Woods Hole Oceanographic Institution

Hongfeng Yang

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Hongfeng Yang, Yajing Liu, and Jian Lin,

Effects of subducted seamounts on megathrust earthquake

nucleation and rupture propagation

, Geophys. Res. Lett., Dec. 19, 2012

 Subducted seamounts have been linked to interplate

earthquakes, but their specific effects on earthquake mechanism

remain controversial. A key question is under what

conditions a subducted seamount will generate or stop

megathrust earthquakes. Here we show results from numerical

experiments in the framework of rate- and state-dependent

friction law in which a seamount is characterized as a patch of

elevated effective normal stress on the thrust interface. We

find that whether subducted seamounts generate or impede

megathrust earthquakes depends critically on their relative

locations to the earthquake nucleation zone defined by depthvariable

friction parameters. A seamount may act as a rupture

barrier and such barrier effect is most prominent when the

seamount sits at an intermediate range of the seamount-totrench

distances (20 100% of the nucleation-zone-to-trench

distance). Moreover, we observe that seamount-induced

barriers can turn into asperities on which megathrust earthquakes

can nucleate at shallow depths and rupture the entire

seismogenic zone. These results suggest that a strong barrier

patch may not necessarily reduce the maximum size of

earthquakes. Instead, the barrier could experience large

coseismic slip when it is ruptured.

FILE » yang_etal_2012GRL_seamount_143004.pdf

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