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PcP and ScP beneath the western Pacific detected by a deep ocean‐Bottom hydrophone array
Author(s) -
Nagumo Shozaburo,
McCreery Charles S.
Publication year - 1992
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/92gl01453
Subject(s) - geology , seismology , hydrophone , pacific ocean , mantle (geology) , attenuation , oceanography , structural basin , pacific plate , deep sea , deep focus earthquake , ocean bottom , oceanic basin , subduction , geophysics , paleontology , tectonics , physics , optics
A deep ocean‐bottom hydrophone array near Wake Island in the western Pacific has detected PcP and ScP from several deep‐focus earthquakes that occurred beneath the Sea of Okhotsk and beneath the Fiji Basin. Two representative events have been analyzed. The PcP of the Okhotsk event is very strong and sharp, with a predominant frequency of 2 Hz, whereas the PcP of the Fiji event is weak, with a predominant frequency closer to 1 Hz. The strong contrast between PcP from these two deep‐focus earthquakes demonstrates differences in reflectivity at the core‐mantle boundary as well as heterogeneities in seismic velocity and attenuation in the lower mantle. Travel times and spectral analyses show that seismic velocity, attenuation factor Q, and reflectivity are all high beneath the Northwest Pacific Basin and normal beneath the equatorial Pacific.