The Meteorological Agency has said that it cannot present an outlook for volcanic activity at the Shinmoedake volcano in the country's southwestern region after a recent series of eruptions.
Increasing volcanic activity has been observed since late June at the mountain in the Kirishima range straddling the prefectures of Miyazaki and Kagoshima. To restrict entry to the mountain, the agency raised its volcanic warning level to 3 from 2.
On June 23, an on-site survey found that discharges of volcanic gas were increasing after an eruption observed on the afternoon of the previous day. Volcanic smoke rose to a height of 5,000 meters from the crater Thursday. The previous time the mountain was observed erupting was June 2018.
The agency said Tuesday that volcanic ash collected mainly by the National Institute of Advanced Industrial Science and Technology (AIST) contained a very small amount of particles seen as fresh magma substance, soon after the eruptions began.
But analysis of samples collected this month showed that the amount increased to around 3% of the ash, the agency added.
"It is believed that the type of eruption at the volcano is changing from phreatic eruption not involving magma to magmatic eruption," an agency official said.
"A large amount of volcanic ash and lava flows will be expected if a full-scale magmatic eruption occurs," the official said, warning citizens not to approach dangerous areas.
According to the transport ministry's Kagoshima airport administrative office, some commercial flights scheduled to depart and arrive at the airport were canceled because of volcanic ash from Shinmoedake.
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