[S-VC31] Active Volcanism

[SVC31-P05] Deformations Detected by Precise Levelling Surveys in the Asama volcano (2005-2022)

*Masayuki Murase¹, Yuji Endo¹, Taishi Sano¹, Sei Ijima², Yoshihiro Otsuka², Yoshiko Teguri², Naoki Kudo² (1.Department of Earth and Environmental Sciences, College of Humanities and Sciences, NIHON University, 2.Japan Meteorological Agency)

Keywords:Asama Volcano, Precise Leveling Survey, Deformation

We conducted the precise leveling survey in the Asama volcano and discussed the relationship between eruptions and vertical deformations.
During the 2004 eruption event, a dike intrusion was estimated west of the summit based on the deformation detected by the GPS measurements (Aoki et al., 2005). Since it was insufficient to detect for a dike intrusion event in the west of the summit using the existing leveling routes, Nagoya University and ERI established a leveling route along the Kurumazaka Pass (Kurumazaka route) in 2005. The leveling surveys were conducted almost once a year until now (2022).
As the recent result of this survey, about 7 mm subsidence was detected at the north part of the Kurumazaka route in the period from November 2021 to June 2022.
The temporal changes in the vertical deformation along Kurumazaka route exhibit a small change during the period from 2005 to 2009 and a significant subsidence during the period from 2009 to 2015. The deformation showed short term uplift during the period from 2015 to 2017 and then went back to a subsidence during the period from 2017 to 2022.