7th August, 2019 Eruption of Mt.Asama

Website launched: 16/08/2019

Mt. Asama, an active volcano  on the border of Gunma and Nagano prefectures, erupted on 7th August around 10:08PM, and JMA (Japan Meteorological Agency) raised the warning level from Level 2(Do not approach the crater) to Level 3 (Do not approach the volcano).

We are updating the report gained from the on-site survey.
*Please contact Yomiuri Shimbun for siting pictures.

9th August 2019

Aerial Observation just after the eruption of Asama Volcano on 7th August, 2019

Following the eruption of Mt. Asama eruption at around 22:00 on 7th August, aerial observation was done from helicopter (air craft operated by Yomiuri Shimbun) .  No significant change in Kamayama crater was found. A small crater was existing from before in the middle of Kamayama crater, and this was still found even after the eruption. There were two clear fumarolic activity on the north western side of the crater. A weak fumaroles were found on other locations too, but they were there from before. No change was found outside of the Kamayama crater(such as the northern slope). This eruption occurred from existing crater, and was not a kind that changes topography inside or outside of the Kamayama crater.

  • At 6:40-7:25AM 8th August. Observed the Kamayama crater of the Asamayama volcano summit and the surrounding from helicopter (air craft operated by Yomiuri Shimbun). (fig.1)
  • A crater of diameter 30m existed inside the Kamayama crater from before, and it was still there even after the eruption and was releasing pale volcanic gas. (fig.2)
  •  Positions of the major volcanic blocks nearby the crater wasn’t changed.
  •  Inside the Kamayama crater, area between the northwestern slope and the 30m crater, were partly grayish white and possibly covered by volcanic ash (about several cm or less). (Figure 4)
  •  There were two clear fumarolic activity on the north western side of the crater. This area was where weak fumaroles and thermal anomalies were seen from before. Also, there were several weak fumaroles inside the crater, but they all existed from before.
Fig.1 Asmayama volcano summit. 06:50AM on 8th August, 2019
Fig.2 Kamayama crater. 07:20AM on 8th August, 2019
Fig.3 Central crater and its surrounding. No changes in positions of volcanic block.(shooting position and scale are different)
Fig.4 Northwestern side inside the crater. Clear fumarolic activity can be seen. Grayish white part may be a coverage by volcanic ash.