Youichi Asano, Norihito Umino, Ayako Nakamura, Tomomi Okada, Shuichiro HORI, Toshio Kono, Kouichi NIDA, Toshiya Sato, Akira Hasegawa, Masahiro Kosuga, Akiko Hasemi,
Seismic array observations were made for about 3 months from July 28 to November 4, 1998, to estimate inhomogeneous structure of the crust and uppermost mantle beneath the Ou backbone range, which is one of the most seismically active areas in northeastern Japan. We deployed L-shaped small aperture seismic arrays at 13 locations in and around the range. Each array is composed of 16 seismometer stations with a 50m separation and 3 sets of DAT recorders, which record 18-channel seismic signals continuously ...
Tópico(s): Seismic Waves and Analysis
1999 - Seismological Society of Japan | Zisin (Journal of the Seismological Society of Japan 2nd ser )
Hidetoshi Miura, Akiko Hasemi, Masahiro Kosuga, Norihito Umino, Akira Hasegawa,
The Onikobe area is an active geothermal area situated in the Ou backbone range near the border between Akita and Miyagi Prefectures, northeastern Japan.There are Tertiary to Quaternary calderas and active volcanoes in this area.We calculated Q of coda waves (Qc) in this area by applying a single scattering model.Seismograms recorded at stations located within 10km of the epicentral distance for earthquakes which occurred at depths shallower than 10km were used in this analysis.The time window for ...
Tópico(s): Seismology and Earthquake Studies
2003 - Seismological Society of Japan | Zisin (Journal of the Seismological Society of Japan 2nd ser )
Akiko Hasemi, Hidetoshi Miura, Mari Ishizawa, Masahiro Kosuga, Norihito Umino, Akira Hasegawa,
The Onikobe area is an active geothermal area situated in the Ou backbone range of northeastern Honshu, Japan. It is home to calderas from the Tertiary to Quaternary eras and active volcanoes. A systematic spatial variation of Qc has been found in this area: Qc values are lower at stations in and around calderas than at other stations. The amplitude of coda waves with high Qcs decreases more slowly after a lapse time of around 7–10 s than that with low Qcs. In the present study, to determine causes ...
Tópico(s): High-pressure geophysics and materials
2015 - Elsevier BV | Physics of The Earth and Planetary Interiors
Akihiko Ito, Masayuki Suzuki, Akira Hasegawa, Satoshi Matsumoto, Shigeki Horiuchi, Toru Matsuzawa, Akira Yamamoto, Norihito Umino, Toshio Kono, Shuichiro HORI, Noriko Tsumura, Kazuo Tanaka, T. Sato, Masahiro Kosuga, Minoru Kasahara, Muneo Okayama, Akiko Hasemi,
The Nikko-Ashio region, northern Kanto district, Japan is known for its active seismicity of microearthquakes. Although there are some permanent seismic networks around this region, the detectability of those networks isn't enough to clarify detailed characteristics of seismic activity in this region. We have performed temporary seismic observations repeatedly with high-gain short period seismographs in this region to investigate microearthquake activity since 1980s. A continuous seismic observation ...
Tópico(s): Seismology and Earthquake Studies
1994 - Seismological Society of Japan | Zisin (Journal of the Seismological Society of Japan 2nd ser )
Soushi Nishimoto, Masahiro Ishikawa, Makoto Arima, Takeyoshi Yoshida,
... Honshu arc [Iwasaki, T., Kato, W., Moriya, T., Hasemi, A., Umino, N., Okada, T., Miyashita, K., Mizogami, ...
Tópico(s): earthquake and tectonic studies
2005 - Elsevier BV | Tectonophysics