Open AccessAftershock modeling based on uncertain stress calculations
Author(s) -
Hainzl S.,
Enescu B.,
Cocco M.,
Woessner J.,
Catalli F.,
Wang R.,
Roth F.
Publication year - 2009
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008jb006011
Subject(s) - aftershock , induced seismicity , standard deviation , geology , slip (aerodynamics) , seismology , sequence (biology) , correlation coefficient , coefficient of variation , stress (linguistics) , geodesy , statistics , mathematics , physics , thermodynamics , linguistics , genetics , philosophy , biology
We discuss the impact of uncertainties in computed coseismic stress perturbations on the seismicity rate changes forecasted through a rate‐ and state‐dependent frictional model. We aim to understand how the variability of Coulomb stress changes affects the correlation between predicted and observed changes in the rate of earthquake production. We use the aftershock activity following the 1992 M7.3 Landers (California) earthquake as a case study. To accomplish these tasks, we first analyze the variability of stress changes resulting from the use of different published slip distributions. We find that the standard deviation of the uncertainty is of the same size as the absolute stress change and that their ratio, the coefficient of variation ( CV ), is approximately constant in space. This uncertainty has a strong impact on the forecasted aftershock activity if a rate‐and‐state frictional model is considered. We use the early aftershocks to invert for friction parameters and the coefficient of variation by means of the maximum likelihood method. We show that, when the uncertainties are properly taken into account, the inversion yields stable results, which fit the spatiotemporal aftershock sequence. The analysis of the 1992 Landers sequence demonstrates that accounting for realistic uncertainties in stress changes strongly improves the correlation between modeled and observed seismicity rate changes. For this sequence, we measure a friction parameter Aσ n ≈ 0.017 MPa and a coefficient of stress variation CV = 0.95.