Seismic reflection profiling across the Itoigawa-Shizuoka Tectonic Line at Matsumoto, Central Japan
2014; Springer Nature; Volume: 56; Issue: 12 Linguagem: Inglês
10.1186/bf03353356
ISSN1880-5981
AutoresYasutaka Ikeda, Takaya Iwasaki, Hiroshi Sato, Nobuhisa Matsuta, Takeshi Kozawa,
Tópico(s)Geological and Geochemical Analysis
ResumoThe Itoigawa-Shizuoka Tectonic Line (ISTL) in Central Japan is a fault zone with a very high slip rate during Pliocene-Quaternary time. Our seismic reflection and gravity surveys across the northern segment of the ISTL at Matsumoto have revealed its geometry to a depth of ∼5 km. The fault plane was found to be of fairly low angle, in spite of the surface geologic observations that late Quaternary movements on this fault zone are dominantly strike slip. Partitioning of slip is taking place between the East Boundary Fault (thrust) and the Gofukuji Fault (left-slip), which constitute the fault zone and are parallel to and a few km apart from each other. However, these two faults are found to merge down-dip at a depth as shallow as 1.5 km below the surface. The geometry of the ISTL is significantly discordant with the orientation of the maximum shear stress acting regionally on Central Japan, indicating that the fault plane is of very low strength.
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