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2014年9月29日 (月)

御嶽山噴火 見せつけられた予知の難しさ

The Yomiuri Shimbun
Eruption of Mt. Ontake demonstrates difficulty in predicting volcanic activities
御嶽山噴火 見せつけられた予知の難しさ

Once again, we have been confronted with a graphic reminder of the ferocity of volcanoes.

Mt. Ontake, a peak more than 3,000 meters above sea level that straddles the Nagano-Gifu prefectural border, erupted shortly before noon Saturday.

With the start of the year’s autumnal foliage season on the weekend, a large number of hikers were on the mountain when it blew its top.

Many people were reported to have been seriously injured from extremely hot volcanic ash. A number of people took refuge in mountain lodges, but rescue operations were hindered as eruptions continued.

The government set up a liaison office at the Crisis Management Center in the Prime Minister’s Office to speed information-gathering efforts concerning casualties and damage. Prime Minister Shinzo Abe issued instructions to officials to place priority on rescuing victims and ensuring the safety of climbers, and ordered the dispatch of Self-Defense Forces personnel to the affected area.

All-out endeavors must be made to minimize the extent of damage, and no time should be wasted in transporting victims and carrying out search-and-rescue operations for people unaccounted for.

It is unclear when Mt. Ontake’s volcanic activity will subside.

Plumes of smoke billowed high into the sky from spots near the mountaintop in the volcano’s eruption, and a huge amount of volcanic ash spread over the mountain’s slopes at tremendous speed. Volcanic rocks were also flung around extensively.

A close watch must be kept on the mountain’s volcanic activities, while efforts should be made to prevent secondary dangers.

The Japan Meteorological Agency issued an alert, warning that further eruptions on a scale similar to Saturday’s are possible. The agency has raised the eruption alert level on its scale of five from the lowest 1 at normal times to 3, meaning climbers are restricted from entering the mountain range.

Beef up observation

Even though Mt. Ontake has long been considered to have an extremely low degree of volcanic activity, it suddenly erupted in 1979, causing volcanic ash to fall over an extensive area. Small-scale eruptions occurred in 1991 and 2007.

The meteorological agency planned to upgrade the surveillance of Mt. Ontake by designating it as one of the 23 most active volcanoes in the country, out of a total of 110 active volcanoes. The agency, however, fell short of detecting signs that the volcano was about to erupt this time.

The agency’s failure to forecast the event shows how difficult it is to predict volcanic eruptions.

Although it had noted a succession of fairly active volcanic tremors in the Mt. Ontake range from early this month, the agency did not predict an eruption, mainly because of a dearth of data. No explicit changes in the crustal movement below the mountain were detected that could have served as clear precursors of the eruption, according to the agency. In light of this, the current method of collecting data must be reviewed.

In spite of Japan being a volcanic country, experts have pointed out that both budgets and personnel required for volcano observation are insufficient. Full-fledged volcanic observation systems are limited to few regions, such as Mt. Sakurajima in Kagoshima Prefecture and Mt. Asama on the border of Nagano and Gunma prefectures.

When Mt. Shindake on Kuchinoerabu Island, Kagoshima Prefecture, erupted in August this year, the local meteorological observatory detected nothing that indicated it would erupt.

No regular observation activities have been conducted for Nishinoshima island, an uninhabited islet in the Ogasawara chain, despite continuing volcanic activities.

Partly because of the rise in popularity of mountain climbing in recent years among middle-aged and elderly people, many volcanic mountains are thronged with hikers. Many well-known hot spring resorts and other sightseeing spots are near volcanoes. Everyone should take to heart the possibility of being involved anytime in an emergency in these areas.

(From The Yomiuri Shimbun, Sept. 28, 2014)Speech


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