Explosion Seismic Observations in the Central Part of the Kitakami Region, Northeastern Japan
Year: 1994
Type: article
Abstract: An experiment of explosion seismic observations was conducted by Research Group for Explosion Seismology (RGES) along a north-south profile in the Kitakami region, northeastern Japan. We observed the explosions by RGES and quarry blasts along a 60km profile in the east-west direction crossing the RGES's profile in the central part of the Kitakami region. Based on travel time analysis of reflected waves, velocity boundaries in the middle and lower crust were found at the depth of 15 and 27km, and the crlustal thickness was estimated to be about 34km. The Kitakami region is divided into northern and southern terranes by Hayachine Tectonic Belt (HTB), where maficultramafic rocks intruded during the end of the Jurassic to the beginning of the Cretaceous period. The profile of this study was almost located along the southern margin of HTB. Velocity structure beneath the profile, however, is similar to that along the north-south profile obtained by RGES and shows no significant differences. Record sections from the shots far from the profile show that boundary in the lower crust and the Moho are distinct in the northern part but are vague in the southern part of the Kitakami region. The quarry blasts generated clear S-waves. Using P ans S travel times from quarry blasts, Vp/Vs in the uppermost part of the crust was estimated to be 1.74-1.75.
Language: English
Topic: Seismic Waves and Analysis
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W2607363049