HR: 0800h
AN: V21D-0654    [Abstracts]
TI: Uplift in the earthquake swarm area of Ontake Volcano, central Japan detected by precise leveling in 2002-2005
AU: * KIMATA, F
EM: kimata@seis.nagoya-u.ac.jp
AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Miyajima, R
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Murase, M
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Ohta, Y
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Kashiwagi, M
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Ohzono, M
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Kariya, S
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AU: Yamamuro, T
V21D-0654 AF: Research Center for Seismology and Volcanology, Nagoya University, Furo, Nagoya, 464-8602 Japan
AB: Earthquake swarm is repeated on the eastern submountain region of Ontake Volcano, Central Japan for 25 years since late 1970s. Ontake Volcano erupted at the summit in 1979, earthquake M6.8 occurred in 1984. However maximum magnitude of the earthquake swarm is limited to M4. We start the precise leveling to detect the vertical movements in the swarm area in 1999 and repeated the leveling every year. As a result of the precise leveling, uplift of few mm is observed. We extend the leveling route to cross the swarm in 2002 and 2004. From the leveling in 2005, we detect the uplift of 5 mm extending circle of 5 km in the just most active segment area of the swarm. Up lift amounts to 10 mm for three years since 2002. It is significant uplift exceeding of the survey error of +- 2.5 mm. One spherical pressure source is estimated at a depth of 3-4 km from the ground surface (2-3 km below sea level) using Mogi solution. Low risibility zone is estimated from AMT observation (Kasaya et al., 2004) and active gas blow of CO2 is observed in the area (Azuma et al., 2004). These observation and uplift ground deformation from our leveling suggest a hydrothermal injection. Vertical deformation is one of important monitor of the earthquake swarm activity.
UR: http://blog.livedoor.jp/kimata_nagoya_u_e/
DE: 1209 Tectonic deformation (6924)
DE: 8419 Volcano monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005