Earthquake Size Research Articles

A Big Problem for Small Earthquakes: Benchmarking Routine Magnitudes and Conversion Relationships with Coda Envelope-Derived Mw in Southern Kansas and Northern Oklahoma

ABSTRACT Earthquake magnitudes are widely relied upon measures of earthquake size. Although moment magnitude (Mw) has become the established standard for moderate and large earthquakes, difficulty in reliably measuring seismic moments for small (generally Mw<4) earthquakes has meant that magnitudes for these events remain plagued by a patchwork of inconsistent measurement scales. Because of this, magnitudes of small earthquakes and statistics derived from them can be biased. Furthermore, because small earthquakes are much more numerous than large ones, many applications, such as seismic hazard modeling, depend critically on analysis of events characterized by magnitudes other than Mw. To assess this problem, we apply coda envelope analysis to reliably determine moment magnitudes for a case study of small earthquakes from northern Oklahoma and southern Kansas. Not surprisingly, we find significant differences among ML, mbLg, and Mw for M ∼2–4 earthquakes examined here. More troublingly, we find that relations designed to convert other magnitudes to Mw, which are relied upon for important applications such as seismic hazard analysis, often increase rather than decrease this bias for our dataset. In our case study, we find that converted magnitudes can result in a systematic bias sometimes exceeding 0.5 magnitude units, a difference that typically corresponds to a factor of ∼3 in seismicity rate. Moreover, we find a correspondingly large bias in Gutenberg–Richter b-values, controlled primarily by inaccurate magnitude scaling in the conversion relationships. Although this study focuses on a relatively small geographic area, we can expect that similar issues exist with varying severity in other regions. Therefore, magnitudes of small earthquakes and their associated statistics, including seismicity rates and b-values, should be treated with caution.

The stepovers of the Central Dead Sea Fault: What can we learn from the confining vertical axis rotations?

The geometry of stepovers along strike-slip faults dictates the deformational field and topography induced around the faults. Stepover geometry also impacts the ability of a fault rupture to propagate from one fault segment to another and therefore acts as a major controlling factor in the size of earthquakes. However, the geometry of stepovers is often poorly resolved, as they tend to underlie young sedimentary successions. Yet, although mostly ignored, the accumulated long-term relative plate motions accommodated by the stepping faults generate permanent rotational deformation in the crust surrounding them. Here we present the results from a combined mechanical and paleomagnetic investigation of the vertical axis rotational pattern confining stepovers. We focus our investigation on the central Dead Sea Fault, where two prominent stepovers are located at the Kinneret and Hula depressions. To better understand their still somewhat elusive geometric settings, we mapped the crustal rotational field by studying the magnetization of the confining volcanic rocks. Remanent magnetization directions reveal localized zones of anomalously high vertical axis rotations in the vicinity of the stepovers that evolve to negligible rotations elsewhere. We then constructed a series of elastic and elasto-plastic slip models aiming to cover possible plate boundary architectures. Comparable patterns between the observed and predicted rotations were achieved when the Dead Sea Fault motion was concentrated along the eastern margins of both the Kinneret and Hula Basins. Our best-fit model suggests that the along-strike under-lapping distance for the Kinneret Stepover is ~8 km whereas for the Hula Stepover is only ~2 km. Our results, supported by historic and paleoseismic records that show no evidence of an earthquake that ruptured through the Kinneret Stepover, imply an enhanced deformation zone in the center of Lake Kinneret, which acts as a major barrier to rupture propagation. Our combined paleomagnetic and modeling analysis approach provides a new avenue for the study of the geometries of plate boundaries.

Assessing Margin-Wide Rupture Behaviors Along the Cascadia Megathrust With 3-D Dynamic Rupture Simulations.

From California to British Columbia, the Pacific Northwest coast bears an omnipresent earthquake and tsunami hazard from the Cascadia subduction zone. Multiple lines of evidence suggests that magnitude eight and greater megathrust earthquakes have occurred ‐ the most recent being 321 years ago (i.e., 1700 A.D.). Outstanding questions for the next great megathrust event include where it will initiate, what conditions are favorable for rupture to span the convergent margin, and how much slip may be expected. We develop the first 3‐D fully dynamic rupture simulations for the Cascadia subduction zone that are driven by fault stress, strength and friction to address these questions. The initial dynamic stress drop distribution in our simulations is constrained by geodetic coupling models, with segment locations taken from geologic analyses. We document the sensitivity of nucleation location and stress drop to the final seismic moment and coseismic subsidence amplitudes. We find that the final earthquake size strongly depends on the amount of slip deficit in the central Cascadia region, which is inferred to be creeping interseismically, for a given initiation location in southern or northern Cascadia. Several simulations are also presented here that can closely approximate recorded coastal subsidence from the 1700 A.D. event without invoking localized high‐stress asperities along the down‐dip locked region of the megathrust. These results can be used to inform earthquake and tsunami hazards for not only Cascadia, but other subduction zones that have limited seismic observations but a wealth of geodetic inference.

Application of deep learning-based neural networks using theoretical seismograms as training data for locating earthquakes in the Hakone volcanic region, Japan

In the present study, we propose a new approach for determining earthquake hypocentral parameters. This approach integrates computed theoretical seismograms and deep machine learning. The theoretical seismograms are generated through a realistic three-dimensional Earth model, and are then used to create spatial images of seismic wave propagation at the Earth’s surface. These snapshots are subsequently utilized as a training data set for a convolutional neural network. Neural networks for determining hypocentral parameters such as the epicenter, depth, occurrence time, and magnitude are established using the temporal evolution of the snapshots. These networks are applied to seismograms from the seismic observation network in the Hakone volcanic region in Japan to demonstrate the suitability of the proposed approach for locating earthquakes. We demonstrate that the determination accuracy of hypocentral parameters can be improved by including theoretical seismograms for different earthquake locations and sizes, in the learning data set for the deep machine learning. Using the proposed method, the hypocentral parameters are automatically determined within seconds after detecting an event. This method can potentially serve in monitoring earthquake activity in active volcanic areas such as the Hakone region.

Deep Learning Can Predict Laboratory Quakes From Active Source Seismic Data

AbstractSmall changes in seismic wave properties foretell frictional failure in laboratory experiments and in some cases on seismic faults. Such precursors include systematic changes in wave velocity and amplitude throughout the seismic cycle. However, the relationships between wave features and shear stress are complex. Here, we use data from lab friction experiments that include continuous measurement of elastic waves traversing the fault and build data‐driven models to learn these complex relations. We demonstrate that deep learning models accurately predict the timing and size of laboratory earthquakes based on wave features. Additionally, the transportability of models is explored by using data from different experiments. Our deep learning models transfer well to unseen datasets providing high‐fidelity models with much less training. These prediction methods can be potentially applied in the field for earthquake early warning in conjunction with long‐term time‐lapse seismic monitoring of crustal faults, CO2 storage sites and unconventional energy reservoirs.

How cementation and fluid flow influence slip behavior at the subduction interface

Abstract Much of the complexity of subduction-zone earthquake size and temporal patterns owes to linkages among fluid flow, stress, and fault healing. To investigate these linkages, we introduce a novel numerical model that tracks cementation and fluid flow within the framework of an earthquake simulator. In the model, there are interseismic increases in cohesion across the plate boundary and decreases in porosity and permeability caused by cementation along the interface. Seismogenic slip is sensitive to the effective stress and therefore fluid pressure; in turn, slip events increase porosity by fracturing. The model therefore accounts for positive and negative feedbacks that modify slip behavior through the seismic cycle. The model produces temporal clustering of earthquakes in the seismic record of the Aleutian margin, which has well-documented along-strike variations in locking characteristics. Model results illustrate how physical, geochemical, and hydraulic linkages can affect natural slip behavior. Specifically, coseismic drops in fluid pressure steal energy from large ruptures, suppress slip, moderate the magnitudes of large earthquakes, and lead to aftershocks.

Intraplate earthquakes in the Potiguar Basin, Brazil: Evidence for superposition of local and regional stresses and implications for moderate-size earthquake occurrence

The understanding of earthquake occurrence in intraplate areas has been one of the most challenging tasks in Seismology. The attenuation of seismic waves in these areas is lower compared to border plate regions. Therefore, even moderate magnitude earthquakes can represent a great hazard. In this case, assessing the stress field in the intraplate areas is important to better understanding the earthquake generating mechanisms. We analyzed 241 earthquakes of the 2017 seismic sequence in the NW part of the Potiguar Basin and estimated the stress regime. Seismically defined faults were determined for four high-precision relocated NW-SE- and NE-SW-trending clusters. Faulting intersection acting in one of these clusters was representative for suggesting an intersection model for intraplate earthquakes to explain why moderate size earthquakes occur in the study region. Another cluster presented a seismically defined fault vertically segmented with a clear spatiotemporal evolution and occurrence of almost entire activity in a very short period, which suggest energy build-up and rapid release between its fault segments. We calculated the composite focal mechanism for three clusters, with predominant strike-slip faulting with a sinistral movement. The inversion of focal mechanisms reinforces evidence for a superposition of local and regional stresses, with major compressional axis subparallel to the continental equatorial margin.

Rupture Models of Recent Mw>7 Thrust Earthquakes in the Guerrero–Oaxaca Region of the Mexico Subduction Zone Using Teleseismic Body Waves

Abstract We invert the teleseismic broadband (1–60 s period) ground-displacement body waveforms recorded for the 1995 Mw 7.3 Copala, the 1996 Mw 7.1 Oaxaca, the 2012 Mw 7.5 Ometepec, and the 2018 Mw 7.2 Pinotepa Nacional thrust earthquakes in the Guerrero–Oaxaca portion of the Mexico subduction zone to derive the best-fit rupture models using a sampling procedure in which input fault parameters are selected from a prescribed range of values. More than 400 independent inversions are performed for each event using random combinations of strike, rake, dip, and hypocenter depth. Waveform fits are observed to be relatively insensitive to variations in strike, rake, and focal depth but show a distinct dependence on fault dip. The lowest residuals are limited to a dip interval of about ±3°, indicating that a relatively precise estimate of the fault dip is necessary for the optimal derivation of slip models using teleseismic body waves. The best-fit teleseismic source models obtained for the four events show varying degrees of spatial detail, with the 2012 and 2018 earthquakes exhibiting more separated slip along the fault than has been observed in rupture models derived using frequency bands covering longer periods. Areas of high-interplate slip for the four events do not overlap, suggesting an adjoining pattern of asperity zones that is consistent with prior observations in northwest Mexico and in the New Britain region of the South Pacific. Additional investigation of this type of asperity interaction for recurrent events would be beneficial, given the implications for estimating the size and location of future large subduction earthquakes.

The Reliance of the Earthquake B-Value on Depth and Focal Mechanism

The earthquake size distribution (b-value) is a significant factor to recognize the seismic activity, seismotectonic, and seismic hazard assessment. In the current work, the connection of the b-constant value with the focal depth and mechanism was studied. The effect of the study scale (global, regional and local) on the dependence of b-value on the focal mechanisms was investigated. The database is quoted from the Global Centroid Moment Tensor catalog. The selected earthquakes are the shallow normal, reverse and strike-slip events. The completeness magnitude (Mc) is 5.3. The maximum likelihood method is utilized to compute the b-value. The obtained results show that the b-value is decreasing with depth to range 10-20 km, then increases to the depth of 40km. The turning point of b-value (increasing of b-value) locates at the depth of the transition brittle-ductile zone. Globally and regionally, low, moderate, and high b-values are associated with reverse, strike-slip, and normal focal mechanisms, respectively, while locally, the relation between b-values and focal mechanisms shows different association trends, such as low, moderate, and high b-values are associated with normal, strike-slip, and reverse focal mechanisms and so on.

Why do continental normal fault earthquakes have smaller maximum magnitudes?

Continental normal fault earthquakes have been reported to have smaller maximum magnitudes (Mmax) than continental earthquakes with other fault geometries. This difference has significant implications for understanding seismic hazards in extensional regions. Using the Global Centroid Moment Tensor (GCMT) catalog, we examine how Mmax varies with fault geometry in continental regions, whether these trends are robust, and potential physical reasons for the smaller magnitudes of continental normal fault earthquakes.We find that the largest continental normal fault earthquakes are in the low Mw 7 range whereas other fault geometries can reach ~Mw 8. The continental normal fault earthquake magnitude-frequency distribution has a lower corner magnitude (a parameterization of Mmax) than other fault geometries. The observed smaller continental normal fault Mmax is not an artifact of classification criteria or catalog length. Probability calculations indicate that the GCMT catalog is long enough to capture differences in Mmax due to fault geometry. Additionally, our analysis indicates that neither fault length nor width is limiting the size of continental normal fault earthquakes. Fault complexity can limit rupture extent, but it is likely not the primary reason for the smaller continental normal fault Mmax.Rather, lithosphere yield stress (strength) appears to be the main factor controlling Mmax. In extension, lithosphere is weaker, failing at lower yield stresses than in compression. Although this yield stress difference is consistent with smaller continental normal fault earthquakes, it appears inconsistent with the occurrence of large oceanic normal fault earthquakes. However, the largest oceanic normal fault earthquakes occur near subduction zones where the lithosphere is bending. Laboratory studies indicate that bending lithosphere likely has a higher yield stress than lithosphere in pure extension, which may allow for larger oceanic normal fault earthquakes. Therefore, yield stress—rather than fault geometry alone—appears to be the key factor limiting an earthquake's maximum magnitude.

Joint inversion of ground gravity data and satellite gravity gradients between Nepal and Bhutan: New insights on structural and seismic segmentation of the Himalayan arc

Along-strike variation in the geometry of lithospheric structures is a key control parameter for the occurrence and propagation of major interplate earthquakes in subduction and collision zones. The lateral segmentation of the Himalayan arc is now well-established from various observations, including topography, gravity anomalies, exhumation rates, and present-day seismic activity. Good knowledge of the main geometric features of these segments and their boundaries is thus the next step to improve seismic hazard assessment in this area. Following recent studies, we focus our approach on the transition zone between Nepal and Bhutan where both M > 8 earthquakes and changes in the geometry of the Indian plate have been documented. Ground gravity data sets are combined with satellite gravity gradients provided by the GOCE mission (Gravity Field and Steady-State Ocean Circulation Explorer) in a joint inversion to assess the location and the geometry of this transition. We obtain a ca. 10 km wide transition zone located at the western border of Bhutan that is aligned with the Madhupur fault in the foreland and coincides with the Dhubri–Chungthang fault zone and the Yadong-Gulu rift in Himalaya and southern Tibet, respectively. This sharp segment boundary at depth can act as a barrier to earthquake rupture propagation. It can possibly restrict the size of large earthquakes and thus reduce the occurrence probability of M > 9 earthquakes along the Main Himalayan Thrust.

The slip deficit on the North Anatolian Fault (Turkey) in the Marmara Sea: insights from paleoseismicity, seismicity and geodetic data

The North Anatolian Fault experienced large earthquakes with 250–400 years recurrence time. In the Marmara Sea region, the 1999 (Mw = 7.4) and the 1912 (Mw = 7.4) earthquake ruptures bound the Central Marmara Sea fault segment. Using historical-instrumental seismicity catalogue and paleoseismic results (≃ 2000-year database), the mapped fault segments, fault kinematic and GPS data, we compute the paleoseismic-seismic moment rate and geodetic moment rate. A clear discrepancy appears between the moment rates and implies a significant delay in the seismic slip along the fault in the Marmara Sea. The rich database allows us to identify and model the size of the seismic gap and related fault segment and estimate the moment rate deficit. Our modelling suggest that the locked Central Marmara Sea fault segment (even including a creeping section) bears a moment rate deficit $${\dot{M}}_{d}$$ = 6.4 × 1017 N.m./year that corresponds to Mw ≃ 7.4 for a future earthquake with an average ≃ 3.25 m coseismic slip. Taking into account the uncertainty in the strain accumulation along the 130-km-long Central fault segment, our estimate of the seismic slip deficit being ≃ 10 mm/year implies that the size of the future earthquake ranges between Mw = 7.4 and 7.5.

Synthetic analysis of the efficacy of the S-net system in tsunami forecasting

The Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench (S-net) is presently the world’s largest network of ocean bottom pressure sensors for real-time tsunami monitoring. This paper analyzes the efficacy of such a vast system in tsunami forecasting through exhaustive synthetic experiments. We consider 1500 hypothetical tsunami scenarios from megathrust earthquakes with magnitudes ranging from Mw 7.7–9.1. We employ a stochastic slip model to emulate heterogeneous slip patterns on specified 240 subfaults over the plate interface of the Japan Trench subduction zone and its vicinity. Subsequently, the associated tsunamis in terms of maximum coastal tsunami heights are evaluated along the 50-m isobath by means of a Green’s function summation. To produce tsunami forecasts, we utilize a tsunami inversion from virtually observed waveforms at the S-net stations. Remarkably, forecasts accuracy of approximately 99% can be achieved using tsunami data within an interval of 3 to 5 min after the earthquake (2-min length), owing to the exceedingly dense observation points. Additionally, we apply an optimization technique to determine the optimal combination of stations with respect to earthquake magnitudes. The results show that the minimum requisite number of stations to maintain the accuracy attained by the existing network configuration decreases from 130 to 90 when the earthquake size increases from Mw 7.7 to 9.1.

Size of Earthquakes

Earthquake size is one of most fundamental source parameter to be used in seismic catalogs. A reliable measure of the “size” of an earthquake is essential for seismological, geological, engineering, seismic risk analysis and scientific researh. The size of a seismic source is measured using two parameters; damage caused (intensity) and energy released (magnitude). Intensity describes the strenght of a seismic event in terms of human recognition, affected region, damage on structures. Intensity depends on local geological conditions, distance from the source that make the objective estimates difficult. Intensity scales are valuable not only for pre-instrumental period for historical earthquakes but also for seismic risk analysis. Intensity scale is classified by macroseismic scales. The advent of seismic recording systems made it possible to determine strength of a seismic event from instrumental data. The concept of magnitude was introduced by Richter to provide objective measure of earthquake size. Magnitude of an earthquake provide quick information on the strength of a seismic event for public and are essential for cataloging. Changes in instrumentation and magnitude formulation resulted calculation of different magnitude scales. In order to obtain a non-saturating uniform magnitude scale, seismic moment magnitude (Mw) is developed based on source parameters.

The relationship between heat flow and seismicity in global tectonically active zones

AbstractThis study aims to analyze the complex relationship between heat flow and seismicity in tectonically active zones worldwide. The problem was quantitatively analyzed by using a geographic detector method, which is well suited for analyzing nonlinear relationships in geography. Moreover,β-value that describes the frequency-magnitude distribution is used to represent the seismicity. The results showed that heat flow (HF) = 84 mW/m2is a critical point for the relevant mechanisms of heat flow with seismicity in these zones. When HF < 84 mW/m2, the heat flow correlates negatively with theβ-value, with a correlation degree of 0.394. Within this interval, buoyant is a primary control on the stress state and earthquake size distribution. Large earthquakes occur more frequently in subduction zones with younger slabs that are more buoyant. Due to zones with a high ratio of large earthquake corresponds to lowβ-values, high heat flow values correspond to lowβ-values. When HF > 84 mW/m2, the heat flow correlates positively with theβ-value, with a correlation degree of 0.463. Within this interval, the increased heat flow decreases the viscosity of the rock plate and then reduces the stress. Lower stress would correspond to a smaller earthquake and then a higherβ-value. Therefore, high heat flow values correspond to highβ-values. This research would be conducive to understand the geologic activity and be helpful to determine the accuracy and timeliness of seismic hazard assessment.

The Impact of Large Erosional Events and Transient Normal Stress Changes on the Seismicity of Faults

AbstractThe long‐term erosion of steep landscapes is punctuated by dramatic erosional events that can remove significant amount of sediments within a timescale shorter than a seismic cycle. However, the role of such large erosional events on seismicity is poorly understood. We use QDYN, a quasi‐dynamic numerical model of earthquake cycles to investigate the effect of a large erosional event on seismicity. The progressive evacuation of landslide sediments is modeled by a transient normal stress decrease. We show that erosional events with a shorter duration compared with the duration of a seismic cycle can significantly increase the seismicity rate, even for small stress changes. Moreover, large erosional events with a shorter period compared with the earthquake nucleation timescale can change earthquake size distribution by triggering more small events. Those results suggest that large erosional events can significantly affect seismicity, illustrating in turn the short‐term impact of surface processes on tectonics.

Continuum of earthquake rupture speeds enabled by oblique slip

Earthquake rupture speed can affect ground shaking and thus seismic hazard. Seismological observations show that large earthquakes span a continuum of rupture speeds, from slower than Rayleigh waves up to P wave speed, and include speeds that are predicted to be unstable by 2D theory. This discrepancy between observations and theory has not yet been reconciled by a quantitative model. Here we present numerical simulations that show that long ruptures with oblique slip (both strike-slip and dip-slip components) can propagate steadily at various speeds, including those previously suggested to be unstable. The obliqueness of slip and the ratio of fracture energy to static energy release rate primarily control the propagation speed of long ruptures. We find that the effects of these controls on rupture speed can be predicted by extending the 3D theory of fracture mechanics to long ruptures with oblique slip. We propose that this model provides a quantitative framework to interpret supershear earthquakes, to constrain the energy ratio of faults based on observed rupture speed and rake angle, and to relate the potential rupture speed and size of future earthquakes to the observed slip deficit along faults.

On the heterogeneity of the earthquake rupture

SUMMARYThe scaling of earthquake parameters with seismic moment and its interpretation in terms of self-similarity is still debated in the literature. We address this question by examining a worldwide compilation of corner frequency-based and elastic rebound theory (ERT)-based fault slip, area and stress drop values for earthquakes ranging in magnitude from −0.7 to 7.8. We find that corner frequency estimates of slip (and stress drop) scale differently than those inferred from the ERT approach, where the latter deviates from the generally accepted constant stress drop behaviour of so-called self-similar scaling models. We also find that average slips from finite-source models are consistent with corner frequency scaling, whereas peak slip values are more consistent with the ERT scaling. The different scaling of corner frequency- and ERT-based estimates of slip and stress drop with earthquake size is interpreted in terms of heterogeneity of the rupture process. ERT-based estimates of stress drop decrease with seismic moment suggesting a self-affine behaviour. Despite the inferred heterogeneity at all scales, we do not observe a clear effect on the Brune stress drop scaling with earthquake size.

Seismic velocity structure at the southern termination of the 2016 Kumamoto Earthquake rupture, Japan

The earthquake rupture termination mechanism and size of the ruptured area are crucial parameters for earthquake magnitude estimations and seismic hazard assessments. The 2016 Mw 7.0 Kumamoto Earthquake, central Kyushu, Japan, ruptured a 34-km-long area along previously recognized active faults, eastern part of the Futagawa fault zone and northernmost part of the Hinagu fault zone. Many researchers have suggested that a magma chamber under Aso Volcano terminated the eastward rupture. However, the termination mechanism of the southward rupture has remained unclear. Here, we conduct a local seismic tomographic inversion using a dense temporary seismic network to detail the seismic velocity structure around the southern termination of the rupture. The compressional-wave velocity (Vp) results and compressional- to shear-wave velocity (Vp/Vs) structure indicate several E–W- and ENE–WSW-trending zonal anomalies in the upper to middle crust. These zonal anomalies may reflect regional geological structures that follow the same trends as the Oita–Kumamoto Tectonic Line and Usuki–Yatsushiro Tectonic Line. While the 2016 Kumamoto Earthquake rupture mainly propagated through a low-Vp/Vs area (1.62–1.74) along the Hinagu fault zone, the southern termination of the earthquake at the focal depth of the mainshock is adjacent to a 3-km-diameter high-Vp/Vs body. There is a rapid 5-km step in the depth of the seismogenic layer across the E–W-trending velocity boundary between the low- and high-Vp/Vs areas that corresponds well with the Rokkoku Tectonic Line; this geological boundary is the likely cause of the dislocation of the seismogenic layer because it is intruded by serpentinite veins. A possible factor in the southern rupture termination of the 2016 Kumamoto Earthquake is the existence of a high-Vp/Vs body in the direction of southern rupture propagation. The provided details of this inhomogeneous barrier, which are inferred from the seismic velocity structures, may improve future seismic hazard assessments for a complex fault system composed of multiple segments.

Earthquake Early Warning System Prototype Based on Lot Using Backpropagation Algorithm

Earthquakes are vibrations that occur on the earth's surface due to the sudden release of energy from the inside that creates seismic waves. An earthquake is caused by the movement of the earth's crust (the earth's plate). The frequency of a region refers to the type and size of earthquakes experienced during a period. Along with the development of early earthquake detection system technology provides a solution to minimize earthquake events. This research will discuss the system's design to determine the occurrence of earthquakes through time pattern analysis and Peak Ground Acceleration value. By using the Radial Basis Function Method, which later to minimize the loss of life from earthquakes. And help the main tools owned by the government. This study aims to determine the occurrence of earthquakes from Peak Ground Acceleration values and time analysis patterns, which are obtained from the decision of the Backpropagation method with an accuracy rate of 88%.