关键词: 2010年智利地震, 破裂过程成像, 破裂速度, 相对反投影方法

Abstract: The Mw 8.8 Chilean earthquake of 27 February 2010 was the greatest Chilean earthquake since 1960. The back projection method based on the non-plane wave assumption is used to image the rupture process on an oblique fault plane with three-component broadband seismograms recorded by the U.S. Array Transportable Network. The results show that the Chilean earthquake was composed of three sub-events, and ruptured with at least 513 km in length and 100 km in width. Moreover, the rupture bilaterally extended northwards and southwards after the initiation of the earthquake and was dominated by the northern branch. The northern branch of the earthquake ruptured over a length of about 340 km in 125 s, which indicates that its average rupture velocity was about 2.87 km/s. Meanwhile, the southern branch had a rupture length of 173 km in 99 s, which means the southern average rupture velocity was about 1.84 km/s. In addition, after the onset of the quake, the energy peaks of two sub-events in the northern branch occurred at 16 and 79 s, which were 75 and 230 km away from the epicenter. The energy peak of the sub-event in the southern branch appeared at 80 s and located about 145 km away from the epicenter.

Key words: 2010 Chilean earthquake, imaging of rupture process, rupture velocity, relative back projection method