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Eos, Transactions American Geophysical Union

Pacific intraplate seismicity reexamined


  • Michael E. Wysession


Extensive and comprehensive examination of all recorded earthquakes occurring during 1913–1988 in the intraplate regions of the Pacific Ocean crust shows that Pacific Basin intraplate earthquakes are much less frequent than previous catalogs and maps have suggested “Wysession et ai, 1991”. Of the 894 earthquakes considered for study that were not part of localized swarms (which account for another 838 teleseismic earthquakes, not including Hawaii), less than half—403—were found to be genuinely intraplate. The examination involved relocating over 500 earthquakes initially identified by other sources—ISC, NEIC, BCIS, etc.—and found that 304 of the supposed intraplate events were actually mislocated plate boundary earthquakes. The remaining listings were typographical bulletin errors, presumed or confirmed nuclear tests, or they contained insufficient data for location). These results, before and after relocation, are shown in Figure 1.

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