Abstract
A barrier may induce a supershear rupture on a fault. This paper focuses on two questions: One is whether the existence of a barrier accelerates the propagation speed of a whole fault rupture, and the other is what are the effects of friction laws and strength of a barrier on the rupture propagation process. For these purposes, classical slip-weakening, rate-state, and modified slip-weakening friction laws are employed to simulate the effect of a barrier on the fault rupture process. The simulation results showed that the rupture speed of the fault obviously decreases when the rupture front propagates to the barriers, and the rupture speed obviously increases when the rupture front leaves barriers. It was also found that a barrier on a fault may induce a supershear rupture via the rate-state friction law. The simulation results also showed that with the increase of barrier strength, the rupture speed near barriers fluctuates more and more; when the barrier strength exceeds a certain level, a supershear rupture area appears on the fault; with the increase of barrier strength, the propagation distance of the rupture at supershear wave velocity correspondingly increases. In addition, with the increase of barrier strength, the overall rupture duration of the fault slightly increases. This indicates that a barrier cannot shorten the total duration of a fault rupture. Though a barrier will lead to a supershear rupture, it just regulates the distribution of the rupture speed on the fault surface. Moreover, with the increase of barrier strength, the peak ground acceleration caused by rupture through the barrier also increases, indicating that the existence of a barrier may lead to the intensification of seismic hazards.
Highlights
The so-called supershear rupture refers to a phenomenon in which the rupture propagation velocity Vr on a fault exceeds the propagation velocity Vs of the shear wave (S-wave) in the medium around the earthquake source area
The propagation distance of each stage was different: (1) The front of the rupture spontaneously propagated along the rupture direction from the nucleation zone, and the propagation velocity gradually increased and tended to be stable; (2) when the rupture propagated to the barrier zone, its velocity gradually decreased; (3) the propagation velocity of the rupture gradually increased after the front of rupture crossed the barrier zone and exceeded the S-wave speed of the medium (3333m/s); (4) the rupture propagates at the supershear wave velocity for about 3 km; (5)
This paper investigated the effects of friction laws and strength of barriers on the rupture propagation process
Summary
The so-called supershear rupture refers to a phenomenon in which the rupture propagation velocity Vr on a fault exceeds the propagation velocity Vs of the shear wave (S-wave) in the medium around the earthquake source area. Sci. 2020, 10, 1687 in Turkey (Mw = 7.2) [2], the 2001 West Kunlun earthquake in China (Mw = 7.8) [3], the 2002 Denali earthquake in Alaska of the United States (Mw = 7.9) [4], and the 2013 Craig earthquake in the United States (Mw = 7.5) [5] It has been proven by theoretical analysis [6,7,8,9], numerical simulations [10,11,12,13,14,15,16,17], and laboratory experiments [18,19,20,21,22,23,24,25,26,27] that fault rupture speed can exceed the S-wave speed and produce a supershear rupture. It is important to study the formation mechanism of supershear rupture earthquakes in order to understand earthquake sources and to evaluate seismic hazards
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