Energy and depth of Usu 2000 phreatic explosions

Akihiko Yokoo, Hiromitsu Taniguchi, Akio Goto, Hiromitsu Oshima

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


On 31 March 2000, the Usu volcano located in Hokkaido, Japan began erupting after 22 years of dormancy. After the first phreato-magmatic explosion, there were many small-scale phreatic explosions at the Nishiyama and Kompirayama Craters. In April and May, observations were made using a piezo blast-sensor and a visible video recorder to get a better understanding of volcanic explosions. The data thus obtained were analyzed using the scaling-laws that relate surface phenomena to both explosion energy and depth. The analysis using the shape of the explosion-cloud and the peak over-pressure of the volcanic blast-wave indicated that the average explosion energy and depth of the phreatic explosions of mid-April ranged from 1010 to 1012 J and originated from between just beneath the ground surface to a depth of a few tens of meters.

Original languageEnglish
Article number015928
JournalGeophysical Research Letters
Issue number24
Publication statusPublished - 2002 Dec 15

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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