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- Rate/state Coulomb stress transfer model for the CSEP Japan seismicity forecas
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- Numerous studies retrospectively found that seismicity rate
jumps (drops) due to coseismic Coulomb stress increase (decrease). The
Collaboratory for the Study of Earthquake Predictability (CSEP)
instead provides us an opportunity for prospective testing of the
Coulomb hypothesis. Here we adapt our stress transfer model
incorporating rate and state dependent friction law to the CSEP Japan
seismicity forecast. We demonstrate how to compute the forecast rates
of large shocks in 2009 using the large earthquakes during the past
120 years. The time dependent impact of the coseismic stress
perturbations explains qualitatively well the occurrence of the recent
moderate size shocks. Such ability is partly similar to that of
statistical earthquake clustering models. However, our model differs
from them as follows: the off-fault aftershock zones can be simulated
using finite fault sources; the regional areal patterns of triggered
seismicity are modified by the dominant mechanisms of the potential
sources; the imparted stresses due to large earthquakes produce stress
shadows that lead to a reduction of the forecasted number of
earthquakes. Although the model relies on several unknown parameters,
it is the first physics based model submitted to the CSEP Japan test
center and has the potential to be tuned for short-term earthquake
forecasts.