The Volcanic Eruption Prediction Liaison Committee, which is made up of experts about "Yake" in the Northern Alps and "Shinmoedake" in the Kirishima mountain range on the prefectural border between Nagano and Gifu, is calming down activities such as volcanic earthquakes, but expansion near the summit continues. We have summarized the results of the study that there is a possibility that activities may be increasing in the medium to long term.
The regular meeting of the Volcanic Eruption Prediction Liaison Committee was held at the Japan Meteorological Agency on the 5th to discuss volcanic activity nationwide.
Of these, the number of small volcanic earthquakes increased near the summit in May, and the number of earthquakes has settled down at Mt. Yake, which was raised to "2" for the first time since the introduction of the eruption alert level.
On the other hand, crustal movements showing gradual expansion continue near the summit, and seismic activity with seismic intensity 1 or higher is observed every few years in the surrounding area, so it is possible that volcanic activity is increasing in the medium to long term. Yes, it is necessary to pay attention to the transition of future activities.
Raised to the eruption alert level "2" of Mt. Shinmoedake in the Kirishima mountain range
In addition, the eruption alert level was raised to "2" because volcanic earthquakes increased in March at Shinmoedake in the Kirishima mountain range on the prefectural border between Kagoshima and Miyazaki, and crustal movements indicating the accumulation of magma deep underground were also observed. Was done.
Since mid-May, the number of earthquakes has been declining, and the expansion of the geothermal area that was seen near the cracks on the western slope has not changed, and the amount of volcanic gas is small.
However, since April, slight crustal movements that are thought to indicate expansion near Shinmoedake have been observed, and activity has increased slightly over the medium to long term, so it is necessary to pay attention to future trends. ..
Slightly uplift near the summit of Mt. Iou in the Kirishima mountain range
At the press conference held after the meeting, the latest research results were introduced that the crustal movement that slightly uplifted near the summit was analyzed by satellite observation from April to last month at Mt. Kirishima. I did.
Hiroshi Shimizu, the chairman of the Volcanic Eruption Prediction Liaison Committee and a specially appointed professor at the Graduate School of Kyushu University, quoted this as saying, "In the Kirishima mountain range, including Shinmoedake, deep magma accumulation has been observed, and the situation is not immediately subdued. Although it is not high, steam eruptions have occurred in the past even with the gradual expansion of the mountain body at Mt. Kirishima. It is necessary to pay close attention to how long the expansion will continue at Shinmoedake and other areas. "
Sakurajima eruptive activity may be activated
On the other hand, in Kagoshima Prefecture's "Sakurajima", eruptive activity has been generally sluggish since February, but in Aira Caldera, it is thought that the magma supplied for a long time has accumulated, so the Minamidake summit crater. It is pointed out that eruptive activity may become more active in the future.
Eruptive activity has been active for a long time at "Suwanosejima" in Kagoshima Prefecture, and it is said that eruptions may continue to occur and large volcanic bombs may reach a range of approximately 2 km from the crater.
In March, the Japan Meteorological Agency determined that an eruption had occurred from the eruption observed by a meteorological satellite at the submarine volcano "Eruption Asane" in the Ogasawara Islands, and issued an eruption warning in the surrounding sea area.
However, no definite traces of the eruption were confirmed in subsequent observations from the sky, and it is pointed out that the clouds may have developed rapidly and rose to the sky, which may have been regarded as an eruption.
In addition, the specialized subcommittee established by the Eruption Prediction Liaison Committee due to the increase in volcanic activity on Kuchinoerabu Island in Kagoshima Prefecture was abolished because its activity declined.