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Seismicity and crustal structure related to the Miyake‐jima volcanic activity in 2000
Author(s) -
Nishizawa A.,
Ono T.,
Otani Y.
Publication year - 2002
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 - 10.1029/2002gl015008
Subject(s) - geology , induced seismicity , volcano , seismology , hypocenter , earthquake swarm , crust , volcanism , intrusion , swarm behaviour , geophysics , tectonics , mathematical optimization , mathematics , geochemistry
The largest earthquake swarm ever recorded in Japan began off the islands of Miyake‐jima, Kozu‐shima and Nii‐jima, and was linked to volcanic activity on Miyake‐jima, at the northern end of the volcanic front of the Izu‐Ogasawara (Bonin) arc. Ocean bottom seismographic observations made directly above the swarm region gave clear indication of a magmatic intrusion. The hypocenter distribution shows a vertical sheet, 2 km wide and at a depth of 12–20 km, that broadens markedly at depths up to 12 km. The P wavespeed structure obtained from a seismic refraction survey shows no significant difference in the characteristics of the shallow crust between the strong swarm region and inactive region. However, a low wavespeed region was detected 10–15 km northwest of Miyake‐jima.