IDENTIFICATION OF TSUNAMIGENIC EARTHQUAKE ZONES IN OCEANIC RIDGES AND TRENCHES

Abstract

Tsunamigenic earthquakes have been known for their near and far field catastrophic impacts on coastal areas near oceanic ridges and trenches, as well as near tectonic faults in closed and semi- enclosed seas. Not all regions of oceanic ridges and trenches are tsunamigenic earthquake zones, but knowledge of the weighted sum of released earthquake energy and of the Gutenberg-Richter relation of the ‘a’ and ‘b’ parameters are needed to better identify them as to their potential for tsunami generation. The present analysis was undertaken in order to better identify tsunamigenic zones near oceanic ridges and trenches in the Mid-Atlantic, in the Pacific, in Chile, in Japan, near the Aleutians and along the Peru-Chile trench. The weighted sum of earthquake energy released and of the Gutenberg-Richter relation parameters were evaluated to identify tsunamigenic earthquake zones along these locations. The present analysis of the Gutenberg-Richter relation of the ‘a’ and ‘b’ parameters indicates that tsunamigenic earthquakes do not occur frequently along the Aleutian Trench, although the historic record supports that destructive tsunamis have occurred along this region in the past. Of the oceanic ridges, the results of the present analysis indicate that the Mid-Atlantic Ridge is the most active tsunamigenic zone, while of all the oceanic trenches, the Japan Trench is the most active.

Keywords

• b-value
• a-value
• tsunamigenic
• oceanic ridges
• oceanic trenches