资源环境科技发展态势分析平台

Using regional seismic data and a 3-D crustal velocity model, we develop a novel multiazimuth backprojection approach and apply it to image time-lapse coseismic ruptures for the 2019 Ridgecrest earthquakes. The time-integrated images for the M(w)6.4 foreshock and M(w)7.1 mainshock agree with the fault geometry delineated by the aftershock distributions. Backprojection images at different times illustrate the detailed rupture processes for these two events. For instance, the M(w)6.4 foreshock initialized close to the hypocenter, then the rupture propagated along a northwest trending fault with an average velocity of 1.0 km/s, and finally jumped to a southwest trending fault and propagated about 20 km with a velocity about 1.5 km/s. In contrast, the M(w)7.1 mainshock initialized near the hypocenter, then propagated to the northwest upon reaching the Coso volcanic field with an average velocity of 1.4 km/s, and later turned to the southeast and propagated along the main fault zone with a complex bilateral process and a velocity about 0.6 km/s.