Deep-ocean seismology seismicity of the northwestern Pacific Basin interior



Recordings from a variety of deep-ocean hydrophone arrays as well as historical accounts and listings of earthquakes from the International Seismological Centre and the National Geophysical Data Center reveal a surprisingly large number of earthquakes from the area of the recently postulated Micronesian subduction zone and from the interior of the Northwestern Pacific Basin, regions generally considered to be aseismic. Unusual patterns of seismicity are observed with lowmagnitude (mb <5.0) earthquakes having epicenters distributed over several hundred kilometers occurring within a few weeks or months of one another. A number of earthquakes within the interior of the Northwestern Pacific Basin are located north and west of Wake Island. Also, the locus of epicenters within the basin suggests a northwest to southeast trending pattern of seismicity. These findings suggest that the world's deep-ocean basins may be more seismically active than is generally believed, that the distribution of epicenters within the interiors of basins may provide important insights into the stress fields between rising and sinking plate edges, and that efforts should be made to accurately assess the seismicity of ocean interiors.