THE GEOTECTONIC ASPECT OF OCEANIC EARTHQUAKE SOURCE PARAMETERS

Abstract

This paper compares the source parameters of oceanic earthquakes determined from records of land-based seismograph stations and OBS, equipped with short- and long-period instruments. Systematic deviations of coordinates and origin times have been revealed and estimated, the deviations being due to lateral variations of upper mantle properties. The OBS records show that the seismicity of the uppermost mantle layer at active oceanic margins is 2-3 orders higher than that of the crust, and that the level of this seismic layer varies with the Moho depth. For earthquakes occurring at mid-ocean ridges the location-based origin times are systematically late.