Volcanic activity detected beneath Turtle Island (Gueishan Island, 龜山島) and the Datun Volcano Group (大屯山火山群) prove that they are active groups, Taiwan Volcano Observatory Director Lin Cheng-horng (林正洪), who is also an earth science researcher at Academia Sinica, said yesterday.
An active volcano is defined as having a magma reservoir or having erupted in the past 10,000 years, Lin said as he told a news conference about his team’s research over the past decade at the observatory on Datunshan (大屯山) in Taipei’s Yangmingshan National Park.
Almost no geologists in Taiwan thought the volcano group might be active about 15 years ago, as earlier studies had suggested its latest eruption might have occurred about 100,000 years ago, he said.
Photo: Lu Chun-wei, Taipei Times
However, his team has documented the existence of magma chambers beneath Datunshan through the variations in primary waves (P waves) and secondary waves (S waves) of earthquakes since the observatory was set up in 2011, he said.
S-waves cannot penetrate a magma reservoir, which also slows the transmission of P-waves — and both phenomena have been observed in the areas beneath Datunshan and Turtle Island, Lin said.
The island, which is about 10km off the coast of Yilan County, is only populated by military personnel, he said.
Volcanic eruptions under the island were more likely than under Datunshan and might trigger small-scale tsunamis off the coast of Yilan, he said.
However, there is no reason for the public to panic, because volcanic eruptions, unlike earthquakes, can be forecast by monitoring increases in the concentrations of carbon dioxide and sulfate ions, he said.
Lin’s team found that several magnitude 4 earthquakes in Taichung and in Hualien County in 2015 triggered regular “tremors” — or as Lin said, “heartbeats” — beneath Datunshan every 18 minutes for more than a day after each quake.
The team is likely to have been the first to have documented such “regular” quake activities, but its monitoring of such activity was later discontinued.
The team’s findings were published in Scientific Reports, the Journal of Volcanology Geothermal Research and other journals between 2016 and last year.
While there have not been any volcanic eruptions in Taiwan during its recorded history, identifying new evidence about earlier volcanic activities is still exciting, he said.
He expects to improve the volcanic surveys on Turtle Island, where there are fewer monitoring devices, he said.
Volcanologists from around Asia are to meet in Taiwan in October for the 4th field camp of the Asian Consortium of Volcanology, which has previously been held in Japan and Indonesia, he added.
Lin said he was originally interested in earthquakes, but switched to volcanology about 15 years ago after visiting Japanese volcanologists.
The workings of lava and gaseous substances of volcanoes was more attractive than the breaks or fault lines of seismology, he said.
SAFETY IN REGULATION: The proposal states that Chiayi should assess whether it is viable to establish such a district and draft rules to protect clients and sex workers The Chiayi City Council passed a motion yesterday to assess the viability of establishing a regulated red-light district. The council yesterday held its last session of the year, at which its fiscal 2024 budget was approved, along with 61 other proposals. The proposal to assess the viability of establishing a red-light district was put forward by independent Chiayi City Councilor Molly Yen (顏色不分藍綠支持性專區顏色田慎節). The proposal cited 2011 amendments to the Social Order Maintenance Act (社會秩序維護法), which stipulate that city and county governments can pass autonomous regulations on the sex trade to manage the industry and guarantee industry workers’ rights. A ban on the
STABILITY AND CHANGE: Flagging in recent polls, Ko this week pledged to maintain President Tsai’s foreign policy, with an emphasis on improving China relations Taiwan People’s Party (TPP) Chairman and presidential candidate Ko Wen-je (柯文哲) yesterday reiterated that he is “deep-green at heart” in response to accusations that he is pivoting his campaign to align closer with the ideology of the Democratic Progressive Party (DPP) in the face of flagging polls. Ko made the remark at an agricultural policy conference in Taipei, repeating his comments from an interview with CTS News a day earlier. Ko told the CTS host that he would continue to pursue President Tsai Ing-wen’s (蔡英文) national defense and foreign policy in general, but with an emphasis on establishing a rapport with
CHINA illness surge: Of 88 travelers from China, Hong Kong and Macau with respiratory symptoms who were encouraged to get tested upon arrival, 70.6% had the flu Two hundred and sixty people with COVID-19 were hospitalized and 31 deaths related to the virus were reported last week — the highest numbers in four weeks, the Centers for Disease Control (CDC) said yesterday, adding that cases are expected to peak next month. CDC Epidemic Intelligence Center Director Guo Hung-wei (郭宏偉) said that of the 260 people hospitalized last week with moderate to severe COVID-19, 98 percent had not received the Omicron XBB.1.5-adapted COVID-19 vaccine. Among the people hospitalized this year, 78 percent were aged 65 or older, while most of the those who were hospitalized or died have or had
Taiwanese who have recently traveled to China for tourism, to visit friends or relatives or for business reasons have been interrogated, detained and faced other forms of unreasonable treatment from Chinese officials, a source said on Sunday. Among them was a Taiwanese who was detained for eight hours at an airport in China due to their research, which is related to religion, while others have had their travel documents for China canceled for a number of reasons, the source said. In July, China expanded the scope of its counterespionage law, and recently announced a draft amendment to the law on the protection