Stress changes induced by the 2008 [formula omitted] Wenchuan earthquake, China

Abstract

We invert the background stress fields of the Longmenshan and its adjacent regions before and after the 2008 great Wenchuan earthquake from focal mechanism data. Our results show that the stress orientations after the 2008 great Wenchuan earthquake are more coherent than those before this event at the epicentral zone. This result includes twofold implications: one is that the Wenchuan event altered the local stress field, the other is that the strength of the Wenchuan fault zone is very high and the characteristic of the seismogenic fault is consistent with the asperity model. We also estimate the stress changes caused by the Wenchuan event using an accurate source model and exhaustive receiver faults. The stress changes of >10kPa mainly occur in the nearby areas of the Longriba, east Kunlun, Qingchuan, Lushan faults and the southeastern section of the Xianshuihe fault, indicating that there is high earthquake hazard in these areas. The seismicity before and after the great Wenchuan earthquake in the Longmenshan and its adjacent regions shows that some subsequent earthquakes in the stress shadow area may be delayed and the 2013 Lushan earthquake may be advanced.