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Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake
Geophysical Research Letters, Vol. 33, L06304, Doi:10.1029/2005gl025429, 2006
[Printable article (2.5 Mb)]
Tom Parsons1, Robert S. Yeats2, Yuji Yagi3 and Ahmad Hussain4
U.S. Geological Survey, Menlo Park, CA
2Department of Geosciences, Oregon State University, Corvallis,
Oregon, USA.
3Graduate School of Life and Environmental Sciences, University of
Tsukuba, Tsukuba, Japan.
4Geological Survey of Pakistan, Peshawar City, Pakistan.
Non-technical summary: A devastating earthquake shook Kashmir in October of 2005 killing more than 87,000 people and making millions homeless. This earthquake along with other recent large shocks have defined a northeast-southwest trending line within the Himalaya. Given the possibility that the October Kashmir earthquake might trigger other large earthquakes in an already vulnerable region, we calculated the stress changes it caused. We found that many of the active structures in the region fell into zones where we calculated reduced stress, including those near Peshawar and Islamabad. However, we also calculated that stress in areas northeast and southwest of the main rupture zone was increased, making other earthquakes more likely there.
Figure caption. Coulomb stress change on optimally oriented fault planes at 10 km depth from the 8 October, 2005 M = 7.6 Kashmir earthquake (epicenter shown by star). Optimal orientations were calculated using principal stress vectors shown at upper right, and we used a friction coefficient of 0.4 (parameter sensitivity of calculations is shown in Figures 3 and 4). The outer edges of the source dislocation is shown by the dashed black rectangle. Surface rupture is shown with a red line and is from Geological Survey of Pakistan mapping. The Indus-Kohistan seismic zone of Armbruster et al. [1978] is shown with a heavy dashed red line extending northwest of the mainshock rupture zone. Blue dots show 1963-2005 earthquake activity. Aftershocks from the first 45 days after the mainshock are shown with yellow dots. Active faults are identified by heavy red lines [Yeats et al., 1992], and inactive faults are finer dashed red lines.
