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.
Taiwan is stepping up plans to create self-sufficient supply chains for combat drones and increase foreign orders from the US to counter China’s numerical superiority, a defense official said on Saturday. Commenting on condition of anonymity, the official said the nation’s armed forces are in agreement with US Admiral Samuel Paparo’s assessment that Taiwan’s military must be prepared to turn the nation’s waters into a “hellscape” for the Chinese People’s Liberation Army (PLA). Paparo, the commander of the US Indo-Pacific Command, reiterated the concept during a Congressional hearing in Washington on Wednesday. He first coined the term in a security conference last
Prosecutors today declined to say who was questioned regarding alleged forgery on petitions to recall Democratic Progressive Party (DPP) legislators, after Chinese-language media earlier reported that members of the Chinese Nationalist Party (KMT) Youth League were brought in for questioning. The Ministry of Justice Investigation Bureau confirmed that two people had been questioned, but did not disclose any further information about the ongoing investigation. KMT Youth League members Lee Hsiao-liang (李孝亮) and Liu Szu-yin (劉思吟) — who are leading the effort to recall DPP caucus chief executive Rosalia Wu (吳思瑤) and Legislator Wu Pei-yi (吳沛憶) — both posted on Facebook saying: “I
Sung Chien-liang (宋建樑), who led efforts to recall Democratic Progressive Party (DPP) Legislator Lee Kun-cheng (李坤城), was released on bail of NT$80,000 today amid outcry over his decision to wear a Nazi armband to questioning the night before. Sung arrived at the New Taipei District Prosecutors’ Office for questioning in a recall petition forgery case last night wearing a red armband bearing a swastika, carrying a copy of Adolf Hitler’s Mein Kampf and giving a Nazi salute. Sung left the building at 1:15am without the armband and covering the book with his coat. Lee said today that this is a serious
Firefighters are working to put out a fire on Taipei’s Yangmingshan (陽明山) reported earlier this morning. The cause of the fire is still under investigation. The Taipei Fire Department said it received a report of a fire at Xiaoyoukeng (小油坑) at 11:17am, dispatching four command vehicles, 16 firetrucks, one ambulance and 72 personnel. The fire is still burning on about 250m² of land, according to initial estimates, as eyewitnesses reported seeing smoke rising from the mountain. The Yangmingshan National Park Headquarters on Facebook said the Qixingshan (七星山) hiking trail starting from Xiaoyoukeng and the Xiaoyoukeng parking lot are closed as firefighters work to put
RSS