A modified Coulomb failure seismicity model to study earthquake occurrence and frequency-magnitude distributions

2021 ◽  
Author(s):  
Torsten Dahm
Keyword(s):  
Tectonic Stress ◽  
Time Dependent ◽  
New Model ◽  
Coulomb Stress Changes ◽  
Stress Effects ◽  
Effective Media ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Coulomb Failure ◽  
Frequency Magnitude

<p>The linear Coulomb failure (LCM) and the rate-and-state model (RSM) are two widely-used physics-based seismicity models both assuming Coulomb stress changes acting on pre-existing populations of faults. While both predict background earthquake rates and time-dependent stress effects, only the RSM can additionally explain the time-dependent triggering of aftershocks.</p><p>We develop a modified effective media Coulomb model which accounts for the possibility of earthquake nucleation and retarded triggering of rupture. The new model has only two independent parameters and explains all statistical features of seismicity equally well as the RMS, but is simpler in its concept and provides insights in the possible nature of time-dependent frequency-magnitude distributions. Some of the statistical predictions are different compared to the RSM or LCM. For instance, the model domain is not limited to positive earthquake background or stressing rates; it can also simulate seismicity under zero stressing assumptions. The increase of background seismicity with tectonic stressing is nonlinear, different to the other models, and may even saturate if the tectonic stress loading is very strong. The Omori aftershock decay is predicted in the new model with an exponent of p=1 also for time periods much larger than the aftershock decay time, however, the productivity factor K is time dependent with a very slow exponential attenuation. The attenuation may explain the apparent variation of p in observed aftershock sequences. Interesting is also that the new model predicts a co-seismic peak of triggered aftershocks, which depends on the magnitude of the stress step and does not influence the attenuation of aftershocks following the stress step. It could be a physical explanation for the c-value in Omori’s law, the origin of which is still under discussion.</p><p>We compare the new model to RSM and LCM and discuss the possible implications for earthquake clustering and frequency magnitude distributions.</p>

The role of afterslip in driving aftershock sequences

2020 ◽  
Author(s):  
Robert Churchill ◽  
Maximilian Werner ◽  
Juliet Biggs ◽  
Ake Fagereng
Keyword(s):  
Empirical Relationship ◽  
Individual Case ◽  
Aftershock Sequence ◽  
Sequence Evolution ◽  
Coulomb Stress Changes ◽  
Temporal Decay ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Tectonic Earthquakes ◽  
Spatio Temporal

<p>Aftershock sequences following large tectonic earthquakes exhibit considerable spatio-temporal complexity and suggest causative mechanisms beyond co-seismic, elasto-static Coulomb stress changes in the crust. Candidate mechanisms include dynamic triggering and postseismic processes such as viscoelastic relaxation, poroelastic rebound and aseismic afterslip, which has garnered particular interest recently. Aseismic afterslip – whereby localized frictional sliding within velocity-strengthening rheologies acts to redistribute lithospheric stresses in the postseismic phase – has been suggested by numerous studies to exert dominant control on aftershock sequence evolution, including productivity, spatial distribution and temporal decay.</p><p>As evidence is based overwhelmingly on individual case study analysis, we wish to systematically compare key metrics of aseismic afterslip and corresponding aftershock sequences to investigate this relationship. We specifically look for any empirical relationship between the seismic-equivalent moment of aseismic afterslip episodes and the corresponding aftershock sequence productivity. We first compile published afterslip models into a database containing moment estimates over varying time periods, as well as spatial distributions, temporal decays and modelling methodology as a supplementary resource. We then identify the corresponding aftershock sequence from the globally comparable USGS PDE catalog. As expected, coseismic moment exerts an obvious control on both afterslip moment and aftershock productivity – an effect we control for by normalising by mainshock moment and expected productivity (the Utsu-Seki law) respectively. Preliminary results suggest broad variability of both afterslip moment and aftershock productivity with no obvious control of afterslip on aftershocks beyond the scaling with mainshock size, including when separated by mainshock mechanism or region. As this study is insensitive to spatial and temporal distributions, we cannot rule out the potential influence afterslip exerts in these but find no evidence that afterslip drives overall productivity of aftershock sequences.</p>

Coseismic Slip Distribution of the 24 January 2020 Mw 6.7 Doganyol Earthquake and in Relation to the Foreshock and Aftershock Activities

2020 ◽  
Vol 92 (1) ◽  
pp. 127-139
Author(s):  
Xin Lin ◽  
Jinlai Hao ◽  
Dun Wang ◽  
Risheng Chu ◽  
Xiangfang Zeng ◽  
...  
Keyword(s):  
Seismic Risk ◽  
Body Wave ◽  
Surface Displacement ◽  
Coulomb Stress ◽  
Slip Model ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
And Migration

Abstract On 24 January 2020 (UTC), a destructive Mw 6.7 earthquake struck the east Anatolian fault of eastern Turkey after a series of foreshocks, causing many casualties and significant property damage. In this study, the rupture process of this earthquake is investigated with teleseismic broadband body-wave and surface-wave records. Results indicate that this earthquake is a left-lateral strike-slip event, and the rupture extends mainly to south. The main slip patch spreads ∼30  km along strike in the shallow above 14 km with a peak slip of ∼1.2  m, and the total seismic moment is 1.69×1019  N·m. The east–west component of horizontal surface displacement predicted with our slip model ranges from ∼0.4 to −0.3  m. The predicted displacements are consistent with the observed ones obtained from satellite images. We relocate 459 foreshocks and early aftershocks to explore the relationship between foreshock and aftershock sequences and coseismic slip. It is noted that there is an anticorrelation relationship between the distributions of early aftershocks and the coseismic slip. The strain energy in the large slip patch may have been sufficiently released by the mainshock; therefore, fewer early aftershocks occurred in that patch. Although we note a similar pattern between the relocated foreshock and coseismic slip, and a migration of foreshock, our dataset may not well resolve the correlation and migration due to the incomplete relocation foreshock catalog. Based on the slip model, we calculate the coulomb stress changes on the surrounding faults caused by the mainshock. The results reveal that the mainshock promoted stress accumulation on the northern and southern ends of the Elazig–Matalya segment and may reactivate the locked fault segment, leading to a high seismic risk in these regions. Although this earthquake does not significantly increase the coulomb stress change, the seismic risk of the Matalya–Kahraman Maras–Antakya segment should draw attention.

scholarly journals The effect of stress changes on time-dependent earthquake probabilities for the central Wasatch Fault Zone, Utah, USA.

2019 ◽  
Author(s):  
A Verdecchia ◽  
S Carena ◽  
B Pace ◽  
C B DuRoss
Keyword(s):  
Salt Lake ◽  
Salt Lake City ◽  
Time Dependent ◽  
Coulomb Stress ◽  
Coulomb Stress Changes ◽  
Probability Of Occurrence ◽  
Stress Changes ◽  
Lake City ◽  
Wasatch Fault ◽  
Large Earthquakes

Summary Static and quasi-static Coulomb stress changes produced by large earthquakes can modify the probability of occurrence of subsequent events on neighboring faults. This approach is based on physical (Coulomb stress changes) and statistical (probability calculations) models, which are influenced by the quality and quantity of data available in the study region. Here, we focus on the Wasatch Fault Zone (WFZ), a well-studied active normal fault system having abundant geologic and paleoseismological data. Paleoseismological trench investigations of the WFZ indicate that at least 24 large, surface-faulting earthquakes have ruptured the fault's five central, 35–59-km long segments since ∼7 ka. Our goal is to determine if the stress changes due to the youngest paleoevents have significantly modified the present-day probability of occurrence of large earthquakes on each of the segments. For each segment, we modeled the cumulative (coseismic + postseismic) Coulomb stress changes (∆CFScum) due to earthquakes younger than the most recent event on the segment in question and applied the resulting values to the time-dependent probability calculations. Results from the Coulomb stress modeling suggest that the Brigham City, Salt Lake City, and Provo segments have accumulated ∆CFScum larger than 10 bars, whereas the Weber segment has experienced a stress decrease of 5 bars, in the scenario of recent rupture of the Great Salt Lake fault to the west. Probability calculations predict high probability of occurrence for the Brigham City and Salt Lake City segments, due to their long elapsed times (> 1–2 ka) when compared to the Weber, Provo, and Nephi segments (< 1 ka). The range of calculated coefficients of variation (CV) has a large influence on the final probabilities, mostly in the case of the Brigham City segment. Finally, when the Coulomb stress and the probability models are combined, our results indicate that the ∆CFScum resulting from earthquakes postdating the youngest events on each of the five segments substantially affects the probability calculations for three of the segments: Brigham City, Salt Lake City, and Provo. The probability of occurrence of a large earthquake in the next 50 years on these three segments may therefore be underestimated if a time-independent approach, or a time-dependent approach that does not consider ∆CFS, is adopted.

scholarly journals Stress Accumulation and Earthquake Activity on the Great Sumatran Fault, Indonesia

2022 ◽  
Author(s):  
Muhammad Taufiq Rafie ◽  
David P. Sahara ◽  
Phil R. Cummins ◽  
Wahyu Triyoso ◽  
Sri Widiyantoro
Keyword(s):  
Time Evolution ◽  
Slip Rate ◽  
Tectonic Stress ◽  
Coulomb Stress ◽  
Earthquake Activity ◽  
Coulomb Stress Changes ◽  
Megathrust Earthquakes ◽  
Stress Changes ◽  
Sumatran Fault ◽  
Stress Accumulation

Abstract The seismically active Sumatra subduction zone has generated some of the largest earthquakes in the instrumental record, and both historical accounts and paleogeodetic coral studies indicate such activity has historical recorded megathrust earthquakes and transferred stress to the surrounding, including the Great Sumatran Fault (GSF). Therefore, evaluating the stress transfer from these large subduction earthquakes could delineate the highly stressed area as potential-earthquake region along the GSF. In this study, we investigated eight megathrust earthquakes from 1797 to 2010 and resolved the accumulated Coulomb stress changes onto the 18 segments along the GSF. Additionally, we also estimated the rate of tectonic stress on the GSF segments which experienced large earthquake using the case of: (1) no sliver movement and (2) with sliver movement. Based on the historical stress changes of large earthquakes and the increase in tectonic stress rate, we analysed the historical stress changes time evolution on the GSF. The Coulomb stress accumulation of megathrust earthquakes between 1797-1907 increase the stress changes mainly on the southern part of GSF which followed by four major events between 1890-1943. The estimation of tectonic stress rates using case (1) produces low rate and long recurrence intervals which implies that the megathrust earthquakes plays an important role in allowing the GSF earthquake to occur. When implementing the arc-parallel sliver movement of case (2) to the calculation, the tectonic stress rates is 9 to 58 times higher than case (1) of no sliver movement. The observed slip rate of 15-16 mm/yr at the GSF is consistent with the recurrence interval for full-segment rupture of 100-200 years obtained from case (2). This suggests that the GSF earthquake is more controlled by the rapid arc-parallel forearc sliver motion. Furthermore, the analysis of stress changes time evolution model shows that some segments such as Tripa (North and South), Angkola, Musi and Manna appear to be brought back in their seismic cycles since these segments have experienced full-segment rupture and likely locked, increasing their earthquake hazard potentials.

scholarly journals Interaction Between Historical Earthquakes and the 2021 Mw7.4 Maduo Event and Their Impacts on the Seismic Gap Areas Along the East Kunlun Fault

2021 ◽  
Author(s):  
Peiyu Dong ◽  
Bin Zhao ◽  
Xuejun Qiao
Keyword(s):  
Source Area ◽  
Historical Earthquakes ◽  
Tectonic Stress ◽  
Inhibitory Effect ◽  
Seismic Gap ◽  
Seismogenic Fault ◽  
Qinghai Province ◽  
Coulomb Stress Changes ◽  
Stress Shadow ◽  
Stress Changes

Abstract On May 21, 2021 (UTC time), a Mw7.4 earthquake struck Maduo County, Qinghai Province, China. The rupture of this typical strike-slip event and its aftershocks along the Kunlun-Jiangcuo fault (JCF) propagated approximately 170 km from the epicenter. In this study, we calculated the coseismic and postseismic Coulomb stress changes induced by 14 historical earthquakes and investigated their impacts on the 2021 Maduo source area. We found that the JCF is in the stress shadow of these historical events with a combined ΔCFS range of approximately -0.4 to -0.2 MPa. Since the seismogenic fault of the 1937 event is nearly parallel and close to the JCF, the rupture of the 1937 event had the greatest inhibitory effect on Maduo source area. We hypothesize that the actual loading rate at the depth of the seismogenic layer in the Maduo source area is much higher than the simulated value (0.3 kPa/a). Consequently, the Maduo earthquake still occurred despite the considerable delaying effect of these historical earthquakes (especially the 1937 event). Our findings also indicate that the tectonic stress in the eastern Bayanhar block is still rapidly accumulating and adjusting. Our investigation further reveals the enhanced stress induced by the historical and Maduo events with ΔCFS values of approximately 30~300 kPa and 50~300 kPa on the XDS and the eastern end of the EKF, respectively, not only on the MMS but also at the eastern end of each branch segment of the EKF. Hence, considering the accumulation of tectonic stress, we suggest that the seismic hazard in these two regions has been promoted.

Variation of the frequency-magnitude relation during earthquake sequences in New Zealand

1973 ◽  
Vol 63 (2) ◽  
pp. 517-528 ◽  
Author(s):  
S. J. Gibowicz
Keyword(s):  
New Zealand ◽  
Main Shock ◽  
Earthquake Swarm ◽  
Rock Deformation ◽  
Laboratory Studies ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Earthquake Sequences ◽  
Largest Aftershock ◽  
Frequency Magnitude

abstract Seven New Zealand earthquake sequences are studied statistically. These comprise six aftershock sequences and one earthquake swarm. The magnitude-stability law of Lomnitz does not hold. During the aftershock sequences the coefficient b, governing the frequency-magnitude relationship, is found to increase rapidly after the main shock, and then to decrease until the occurrence of the largest aftershock, when it again begins to increase. During the earthquake swarm, the coefficient b decreases logarithmically with time. This can be explained in terms of stress changes and is consistent with laboratory studies on rock deformation.

scholarly journals STRESS INTERACTION BETWEEN THRUST FAULTS ALONG THE SW HELLENIC ARC (GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 386
Author(s):  
A. Messini ◽  
E. E. Papadimitriou ◽  
V. G. Karakostas ◽  
I. Baskoutas
Keyword(s):  
Tectonic Stress ◽  
Elastic Half Space ◽  
Coulomb Stress ◽  
Thrust Faults ◽  
Tectonic Plates ◽  
Coulomb Stress Changes ◽  
Seismic Slip ◽  
Hellenic Arc ◽  
Stress Changes ◽  
Major Fault

The occurrence of strong earthquakes (M>6.3) and the evolution of the stress field along the southwestern part of the Hellenic arc since 1959 are examined by the calculation of Coulomb stress changes. The study area is characterized by low angle thrust faults and high seismicity as being part of the subduction interface. Coulomb stress changes were calculated assuming that earthquakes can be modeled as static dislocations in an elastic half-space, considering the co-seismic slip during strong events and the slow tectonic stress build-up along major fault segments due to the movements of the tectonic plates. The ruptures are modeled taking into account the strike, dip, and rake appropriate to each event examined. It is evaluated whether the stress changes brought a given earthquake closer to, or farther away from, failure. It was found that the majority of the events (strong and smaller) are located in stress enhanced areas.

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