Southern California Earthquake Data Center

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Special Data Sets

Alternate Catalogs

The standard Caltech/USGS southern California catalog does not account for local variations in the seismic velocity structure, which limits the accuracy of its event locations. By applying various techniques in post-processing of the data, it is possible to improve location accuracy, and some of these improved catalogs are listed here.


Several of these catalogs (Lin et al. 2007; Hauksson and Shearer, 2007; Shearer et al., 2005) use results from SCEC-sponsored projects that apply waveform cross-correlation to make precise differential times between nearby events. In turn, the absolute picks combined with the differential travel times are applied to improve greatly the relative location accuracy within clusters of similar events.


Note that locations in these catalogs do not always agree in detail, reflecting the different modeling assumptions and seismic velocity structures that went into their construction. However, their overall agreement is quite good, particularly when compared to the standard catalog locations, and many details in the fine-scale structure of southern California seismicity can be resolved. Evaluating and improving earthquake locations remains an active research area.


Location Catalogs: Also available via FDSN Event Web Service



Focal Mechanism Catalogs: