Significance of Findings

The state-wide $\log{A_{o}}$ and station corrections for determining magnitudes will improve reporting for earthquakes in all of California on several counts. First, $M_{L}$ was being calculated using only a subset of the currently existing broadband stations in both Northern and Southern California, as only they had been calibrated. In the past 10 years, many broadband stations and strong motion stations have been added to the networks. With the additional stations, $M_{L}$ determination should become much more reliable. Second, until now Northern (Uhrhammer et al, 1996) and Southern California (Kanamori et al, 1999) have been using different $\log{A_{o}}$ functions, with their attendant $dM_{L}$ values for each SNCL. Thus different magnitudes were often determined by Northern or Southern California for an earthquake if it was near the boundary of the reporting regions, or for very large earthquakes in the other region. When the results of this project are implemented in the realtime and event review systems, this should no longer be the case.

Berkeley Seismological Laboratory
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