Nontrivial decay of aftershock density with distance in Southern California

Static stress triggering explains the empirical aftershock distance decay

The shape of the spatial aftershock decay is sensitive to the triggering mechanism and thus particularly useful for discriminating between static and dynamic stress triggering. For California seismicity, it has been recently recognized that its form is more complicated than typically assumed consisting of three different regimes with transitions at the scale of the rupture length and the thickn...

California aftershock hazard forecasts.

1) quantile points at the selected times, S, corresponding to the expected probability and ± 1 SD (Table 1). The standard error in P rapidly decreases with increasing time after the mainshock due to the inclusion of current data. For example, at S = 1 day after the mainshock, the ± 1 SD range about the generic 1-day interval probability (0.052) is 0.034 to 0.075 (Table 1). Rydelek suggests esti...

California aftershock model uncertainties.

Anomalous early aftershock decay rate of the 2004 Mw6.0 Parkfield, California, earthquake

[1] We analyze the seismicity rate immediately after the 2004 Mw6.0 Parkfield, California, earthquake from nearsource seismograms. By scrutinizing high-frequency signals, we can distinguish mainshock coda from early aftershocks occurring as soon as 30 s after the mainshock. We find, as expected, that a significant fraction of aftershocks in the first few hours after the main shock are missing i...

A Preliminary Descriptive Model for the Distance Dependence of the Spectral Decay Parameter in Southern California by John G. Anderson

The spectral decay parameter, K, defined by Anderson and Hough (1984) is described as a function of distance, R, and site, S, as K(R, S) = Ko(S ) + E(R). The terms E(R) and K0(S) are found by a method that is unbiased by prior assumptions about the nature of the distance dependence. Variance using this model is substantially smaller than in simpler models that do not incorporate both site effec...