Underground Structure And Magmatic Activity Of Izu-Oshima Volcano, Japan As Inferred From Seismic Reflection Survey

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Journal Article: Underground Structure And Magmatic Activity Of Izu-Oshima Volcano, Japan As Inferred From Seismic Reflection Survey

Abstract
A seismic reflection survey using the VIBROSEIS (Trademark of Continental Oil Co.) method was carried out on Izu-Oshima volcano fifteen months after the eruption of November, 1986. The survey line of about 10 km in length traverses the northern part of the volcano from east to west and intersects the fissure eruption craters which were formed by the 1986 eruption. Although the measurement condition was not excellent due to thick layers of unconsolidated volcanic products, we obtained a good profile reaching to a depth of about 3 km below. The main results obtained are summarized as follows: (1) a remarkable reflector exists at a depth of 300-500 m below the surface, which corresponds to the upper boundary of the Neogene system forming the basement of the Izu-Oshima volcano; (2) the reflector is broken beneath the lateral volcanoes of past eruptions, indicating ascent routes of magma; (3) a remarkable fragmentation of reflectors in the basement is observed beneath the central part of the volcano, which indicates repeated intrusion of magma into the basement; (4) a low-velocity zone is found at a depth of 2-4 km in the basement, which most probably indicates the magma reservoir of the 1986 eruption. Although deeper structure was not well resolved, these results demonstrate that the VIBROSEIS method is quite effective for revealing the underground structure of a volcano.

Authors 
Hiroyoshi Suzuki, Keiji Kasahara, Masakazu Ohtake, Akihisa Takahashi, Takeshi Ikawa, Susumu Abe and Yoshiaki Kawabe








Published Journal 
Journal of Volcanology and Geothermal Research, 1992





DOI 
Not Provided
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Citation

Hiroyoshi Suzuki,Keiji Kasahara,Masakazu Ohtake,Akihisa Takahashi,Takeshi Ikawa,Susumu Abe,Yoshiaki Kawabe. 1992. Underground Structure And Magmatic Activity Of Izu-Oshima Volcano, Japan As Inferred From Seismic Reflection Survey. Journal of Volcanology and Geothermal Research. (!) .