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On the relationship between lower magnitude thresholds and bias in ETAS parameter estimates

Frederic P. Schoenberg, & Annie Chu

Under Review 2009, SCEC Contribution #1281

Modern earthquake catalogs are often described using spatial-temporal point process models such as the epidemic-type aftershock sequence (ETAS) models of Ogata (1998). Earthquake catalogs often have issues of incompleteness and other inaccuracies for earthquakes of magnitude below a certain threshold, and such earthquakes are typically removed prior to fitting a point process model. This paper investigates the bias in the parameters in ETAS models introduced by the removal of the smallest events. It is shown that, in the case of most of the ETAS parameters, the bias increases approximately exponentially as a function of the lower magnitude cutoff.

Citation
Schoenberg, F. P., & Chu, A. (2009). On the relationship between lower magnitude thresholds and bias in ETAS parameter estimates. Journal of Geophysical Research, (under review).