Asama volcano eruption Possibility of "water vapor eruption" Eruption caution level 3 continued August 9 20:08
On the 7th, the Meteorological Agency announced that there was a high possibility of a "water vapor eruption" for a small eruption that occurred at Mt. Asama on the prefectural border between Gunma and Nagano. On that basis, the Japan Meteorological Agency continues eruption alert level 3 and continues to call for alerts in the range of approximately 4 km from the crater.
At Asama, where a small eruption occurred on the night of the 7th, there was no eruption after that, volcanic earthquakes and volcanic gases had been slightly reduced, and crustal movements indicating rising magma were observed. That is not.
In addition, as a result of research institutions collecting and analyzing volcanic ash from the eruption on the 7th, almost all of the volcanic ash is old rock fragments located in a shallow area near the crater, and no material related to new magma deep in the subsurface is found. It is that.
For this reason, the Japan Meteorological Agency believes that this eruption was not an eruption directly from underground magma, but rather a “water vapor eruption” in which groundwater heated by magma expands and erupts.
On top of that, the Japan Meteorological Agency has called for eruption alert level 3 to continue with volcanic activity on Mt. Asama, and to be cautious of large cinders and pyroclastic flows associated with eruptions, approximately 4 km from the crater.