Deformation source revealed from leveling survey in Jigokudani valley,
Tateyama volcano, Central Japan
Abstract
To confirm whether the uplift in Jigokudani valley between 2007 and 2010
detected by Interferometric Synthetic Aperture Radar has continued to
the present, we conducted leveling survey since 2015. Most bench marks
showed subsidence up to 5.6 cm from October 2016 to September 2020,
while a bench mark locates at the center of the leveling route uniquely
showed uplift. A crack with a length of 350 m, a width of 100 m, a dip
of 61° and striking parallel to the old explosion craters is identified
at a depth of 50 m near the center of Jigokudani valley. The estimated
crack is located at a similar position of the gas chamber identified
from the audio-frequency magnetotelluric survey. Opening of the crack
turned to closing between 2017 and 2020 probably because of the increase
in emission of volcanic fluid or gas with a formation of a new crater.