Source Parameters Variations Among Oceanic Earthquakes and Tectonic Implications

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This research deals with the investigation of relative strengths of oceanic crust at ridges and transforms relative to the remaining oceanic lithosphere by means of seismologically-determined stress drops from earthquakes. Preliminary results show several interesting differences in the relative body and surface wave magnitudes, seismic moments, and source time functions. These data suggest that with respect to intraplate events, ridge earthquakes are generally "fast" (releasing energy preferentially at short periods) whereas transform earthquakes are generally "slow" (releasing energy preferentially at long periods). Using seismic source models, the investigators have found that these differences are consistent with ridge events having higher stress drops than transform events, which implies a higher strength of the relatively thin crust at ridges. This research seeks to expand the data set, continue and refine the seismological analysis, and explore the tectonic implications.