2 Helmstetter and Sornette : Importance of Triggered Seismicity
نویسنده
چکیده
Using the simple ETAS branching model of seismicity, which assumes that each earthquake can trigger other earthquakes, we quantify the role played by the cascade of triggered seismicity in controlling the rate of aftershock decay as well as in the overall level of seismicity in the presence of a constant external seismicity source. We show that, in this model, the proportion of triggered seismicity is equal to the proportion of secondary plus later-generation aftershocks, and is given by the average number of triggered events per earthquake. Based on these results and the observation that a large fraction of seismicity are triggered earthquakes, we conclude that similarly a large fraction of aftershocks occurring a few hours or days after a mainshock are triggered indirectly by the mainshock.
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