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Volcanic alert lowered for Mt. Asama after eruption in early Aug.

This photo taken on Aug. 8, 2019 from a Kyodo News helicopter shows a crater of Japan's Mt. Asama straddling Gunma and Nagano prefectures following a small eruption that occurred the previous night. (Kyodo)

TOKYO (Kyodo) -- The weather agency on Monday lowered the volcanic alert level for Mt. Asama in central Japan, saying volcanic activity is now not expected to intensify following a small eruption in early August.

The alert level on a 5-point scale was lowered to 2, which warns against approaching the crater, from 3, which advises not approaching the 2,568-meter-high volcano near the Karuizawa resort area northwest of Tokyo.

The Japan Meteorological Agency still warns of the likelihood of flying rocks and pyroclastic flows within about a 2-kilometer radius of the crater.

On Aug. 7, Mt. Asama experienced a small eruption and the agency raised the alert level from 1 to 3. There were no reports of casualties caused by the eruption but volcanic ash was found on the Gunma prefectural side of the mountain.

The agency said the eruption was highly likely to be a steam explosion, in which groundwater heated by lava turns into vapor and explodes without spewing magma.

It concluded that the possibility of an eruption affecting areas beyond the 2-km radius from the crater is low.

As of Monday, no crustal movement suggesting the rise of magma has been observed, it said, adding that there have not been many volcanic earthquakes and only a small amount of volcanic gas has been released.

The agency also said it has changed the standards for the volcanic alert level for Mt. Asama.

If a small eruption occurs while showing signs of increasing volcanic activity including an expansion of the mountain shape, the alert level will be 3 as before. However, if there are no such signs, similar to the Aug. 7 eruption, the level will be 2.

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