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A major interplate earthquake occurred on September 16th, 2015, near Illapel, central Chile. This event generated a tsunami of moderate height, however, one which caused significant near field damage. In this study, we model the tsunami produced by some rapid and preliminary fault models with the potential to be calculated within tens of minutes of the event origin time. We simulate tsunami signals from two different heterogeneous slip models, a homogeneous source based on parameters from the global CMT Project, and furthermore we used plate coupling data from GPS observations to construct a heterogeneous fault based on a priori knowledge of the subduction zone. We compare the simulated signals with the observed tsunami at tide gauges located along the Chilean coast and at offshore DART buoys. For this event, concerning rapid response, the homogeneous source and coupling model represent the tsunami at least as well as the heterogeneous sources. We suggest that the initial heterogeneous fault models could be better constrained with continuous GPS measurements in the rupture area, and additionally DART records directly in front of the rupture area, to improve the tsunami simulation based on quickly calculated models for near coastal areas. Additionally, in terms of tsunami modeling, the source estimated from prior plate coupling information in this case is representative of the event that later occurs; placing further importance on the need to monitor subduction zones with GPS.

On 16 September 2015, an Mw 8.3 earthquake struck middle Chile due to the subduction of the Nazca plate beneath the South America plate. This earthquake is the consequence of 72 years of strain accumulation in the region since the 1943 M 8.3 event. In this study, we apply the compressive sensing method (CS) to invert for the spatiotemporal distribution of the coseismic radiation at different frequencies of this event. The results show clear frequency-dependent feature of earthquake rupture with low-frequency (LF) radiation located in the updip region while high-frequency (HF) radiation concentrated in the downdip region of the megathrust. We also compare the CS results with three coseismic slip models as well as the stress drop distributions inferred from these slip models. The comparison confirms our understanding of coseismic radiation that energy sources are mostly located in the margin of large coseismic slip regions. Furthermore, we find that the LF radiation sources are mainly within the stress-decreasing (releasing) regions while the HF radiation sources are mainly located in the stress-increasing (loading) regions due to rupturing of relatively large asperities nearby (stress decreasing and releasing). These results help to better understand the physics of the rupture process during megathrust earthquakes. Moreover, our results do not show radiation sources south of the epicenter, suggesting that the subducting Juan Fernandez Ridge probably stopped the rupture of this earthquake toward the south.

A model is constructed for one type of earthquake starting from the preparation through the completion of the event. This model, which is completely based on the laws of physics and mechanics, makes it possible to reveal, probably, a new type of dumping earthquake called “starting” because it precedes strong crustal earthquakes related to the interactions of lithospheric plates.

The Namie (Japan) 2016.11.21 Mw 6.9 earthquake (d = 9.0 km) initiated a tsunami which, contrary to forecasts of up to 3 m based on preliminary earthquake magnitude, nowhere exceeded 1.4 m. The hypocentre of the main shock was bordered in the succeeding 24 h by a tight cluster of 24 M ≤4.5 shallow (d ≤ 20 km) earthquakes. Two of them nucleated close to a M4.6 tremor that had preceded the main earthquake by 2.34 h, raising the possibility that a single structure hosted all three. Granted the ultimate cause was subduction at the Japan Trench, these events reaffirm the need for focused seafloor monitoring and fault history to supplement teleseismic data for realistic tsunami forecasting. Earthquake clustering in the 24 h after the main earthquake may also reflect a mode of megathrust segmentation which discourages the generation of great (Mw ∼ 9) earthquakes.

El Servicio Sismológico Nacional (SSN) reportó un sismo el día 7 de septiembre de 2017 con Mw 8.2 a una profundidad de 59 km y otro con Mw 7.1 y profundidad de 57 km el 19 de septiembre, curiosamente a 32 años del sismo interplaca de 1985 (M 8.1). Ambos eventos presentaron similitudes en cuanto al tipo de fallamiento (normal), profundidad y la placa tectónica donde se originó la ruptura. Para estudiar lo que concierne al impacto de estos sismos en el estado de Veracruz, se obtuvieron los valores máximos observados de aceleración y velocidad (PGA y PGV) durante ambos sismos en cada una de las estaciones de la Red Sísmica de Banda Ancha de Veracruz (RSBAV) y dos estaciones de banda ancha del Servicio Sismológico Nacional (SSN). Estos fueron relacionados con algunos daños reportados en esta entidad (para Xalapa con apoyo de una encuesta vía web), permitieron observar la atenuación con la distancia y analizar el contenido de frecuencias dominantes a partir de los registros de aceleración.Palabras clave: Placas tectónicas; sismo intraplaca; magnitud; intensidad; aceleración AbstractThe National Seismological Ser­vice (SSN) reported one earthquake on 7 Sep­tember 2017 with Mw 8.2 at a depth of 59 km. Another earthquake, with Mw 7.1 and depth of 57 km, occurred on September 19, curiously 32 years after the interplate earthquake of 1985 (Mw 8.1). Both recent events presented similarities as to the fault type (normal), depth and the tectonic plate where the rupture origina­ted. We study the impact of these earthquakes in the state of Veracruz, by obtaining the peak ground acceleration and velocity (PGA and PGV) at stations of the Veracruz Broadband Seismic Network (RSBAV) and two broadband stations of the National Seismological Servi­ce (SSN) during both earthquakes. We relate them to some damages reported in the Vera­cruz state (for Xalapa city with the support of a web survey), observe the attenuation with distance, and analyze the content of dominant frequencies from the records of acceleratio.Keywords: Tectonic Plates; intraplate earth­quake; magnitude; intensity; acceleration

We use coseismic offsets, derived from continuous GPS measurements at six nearby sites, due to the twin Varzaghan-Ahar earthquakes (northwest Iran) of 11 August 2012 (Mw 6.4 and 6.3) to constrain slip distribution on the ruptures of two earthquakes. We assume that slip during the two earthquakes occurred on conjugate faults. Majority of the slip occurred during the first earthquake which involved dextral slip on the east west trending vertical plane. The earthquake involved slip at shallow depth which reached up to ∼0.9 m at the surface, consistent with the evidence of surface rupture and the observed offsets. During the second earthquake oblique slip occurred on a north–south rupture having steep dip towards east and extending towards north from the eastern edge of the first earthquake. Maximum slip of ∼0.4 m occurred at depth of ∼6–8 km. Derived moment magnitude of the first earthquake (6.45) from our analysis is consistent with the reported moment magnitude, while that of the second earthquake (6.1) is slightly underestimated from our analysis.

This paper is about short review of earthquake statistics and efforts for earthquake mitigation, hazard and risk assessment studies in Pakistan. Pakistan and adjoining region lying between longitude 60°E to 78°E and latitude 20°N to 45°N are selected for the study as this region has a history of many large earthquakes because of its location in the region of intersection of three plates namely Indian, Eurasian and Arabian Sea plate. This paper is based on the study of both seismological history of the region which includes recent and historical seismicity based on earthquake catalogue as well as geological knowledge supplemented with available fault system information. In this study, Pakistan and adjoining regions are divided into 14 seismogenic zones. Seismicity of each zone is studied considering also the major cities in the respective zone and type of infrastructure which is mainly responsible for earthquake disaster rather than earthquake itself.

In accordance with the Seismo-Geothermics theory about methods of intracrustal strong earthquake and volcano prediction, we use the ANSS earthquake catalogue from the Northern California earthquake data center and the EMSC earthquake catalogue from the European-Mediterranean Seismological Centre to study the seismic activities of the Turkish Branch Seismic Cone in the Mediterranean Seismic Cone and the following Aegean Sea Seismic Cone, and show reproduction through graphics and animation, the seismogenic process and seismogenic mechanism of the earthquake Mw6.9 on May 24,2014 innorthern Aegean Sea. It was concluded that the energy of strong earthquake of magnitude around7 inAegean Seawas probably from energy transfer and accumulation in deep mantle and incentive lithosphere in the way of wave pattern, and then the strong earthquake occurs suddenly in search of the weak parts of the surface structure. The purpose of this paper is to open a hole in the traditional seismic genesis, and it is beneficial to the further research on the theory and method of earthquake prediction. It is our first attempt to study this case and it needs further examination. In this paper, we divide the Turkish Branch Seismic Cone of the Mediterranean Seismic Cone into 4 tertiary seismic cones, and we show a preliminary seismo-tectonic model of Aegean region. It will be conducive to seismic monitoring and earthquake prediction research inGreece,Turkey,RomaniaandPolandregions. At present, the world’s earthquake prediction has little effect, and it even tends to be not cognitive. Innovative thinking is the only way out.

Earthquakes in subduction zones rupture the plate boundary fault in discrete segments. One factor that may control this segmentation is topography on the downgoing plate, although it is controversial whether this is by weakening or strengthening of the fault. We use multichannel seismic and gravity data to map the top of the downgoing oceanic crust offshore central Sumatra, Indonesia. Our survey spans a complex segment boundary zone between the southern termination of the M w = 8.7, A.D. 2005 Simeulue-Nias earthquake, and the northern termination of a major 1797 earthquake that was partly filled by an M w = 7.7 event in 1935. We identify an isolated 3 km basement high at the northern edge of this zone, close to the 2005 slip termination. The high probably originated at the Wharton fossil ridge, and is almost aseismic in both local and global data sets, suggesting that while the region around it may be weakened by fracturing and fluids, the basement high locally strengthens the plate boundary, stopping rupture propagation.

OVSICORI On 5 September 2012, a moment magnitude (MW) 7.6 earthquake occurred directly beneath the Nicoya Peninsula, an area with dense seismic and geodetic network coverage. The mainshock ruptured a portion of a previously identified locked patch that was recognized due to a decade-long effort to delineate the megathrust seismic and aseismic processes in this area. Here we conduct a comprehensive study of the seismicity prior to this event utilizing a matched-filter analysis that allows us to decrease the magnitude of catalog completeness by 1 unit. We observe a statistically significant increase in seismicity rate below the Nicoya Peninsula following the 27 August 2012 (MW 7.3) El Salvador earthquake (about 450 km to the northwest and 9 days prior to the Nicoya earthquake). Additionally, we identify a cluster of small-magnitude (

Detecting anomalies before an earthquake has become an important task in seismic hazard prevention. The purpose of this research is to use the intrinsic attenuative dispersion of the P-wave, Qp, to serve as an anomaly before an earthquake. On November 5, 2009, an earthquake (ML = 6.2; depth = 24 km) occurred in Ming-Jen, Nantou county, Taiwan. The vertical-component of the first-cycle of P-wave data recorded from the Central Weather Bureau Seismic Network from 2009/01 to 2010/01 was calculated to obtain the Qp parameter. Meanwhile, this study also utilizes global positioning system stations to examine changes in surface displacements that occurred during the Mingjen earthquake. Analysis results indicate that 2-months before the mainshock occurred; the Qp began to decrease for all stations, which implies that the crustal area became more fractured owing to a high stress accumulation. Such a lead time of ∼2 months is equal to the average lead time of Seismic Electric Signals (SES) activities being also compatible with a physical model suggested long ago for the SES generation. With stress accumulating a few days before the earthquake, an impeded region can be clearly identified by relatively-large difference values when the mainshock is going to occur. We conclude that the analysis of the Qp parameter and GPS index are very sensitive to changes in the stress state and may serve as a useful index in early warning of earthquake.

The Zhangjiakou-Penglai Fault Zone (ZPFZ), as a large-scale WNW-trending active fault zone with frequent seismic activity, is an area prone to moderate to intense earthquakes across North China. A detailed analysis of the ZPFZ has been carried out based on earthquake activity, deep structural response, dynamic mechanism and physical simulation by conducting an en echelon fault model experiment. The results show that the ZPFZ is a lithospheric active fault zone that has controlled some small en echelon Quaternary pull-apart basins and has triggered many earthquakes as seismogenic structures. The earthquake location and intensity distribution by the experimental simulation fit well with those of actual earthquakes. The earthquake distribution is controlled obviously by the en echelon structural properties. The intensity of seismic activity is strong in the middle and weak at the western and eastern ends of the fault zone, migrating from the southeast to the northwest along the entire fault zone. This WNW-trending fault zone in North China, is closely related to the surrounding plate activities. The ZPFZ is not only dominated by the collision of the Indian Plate to the Eurasian Plate, but is also influenced by the subduction of the Pacific Plate. It depends on the comprehensive reflection of two geodynamic settings from the western collision of the Indian to the Eurasian plates and the eastern subduction of the Pacific Ocean Plate to the Eurasian Plate.

The 2014 M w 7.9 Rat Islands intermediate-depth (∼107 km) earthquake is studied using seismic observations at teleseismic distances. The nodal plane with a steep-dip angle (87°) and a strike of 308° inferred from the Global CMT solution is selected as the causative fault plane because of the consistency with the distribution of the aftershocks relocated using the Joint Hypocenter Determination method. Its slip history is constrained using broadband P and SH waveforms and long-period (3–6 mHz) seismic waves in vertical and transverse components. The rupture process associated with this plane shows a rupture propagating at ∼2 km/s. The rupture essentially breaks one large slip patch (peak slip amplitude of 3.5 m) located 30 km west of the hypocenter. The size of this slip patch extends from 80 to 140 km depth, which would be the largest depth extent of earthquake slip ever documented. We show that this earthquake breaks the entire cold core of the subducting slab defined by the depth of the 600–650 °C isotherm. In addition, the lateral extent of the rupture appears to be bounded by the heterogeneities of subducting slab. Our results further indicate that, along this segment of Aleutian Arc, the intermediate-depth earthquakes might contribute to the westward transporting motion of Rat block. Lastly, the slip distribution of this earthquake as well as that of two other well studied M w > 7.5 intermediate-depth earthquakes suggests that the coldest portion of the subducting slab, outlined by the double Wadati–Benioff zone, is seismic during large intermediate-depth earthquakes. Such a result is important for estimating the seismic hazard of future large intermediate-depth earthquakes.

A decadal-scale deformation transient preceding the 2011 Mw 9 Tohoku-oki, Japan, earthquake was reported from continuous GPS data and interpreted as accelerating aseismic slip on the Japan Trench megathrust. Given the unprecedented nature of this transient, independent confirmation of accelerating slip is required. Here we show that changes in the recurrence intervals of repeating earthquakes on the Japan Trench megathrust in the period 1996 to 2011 are consistent with accelerating slip preceding the Tohoku-oki earthquake. All sequences of repeating earthquakes with statistically significant trends in recurrence interval (at 95% confidence) offshore south central Tohoku occurred at an accelerating rate. Furthermore, estimates of the magnitude of slip acceleration from repeating earthquakes are consistent with the completely independent geodetic estimates. From a joint inversion of the GPS and seismicity data, we infer that a substantial portion of the megathrust experienced accelerating slip, partly surrounding the eventual rupture zone of the Mw 9 earthquake.

The moderate earthquake of 13 August 2006 which occurred in the coastal area of Michoacan, Mexico, offered the first opportunity to study an earthquake that has a focal mechanism oriented practically perpendicular to the vast majority of the earthquakes occurring along the subduction zone of the Mexican Pacific continental margin. The location and focal mechanism estimated in this study are in close agreement with those estimated by the Global Centroid Moment Tensor (CMT) project and the US Geological Survey, National Earthquake Information Center (NEIC) and place the earthquake in a complex tectonic region where 3 lithospheric plates converge. Our review shows that for the most severe historical earthquakes in the area the seismic recurrence period has expired, consequently the seismic hazard of this region is high and the analysis of the unusual event must be considered important. The main purposes of this study are (i) re-estimate the location and focal mechanism of the unusual event by using available seismic records close to the source, (ii) conduct a tectonic analysis of the area in relation with the previous fault plane estimated, (iii) evaluate the peak ground accelerations generated for this particular thrust event relative to those occurring during the more common events and (iv) generate the isoseismal map. The analysis of the intensities of this event together with a tectonic analysis of the area where this event occurred, attest to an unexpected behavior of this event in this region.

On 27 March and 2 June 2013, two large earthquakes with magnitudes of ML 6.2 and ML 6.5, named the Nantou earthquake series, struck central Taiwan. These two events were located at depths of 15–20km, which implied that the mid-crust of central Taiwan is an active seismogenic area even though the subsurface structures have not been well established. To determine the origins of the Nantou earthquake series, we investigated both the rupture processes and seismic wave propagations by employing inverse and forward numerical simulation techniques. Source inversion results indicated that one event ruptured from middle to shallow crust in the northwest direction, while the other ruptured towards the southwest. Simulations of 3-D wave propagation showed that the rupture characteristics of the two events result in distinct directivity effects with different amplified shaking patterns. From the results of numerical earthquake modeling, we deduced that the occurrence of the Nantou earthquake series may be related to stress release from the easternmost edge of a preexistent strong basement in central Taiwan.

The subduction rate of an oceanic plate may accelerate after large earthquakes rupture the interplate coupling between the oceanic and overriding continental plates. To better understand postseismic deformation processes in an incoming oceanic plate, we directly measured the displacement rate of the Pacific Plate near the Japan Trench after the 2011 Tohoku-Oki earthquake using a GPS/acoustic technique over a period of 2 years (September 2012 to September 2014). The displacement rate was measured to be 18.0 ± 4.5 cm yr−1 (N302.0°E) relative to the North American Plate, which is almost twice as fast as the predicted interseismic plate motion. Because the sum of steady plate motion and viscoelastic response to the Tohoku-Oki earthquake roughly accounts for the observed displacement rate, we conclude that viscoelastic relaxation is the primary mechanism responsible for postseismic deformation of the Pacific Plate and that significant subduction acceleration did not occur at least not during the observation period.

The 2015 M7.8 Nepal earthquake ruptured part of the Main Himalayan Thrust beneath Kathmandu. To study the dynamics of this event, we compute P wave spectra of the main shock and of two large aftershocks to estimate stress drop and radiated energy. We find that surface reflections (depth phases) of these shallow earthquakes produce interference that severely biases spectral measurements unless corrections are applied. Measures of earthquake dynamics for the main shock are within the range of estimates from global and regional earthquakes. We explore the azimuthal and temporal variations of radiated energy and highlight unique aspects of the M7.8 rupture. The beginning of the earthquake likely experienced a dynamic weakening mechanism immediately followed by an abrupt change in fault geometry. Correlation of backprojection results with frequency-dependent variations in the radiated energy rate and with the suggested geometry of the Main Himalayan Thrust yields new constraints on dynamic ruptures through geometrical barriers.

Many efforts have been made to quickly estimate the maximum runup height of tsunamis associated with large earthquakes. This is a difficult task because of the time it takes to construct an accurate tsunami model using real-time data from the source. It is possible to construct a database of potential seismic sources and their corresponding tsunami a priori. However, such models are generally based on uniform slip distributions and thus oversimplify the knowledge of the earthquake source. Here we show how to predict tsunami runup from any seismic source model using an analytic solution that is specifically designed for subduction zones with a well-defined geometry, i.e., Chile, Japan, Nicaragua, and Alaska. The main idea of this work is to provide a tool for emergency response, trading off accuracy for speed. The solutions we present for large earthquakes appear promising. Here runup models are computed for the following: the 1992 Mw 7.7 Nicaragua earthquake, the 2001 Mw 8.4 Peru earthquake, the 2003 Mw 8.3 Hokkaido earthquake, the 2007 Mw 8.1 Peru earthquake, the 2010 Mw 8.8 Maule earthquake, the 2011 Mw 9.0 Tohoku earthquake, and the recent 2014 Mw 8.2 Iquique earthquake. The maximum runup estimations are consistent with measurements made inland after each event, with a peak of 9 m for Nicaragua, 8 m for Peru (2001), 32 m for Maule, 41 m for Tohoku, and 4.1 m for Iquique. Considering recent advances made in the analysis of real-time GPS data and the ability to rapidly resolve the finiteness of a large earthquake close to existing GPS networks, it will be possible in the near future to perform these calculations within the first minutes after the occurrence of similar events. Thus, such calculations will provide faster runup information than is available from existing uniform-slip seismic source databases or past events of premodeled seismic sources.

A moderate earthquake ( M L 5.0, M W 4.9) occurred in the Kangra region of Himachal Pradesh on 21 August, 2014 (08:11 UT). The earthquake attains significance as it occurred immediately northeast of the source zone of the large Kangra earthquake of 1905 ( M W 7.8), the source mechanism of the later earthquake remains a subject of debate. Further, the seismic event is nucleated in a narrow block, where intense clustering of small and moderate events has been indicated by earlier campaign mode surveys. Taking advantage that recent earthquake is well recorded by a regional BBS network, the source parameters are estimated and interpreted to provide fresh constraint on the elements of seismotectonic model. The earthquake with its epicenter at 32.34°N and 76.52°E is seated on the Panjal Thrust, boundary between Panjal imbricate zone and the Chamba nappe. The travel time inversion and wave form inversion technique suggest focal depth no more than 5 km. A stress drop of 92 bars and a source radius of 1.1 km. The moment magnitude ( M W ) for this event is calculated as 4.9. The anomalous high value of stress drop compared to the generally low values prevailing over much of the Kangra–Chamba region indicates that the earthquake of 21 August 2014 is rooted in crustal blocks characterised by strong material strength to support accumulation of high strain during the earthquake building cycle. Fault plane solution of the event under study suggested that source fault is striking 323° with dip of 34°. The rake value of 105° indicated thrust movement with a very negligible right lateral movement. Synthesis of source parameters, especially the shallow focal depth, strike paralleling the Panjal thrust/MBT with steep dip, favour the seismotectonic model where moderate magnitude earthquake of 21st August 2014 is a typical example caused by the reverse fault displacement on the Panjal thrust fault. In the compressive regime of the Kangra Himalaya, such movements are facilitated by the stresses resulting in response to the southward sliding of the Chamba nappe and thus activating the contact zone between the nappe and Panjal imbricate zone.

The existence of earthquakes within continental lithospheric mantle remains a highly controversial topic. Here, we present a detailed set of seismological analyses confirming the occurrence of a mantle earthquake beneath the Wind River Range of central Wyoming. Combining regional waveform inversion with the analysis of the delay and relative amplitudes of teleseismically-observed depth phases, we demonstrate that the 2013 Wind River earthquake – a M W 4.7 highly-oblique thrust-faulting event – occurred at 75 ± 8 km , well beneath the base of the crust. The magnitude, mechanism, and location of this earthquake suggest that it represents simple brittle failure at relatively high temperatures within the mantle lithosphere, as a result of tectonic, rather than magmatic, processes.

Field investigations reveal that the Mj 6.8 (Mw 6.2) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km-long co-seismic surface rupture zone. The slip occurred on the pre-existing active Kamishiro Fault, which developed along the Itoigawa–Shizuoka tectonic line, and is inferred as the boundary between the Eurasian and North American plates. The surface-rupturing earthquake produced dominant thrusting and subordinate strike-slip displacement. Structures that developed during the co-seismic surface rupture include thrust faults, fault scarps, en-echelon tension cracks, folding structures such as mole tracks and flexural folds, and sand-boils. The surface displacements measured in the field range from several centimeters to 1.5 m in the vertical (typically, 0.4–1 m), accompanied by a strike-slip component that reached 0.6 m along NNE trending ruptures. These observations indicate a thrust-dominated displacement along the seismogenic fault. Our results show that (i) the pre-existing Kamishiro Fault, which strikes NNE–SSW, controlled the spatial distribution of co-seismic surface ruptures and displacements; and (ii) the style and magnitude of thrust displacements indicate that the present-day shortening strain on the Eurasian–North American plate boundary in the study area is released mainly by seismic thrust displacements along the active Kamishiro Fault.

We estimate the seismic hazard potential in the Sichuan-Yunnan region, western China using three different approaches. Our first approach, based on the assumption that the earthquake probability is proportional to the past seismicity rate, uses a regional earthquake catalog to constrain the probability model. A retrospective test shows that the ‘forecasts’ have some predictive power for strong events occurred on fault segments with shorter earthquake recurrence time, but not for that with longer recurrence time such as the Longmenshan fault. Our second approach, based on the assumption that the earthquake probability is proportional to crustal strain rate, uses secular geodetic strain rate deduced from GPS velocity data to constrain the probability model. A retrospective test of the model with earthquake occurrence of the past 30 years shows that the model ‘forecasted’ poorly. However, the model seems to ‘forecast’ spatial intensity of earthquakes for the past 500 years reasonably well, suggesting that the geodetic strain rate obtained at the decadal scale may still be a good indicator of long term earthquake activity in the region, but only at a time scale of hundreds of years. Our third approach uses GPS velocity data to determine the seismic moment accumulation rates on major faults, and a historical earthquake catalog to estimate seismic moments released in the past. Comparison of the two yields estimates of present day seismic moments cumulated on major faults, and a retrospective test shows some predictive power of the method. Our result suggests that numerous faults in the Sichuan-Yunnan region have cumulated seismic moments capable of producing M > 7.5 earthquakes, including the Xiaojiang, Jiali, Northern Nujiang, Nandinghe, and Red River–Puer faults, and the junction fault between the Xianshuihe and Ganzi-Yushu faults.

Megathrusts produce large permanent lithospheric displacements as well as strong transient ground shaking up to regional distances. The influence of the 2011 M9.0 Tohoku-Oki earthquake on the seismicity in stable intraplate regions around the Korean Peninsula is investigated. The differential lateral displacements by the megathrust build transient radial tension field over the backarc lithosphere, constructing stress shadows for all types of faults in optimal orientation over the wide backarc region including the southern Korean Peninsula. A characteristic seismic-velocity decrease after the megathrust supports the medium relaxation. The number of earthquakes with magnitudes greater than or equal to 2.5 was increased by 61% after the megathrust. The earthquakes occurred episodically. A series of unusual earthquake swarms and a temporal cluster of moderate-size earthquakes were observed in the Yellow Sea region. The significant seismicity increase since the megathrust may be due to the fluid diffusion during the transient tension field and the pore-fluid pressure increase during the ambient compressional-stress field recovery by tectonic loading. The induced seismicity may continue until the ambient stress field is fully recovered.

Large earthquakes that occur in subduction zones are likely to generate long-period ground motions that can cause severe damage even at great distances from the epicenter. We extracted surface-to-surface impulse response functions from the ambient seismic field recorded by offshore ocean bottom seismometers located atop the Nankai subduction zone and onshore stations. We showed that these offshore-onshore impulse response functions can be used to accurately simulate the long-period ground motions generated by an offshore moderate subduction earthquake. Moreover, we also found that the distributions of the earthquake and impulse response function pseudovelocity response spectra have similar maximum amplifications in the same area close to the earthquake epicenter. This suggests that the ambient seismic field recorded by the increasing number of ocean bottom seismometers around the world can be used to assess seismic hazard related to offshore subduction earthquakes without prior knowledge of the velocity structure.

The M s 8.1 earthquake on April 25, 2015 was located in the Himalaya Arc Belt consisting of a series of thrusts. The earthquake focus was at a depth of 20 km, which is a breaking at the hanging wall of the Main Himalaya Thrust (or Detachment), promoting a series of smaller earthquakes at smaller depth to the south. The earthquake may give a new thrust, or may be the MBT reactivation. It made the crust wedges at the north and south side of MBT uplifting. The release of stress at depth will make the earthquakes happen in the east and north side. Big earthquakes in the Himalaya arc belt may occurred in a period of 20 years. The M s 8.1 earthquake was just located in the section of Himalaya arc belt where earthquake may occur in the near future.

After 137 years without a great earthquake, the Mw 8.1 Pisagua event of 1 April 2014 occurred in the central portion of the southern Peru–northern Chile subduction zone. This megathrust earthquake was preceded by more than 2 weeks of foreshock activity migrating ∼3.5 km/day toward the mainshock hypocenter. This foreshock sequence was triggered by an Mw 6.7 earthquake on a reverse fault in the upper plate that strikes at a high angle to the trench, similar to well-documented reverse faults onshore. These margin-oblique reverse faults accommodate north-south shortening resulting from subduction across a plate boundary that is curved in map view. Reverse slip on the crustal fault unclamped the subduction interface, precipitating the subsequent megathrust foreshock activity that culminated in the great Pisagua earthquake. The combination of crustal reverse faults and a curved subduction margin also occurs in Cascadia and northeastern Japan, indicating that there are two additional localities where great megathrust earthquakes may be triggered by upper plate fault activity.

A major interplate earthquake occurred on April 1, 2014, in northern Chile with magnitude $${M}_w = 8.1$$ , which ruptured part of the 1877 seismic gap segment. Following the earthquake, a tsunami was observed having a moderate impact in the nearest coastal areas. Here we propagate a tsunami generated by two different slip model distributions, as well as a homogeneous one, and compare them using observed tide gauge data from four stations along the Chilean coast, in order to estimate which best represents the measured tsunami waveforms. The heterogeneous models reproduce the general shape and amplitude of the observed data, while the tsunami signal modeled by the homogeneous slip overestimates the amplitude and underestimates the arrival time. This study shows that it is possible to accurately model near-field tsunami observations in Chile, using high-resolution bathymetry, and that they are better represented by heterogeneous sources.

We found very low frequency earthquakes (VLFEs) at a shallow subduction zone close to the Japan Trench off the Pacific coast of Tohoku, Japan. Centroid moment tensor solutions of VLFEs showed reverse fault mechanisms with a compression axis in the east-west direction. A cross-correlation analysis of seismograms with template events between 2005 and 2013 revealed three major VLFE clusters and their temporal evolution. A VLFE cluster in the central off-Tohoku region located in the large slip area of the 2011 Tohoku earthquake was detectable only before the Tohoku earthquake. However, VLFEs in the northern and southern off-Tohoku regions at the rim of the large slip area were activated after the Tohoku earthquake. The change in the activity may reflect the stress redistribution by the coseismic and/or afterslip processes of the Tohoku earthquake.

On 22 April 1997 the largest earthquake recorded in the Trinidad-Tobago segment of the Caribbean-South American plate boundary zone (Mw 6.7) ruptured a shallow (~9 km), ENE striking (~250° azimuth), shallowly dipping (~28°) dextral-normal fault ~10 km south of Tobago. In this study, we describe this earthquake and related foreshock and aftershock seismicity, derive coseismic offsets using GPS data, and model the fault plane and magnitude of slip for this earthquake. Coseismic slip estimated at our episodic GPS sites indicates movement of Tobago 135 ± 6 to 68 ± 6 mm NNE and subsidence of 7 ± 9 to 0 mm. This earthquake was anomalous and is of interest because (1) its large component of normal slip and ENE strike are unexpected given the active E-W dextral shearing across the Caribbean-South American plate boundary zone, (2) it ruptured a normal fault plane with a low (~28°) dip angle, and (3) it reactivated and inverted the preexisting Tobago terrrane-South America ocean-continent (thrust) boundary that formed during early Tertiary oblique plate convergence.

We analyze foreshock activity in California and compare observations with simulated catalogs based on a branching aftershock-triggering model. We first examine foreshock occurrence patterns for isolated $$M \ge 5$$ earthquakes in southern California from 1981 to 2011 and in northern California from 1984 to 2009. Among the 64 $$M \ge 5$$ mainshocks, excluding 3 swarms and 3 doubles, 53 % of the rest are preceded by at least one foreshock within 30 days and 5 km. Foreshock occurrence appears correlated with mainshock faulting type and depth. Foreshock area is correlated with the magnitude of the largest foreshock and the number of foreshocks, however, it is not correlated with mainshock magnitude. We then examine the occurrence pattern of all seismicity clusters without a minimum magnitude requirement, and the possibility that they are “foreshocks” of larger mainshocks. Only about 30 % of the small clusters lead to a larger cluster. About 66 % of the larger clusters have foreshock activities, and the spatial distribution pattern is similar to $$M \ge 5$$ mainshocks, with lower occurrence rates in the Transverse Range and central California and higher occurrence rates in the Eastern California Shear Zone and the Bay Area. These results suggest that foreshock occurrence is largely controlled by the regional tectonic stress field and fault zone properties. In special cases, foreshock occurrence may be useful for short-term forecasting; however, foreshock properties are not reliably predictive of the magnitude of the eventual “mainshock”. Comparison with simulated catalogs suggest that the “swarmy” features and foreshock occurrence rate in the observed catalogs are not well reproduced from common statistical models of earthquake triggering.

Time series analysis of interferometric synthetic aperture radar data reveals coseismic and postseismic surface displacements associated with the 2007 M5.5 earthquake along the southern Ghazaband fault, a major but little studied fault in Pakistan. Modeling indicates that the coseismic surface deformation was caused by ~9 cm of strike-slip displacement along a shallow subvertical fault. The earthquake was followed by at least 1 year of afterslip, releasing ~70% of the moment of the main event, equivalent to a M5.4 earthquake. This high aseismic relative to the seismic moment release is consistent with previous observations for moderate earthquakes (M

Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative constraints were introduced. A total of 33 teleseismic stations and 5 strong ground motion stations supplied data. The teleseismic and strong ground motion data were separately windowed for 150 s and 250 s and band-pass filtered with frequencies of 0.001–1.0 Hz and 0.005–0.5 Hz, respectively. The finite-fault model was established with length and width of 190 km and 70 km, and the initial seismic source parameters were set by referring to centroid moment tensor (CMT) solutions. Joint inversion results indicate that the focal mechanism of this earthquake is thrust fault type, and the strike, dip, and rake angles are generally in accordance with CMT results. The seismic moment was determined as 5.814 × 10 20 Nm ( M w7.8) and source duration was about 102 s, which is greater than those of other earthquakes of similar magnitude. The rupture nucleated near the hypocenter and then propagated along the strike direction to the northwest, with a maximum slip of 3.9 m. Large uncertainties regarding the amount of slip retrieved using different inversion methods still exist; however, the conclusion that the majority of slip occurred far from the islands at very shallow depths was found to be robust. The 2010 Mentawai earthquake was categorized as a tsunami earthquake because of the long rupture duration and the generation of a tsunami much larger than was expected for an earthquake of its magnitude.

One approach that can be used to evaluate the potential for an earthquake occurrence is the detection of the stress concentration at an earthquake fault. While the stress fields for pre- and post-seismic event stages differ, this change cannot provide information regarding the potential for an earthquake. Here, we propose a detection method for states of stress that uses focal mechanism data from microearthquakes. The state of stress can be defined both by the background stress and by a moment tensor equivalent to the stress concentration. We applied this method to actual focal mechanism data from the 2013 Awaji Island earthquake (M6.3), Japan, and the results showed the presence of stress concentration around the earthquake fault before the mainshock. In addition, the regional differential stress was shown to be about 13 MPa. The magnitude of the obtained stress concentration in the focal area and the high dip angle of the mainshock fault imply that the faulting occurred in the crust where it was overpressurized to a level near the lithostatic pressure.

The co-seismic displacement and stress fields of the Nepal Ms8.1 earthquake on 25 April 2015 were calculated using the finite element method. Curvature of the Earth was included in our model to get accurate results in the far field. We adopted the PREM earth model and two different slip models in the calculation. The Nepal Ms8.1 earthquake is a typical low-angle thrust event, of which the co-seismic deformation is dominated by horizontal components. The co-seismic displacement is mainly in north-south direction and concentrates near Kathmandu. East-west and vertical components are relatively small. The USGS slip model gave a maximum displacement around 3.5 m, while that of the CEA slip model is up to 1.2 m. The range of influence is about 300 km within which co-seismic displacement is over 0.1 m. Coulomb failure stress change caused by the earthquake is positive in the vicinity of Nepal and its maximum is about 0.1 MPa. The Ms8.1 earthquake could affect China's Tibet region, especially in areas of the Yarlung Zangbo Jiang and the Lhasa block, where Coulomb failure stress changes are positive and the magnitude is up to 10 kPa for N-S trending normal faults, which implies possibilities of triggering new major earthquakes.

Based on the brittle failure theory of multiple locked patches in a seismogenic fault system and interplate seismic zoning principle proposed by the authors of this paper, the Islamabad–Kathmandu seismic zone is defined. Through seismogenic period definition and main shock event recognition, the seismogenic process of major/great earthquakes in this seismic zone is analyzed and the future trend of earthquake occurrence is predicted. The results show that the Islamabad–Kathmandu seismic zone is an Mw8.3∼8.6 earthquake hazard zone, and has undergone at least three complete seismogenic periods; the Nepal Mw7.8 earthquake on April 25, 2015 was a representative major earthquake event in the current seismogenic period when the damage of the third locked patch was accumulated to the peak strength point; After the Mw7.3 earthquake in Nepal on May 12, 2015, this seismic zone is already in another critical state of the current seismogenic period, and an Mw8.0∼8.2 earthquake would occur in short-middle term.

We study three recent earthquakes of different types in the Guerrero seismic gap zone with M ≥ 6.5: the 15 July 1996 Guerrero near-coast interplate earthquake (M w = 6.6), the 18 April 2002 Guerrero near-trench interplate earthquake (M w = 6.7), and the 11 December 2011 Guerrero normal-faulting inslab earthquake (M w = 6.5). We compute the slip distributions, estimate source parameters, and model strong ground motions with the finite-fault stochastic method. We use different methods to estimate source parameters in order to observe differences in stress drop and radiated seismic energy among these events. The similarity in seismic magnitude gives us the opportunity to compare our results for the three different types of earthquake and interpret them in terms of the tectonic environments and seismic hazard. We analyze the peak ground accelerations and their relation with the stress drop. We simulated ground motions with the stochastic method. The model parameters are validated against recordings and a stress drop of 3, 15, and 70 MPa is estimated for the near-trench interplate, near-coast interplate, and normal-faulting inslab events, respectively. The near-trench interplate event has the lowest radiated seismic energy and the lowest rupture velocity. This is reflected in the energy to moment ratio of 2.17 × 10−6, 4.52 × 10−6, and 3.96 × 10−6 for the near-trench interplate, near-coast interplate, and normal-faulting inslab events, respectively. We define asperities using two different criteria: (1) based on average displacement and (2) maximum displacement. The asperity area for the near-coast and near-trench interplate events represents about 23 and 24–25 % of the total rupture area, which in the case of the normal-faulting inslab event, it is only 19 and 23 % based on average and maximum displacement, respectively.

Slow earthquakes are important constituents of the seismic cycle and are involved in the stress transfer between the viscously slipping portion of the plate interface and the seismogenic zone. Their occurrence is likely associated with the near-lithostatic pore pressure in the slow earthquake source region, where fluids might modify fault friction and whose presence is indicated by high ratios of compressional (P)–wave velocity to shear (S)–wave velocity observed at the interface between the subducting plate and the overlying crust. Here we compare two slow earthquake phenomena observed in the Guerrero region of the Mexican subduction zone: low-frequency earthquakes (LFEs) and a slow-slip event (SSE) recorded by GPS. We observe variations of the LFE occurrence rates over month-long time scales during a large SSE that we interpret as a manifestation of transient changes in the fault shear strength. We argue that these transient changes are caused by a pore pressure fluctuation that migrates updip along the subduction interface. This mechanism suggests that fluids do not only passively weaken the plate interface but also play an active role in slow earthquake source regions.

The results of computer visualization of the spatiotemporal distribution of the total earthquake energy for the instrumental period are presented. This visualization was implemented to determine the parameters of slow earthquake migrations (of a few kilometers to a few hundreds of kilometers per year) in strike-slip zones. A case study of the San Andreas and Mendocino fault zones referring to the boundary between the North American and Pacific plates is considered. The obtained results are compared with the migration peculiarities revealed for the structures under other geodynamical conditions, in particular those in Trans-Bakalia. The spatiotemporal analysis is carried out with the use of strong, moderate, and weak events. Migration episodes are detected in the seismic data projection zones constructed for epicenter concentrations at the Mendocino triple junction, at the junction of the San Andreas and Calaveras faults, the Santa Monica and San Gabriel ones, and the Camp Rock Fault Zone; these areas host the strongest earthquakes of the instrumental period. Migration in these zones is manifested as a phenomena both preceding and following the seismic events and can reflect the dynamics of the stress redistribution in the zone of interaction between tectonic structures. The calculated migration rates vary from 7 ± 2 to 250 ± 50 km/yr. It is concluded that there is no dependence of the seismic activity migration on the geodynamical type of the fault zones, because similar rates (10–70 km/yr) are reported for the Mendocino and San Andreas faults and the Baikal Rift System. The migration rates for the Mendocino and San Andreas, exceeding 70 km/yr, are likely caused by a high rate of the interplate displacements, which is higher than that in the Baikal Rift System by more than an order. The extent of the seismoactive segments of faults zones along which migration episodes were detected is from 20 to 70 km. The results of the mutual correlation analysis of time series carried out for such parameters as the earthquake numbers and earthquake energy suggest that migrations are caused by local geodynamical conditions affecting the seismicity on the scale of zones where large segments of fault zone interact with each other.

The relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998–2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthquakes originated in the plate boundary or within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress accumulation produced an abrupt gravity change, which was further enhanced by the earthquake. The gravity data from mainland China since 2000 obviously reflected five major earthquakes ( M s > 7), all of which were better reflected than before 2000. Regional gravity anomalies and a gravity gradient change were observed in the area around the epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change may be a seismic precursor. Furthermore, in this study, the medium-term predictions of the M s7.3 Yutian, M s8.0 Wenchuan, and M s7.0 Lushan earthquakes are analytically presented and evaluated, especially to estimate location of earthquake.

The 26 December 2004, Mw 9.3 Sumatra earthquake and tsunami was a pivotal turning point in our awareness of the dangers posed by subduction zone earthquakes and tsunamis. This earthquake was the world’s largest in 40 years, and it produced the world’s deadliest tsunami. This earthquake ruptured a subduction zone that has many similarities to the Cascadia Subduction Zone. In this article, I summarize lessons learned from this tragedy, and make comparisons with potential rupture characteristics, slip distribution, deformation patterns, and aftershock patterns for Cascadia using theoretical modeling and interseismic observations. Both subduction zones are approximately 1,100–1,300 km in length. Both have similar convergence rates and represent oblique subduction. Slip along the subduction fault during the 26 December earthquake is estimated at 15–25 m, similar to values estimated for Cascadia. The width of the rupture, ~80–150 km estimated from modeling seismic and geodetic data, is similar to the width of the “locked and transition zone” estimated for Cascadia. Coseismic subsidence of up to 2 m along the Sumatra coast is also similar to that predicted for parts of northern Cascadia, based on paleoseismic evidence. In addition to scientific lessons learned, the 2004 tsunami provided many critical lessons for emergency management and preparedness. As a result of that tragedy, a number of preparedness initiatives are now underway to promote awareness of earthquake and tsunami hazards along the west coast of North America, and plans are underway to develop prototype tsunami and earthquake warning systems along Cascadia. Lessons learned from the great Sumatra earthquake and tsunami tragedy, both through scientific studies and through public education initiatives, will help to reduce losses during future earthquakes in Cascadia and other subduction zones of the world.

Constraints on the recurrence times of subduction zone earthquakes are important for seismic hazard assessment and mitigation. Models of such megathrust earthquakes often assume that subduction zones are segmented and earthquakes occur quasi-periodically owing to constant tectonic loading. Here we analyse the occurrence of small earthquakes compared to larger ones—the b-values—on a 1,000-km-long section of the subducting Pacific Plate beneath central and northern Japan since 1998. We find that the b-values vary spatially and mirror the tectonic regime. For example, high b-values, indicative of low stress, occur in locations characterized by deep magma chambers and low b-values, or high stress, occur where the subducting and overriding plates are strongly coupled. There is no significant variation in the low b-values to suggest the plate interface is segmented in a way that might limit potential ruptures. Parts of the plate interface that ruptured during the 2011 Tohoku-oki earthquake were highly stressed in the years leading up to the earthquake. Although the stress was largely released during the 2011 rupture, we find that the stress levels quickly recovered to pre-quake levels within just a few years. We conclude that large earthquakes may not have a characteristic location, size or recurrence interval, and might therefore occur more randomly distributed in time. The 2011 Tohoku-oki earthquake released stress within a subduction zone. Analysis of seismic data shows that stresses returned to pre-quake levels within a few years, implying that large quakes could occur more often than previously thought.

We review recent findings on the causal mechanism of the great 2011 Tohoku earthquake (Mw 9.0) sequence and related issues on seismic structure and subduction dynamics in Western Pacific and East Asia. High-resolution tomography revealed significant lateral heterogeneities in the interplate megathrust zone beneath the Tohoku, South Kuril and Southwest Japan forearc regions. Large megathrust earthquakes since 1900 generally occurred in or around high-velocity (high-V) patches in the megathrust zone, which may reflect asperities resulting from subducted seamounts, oceanic ridges and other topographic highs on the Pacific seafloor. In contrast, low-velocity (low-V) patches in the megathrust zone may contain more sediments and fluids, where the subducting oceanic plate and the overlying continental plate are less coupled or even decoupled. The nucleation of large crustal earthquakes in the Japan Islands, including the 11 April 2011 Iwaki earthquake (M 7.0) in SE Tohoku, is affected by arc magma and fluids resulting from slab dehydration. The Philippine Sea plate has subducted aseismically down to 430–460 km depth under East China Sea, Tsushima Strait and Japan Sea. A window in the aseismic Philippine Sea slab is detected, which may be caused by splitting of weak parts of the slab at the subducted ridges (e.g., Kyushu-Paula ridge) and hot upwelling in the mantle wedge above the Pacific slab. The intraplate volcanism in Northeast Asia is caused by hot and wet upwelling flows in the big mantle wedge above the stagnant Pacific slab in the mantle transition zone. Frequent generation of large deep earthquakes (>500 km depth) in the Pacific slab may supply additional fluids preserved in the slab to the mantle wedge under the Changbai volcano, making Changbai the largest and most active intraplate volcano in Northeast Asia. Fluids may be involved in nucleation and rupture processes of all types of earthquakes.

Complexities in the rupture process during a megathrust earthquake can be attributed to the combined effect of inhomogeneous distribution of stress accumulated during the interseismic period and inhomogeneous rheology of the seismogenic contact. We modeled the free-air gravity field of the southern Central Chile convergent margin along five 2-D profiles that cross the patch of highest slip during the Chilean 2010 megathrust earthquake in order to analyze variability in the density and shape of the continental wedge and its relationship with seismotectonics. We also analyzed the bathymetry to derive the long-term interplate friction coefficient. The results show that the high slip patch during the Maule earthquake corresponds to a segment of the margin characterized by (1) low densities in the continental wedge, (2) low vertical loading over the inter-plate contact, (3) a well-developed shelf basin and, (4) low taper angles consistent with a low effective basal friction coefficient. We interpret the correlation between these parameters in terms of the total potential energy change during the earthquake and conclude that if the normal stress or frictional coefficient are low, then a large slip does not necessarily imply a large amount of coseismic work. Heterogeneities in density of the continental basement can therefore be related to complexities in the pattern of coseismic slip and in the aftershock distribution. Locally, a subducted seamount or seaward spur of high-density continental crust may be present near the high slip patch.

On October 14, 2011, an earthquake with the magnitude Mw = 6.0 occurred 15 km northwest of the town of Skovorodino in East Siberia. This earthquake aroused interest among geophysicists. In this paper, we present some results on the prior seismicity in the region, which are based on the macroseismic and instrumental data. The assessment of the seismic regime immediately before the main shock and the analysis of the aftershock sequence rely on the data provided by the field network of the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. The network was in operation from the end of July 2011 to January 2012. The analysis of the entire dataset suggests that the Skovorodino earthquake was outstanding in a vast region: only seismic events with low magnitudes (at most 4) occurred in the epicentral zone of this earthquake and its nearest neighborhood. The positions of the source of the main shock and the hypocenters of the after-shocks (more than 1300 events) are determined. The aftershock sequence is anomalous—it lacks sufficiently strong seismic events (M ≥ 3.5). The spatiotemporal distribution of the aftershocks shows two clusters of the epicenters to the west and east of the epicentral zone. These clusters drastically differ in their parameters, indicating that the source has a complex structure. Generally, the source can be understood as a shear displacement on the subvertical fault plane trending approximately along the latitude. The size of the source is 17 × 17 km; the average slip is 63 cm, which is at least 30% larger than the characteristic values for the earthquakes with M = 6.0.

The characteristic earthquake hypothesis is the basis of time-dependent modeling of earthquake recurrence on major faults. However, the characteristic earthquake hypothesis is not strongly supported by observational data. Few fault segments have long historical or paleoseismic records of individually dated ruptures, and when data and parameter uncertainties are allowed for, the form of the recurrence distribution is difficult to establish. This is the case, for instance, of the Corinth Gulf Fault System (CGFS), for which documents about strong earthquakes exist for at least 2000 years, although they can be considered complete for M ≥ 6.0 only for the latest 300 years, during which only few characteristic earthquakes are reported for individual fault segments. The use of a physics-based earthquake simulator has allowed the production of catalogs lasting 100,000 years and containing more than 500,000 events of magnitudes ≥ 4.0. The main features of our simulation algorithm are (1) an average slip rate released by earthquakes for every single segment in the investigated fault system, (2) heuristic procedures for rupture growth and stop, leading to a self-organized earthquake magnitude distribution, (3) the interaction between earthquake sources, and (4) the effect of minor earthquakes in redistributing stress. The application of our simulation algorithm to the CGFS has shown realistic features in time, space, and magnitude behavior of the seismicity. These features include long-term periodicity of strong earthquakes, short-term clustering of both strong and smaller events, and a realistic earthquake magnitude distribution departing from the Gutenberg-Richter distribution in the higher-magnitude range.