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Council in northern Japan unveils hazard map for local volcano

This July 11, 2017 file photo shows Lake Towada, which falls in the area outlined in the Towada volcano disaster prevention council's hazard map, on the border of Aomori and Akita prefectures. (Mainichi)

A volcano disaster prevention council in northern Japan unveiled a hazard map on Jan. 24 showing the areas likely to be affected in the event of a local volcanic mountain erupting.

This is the first time for the Towada volcano disaster prevention council, which is made up of organizations such as Aomori and Akita prefectural governments, to announce the creation of such a map. The cartograph relates to Mount Towada, a nearby volcanic mountain that straddles the border of Aomori and Akita prefectures.

The hazard map comes amid apparent fears that several hundreds of thousands of people in the northern prefectures of Aomori, Akita and Iwate would have to evacuate should there be a large-scale eruption of Mount Towada. Such concerns are based on the prediction that a major eruption of the mountain would result in not only ash deposits and ash showers, but also pyroclastic flows emerging from the crater, and spreading as far as 30 kilometers.

Looking ahead, the council is also aiming to introduce "eruption alert levels" and draw up an evacuation plan.

The hazard map lays out three different hazard zones -- for minor, moderate and major eruptions -- and was created with reference to previous Mount Towada eruptions over the past 11,000 years.

In the event of a major eruption of the mountain, it is predicted that pyroclastic flows and pyroclastic surges (which are blasts of hot air containing both volcanic ash and volcanic gas) would reach 17 cities, towns and villages up to 30 kilometers away from the crater. The places feared to be affected include the cities of Aomori, Odate in Akita Prefecture, and Ninohe in Iwate Prefecture.

Furthermore, for eruptions that occur during periods of snow, there are said to be fears that huge volumes of water could be created due to snow melting under the heat of pyroclastic flows -- which in turn could cause "volcanic mudflows due to melted snow" descending along rivers and valleys, together with rocks.

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