The Central Weather Bureau (CWB) yesterday said that a steam explosion caused the eruption on Japan’s Mount Ontake and that the eruption had been difficult to forecast due to a lack of signs, adding that a similar event hit the Datun Volcano Group (大屯火山群) 6,000 years ago.
As of press time, the eruption of Japan’s second-highest volcano on Saturday had killed 36 people and injured 63.
Though Ontake is one of 47 active volcanoes on the Japan Meteorological Agency’s watchlist, the agency did not issue a warning about a possible eruption.
Retired Tokyo University professor Shiego Aramaki, a highly regarded expert on volcanoes, said in an interview with the Nikkei Asian Review that the eruption might have been caused by steam, rather than by the explosive eruption of lava.
CWB Seismology Center Director Kuo Kai-wen (郭鎧紋) said that these are two different types of eruptions.
“Before an explosive eruption of lava occurs, there would be an increase in minor earthquakes. Because of the signs, seismologists in the Philippines were able to issue warnings 68 days before Mount Pinatubo erupted in 1992,” Kuo said.
Kuo said the signs for eruptions caused by steam explosions are less obvious, making them more difficult to forecast.
He said that the Japanese agency recorded 85 earthquakes in the vicinity of Mount Ontake on Sept. 11, but the activity then gradually declined from Sept. 12 onward. As such, the agency did not escalate its warnings, he said.
Steam explosions happen when groundwater is heated by surging lava and the steam’s pressure blows open the Earth’s crust, Kuo said.
A similar event happened in the Datun Volcanic Group 6,000 years ago, he added.
“Eruptions produce rocks like andesite. However, what geologists find on Datun is granite, which is produced through the cooling and solidification of lava below the Earth’s surface,” he said, adding that the discovery of granite rather than andesite is seen as evidence of steam explosions.
Lava explosions can cause much more damage than steam explosions. The eruption of Mount Vesuvius in 79AD, for example, destroyed the city of Pompeii, Kuo said.
While Japan monitors 47 volcanoes closely, Kuo said Taiwan’s weather bureau mainly monitors the Datun Volcanic Group and volcanoes in the sea near Kueishan Island (龜山).
The bureau has been closely monitoring the nation’s active volcanoes and none of them shows any signs of erupting, Kuo said.
“Mud volcanoes” that emerge occasionally in southern Taiwan are not really volcanoes, he said, saying the phenomenon is simply muddy water gushing from under the ground.
FAMILY FEUD: Weng Jen-hsien, who was convicted of killing six people in 2016, was the second prisoner to be executed since President Tsai Ing-wen took office A death row inmate was executed on Wednesday, less than a year after he was convicted of killing six people by setting fire to his home. Minister of Justice Tsai Ching-hsiang (蔡清祥) said that he signed the order and the death sentence was carried out on Wednesday afternoon in New Taipei City. The Supreme Court on July 10 last year sentenced 53-year-old Weng Jen-hsien (翁仁賢) to death after he was convicted of killing his parents, niece, nephew and nephew’s wife and his parents’ caregivers. Weng set fire to his home in Taoyuan’s Longtan District (龍潭) on Feb. 7, 2016, after a family feud
HOME AWAY FROM HOME: The central government is offering subsidies to hotels to house people who have been ordered to undergo 14-day home quarantine Minister of Health and Welfare Chen Shih-chung (陳時中) yesterday elaborated on the rules for “social distancing” and said that the government is providing subsidies to encourage more hotels to become quarantine hotels. Chen on Tuesday urged the public to practice social distancing by keeping at least 1m apart outdoors and 1.5m apart indoors. If maintaining such distances is not possible due to confined or crowded spaces, then everyone should wear a mask, Chen yesterday told a daily news briefing at the Central Epidemic Command Center (CECC) in Taipei. The center also suggested that people avoid exhibitions, sports events, concerts and other social
At a campground in Nantou County, a team of women are using ropes to shimmy up a towering seven-story tall Chinaberry tree, fighting their fear of heights and reconnecting with nature. Tree climbing remains somewhat niche in Taiwan, but a growing number of women are embracing the challenge thanks to the island’s first international certified female climber arborist. Sylvia Hsu (許芢涵), 26, said she was inspired to set up her own women-only tree climbing classes after seeing the popularity of similar gatherings in Europe. “A women-only camp is a more relaxed environment,” she said. “I was hooked on trees after my first climb...
STRENGTH IN UNITY: The Executive Yuan respects KMT legislators’ viewpoints, but has no comment on calls for the premier to step down, spokeswoman Kolas Yotaka said The Chinese Nationalist Party (KMT) caucus yesterday accused Premier Su Tseng-chang (蘇貞昌) of treating the Legislative Yuan with disdain and demanded that he apologize or step down for saying that KMT Legislator Chen Yu-jen (陳玉珍) is unfit for her job. Prior to a question-and-answer session at the legislature on Tuesday, Su was asked by reporters to comment on Chen’s remark on Monday that Taiwan is not a country. “Then she is not qualified to be a lawmaker,” the premier said. Chen made the remark during a question-and-answer session with Mainland Affairs Council Minister Chen Ming-tong (陳明通), when she asked him about his view