Approach

Following a sequence of exploratory inversions, the data set was culled to remove events and SNCL's with fewer than 7 data each and to also remove data with event-SNCL distances greater than 500 km. The remaining differential data were then inverted simultaneously, via constrained linear least-squares, to determine the perturbations to the amplitude decay function ($\log{A_{o}}$) and the adjustment ($dM_{L}$) for each SNCL with the constraints: (1) $\log{A_{o}(100 km)}$ = -3; and (2) the sum of the $dM_{L}$s for selected SNCLs with historical $dM_{L}$ values = the sum of their historical $dM_{L}$ values. This approach was taken to ensure consistency with past magnitudes determined in Northern and Southern California.