Evidence for anthropogenic surface loading as trigger mechanism of the 2008 Wenchuan earthquake |
| |
| Authors: | Christian D Klose |
| |
| Institution: | (1) Think Geohazards, New York, USA |
| |
| Abstract: | Two and a half years prior to China’s M7.9 Wenchuan earthquake of May 2008, at least 300 million metric tons of water accumulated
with additional seasonal water level changes in the Minjiang River Valley at the eastern margin of the Longmen Shan. This
article shows that static surface loading in the Zipingpu water reservoir induced Coulomb failure stresses on the nearby Beichuan
thrust fault system at <17 km depth. Triggering stresses exceeded levels of daily lunar and solar tides and perturbed a fault
area measuring 416 ± 96 km2. These stress perturbations, in turn, likely advanced the clock of the mainshock and directed the initial rupture propagation
upward towards the reservoir on the "Coulomb-like" Beichuan fault with rate- and state-dependent frictional behavior. Static
triggering perturbations produced up to 60 years (0.6%) of equivalent tectonic loading, and show strong correlations to the
coseismic slip. Moreover, correlations between clock advancement and coseismic slip, observed during the mainshock beneath
the reservoir, are strongest for a longer seismic cycle (10kyr) of M > 7 earthquakes. Finally, the daily event rate of the
micro-seismicity (M ≥ 0.5) correlates well with the static stress perturbations, indicating destabilization. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
