The elliptic stress thermal field prior to M_S 7.3 Yutian, and M_S 8.0 Wenchuan earthquakes in China in 2008

摘要

Some thermal infrared anomalies on the earth’s surface are omens of stronger earthquakes, and have a close relationship with the stress fields. Satellite-based remote sensing is an important means of monitoring and researching this phenomenon. The M _S 7.3 Yutian earthquake in Xinjiang on March 20, 2008 and the M _S 8.0 Wenchuan earthquake in Sichuan on May 12, 2008 both happened in the Qinghai–Tibet Plateau, China, with epicenters more than 2,000 km apart. The two events, however, were a production of an identical stress field in different developing phases. Prior to the M _S 7.3 Yutian earthquake, a large-scale abnormal temperature rise not only covered the epicenter of the forthcoming Yutian earthquake, but also arrived at the epicenter of the farther Wenchuan earthquake. The revolving elliptic stress thermal field reflecting earthquake gestation moved from the west to the east of the Wenchuan epicenter at the time of the Yutian event occurrence. The rotation of the calefactive ellipses and belts prior to the two strong events agreed with the stress field, the focal mechanism, and modality and mechanism property of the ruptures in the crustal surface induced by the events. It should be a reflection of the partial mantle uprush and rotation.