Volcanic activity at Mount Sakurajima in Kagoshima Prefecture has quieted down after intensifying Saturday morning, but the Meteorological Agency said Monday it will remain on alert for signs of a major eruption.
Tectonic movements indicating swelling of the mountain has also slowed, the agency said. It believes the rise of magma from an underground chamber has subsided for now.
Takeshi Koizumi, senior coordinator for volcanic disaster mitigation at the agency, said: “We need to remain on alert because it is not known when magma will start to rise again and when a major eruption will occur as a result.”
At a meeting Sunday, officials of relevant government agencies agreed on a policy to enhance monitoring at Sakurajima, to provide accurate information and to offer support for evacuees.
Eriko Yamatani, minister for disaster prevention and reduction, called on the public to remain calm.
In a video conference linking national officials with prefectural officials, Kagoshima Gov. Yuichiro Ito warned that additional evacuation and protective measures could become necessary if the situation worsens.
Masato Iguchi, a professor at Kyoto University’s Disaster Prevention Research Institute who monitors Mount Sakurajima, said monitoring for volcanic activity will need to remain intense for at least another two weeks.
On Saturday, residents near Sakurajima evacuated to safer places after the government raised the alert level to 4 on a 5-point scale, indicating a major eruption could be imminent.
Level 4 is the highest ever for Sakurajima — which is located just 4 km across the water from the major port city of Kagoshima — since the current volcanic alert system was launched in 2007.
The alert level was still at 4 as of Monday.
Evacuees moved to evacuation centers set up by the city or to other places, including relatives’ homes.
“I’m concerned an eruption will damage my home,” said Yoshiko Ikeda, 87.
“I have lived in Sakurajima for more than 50 years, but I never imagined we would have to evacuate,” said Emiko Miyashita, 80.
The municipal government displayed the alert in Japanese and English on digital boards at the ferry landing on the Sakurajima route in case non-Japanese in the area had not received the information.
Officials told evacuees Sunday night that their evacuation may last a week or longer.
Kyushu Electric Power Co.’s Sendai nuclear power plant is located 50 km from the volcano. Last Tuesday, it became the first nuclear plant to restart under tighter safety rules adopted in the wake of the 2011 Fukushima nuclear crisis.
No abnormality has been reported at the Sendai plant.
Before the alert level was raised to 4 by the Meteorological Agency, it had been set at 3, which restricts entry to the mountain area. When it was raised, the Kagoshima Municipal Government issued an evacuation advisory for areas near the mountain, affecting 77 residents. All of them had left the area by Saturday evening.