Bayesian analysis of the modified Omori law

M. Holschneider; C. Narteau; P. Shebalin; Z. Peng; D. Schorlemmer

doi:10.1029/2011jb009054

Bayesian estimation of the Modified Omori Law parameters for the Iranian Plateau

Journal of Seismology ◽

10.1007/s10950-016-9574-8 ◽

2016 ◽

Vol 20 (3) ◽

pp. 953-970 ◽

Cited By ~ 5

Author(s):

S. Ommi ◽

H. Zafarani ◽

V. B. Smirnov

Keyword(s):

Bayesian Estimation ◽

Iranian Plateau ◽

Omori Law ◽

Modified Omori Law

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Sequence-based hazard analysis for Italy considering a grid seismic source model

Annals of Geophysics ◽

10.4401/ag-8586 ◽

2021 ◽

Vol 64 (2) ◽

Author(s):

Eugenio Chioccarelli ◽

Pasquale Cito ◽

Francesco Visini ◽

Iunio Iervolino

Keyword(s):

Earthquake Engineering ◽

Hazard Analysis ◽

Seismic Source ◽

Source Model ◽

Classical Formulation ◽

Omori Law ◽

Model Account ◽

Before And After ◽

Seismic Source Model ◽

Modified Omori Law

Earthquakes are usually clustered in both time and space and, within each cluster, the event of highest magnitude is conventionally identified as the mainshock, while the foreshocks and the aftershocks are the events that occur before and after it, respectively. Mainshocks are the earthquakes considered in the classical formulation of the probabilistic seismic hazard analysis (PSHA), where the contribution of foreshocks and aftershocks is usually neglected. In fact, it has been shown that it is possible to rigorously, within the hypotheses of the model, account for the effect of mainshock-aftershocks sequences by means of the sequence-based PSHA (i.e., SPSHA). SPSHA extends the usability of the homogeneous Poisson process, adopted for mainshocks within PSHA, to also describe the occurrence of clusters maintaining the same input data of PSHA; i.e., the seismic rates derived by a declustered catalog. The aftershocks’ occurrences are accounted for by means of conditional non-homogeneous Poisson processes based on the modified Omori law. The seismic source model for Italy has been recently investigated, and the objective of the study herein presented is to include and evaluate the effect of aftershocks, by means of SPSHA, based on a new grid model. In the paper, the results of PSHA and SPSHA are compared, considering the spectral and return periods that are of typical interest for earthquake engineering. Finally, a comparison with the SPSHA map based on a well- established source model for Italy is also provided.

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Bulk-friction modeling of afterslip and the modified Omori law

Tectonophysics ◽

10.1016/s0040-1951(97)00081-4 ◽

1997 ◽

Vol 277 (1-3) ◽

pp. 109-136 ◽

Cited By ~ 12

Author(s):

Leif Wennerberg ◽

Robert V. Sharp

Keyword(s):

Friction Modeling ◽

Omori Law ◽

Modified Omori Law

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Anomalous statistics of aftershock sequences generated by supershear ruptures

Research in Geophysics ◽

10.4081/rg.2012.e6 ◽

2012 ◽

Vol 2 (1) ◽

pp. 6 ◽

Cited By ~ 1

Author(s):

Pathikrit Bhattacharya ◽

Robert Shcherbakov ◽

Kristy F. Tiampo ◽

Lalu Mansinha

Keyword(s):

Wave Velocity ◽

Imperial Valley ◽

Rayleigh Wave Velocity ◽

Omori Law ◽

Aftershock Sequences ◽

Stress Changes ◽

Earthquake Ruptures ◽

Local Shear ◽

Modified Omori Law ◽

Fault Distribution

Most earthquake ruptures propagate with speeds smaller than the Rayleigh wave velocity of the medium. These are called sub- Rayleigh ruptures. However, under suitable conditions, segments of otherwise sub- Rayleigh seismogenic ruptures can occasionally accelerate to speeds higher than the local shear wave velocity, giving rise to so-called supershear ruptures. The occurrence of supershear ruptures is usually associated with a locally higher value of pre-stress on the fault segment compared to the sub-Rayleigh segments of the same fault. Additionally, shear stress changes generated by the supershear rupture are radiated out unattenuated to distances comparable to the depth of rupture instead of rapidly decaying at much smaller distances from the rupture. This leads to aftershocks being distributed away from the fault on the supershear segment. This study attempts to verify whether these pre- and postseismic stress conditions and the resultant spatial aftershock distributions lead to discernible features in the statistical properties of the aftershock sequences of the earthquakes known to be associated with supershear ruptures. We analyze the Gutenberg-Richter scaling, the modified Omori law and Båth’s law for the aftershock sequences of two supershear mainshocks: the 1979 MW 6.5 Imperial Valley (California) and 2002 MW 7.9 Denali (Alaska) earthquakes. We observe that the b-value is always higher in the supershear zone than the rest of the sequence. We also observe that there is no systematic trend in the exponent of the modified Omori law when comparing the aftershocks in the supershear zone with the rest of the aftershocks. We argue that the b-value anomaly can be explained in terms of the off-fault distribution of aftershocks around the supershear segment of the rupture.

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