Supershear rupture in the 24 May 2013 M_w 6.7 Okhotsk deep earthquake: Additional evidence from regional seismic stations

Abstract

Zhan et al. (2014a) reported supershear rupture during the Mw 6.7 aftershock of the 2013 Mw 8.3 Sea of Okhotsk deep earthquake, relying heavily on the regional station PET, which played a critical role in constraining the vertical rupture dimension and rupture speed. Here we include five more regional stations and find that the durations of the source time functions derived from these stations are consistent with Zhan et al.'s supershear rupture model. Furthermore, to reduce the nonuniqueness of deconvolution and combine the bandwidths of different stations, we conduct a joint inversion of the six regional stations for a single broadband moment‐rate function (MRF). The best fitting MRF, which explains all the regional waveforms well, has a smooth shape without any temporal gaps. The Mw 6.7 Okhotsk deep earthquake is more likely a continuous supershear rupture than a dynamically triggered doublet.

RevivingmB

“…(iii) The supershear deep event (H6 in Fig. 8, Zhan et al 2015) has a large σ a B (∼15 MPa) for the relatively small M w , 6.7.…”

Stress Drop Variation of Deep‐Focus Earthquakes Based on Empirical Green's Functions

“…In the second mechanism, frictional melts on preexisting faults lubricate the fault plane, reduce dynamic shear strength, and facilitate earthquake rupture. Once triggered, a shear instability evolves into a cascading failure (Chen & Wen, ), which may propagate at a supershear rupture velocity (Zhan et al, ).…”

Toward automated directivity estimates in earthquake moment tensor inversion

“…source duration) as in most of previous studies. Similar ideas based on source time function stretching has also been exploited recently (Zhan et al 2015;Prieto et al 2017). However, they still rely on EGF deconvolution to obtain ASTFs first before stretching them to search for directivity, which causes additional challenges for the more automated goal we have in mind.…”