The Effect of Declustering on the Size Distribution of Mainshocks

Declustering aims to divide earthquake catalogs into independent events (mainshocks), and dependent (clustered) events, is an integral component of many seismicity studies, including seismic hazard assessment. We assess the effect declustering on frequency-magnitude distribution mainshocks. In particular, we examine dependence b-value declustered choice approach algorithm-specific parameters. Using catalog earthquakes in California since 1980, show that decreases by up 30% due with respect undeclustered catalog. The extent reduction highly method parameters applied. then reproduce a similar synthetic known b-value, which have been generated using Epidemic-Type Aftershock Sequence (ETAS) model. Our analysis suggests observed decrease must, at least partially, arise from application algorithm catalog, rather than differences nature mainshocks versus fore- or aftershocks. conclude should be considered as potential source bias studies.