2024-03-28T20:51:59Z
https://nagoya.repo.nii.ac.jp/oai
oai:nagoya.repo.nii.ac.jp:00024369
2023-01-16T05:07:51Z
488:489:490
Modeling the dynamics of a phreatic eruption based on a tilt observation: Barrier breakage leading to the 2014 eruption of Mount Ontake, Japan
Maeda, Yuta
72184
Kato, Aitaro
72185
Yamanaka, Yoshiko
72186
Although phreatic eruptions are common volcanic phenomena that sometimes result in significant disasters, their dynamics are poorly understood. In this study, we address the dynamics of the phreatic eruption of Mount Ontake, Japan, in 2014 based on analyses of a tilt change observed immediately (450 s) before the eruption onset. We conducted two sets of analysis: a waveform inversion and a modified phase-space analysis. Our waveform inversion of the tilt signal points to a vertical tensile crack at a depth of 1100 m. Our modified phase-space analysis suggests that the tilt change was at first a linear function in time that then switched to exponential growth. We constructed simple analytical models to explain these temporal functions. The linear function was explained by the boiling of underground water controlled by a constant heat supply from a greater depth. The exponential function was explained by the decompression-induced boiling of water and the upward Darcy flow of the water vapor through a permeable region of small cracks that were newly created in response to ongoing boiling. We interpret that this region was intact prior to the start of the tilt change, and thus, it has acted as a permeability barrier for the upward migration of fluids; it was a breakage of this barrier that led to the eruption.
journal article
Wiley
2017-02
application/pdf
Journal of Geophysical Research - solid earth
2
122
1007
1024
http://doi.org/10.1002/2016JB013739
http://hdl.handle.net/2237/26583
2169-9356
https://nagoya.repo.nii.ac.jp/record/24369/files/Maeda_et_al-2017-Journal_of_Geophysical_Research__Solid_Earth.pdf
eng
https://doi.org/10.1002/2016JB013739
© 2017 American Geophysical Union