| 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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