[HTT19-P06] Very shallow S-wave seismic reflection survey across the surface rupture of 2014 Naganoken-hokubu earthquake, central Japan
Keywords:very shallow S-wave seismic reflection survey, 2014 Nagano-ken-hokubu earthquake, Kamishiro fault, Itoigawa-Shizuoka tectonic line active fault zone
In this survey, to reveal the subsurface structure of the northern part of the surface rupture, we conducted very shallow S-wave seismic reflection survey from November 21 to 23, 2016 at Oide in Hakuba village, Nagano prefecture. The length of seismic reflection survey line was 300 m from west to east across the 2014 surface rupture. To generate SH-waves in a direction perpendicular to seismic line, we hit a sidewall of square wooden log (0.2 x 0.4 x 1.0 m, 28 kg, pine wood) with a sledgehammer as a source in this survey. The receiver was GS-32CT (natual frequency, 10 Hz), and sampling rate is 1 ms during 2 sec of recording time. The source and receiver spacing was 1 m with 96 ch geophones used for each recording. We selected the DSS-12 (Suncoh consultants co. ltd.) for the recording system. In this presentation, we demonstrate the very shallow S-wave seimic reflection survey across the 2014 surface rupture along the Kamishiro fault in Oide of Hakuba village, Nagano prefecture.
This survey was supported by a special grant of the Ensemble Project for Young Researchers, Tohoku University. We thank land owner, local people, and village office for their support during our survey.