TAIPEI (Taiwan News) -- After carrying out a long-term study, a research team at Academia Sinica has determined that the Tatun volcano group (TVG) and Guishan Island are both active volcanoes and a volcanic "pulse" was discovered in Taipei's Yangmingshan.
With the assistance of the Ministry of Science and Technology and the Ministry of the Interior, Lin Cheng-horng (林正洪), a researcher at the Academia Sinica's Institute of Earth Sciences, and his team set up the Taiwan Volcano Observatory at Tatun (TVO) in 2011 at the Jinshan Nature Center in the Yangmingshan National Park Office. The team set up various real-time volcanic monitoring systems to carry out long-term monitoring of the TVG and submarine volcanoes off the coast of Guishan Island.
At a press conference on Wednesday (May 29), TVO researchers announced that for a volcano to be active, it must have erupted within the past 10,000 years and currently have a magma chamber underneath. After many years of monitoring, TVO researchers have concluded that both the TVG and Guishan Island are active volcanoes, reported CNA.
Lin reporting the team's findings. (CNA photo)
Lin said that S wave shadows and P wave deceleration have proven the existence of a magma chamber under the crust of northern Taiwan covering about 1/4 the area of Taipei City at about 15 kilometers in length and 16 kilometers in width and is about four to ten kilometers thick. He said that the magma chamber under Guishan Island is 1.5 times larger than that of TVG, and if a volcanic eruption occurred on the island, it may produce a small-scale tsunami that would hit the extremely flat plains of Yilan.
The researcher said that the TVO has found many interesting special volcanic phenomena over the past three years, including periodic seismic activity in the Dayoukeng area on Yangmingshan. He said that on average, a seismic event occurs once every 18 minutes and this cycle can be repeated over the course of dozens of hours, reported CNA.
Lin claimed that this is the first time that an animal-like "pulse" had been detected in a supposedly "dormant" volcano, according to the report. He said that about 150 earthquakes are detected every month in TVG and the volcanoes issue a pulse about 70 or 80 times a day, but not always.
Qixing Mountain. (Wikimedia Commons photo)
Lin compared the way earthquakes jolt the volcanic pulse back into action to the way a defibrillator shocks a heart back into rhythm. For example, seismic waves generated by earthquakes in Hualien, spread to Taipei and restart the TVG pulse, said Lin.
Ministry of Science and Technology (MOST) Deputy Minister Shieh Dar-bin (謝達斌) said the TVG is very close to the Taipei metropolitan area, reported CNA. Shieh said the highest peak, Qixing Mountain, is less than 15 kilometers away from Taipei 101.
Shieh said that if the volcano were to erupt one day, the accompanying earthquakes and volcanic ash would bring great harm to the Taipei area. Therefore, understanding the volcanoes can help minimize the impact of a disaster, said Shieh.
Guishan Island. (Photo from flickr user Chen Liang Dao)
According to experts, if the Tatun volcanoes were to erupt, residents on Yangmingshan, Shilin, Tianmu, and Beitou districts would bear the brunt of its force. Volcanic ash would cover northern Taiwan, Taipei would experience earthquakes over 6 in magnitude, and the safety of two nearby nuclear power plants would be threatened.
In February of 2017, Lin and his team concluded in a study published in the journal Nature that there is a magma chamber 20 kilometers beneath the Wanli and Jingshan districts of New Taipei. He reached his conclusion in 2016 after analyzing data from 40 seismic monitoring stations positioned around the TVG over the course of three years.
Previous studies of lava dating showed that the volcanoes last erupted 200,000 years ago. However, the most recent study carried out on volcanic lava cores in 2009 indicated that an eruption may have occurred as recently as 5,000 years ago.
Illustration of magma chamber beneath Yellowstone National Park. (Wikimedia Commons)
As for when the next eruption may occur, Lin in 2017 told Apple Daily "it could happen in a few years, 10 years, or many decades later, it will require much more research to be better understood." Lin said that the impact of a volcanic eruption depends on its scale, and the time, size, and location can be predicted through instrumental observations.
Lin said that the period of advanced warning could be as short as few weeks or two months. He said that signs of an impending eruption would include intensive earthquakes, deformation of the terrain, rapid accumulations of volcanic gases, and rising surface temperatures in excess of averages.
The TVO has positioned a variety of real-time monitoring systems for volcanoes, including readings on fumaroles, hot springs, seismic events, GPS, and ground temperatures.
(Image from TVO Tatun Volcano Observatory)
TVO devices monitoring seismic activity, fumaroles, hot springs, GPS, and ground temperature. (Screenshot from dmip.tw/Lfive)