Slip distribution of the 11 March 2011 Tohoku-Oki earthquake (Mw 9.0) inferred from the refined homomorphic deconvolution method

Abstract

The kinematic rupture process of the 2011 Tohoku-Oki earthquake (Mw 9.0) was derived given apparent source time functions (ASTFs) retrieved from Rayleigh waves using a refined homomorphic deconvolution method. The total duration of the rupture process was about 165s. Three slip-concentrated areas were identified based on images of static slip distribution. The largest asperity, located up-dip from the hypocenter with an area of 250km×110km extending to the trench on the fault, had a maximum slip of about 54m. The other asperities with smaller slip down-dip from the hypocenter were centered on the north and south of the hypocenter, respectively. The preferred average rupture expansion velocity was 1.2km/s within 130km from the hypocenter and up to 2.3km/s over other areas on the fault. Thus, the region near the vicinity of the hypocenter with lower rupture velocity had higher slip amplitude, strongly suggesting brittle failure on a high friction fault. Based on ASTF results, our proposed method offers another way of directly detecting the kinematic source parameters of earthquakes.