially to earthquake hazards. The newest geological research published by Geophysical Research Letter (2016) shows the existence of Fault Kendeng, a fault stretches along 300 km from South Semarang, Central Java, to East Java with a movement of 0,05 millimeter per year [1]. As a result of its research, an evaluation using a non-linear time history analysis for structural buildings is necessary. The objective of this study is to evaluate structural buildings using a non-linear time history analysis. This study applies DSHA (Deterministic Seismic Hazard Analysis) method to obtain acceleration time history on bedrocks. Since the record of ground movement in Indonesia is limited, the attenuation function equation used to scale and match other country’s time acceleration history data. SSA (Site-Specific Analysis) is used to propagate earthquake acceleration from bedrocks to the surface. The earthquake acceleration on the surface generates as the earthquake load on the buildings. The results of Kendeng fault earthquake simulation using non-linear time history analysis shows that column members capacity is more robust than beam members capacity which the beam collapse mechanism occurs initially. From the maximum total drift ratio result, when the Kendeng fault earthquake occurs, the building structure performance level is at collapse prevention level Based on ATC-40 [2]. This research result shows that 96,7% of plastic hinge has not yielded. However, some elements are already damaged. Since most damage members are column, then it may require column strengthening to enhance maximum performance level at life safety condition category.

This study investigates the potential for seismic seiches in Lake Tekapo, New Zealand, triggered by ground shaking from an Mw8.2 Alpine Fault earthquake. Synthetic ground motions are used as a forcing boundary to drive lake water motions by further developing a tsunami simulation model—COMCOT—and coupling it with earthquake simulation model outputs. Our modelling results reveal that lake water oscillations are mobilised immediately by the ground movement and further amplified by cross-lake seiches. Amplitudes of lake oscillations can reach up to 4.0 m in the lake’s narrow southern arm, over 1.0 m along the shore of Lake Tekapo township, and about 1.5–2.5 m along many other parts of the lake shore. Large-amplitude water oscillations quickly attenuate in the first 5–10 min after the earthquake due to their relatively short periods, while long-period oscillations continue for a long time, albeit with much smaller amplitudes. Spectral analysis clearly reveals that the ground motions trigger both fundamental and higher modes in the lake whose oscillation periods are consistent with theoretical estimates. We find that large-amplitude lake water oscillations are better correlated with low-frequency, less energetic ground motion content than with high-frequency large-amplitude ground motions. Ground motion-triggered lake oscillations are large enough to pose potential threat to tourists, residents, boats and infrastructure both in the lake water and onshore near the waterfront. In contrast, vertical co-seismic displacements in the lake area, the conventional mechanism for tsunami generation, are too small to trigger tsunami waves of concern.

SUMMARYThe application of a physics-based earthquake simulator to Central Italy allowed the compilation of a synthetic seismic catalogue spanning 100 000 yr, containing more than 300 000 M ≥ 4.0 simulated earthquakes, without the limitations that real catalogues suffer in terms of completeness, homogeneity and time duration. The seismogenic model upon which we applied the simulator code was derived from version 3.2.1 of the Database of Individual Seismogenic Sources (DISS; http://diss.rm.ingv.it/diss/), selecting, and modifying where appropriate, all the fault systems that are recognized in the portion of Central Italy considered in this study, with a total of 54 faults. Besides tectonic stress loading and static stress transfer as in the previous versions, the physical model on which the latest version of our simulation algorithm is based also includes the Rate and State constitutive law that helps to reproduce Omori's law. One further improvement in our code was also the introduction of trapezoidal-shaped faults that perform better than known faults. The resulting synthetic seismic catalogue exhibits typical magnitude, space and time features which are comparable to those in real observations. These features include the total seismic moment rate, the earthquake magnitude distribution, and the short- and medium-term earthquake clustering. A typical aspect of the observed seismicity in Central Italy, as well as across the whole Italian landmass and elsewhere, is the occurrence of earthquake sequences characterized by multiple main shocks of similar magnitude. These sequences are different from the usual earthquake clusters and aftershock sequences, since they have at least two main shocks of similar magnitude. Therefore, special attention was devoted to verifying whether the simulated catalogue includes this notable aspect. For this purpose, we developed a computer code especially for this work to count the number of multiple events contained in a seismic catalogue under a quantitative definition. We found that the last version of the simulator code produces a slightly larger number of multiple events than the previous versions, but not as large as in the real catalogue. A possible reason for this drawback is the lack of components such as pore-pressure changes due to fluid-diffusion in the adopted physical model.

Neo-deterministic seismic hazard assessment (NDSHA), which includes the physics-based earthquake simulation, has been applied to the Alborz region in the north of Iran. In addition, two validation tests of NDSHA at a local scale have been performed for Tehran city, which is located in Alborz. Results of NDSHA at a regional scale indicate high seismic hazard in the Alborz region, compared with the adjacent regions. The maximum range of the peak ground displacement, peak ground velocity, and design ground acceleration has been estimated 30–60 cm, 30–60 cm/s, and 0.6–1.2 g, respectively. The performed validation tests of NDSHA for Tehran city show that the hybrid technique (combing of modal summation and finite difference methods) can be implemented for the generation of the synthetic waveforms and then computation of the acceleration response spectra along the 2D sediment structure in Tehran. Results of a new validation test performed in this study show that the predicted peak ground acceleration (PGA) values from the simulated acceleration response spectra along the selected section are quite reliable. Therefore, the supposed geophysical parameters of the 2D sediment structure and 1D bedrock model presented in this study can be used to estimate PGA and spectral amplification from different earthquake scenarios of the active faults around Tehran.

The prediction of earthquake ground motions in accordance with recorded observations from past events is the core business of engineering seismology. An attenuation model presents values of parameters characterising the intensities and properties of ground motions estimated of projected earthquake scenarios (which are expressed in terms of magnitude and distance). Empirical attenuation models are developed from regression analysis of recorded strong motion accelerograms. In situations where strong motion data are scarce the database of records has to cover a very large area which may be an entire continent (eg. Ambrasey model for Europe) or a large part of a continent (eg. Toro model for Central & Eastern North America) in order that the size of the database has statistical significance (Toro et al., 1997; Ambrasey, 1995). Thus, attenuation modelling based on regression analysis of instrumental data is problematic when applied to regions of low and moderate seismicity. This is because of insufficient representative data that has been collected and made available for model development purposes.

In regions with slow-moving faults, the incompleteness of earthquake and fault data complicates the study of seismic hazard. The instrumental and historical seismic catalogs cover a short period compared with the long-time interval between major events. Paleoseismic evidence allows us to increase the time frame of actual observations, but data is still scarce and imprecise. Physics-based earthquake simulations overcome the limitations of actual earthquake catalogs and generate long-term synthetic seismicity. The RSQSim earthquake simulator used in our study reproduces the earthquake physical processes based on a 3D fault model that contains the kinematics, the long-term slip rates and the rate-and-state friction properties of the main seismogenic sources of a region. The application of earthquake simulations to the Eastern Betic Shear Zone, a slow fault system at southeastern Spain, allows the compilation of 100 kyr-synthetic catalogs of MW > 4.0 events. Multisection earthquakes and complete ruptures of some faults in this region, preferentially on strike-slip dominant ruptures, are possible according to our simulations. The largest MW > 6.5 events are likely as a result of jumping ruptures between the Carboneras and the Palomares faults, with recurrence times of < 20,000 years; and less frequently between the Alhama de Murcia and the Los Tollos faults. A great variability of interevent times is observed between successive synthetic seismic cycles, in addition to the occurrence of complex co-ruptures between faults. Consequently, the occurrence of larger earthquakes, even MW ≥ 7.0, cannot be ruled out, contrasting with the low to moderate magnitudes recorded in the instrumental and historical earthquake catalog.

On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens of temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA.

We present a highly scalable 3D fully-coupled Earth & ocean model of earthquake rupture and tsunami generation. We model seismic, acoustic and surface gravity wave propagation in elastic (Earth) and acoustic (ocean) materials sourced by physics-based non-linear earthquake dynamic rupture. Complicated geometries, including high-resolution bathymetry, coastlines and segmented earthquake faults are discretized by adaptive unstructured tetrahedral meshes. A Discontinuous Galerkin discretization with ADER local time-stepping (ADER-DG) yields petascale computational efficiency and high-order accuracy in time and space. We compare the 3D fully-coupled approach to a benchmark problem for 3D-2D linked models that use 2D shallow-water modeling. We present a large-scale fully-coupled model of the 2018 Sulawesi events that links the dynamics from supershear earthquake faulting to elastic and acoustic waves in Earth and ocean to tsunami gravity wave propagation in the narrow Palu Bay. And we demonstrate scalability and performance of the MPI+OpenMP parallelization on three petascale supercomputers., 13 pages, 6 figures; European Commission Project: ChEESE - Centre of Excellence for Exascale in Solid Earth (EC-H2020-823844)

According to the potential disaster points of the rock bedding slope with a weak structural plane along the Sichuan Tibet railway, the shaking table test of earthquake simulation was designed and carried out. The acceleration response and displacement response of the slope under different input earthquake conditions were monitored, and the HHT method was mainly used to analyze the seismic response of the slope. The results show that the rock bedding slope shows obvious “elevation effect” and “surface effect” under the action of seismic waves of different intensities. With the increase of the amplitude value of the input earthquake, the elevation effect and the surface effect gradually weakened. When the amplitude of the seismic wave reached 0.9 g, the movement inconsistency of the slope on both sides increased, and the slope gradually separated from the main body of the slope, resulting in slope instability. The characteristics of the seismic signal in the time–frequency domain can be better described by the Hilbert-Huang transform. In the time domain, the energy is mainly concentrated in 2–6 and 12–15 s, and the predominant frequency is concentrated between 5 and 40 hz. With the increase of elevation, the former increases and the latter decreases. In addition, the change of the peak value of the marginal spectrum can clearly show the development process of the earthquake damage inside the slope. At the height of 100 cm, the inflection point can be seen obviously in the slope. It shows that the damage occurs at the height of 100 cm, and the degree of earthquake damage near the slope is stronger than that inside the slope. The recognition results of marginal spectrum are in good agreement with the experimental results.

The potentiality of an improved physics-based earthquake simulation algorithm for modelling the long-term spatiotemporal process of strong earthquakes preparation is explored. The physical model on...

International audience; In this paper, we are interested in the seismic wave propagation into an uncertain medium. To this end, we performed an ensemble of 400 large-scale simulations that requires 4 million core-hours of CPU time. In addition to the large computational load of these simulations, solving the uncertainty propagation problem requires dedicated procedures to handle the complexities inherent to large data set size and the low number of samples. We focus on the peak ground motion at the free surface of the 3D domain, and our analysis utilizes a surrogate model combining two key ingredients for complexity mitigation: i) a dimension reduction technique using empirical orthogonal basis functions and ii) a functional approximation of the uncertain reduced coordinates by polynomial chaos expansions. We carefully validate the resulting surrogate model by estimating its predictive error using bootstrap, truncation, and cross-validation procedures. The surrogate model allows us to compute various statistical information of the uncertain prediction, including marginal and joint probability distributions, interval probability maps, and 2D fields of global sensitivity indices.

Understanding of lithosphere dynamics, tectonic stress localization, earthquake occurrences, and seismic hazards has significantly advanced during the last decades. Meanwhile, despite the major advancements in geophysical sciences, yet we do not see a decline in earthquake disaster impacts and losses. Although earthquake disasters are mainly associated with significant vulnerability of society, comprehensive seismic hazards assessments and earthquake forecasting could contribute to preventive measures aimed to reduce impacts of earthquakes. Modeling of lithosphere dynamics and earthquake simulations coupled with a seismic hazard analysis can provide a better assessment of potential ground shaking due to earthquakes. Here we present a block-and-fault dynamics (BAFD) model, which simulates earthquakes due to lithosphere dynamics and allows for studying the influence of fault network properties and regional movements on seismic patterns. The model's performance is analyzed in terms of reproduction of basic features of the observed seismicity such as the frequency-magnitude relationship, clustering of earthquakes, occurrences of large events, fault slip rates, and earthquake mechanisms. Several studies related to the application of the BAFD model to the following earthquake-prone regions are reviewed: the southeastern Carpathians, Caucasus, the western India, Tibet-Himalaya, and the Sunda Arc. We examine then a new approach to seismic hazard analysis, which is based on instrumentally recorded, historical and BAFD-simulated earthquakes, and analyze how earthquake modeling can assist in hazard assessment. Finally, we discuss perspectives in modeling of earthquake occurrences and improvements in hazard assessment.

The application of a newly developed physics-based earthquake simulator to the active faults inferred by aeromagnetism in southern Calabria has produced a synthetic catalog lasting 100 ky including more than 18,000 earthquakes of magnitude ≥ 4.0. This catalog exhibits temporal, spatial and magnitude features, which resemble those of the observed seismicity. As an example of the potential use of synthetic catalogs, a map of the peak ground acceleration (PGA) for a given exceedance probability on the territory under investigation has been produced by means of a simple attenuation law applied to all the events reported in the synthetic catalog. This map was compared with the existing hazard map that is presently used in the national seismic building regulations. The comparison supports a strong similarity of our results with the values given in the present Italian seismic building code, despite the latter being based on a different methodology. The same similarity cannot be recognized for the comparison of our present study with the results obtained from a previous study based on our same methodology but with a different geological model.

A method for simulating an ensemble of orthogonal horizontal near-fault ground motion components for a specified set of earthquake source and site characteristics is presented. We develop a parameterized stochastic model of the near-fault ground motion in two orthogonal horizontal directions. Near-fault ground motions may or may not contain a forward directivity pulse in at least one direction, and our final model will account for both pulselike and nonpulselike cases. In this paper we focus only on the pulselike motions. By fitting the model to a database of pulselike near-fault ground motions, we develop predictive equations for the model parameters in terms of the earthquake source and site characteristics, and we estimate the correlations between the model parameters. We use the predictive equations to generate sets of correlated model parameters and a corresponding ensemble of synthetic pairs of orthogonal horizontal near-fault ground motion components for a given design scenario specified in terms of earthquake and site characteristics. The resulting synthetic motions have the same statistical characteristics as the motions in the database, including the variability for the given set of earthquake source and site characteristics. Use of simulated motions is of particular interest in performance-based earthquake engineering due to scarcity of near-fault recordings.

We study the spatio-temporal characteristics of earthquakes, and find that power laws and allometric growth laws are both statistically significant in the seismic dataset. For further analyzing the complexity of earthquake sequence, an approach of weighted earthquake networks modeling is presented with using the seismic and rock mass datasets. The rock masses covering the entire region are used to divide the region into a lot of small areas. It is shown that the distributions of connectivities and link weights both follow power law decay forms. The discovery of allometric growth laws is important for studying the dynamics of massive earthquakes. The suggested earthquake network is helpful to study the interactions between rock masses and expand a research prototype for modeling seismicity on complex networks.

Earthquake magnitude distributions among faults within a fault system are determined from regional seismicity and fault slip rates using binary integer programming. A synthetic earthquake catalog (i.e., list of randomly sampled magnitudes) that spans millennia is first formed, assuming that regional seismicity follows a Gutenberg-Richter relation. Each earthquake in the synthetic catalog can occur on any fault and at any location. The objective is to minimize misfits in the target slip rate for each fault, where slip for each earthquake is scaled from its magnitude. The decision vector consists of binary variables indicating which locations are optimal among all possibilities. Uncertainty estimates in fault slip rates provide explicit upper and lower bounding constraints to the problem. An implicit constraint is that an earthquake can only be located on a fault if it is long enough to contain that earthquake. A general mixed-integer programming solver, consisting of a number of different algorithms, is used to determine the optimal decision vector. A case study is presented for the State of California, where a 4 kyr synthetic earthquake catalog is created and faults with slip ≥3 mm/yr are considered, resulting in > 10 6 variables. The optimal magnitude distributions for each of the faults in the system span a rich diversity of shapes, ranging from characteristic to power-law distributions.

The 1995 MW 6.4 Aigion earthquake is one of the largest and most destructive seismic events that have occurred in Greece over the past few decades. The ground shaking in the near-fault region was recorded by a strong-motion accelerograph in the city of Aigion, at a distance of about 16 km from the epicenter. The recorded horizontal ground acceleration exceeded 0.5 g, whereas the horizontal components of ground velocity exhibited pulse-like motions of large amplitude. These ground-motion characteristics have been attributed to forward rupture directivity combined with the effects of soil and topography. In this article, broadband synthetic ground motions are generated at selected locations and at a dense grid of observation points extending over the causative fault of the 1995 Aigion earthquake using a hybrid deterministic-stochastic method. The low-frequency components of the synthetic ground motion are simulated using the discrete wavenumber method and the generalized transmission and reflection coefficient technique, whereas the high-frequency components of the synthetic ground motion are generated using the stochastic modeling approach and the specific barrier model. The two independently derived ground-motion components are then combined using matched filtering at a crossover frequency of 2 Hz to generate broadband ground-motion time histories and response spectra. The effects of soil and topography on the simulated ground motion in the city of Aigion are also investigated through site response analysis. In addition, the strong motion recorded at Aigion is corrected for crustal anisotropy using the cross-correlation technique, thus further enhancing the alignment of recorded and synthetic ground-motion time histories. Finally, the synthetic ground motions are compared with ground-motion estimates obtained from observed geotechnical damage, USGS ShakeMaps, and ground-motion prediction equations.

The earthquake occurrence in the Corinth Gulf (Greece) is modeled by means of the Linked Stress Release Model, which combines the gradual increase of the strain energy due to continuous tectonic loading and its sudden release when an event occurs. The modeling is based on the theory of stochastic point processes and it is determined by the conditional intensity function. The modeled time–dependent seismicity incorporates stress transfer and interactions among the major fault segments that belong either to the western or to the eastern part of the study area. Static stress changes caused by the coseismic slip of eight characteristic events that occurred during the instrumental era were calculated. Their perturbations reveal that earthquakes occurring in the eastern part provoke excitation in the western part while the events that occurred in the western part do not affect the seismicity of the eastern part. This result was taken into account and the values of the model parameters were constrained accordingly. The analysis is also performed on synthetic earthquake catalogs developed by an earthquake simulator algorithm that can replicate the seismic activity in the study area and yields to comparable results.

Subduction is substantially multi-scale process where the stresses are built by long-term tectonic motions, modified by sudden jerky deformations during earthquakes, and then restored by following multiple relaxation processes. Here, we develop a cross-scale thermomechanical model aimed to simulate the subduction process from 1 minute to million years' time scale. The model employs elasticity, nonlinear transient viscous rheology, and rate-and-state friction. It generates spontaneous earthquake sequences and by using an adaptive time-step algorithm, recreates the deformation process as observed naturally during the seismic cycle and multiple seismic cycles. The model predicts that viscosity in the mantle wedge drops by more than three orders of magnitude during the great earthquake with a magnitude above 9. As a result, the surface velocities just an hour or day after the earthquake are controlled by viscoelastic relaxation in the several hundred km of mantle landward of the trench and not by the afterslip localized at the fault as is currently believed. Our model replicates centuries-long seismic cycles exhibited by the greatest earthquakes and is consistent with the postseismic surface displacements recorded after the Great Tohoku Earthquake. We demonstrate that there is no contradiction between extremely low mechanical coupling at the subduction megathrust in South Chile inferred from long-term geodynamic models and appearance of the largest earthquakes, like the Great Chile 1960 Earthquake.

Indonesia is located at the junction of three tectonic plates and has many active faults. The consequence of this tectonic arrangement makes Indonesia prone to earthquakes. Therefore, earthquake mitigation efforts based on an early warning system need to be done. The design of an earthquake strength estimation system, based on python, for this early warning, analyzes the initial phase of the first three seconds since the arrival of the P wave, using parameters in the form of Pd (the maximum amplitude of the first three seconds of the arrival of the P wave). The resulting tools and systems consist of hardware in the form of Raspberry Pi3B + and ADXL345. The system will detect in real time and automatically trigger an earthquake using the STA / LTA method. When the Pd and Td parameters have been obtained, the system will calculate and issue earthquake strength information, in the form of magnitude and intensity scale of earthquake damage MMI (Modified Mercally Intensity), which will then be sent automatically via the telegram application. Testing of tools and systems was carried out in an earthquake simulator, using the Padang earthquake parameters on 30 September 2009, 17:16:09 WIB. The results of the test produce an intensity scale of VIII MMI, these results are close to the results of the BMKG for the earthquake, with an intensity scale of VIII MMI. From these results the designed tools and systems can be used to provide early warning in the event of an earthquake.

We investigate the structural properties of a spatio-temporal network of earthquake events that incorporates magnitude information between the connected events. The network creates temporally directed links from an origin event towards a later event if it breaks the record closest distance from the origin among all the events in the catalog so far. Additionally, the links are conditionally classified based on the magnitude difference between connected events: “up” (“down”) connections point from a weaker (stronger) to a stronger (weaker) event. Using earthquake records from the Philippines from 1973 to 2012 and southern California from 1982 to 2012, we observe that the out-degree distributions show slight deviations from the corresponding Poisson distribution of the same mean. The space and time separations of connected earthquakes both show power-law regimes, suggesting spatio-temporal (self-)organization. More importantly, the conditional distributions of “up” and “down” connections in space, time, and network structure point to a higher likelihood of a stronger event triggering a nearby weaker event for the first few connections, as in the case of aftershocks. The results are captured by a sandpile-based model where a small but finite probability of preferentially targeting the most susceptible grid site is introduced. Our analysis, coupled with the discrete model analog, provides a quantitative picture of the spatio-temporal and magnitude organization of seismicity beyond just the successive events. The technique may be extended to further characterize similar long-period earthquake records to yield a more complete picture of the underlying processes involved in seismicity.

The seismic performance of an important structure in Christchurch, New Zealand was well-documented during the 2010–2011 Canterbury earthquake sequence. Minor ground deformation and negligible-to-minor structural damage occurred during the primary events of the sequence, except for the 22 February 2011 Mw6.2 Christchurch earthquake, which produced differential movement of the basement mat and architectural and structural damage. This case history is evaluated to garner insights. Static settlements are estimated to establish the pre-seismic conditions of the building. Dynamic nonlinear effective stress soil-structure-interaction analysis are performed for the primary events of the Canterbury earthquake sequence using FLAC2D with the PM4Sand constitutive model to capture the cyclic response of the key soil units. The analytical results indicate the post-Canterbury earthquake sequence measured differential mat movements were primarily due to the earthquake events. A thin liquefiable layer, which historic maps indicate is now a buried stream deposit, is largely responsible for the ground movements. A medium dense sandy gravel also appeared to contribute significantly to the observed foundation movements.

A procedure for estimating the number of simultaneously yielding stories (NSYS) in a shear type building subjected to seismic ground excitation is proposed. Proper estimation of NSYS values will lead to more accurate estimation of axial force demand in columns which will result in economical design of columns. In this procedure, the main pulse of the velocity record responsible for causing the maximum number of stories to yield simultaneously was identified and isolated to idealize it by a full-sine velocity pulse, as an extension of the procedure for estimating the NSYS for a full-sine pulse velocity base excitation developed previously by the authors. A set of eighteen earthquake records sorted into three categories of earthquakes were considered, namely: earthquake excitations having (i) a single dominant pulse (ii) multiple distinct pulses, and; (iii) no distinct pulses in their velocity record. Since most of these earthquakes have relatively long duration main pulses, another set of eighteen earthquake records was obtained by condensing their acceleration time scale and was used to study the proposed procedure for earthquakes that have shorter duration main pulses. The estimated maximum value of NSYS obtained from the proposed procedure was found to be adequately close to the actual value observed from OpenSees analysis for the structures and earthquakes considered.

Earthquake precursors are vitally important for warning and risk evaluation, but shedding light on them is a complex task for seismologists and geologists. We attempted to illuminate the precursory rules of fault failure by traditional biaxial-direction shear tests for a zigzag-type gouge with different size and arrangement of simulated faults manufactured from polymethyl methacrylate materials. Shear stress, acoustic emissions, and vibration signals were recorded and comparatively analyzed. Two important findings were obtained: (1) the linearly increasing trend of shear stress peaks generated by foreshocks may indicate the foreshock effect before a larger earthquake triggered by natural fault gouge failure; and (2) four kinds of earthquake precursors were discovered, and earthquake intensity and precursors may be dependent on the time of macro-fracture formation and the quantity of micro-fractures initiated before mainshock. The study contributes to interpreting earthquake shear-slip characteristics and may even help provide warnings of failure and instability.

The purpose of this study is to verify fault modeling in the source region of the 1940 Shakotan-Oki earthquake using active faults offshore of Japan. Tsunami heights simulated in previous studies are found to be lower than observed levels, which makes it difficult to explain historical tsunami records of this earthquake. However, the application of appropriate slip magnitudes in the fault models may explain these differences. In the “Project for the Comprehensive Analysis and Evaluation of Offshore Fault Informatics (the Project),” a new fault model is constructed using marine seismic data and geological and geophysical data compiled by the Offshore Fault Evaluation Group, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) as part of the Project for Fault Evaluation in the Seas around Japan (Ministry of Education, Culture, Sports, Science and Technology, MEXT). Single-channel and multichannel reflection seismic data were used that includes information from a new fault identified in previous surveys. We investigated fault geometries and their parameters using the above data. Here, we show that the geometric continuity of these faults is adjusted by increasing the magnitude of fault slip. Standard scaling laws are applied on the basis of strong ground motion of the fault parameters, and the validity of the fault model is examined by comparing tsunami heights along the Japanese coastline from historically observed records with tsunami height from simulation analysis. This verification quantitatively uses Aida’s K and κ scale and variance parameters. We determine that the simulated tsunami height determined using the new model approach the heights observed historically, which indicates that the model is valid and accurate for the source region.

The Himalayan–Tibetan region has a long history of devastating earthquakes with wide-spread casualties and socio-economic damages. Here, we conduct the probabilistic seismic hazard analysis by incorporating the incomplete historical earthquake records along with the instrumental earthquake catalogs for the Himalayan–Tibetan region. Historical earthquake records back to more than 1000 years ago and an updated, homogenized and declustered instrumental earthquake catalog since 1906 are utilized. The essential seismicity parameters, namely, the mean seismicity rate γ, the Gutenberg–Richter b value, and the maximum expected magnitude M max are estimated using the maximum likelihood algorithm assuming the incompleteness of the catalog. To compute the hazard value, three seismogenic source models (smoothed gridded, linear, and areal sources) and two sets of ground motion prediction equations are combined by means of a logic tree on accounting the epistemic uncertainties. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 and 1.0 s are predicted for 2 and 10% probabilities of exceedance over 50 years assuming bedrock condition. The resulting PGA and SA maps show a significant spatio-temporal variation in the hazard values. In general, hazard value is found to be much higher than the previous studies for regions, where great earthquakes have actually occurred. The use of the historical and instrumental earthquake catalogs in combination of multiple seismogenic source models provides better seismic hazard constraints for the Himalayan–Tibetan region.

We develop a framework for assessing the sensitivity and variability of tsunami inundation characteristics for stochastic physics-based scenarios of mega-thrust subduction earthquakes. The method is applied to the 2011 Tohoku, Japan earthquake, and tested against observed inundation maps at several locations along the Tohoku coast, using 11 different, previously published, rupture models for this devastating tsunamgenic earthquake. The earthquake rupture models differ in fault dimension (length and width), geometry (dip, strike and top-edge depth), as well as asperity characteristics (slip heterogeneity on the fault plane). The resulting source variability allows exploring a wide range of tsunami scenarios for an M w 9 mega-thrust subduction earthquake in the Tohoku region to conduct thorough sensitivity analyses and to quantify the inundation variability. The numerical results indicate a strong influence of the reference source models on inundation variability, and demonstrate significant sensitivity of inundation to the details of the rupture realization. Therefore, relying on a single particular earthquake rupture model as a representative case when varying earthquake source characteristics may lead to under-representation of the variability of potential scenarios. Moreover, the proposed framework facilitates the rigorous development of critical scenarios for tsunami hazard and risk assessments, which are particularly useful for tsunami hazard mapping and disaster preparedness planning.

In July 2013, a sequence of more than 340 earthquakes was induced by reservoir stimulations and well‐control procedures following a gas kick at a deep geothermal drilling project close to the city of St. Gallen, Switzerland. The sequence culminated in an ML 3.5 earthquake, which was felt within 10–15 km from the epicenter. High‐quality earthquake locations and 3‐D reflection seismic data acquired in the St. Gallen project provide a unique data set, which allows high‐resolution studies of earthquake triggering related to the injection of fluids into macroscopic fault zones. In this study, we present a high‐precision earthquake catalog of the induced sequence. Absolute locations are constrained by a coupled hypocenter‐velocity inversion, and subsequent double‐difference relocations image the geometry of the ML 3.5 rupture and resolve the spatiotemporal evolution of seismicity. A joint interpretation of earthquake and seismic data shows that the majority of the seismicity occurred in the pre‐Mesozoic basement, hundreds of meters below the borehole and the targeted Mesozoic sequence. We propose a hydraulic connectivity between the reactivated fault and the borehole, likely through faults mapped by seismic data. Despite the excellent quality of the seismic data, the association of seismicity with mapped faults remains ambiguous. In summary, our results document that the actual hydraulic properties of a fault system and hydraulic connections between its fault segments are complex and may not be predictable upfront. Incomplete knowledge of fault structures and stress heterogeneities within highly complex fault systems additionally challenge the degree of predictability of induced seismicity related to underground fluid injections.

This paper proposes a stochastic approach to model the earthquake uncertainties in terms of the rupture location and the slip distribution for a future event, with an expected earthquake magnitude. Once the statistical properties of earthquake uncertainties are described, they are then propagated into the tsunami response and the inundation at assessed coastal areas. The slip distribution is modeled as a random field within a non-rectangular rupture area. The Karhunen-Loeve (K-L) expansion method is used to generate samples of the random slip, and a translation model is employed to obtain target probability properties. A strategy is developed to specify the accuracy of the random samples in terms of numbers of sub-faults of the rupture area and the truncation of the K-L expansion. The propagation of uncertainty into the tsunami response is performed by means of a Stochastic Reduced Order Model. To illustrate the methodology, we investigated a study case in north Chile. We first demonstrate that the stochastic approach generates consistent earthquake samples with respect to the target probability properties. We also show that the results obtained from SROM are more accurate than those obtained with classic Monte Carlo simulations. To validate the methodology, we compared the simulated tsunamis and the tsunami records for the 2014 Chilean earthquake. Results show that leading wave measurements fall within the tsunami sample space. At later times, however, there are mismatches between measured data and the simulated results, suggesting that other sources of uncertainties are as relevant as the uncertainty of earthquakes.

Over the past decades, several studies have compared damage induced by near-fault and far-fault earthquakes in a deterministic approach. Following a probabilistic approach and generating several scenarios, the present study was aimed at assessing the probabilistic two-hazard risk of a structure concurrently subjected to earthquake and earthquake-induced blast. The two critical events (earthquake and blast explosion) were considered as compatible and dependent events, such that the blast would occur simultaneously with the earthquake and as the result of it. The probabilistic two-hazard risk was evaluated in two separate phases: one was characterized by near-fault earthquakes with blast; and the other phase was defined by far-fault earthquakes with blast. Comparing the probabilistic risk for the two phases revealed that the probabilistic risk of the near-field earthquake, though with a long return period, is substantially greater than that of the far-fault earthquake.

Back-projection analysis of earthquakes is a type of array processing that images the source of seismic waves coherently recorded at stations throughout the seismic network. The method was developed following the magnitude 9.2 Sumatra-Andaman earthquake in 2004. Although properties of earthquakes have been investigated using array data prior to the introduction of the back-projection method, this technique differs from other approaches because it makes limited assumptions and allows detailed and complex rupture propagation to be examined. These advantages have led several researchers to apply the method to many of the largest earthquakes to occur this century. The method has also been effective for the detection of smaller events. A critical component of the success of back-projection has been the development of large-scale, dense seismic arrays. Further improvements and future applications of the method will depend greatly on the continued maintenance and development of these networks.

Statistical methods and various models in time-space-magnitude parameter space of earthquakes are being developed to analyze seismic activity based on earthquake hypocenter catalogs that are routinely accumulated. Considering complex geophysical environments and uncertainties, we seek proper stochastic modeling that depends on the history of earthquake occurrences and relevant geophysical information for describing and forecasting earthquake activity. Also, we need empirical Bayesian models with many parameters in order to describe nonstationary or nonhomogeneous seismic activity. This review is concerned with earthquake predictability research aimed at realizing practical operational forecasting. In particular, uncertainty lies in identifying whether abnormal phenomena are precursors to large earthquakes. The predictability of such models can be examined by certain statistical criteria.

To establish viable earthquake counterplans for ports in Korea, data regarding earthquake motion on the ground and in buildings must be collected using acceleration monitoring systems. Acceleration monitoring-based strategies for port facilities are useful not only for ensuring rapid responses during and after earthquakes but also for regional data collection to assist reliable seismic design. Acceleration monitoring systems were installed at coastal facility sites in target ports, including a soil site to represent the facility and a rock site as a reference. The systematic earthquake alert software was designed to help them in decision-making about a possible seismic hazard and its reporting. The earthquake alert system was composed of two sequential functional software systems sharing an acceleration monitoring database applied to the target ports. The earthquake response software system triggers an alarm based on the peak ground acceleration per second computed from the monitored data. Then, t...

We develop a new approach to image earthquake rupture from strong motion data. We use a large data set of aftershock waveforms, interpolated over the seismic fault to obtain Green's function approximations. Next we deploy a Bayesian inversion method to characterize the slip distribution, the rupture velocity, the slip duration, and their uncertainties induced by errors in the Green's functions. The method is applied to the 29 May 2012 Mw 6 Emilia earthquake, which ruptured a fault buried below the Po Plain sediments (Northern Italy). Despite the particularly complex wave propagation, the near-field strong motion observations are well reproduced with 15 rupture parameters. The rupture and slip velocities were notably slow (~0.5 Vs and

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reli- able and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489–508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93–165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489–508, 2003): the computer codes were improved to better fit the need of producing real- istic ground shaking maps and ground shaking scenar- ios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.

International audience; We investigate temporal variations of the polarization anomaly of surface waves (Rayleigh and Love) relative to an isotropic medium, before and after the 2008 June 13, Iwate-Miyagi Nairiku earthquake (Mw = 6.9) in Japan, using passive image interferometry. We use continuous data records of 20 high-sensitivity three-component seismic stations (National Institute for Earth Sciences and Disaster Resilience—NIED Hi-net) from mid-2007 to the end of 2009. We compute cross-correlations of ambient seismic noise between each pair of stations, in the frequency range of 0.08-0.22 Hz. The temporal variations of the surface wave polarization show slow and weak variations due to seasonal changes to which rapid and strong variations are superposed at the time of the earthquake, and more surprisingly, also a month and a half before the earthquake. Strong changes in the polarization of surface waves might be related to changes in the distribution of crack orientation affecting seismic anisotropy.

A new algorithm is proposed to implement viscoelastic wave propagation in earth medium with surface topography by introducing history variables into integral type GZB constitutive equations and by using the recursive formulae of these history variables. Combining the proposed algorithm with the flexural wave algorithm for frame structure and the algorithm for bidirectional wave propagation, a new type of integrated method is developed for earthquake response analyses of near-fault building clusters in mountain city due to rupture of causative fault. The earthquake responses of building clusters of frame structures situated at different sites of a mountain in Chongqing city, China, are studied during a hypothetical M w 6.2 near-fault earthquake. The numerical results show that, for the multi-story buildings, the maximum peak value of beam-end bending moments appears in the building on the hill top and the earthquake risk positions are mainly at the bottom and/or the top of the buildings. For the high-rise buildings, the maximum peak value of beam-end bending moments appears in the building on the mountainside and the earthquake risk positions are mainly at the bottom and/or the middle of the buildings.

We use ground-motion simulations of the 2013 Bohol, Philippines, earthquake along with a new post-disaster exposure/damage database to constrain building fragility and vulnerability. The large number of damaged buildings (>70,000) and the wide spread of seismic intensities caused by this earthquake make it an ideal candidate for such a study. An extensive survey was conducted leading to a robust description of over 25,000 damaged and undamaged structures. Ground-motion fields were simulated using ground-motion prediction equations and stochastic modeling, and the estimated and observed values were compared. The finite source model used in the simulation was based on the analysis of aftershocks and SAR data. The ground motions were associated with the empirical database to derive fragility and vulnerability models. Results indicate that the pattern of damage is best captured in the stochastic simulation. Constraints were placed on seismic building fragility and vulnerability models, which can promote more effective implementation of construction regulations and practices.

This paper describes earthquake and tsunami scenarios as basic information for preparing for the next Nankai megathrust earthquakes. Models to clarify the size of the Nankai megathrust earthquake and changes in occurrence intervals, simulations using such models, and simulations of crustal deformations and tsunamis based on the simulations were employed. This paper re-examines past earthquakes and tsunamis, the possibility of slightly larger earthquakes and tsunamis, their sizes, the necessity of countermeasures against subsidence caused by earthquakes in the Inland Sea, the possibility of the Nankai earthquake occurrence before the Tokai (Tonankai) earthquake, and the possibility of the triggering of the Nankai earthquake by the Hyuga-nada earthquake.

The recent strong earthquakes in Central Italy allow for a comparative analysis of their aftershocks from the viewpoint of the Unified Scaling Law for Earthquakes, USLE, which generalizes the Gutenberg–Richter relationship making use of naturally fractal distribution of earthquake sources of different size in a seismic region. In particular, we consider aftershocks as a sequence of avalanches in self-organized system of blocks-and-faults of the Earth lithosphere, each aftershock series characterized with the distribution of the USLE control parameter, η. We found the existence, in a long-term, of different, intermittent levels of rather steady seismic activity characterized with a near constant value of η, which switch, in mid-term, at times of transition associated with catastrophic events. On such a transition, seismic activity may follow different scenarios with inter-event time scaling of different kind, including constant, logarithmic, power law, exponential rise/decay or a mixture of those as observed in the case of the ongoing one associated with the three strong earthquakes in 2016. Evidently, our results do not support the presence of universality of seismic energy release, while providing constraints on modelling seismic sequences for earthquake physicists and supplying decision makers with information for improving local seismic hazard assessments.

This work focuses on the evaluation of the seismic hazard for Romania using earthquake catalogues generated by a Monte Carlo approach. The seismicity of Romania can be attributed to the Vrancea intermediate-depth seismic source and to 13 other crustal seismic sources. The recurrence times of large magnitude seismic events (both crustal and subcrustal), as well as the moment release rates are computed using simulated earthquake catalogues. The results show that the largest contribution to the overall moment release for the crustal seismic sources is from the seismic regions in Bulgaria, while the seismic regions in Romania contribute less than 5% of the overall moment release. In addition, the computations show that the moment release rate for the Vrancea subcrustal seismic source is about ten times larger than that of all the crustal seismic sources. Finally, the Monte Carlo approach is used to evaluate the seismic hazard for 20 cities in Romania with populations larger than 100,000 inhabitants. The results show some differences between the seismic hazard values obtained through Monte-Carlo simulation and those in the Romanian seismic design code P100-1/2013, notably for cities situated in the western part of Romania that are influenced by local crustal seismic sources.

Seismic surges and landslides are both major secondary mountain hazards during an earthquake. This paper investigates earthquake- and landslide-induced composite surges through large-scale shaking table water tank model experiments. A series of tests were conducted for various initial water depths, peak ground accelerations, slide impact velocities, and slide volumes. Based on the results of the tests, the effects of these parameters on the maximum wave heights of the earthquake- and landslide-induced composite surges were analyzed. An amplification coefficient of seismic surges was defined, and the prediction equation for the amplification coefficient was developed through non-dimensional multiple linear regression analysis. Then, an empirical equation for the maximum wave heights of the composite surges was developed based on the amplification coefficient and Demirel’s method. This equation provides a calculation method for earthquake- and landslide-induced composite surge waves.

Strong ground shaking during earthquakes can greatly affect the ancient monuments and subsequently demolish the human heritage. On October 12th 1992, a moderate earthquake (Ms = 5.8) shocked the greater Cairo area causing widespread damages. Unfortunately, the focus of that earthquake is located about 14 km to the south of Zoser pyramid. After the earthquake, the Egyptian Supreme council of antiquities issued an alarm that Zoser pyramid is partially collapsed and international and national efforts are exerted to restore this important human heritage that was built about 4000 years ago. Engineering and geophysical work is thus needed for the restoration process. The definition of the strong motion parameters is one of the required studies since seismically active zone is recorded in its near vicinity. The present study adopted the stochastic method to determine the peak ground motion (acceleration, velocity and displacement) for the three largest earthquakes recorded in the Egypt’s seismological history. These earthquakes are Shedwan earthquake with magnitude Ms = 6.9, Aqaba earthquake with magnitude Mw = 7.2 and Cairo (Dahshour earthquake) with magnitude Ms = 5.8. The former two major earthquakes took place few hundred kilometers away. It is logic to have the predominant effects from the epicentral location of the Cairo earthquake; however, the authors wanted to test also the long period effects of the large distance earthquakes expected from the other two earthquakes under consideration. In addition, the dynamic site response was studied using the Horizontal to vertical spectral ratio (HVSR) technique. HVSR can provide information about the fundamental frequency successfully; however, the amplification estimation is not accepted. The result represented as either peak ground motion parameters or response spectra indicates that the effects from Cairo earthquake epicenter are the largest for all periods considered in the present study. The level of strong motion as indicated by peak ground acceleration reaches the value of 250 gals which is considerably high. At the end, it is worth to mention that the information resulted from the present work may be useful for the planned restoration decision of the Zoser pyramid site.