Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Poster

S (Solid Earth Sciences) » S-VC Volcanology

[S-VC41] Active Volcanism

Wed. May 23, 2018 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yuta Maeda(Nagoya University), Takahiro Miwa(National research institute for earth science and disaster prevention), Yosuke Aoki(東京大学地震研究所, 共同), Takeshi Nishimura(Department of Geophysics, Graduate School of Science, Tohoku University), Takahiro Ohkura(Aso Volcanological Laboratory, Institute for Geothermal Sciences, Graduate School of Science, Kyoto University), Satoshi Okumura(Division of Earth and Planetary Materials Science, Department of Earth Science, Graduate School of Science, Tohoku University), Tomofumi Kozono(Department of Geophysics, Graduate School of Science, Tohoku University)

[SVC41-P23] Vertical Deformation Detected by the Precise Levelling Survey after the 2014 Mt. Ontake Eruption (2014-2017)

*Masayuki Murase1, Hitoshi Yamashita Mori1, Yang Li1, Kazuki Ofuchi1, Yoshiko Yamanaka2, Yuta Maeda2, Takahiro Kunitomo2, Shinichiro Horikawa2, Takashi OKUDA2, Kenjiro Matsuhiro2, Kazushi Tanoue2, Takeshi Matsushima3, Yoshiko Teguri3, Rintaro Miyamachi3, Kaori Morita3, Shin Yoshikawa4, Hiroyuki Inoue4, Fumiaki Kimata5, Hiroaki Yanagisawa6, Tomoyuki Muramatsu6, Tatafumi Taniguchi6 (1.Department of Earth and Environmental Sciences, College of Humanities and Sciences, NIHON University, 2.Graduate School of Environmental Studies, Nagoya University, 3.Graduate School of Science, Kyushu University, 4.Graduate School of Science, Kyoto University, 5.Tono Research Institute of Earthquake Science, 6.Japan Meteorological Agency)

Keywords: Precise Leveling Survey, Ontake Volcano, Vertical Deformation

We conducted the precise leveling surveys in the Ontake volcano in October 2014, April 2015, September 2016 and April 2017, and discussed vertical deformations in the periods of after the 2014 Mt. Ontake Eruption.

The leveling routes of about 38 km with 98 benchmarks were established on the eastern flank of Mount Ontake volcano. The main routes were extended to the Yashikino village (Kakehashi and Yashikino routes). In order to improve the spatial layout of the benchmarks, a branched leveling routes were established (Kiso-Onsen, Ontake Ropeway and Nakanoyu routes).

In the half year after the 2014 eruption (October 2014-April 2015), the small uplift less than 4mm was detected on the Ontake Ropeway route. In the period between April 2015 and September 2016, the uplift of about 6mm was detected in the Ontake Ropeway and Nakanoyu routes. However the subsidence of about 5mm was detected in the Ontake Ropeway and Nakanoyu routes in the period between September 2016 and April 2017.

In the period of before the 2014 eruption (2006-2009), notable uplifts were detected on theYahikino and the Kiso-Onsen routes. The pressure source model based on this notable uplift was estimated to infer preparatory process preceding the 2014 eruption.

Although small uplifts were detected in the period between 2014 and 2016, the subsidence of 5mm was detected in the period between September 2016 and April 2017. This result suggests that the volcanic activity associated with the 2014 eruption was decreased in Mt Ontake.

The M5.6 earthquake occurred just beneath the leveling routes in June 25, 2017. In order to detect the vertical deformation associated with this earthquake, the leveling survey was conducted in the Yashikino and Kiso-Onsen routes. The benchmarks of the Yashikino and Kiso-Onsen routes showed uplift. The maximum uplift of 28mm was detected in central part of Yashikino route. We need continued and careful observation of the deformation in Mt. Ontake volcano.