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-P01] The Estimation of the Deformation Sources Beneath Meakandake and Oakandake Volcanoes in Hokkaido, Japan -Trial of Finite Element Method-

*Yudai SATO1, Tomokazu KOBAYASHI1, Masayuki Yamanaka1 (1.Geospatial Information Authority of Japan)

Keywords:Meakandake, Oakandake, crustal deformation, GNSS, ALOS-2, FEM

Meakandake volcano is located in Hokkaido and one of active volcanoes where Japan Meteorological Agency (JMA) observes its volcanic activities continuously. The data of continuous GNSS stations and ALOS-2 indicated the inflation of Meakandake volcano and its eastern area ranging from October 2016 to May 2017. The local inflation atop Oakandake volcano was also detected by ALOS-2 data that suggests the source depth can be shallow.

The small-scale inflation of Meakandake volcano and its eastern area has still been observed since May 2017, thus understanding the volcanic activity beneath the volcano is important for disaster mitigation. The possible shallow source of Oakandake volcano and its activity can be concerns of nearby communities. However, since continuous GNSS observation is not carried on Oakandake volcano, it is difficult to monitor the deformation every day. Therefore, we believe the estimation of the source will help to understand the volcanic activity of Oakandake volcano.

In this study, we estimated the deformation sources of Meakandake and Oakandake volcanoes by analyzing the data of continuous GNSS observations and ALOS-2 spanning from October 2016 to May 2017. Firstly, we assumed the opening of sill for the inflation source of Meakandake volcano and its eastern area and calculated best-fit parameters of the model using MCMC method. On the other hand, analytical models that require a deep source to calculate displacements cannot be good models in terms of a shallow source. Thus we adopted finite element method to estimate a shallow source beneath Oakandake volcano using a software “GSIFEM” that we have been developing since 2016. GSIFEM makes a mesh of a target area including a model to be assumed and calculates the displacements at each site. Finally, we estimated the deformation sources were located in the eastern area of Meakandake volcano and beneath Oakandake volcano, respectively.
We report the results of the estimations and the outline of GSIFEM.