Possibility of major eruption growing

21/08/2015 00:59

August 20, 2015

Mount Sakurajima may be ready to blow its top, agency warns

http://ajw.asahi.com/article/behind_news/social_affairs/AJ201508200016

THE ASAHI SHIMBUN

There is a growing possibility of a major eruption at Mount Sakurajima in Kagoshima, according to the Japan Meteorological Agency.

The agency on Aug. 19 urged residents to continue to take precautions. It raised the warning for the mountain from Level 3 (restricting entry to the mountain) to Level 4 (preparing to evacuate) on Aug. 15.

A decrease in the amount of volcanic gas discharged from the 1,117-meter-high mountain means that the volcanic pipe, which is a conduit for magma to pass through, is probably clogged up, the agency said.

Kyoto University’s Disaster Prevention Research Institute and other organizations said observations of the mountain on Aug. 19 showed that the volcanic gas discharge was around 100 tons per day, which is small. The amount sometimes exceeds 5,000 tons per day.

A large-scale eruption often occurs when the amount of gas discharged decreases to several hundred tons, the meteorological agency said.

A minor eruption occurred at 3:13 a.m. Aug. 19. It was the first eruption since the warning was raised to Level 4. A plume of smoke rose about 500 meters and volcanic tremors, which indicate the movement of magma, were confirmed.

Prior to the eruption, light from high-temperature volcanic gas turned the smoke around the mountain's vents into red. The phenomenon is called “kaei” (volcanic glow), and is not uncommon at Sakurajima.

Larger eruptions than the one on Aug. 19 have taken place 691 times this year.

Volcanic earthquakes centered around the Minamidake vent occurred 1,023 times on Aug. 15. The figure decreased to 71 on Aug. 16. It stood at nine during the first three hours of Aug. 19.