Effects of Coulomb stress change on Mw > 6 earthquakes in the Caucasus region

Publication date: December 2019Source: Physics of the Earth and Planetary Interiors, Volume 297Author(s): Bahruz Ahadov, Shuanggen JinAbstractCoulomb stress variations may trigger earthquakes, while the stress transfer process is not clear. In this paper, Coulomb stress changes are investigated for the sequences of strong earthquakes in the Caucasus region, which followed the 1988 Mw6.8 in Spitak, the 1991 Mw6.9 in Racha and the 2000 Mw6.2 in Baku. Our results show that the mainshocks induced variations in the stress field where most of the seismic events occurred. Coulomb stress increases 2 bars corresponding nearly to places of aftershocks, while the stress falls above 10 bars for Racha mainshock. The calculated Coulomb stress loaded about 5 bars at the end of rupture plane and the stress falls ~9 bars for Spitak mainshock. Our stress pattern shows a correlation within the areas of Coulomb stress caused by the combination of seismicity. Correlations between the coseismic Coulomb stress changes and the observed spatial patterns of the aftershocks created by the mainshock are illustrated by the stress variations over both optimally oriented and specified fault planes. An apparent correlation between the mainshock stress changes and the detected spatial pattern of the aftershocks is found, confirming the utility of the stress maps in constraining the expected locations of the forthcoming aftershocks and mitigating earthquake hazards.

Source: Physics of the Earth and Planetary Interiors - October 31, 2019 Category: Physics Source Type: research