Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/1582
AuthorsSasai, Y.* 
Ishikawa, Y.* 
TitleSeismomagnetic models for earthquakes in the eastern part of Izu Peninsula, Central Japan
Issue DateMar-1997
Series/Report no.40/2
URIhttp://hdl.handle.net/2122/1582
Keywordsseismomagnetic effect
piezomagnetic effect
Izu Peninsula
magnetic precursor to earthquake
preseismic slip
Subject Classification04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques 
AbstractSeismomagnetic changes accompanied by four damaging earthquakes are explained by the piezomagnetic effect observed in the eastern part of Izu Peninsula, Central Japan. Most of the data were obtained by repeat surveys. Although these data suffered electric railway noise, significant magnetic changes were detected at points close to earthquake faults. Coseismic changes can be well interpreted by piezomagnetic models in the case of the 1978 Near Izu-Oshima (M 7.0) and the 1980 East Off Izu Peninsula (M 6.7) earthquakes. A large total intensity change up to 5 nT was observed at a survey point almost above the epicenter of the 1976 Kawazu (M 5.4) earthquake. This change is not explained by a single fault model; a 2-segment fault is suggested. Remarkable precursory and coseismic changes in the total force intensity were observed at KWZ station along with the 1978 Higashi-Izu (M 4.9) earthquake. KWZ station is located very close to a buried subsidiary fault of the M 7.0 Near Izu-Oshima earthquake, which moved aseismically at the time of the M 7.0 quake. The precursory magnetic change to the M 4.9 quake is ascribed to aseismic faulting of this buried fault, while the coseismic rebound to enlargement of the slipping surface at the time of M 4.9 quake. This implies that we observed the formation process of the earthquake nucleation zone via the magnetic field.
Appears in Collections:Annals of Geophysics

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