Taiwan volcano: active, dormant, or what?

The Tatun (or Datun) volcano group (TVG) is in the north of Taiwan, 15 km to the north of the capital, Taipei. New research in the area by a Taiwanese/Russian scientific team involving the dating of eruption products at is now provoking alarm, it says here:

Datun Mountain, a dormant volcano located on the north of Taipei City, is an active volcano with a possible magnitude that can devastate the entire wider Taipei area with approximately six million residents if eruption occurs, a new study by the Academia Sinica says. The recent report used volcanic ash and mudflow in the analysis and claimed that Datun Mountain was an active volcano. A previous study had showed that the last eruption occurred 200,000 years ago and classified it as a dormant volcano.

The new study appears to suggest that the most recent eruption was a mere 5000 years ago: hence headlines claiming Taipei risks volcanic devastation, alarming comparisons between a putative eruption and the earthquakes of 1999, and even that old favourite, warnings of a new Pompeii. However, the most recent eruptive activity before the latest study had been dated at 20,000 years ago, not 200,000 years ago, so it was already understood that the volcano had been active in relatively recent times. The Global Volcanism Program notes: ‘The latest dated eruptions in the group took place over a roughly 3000-year period beginning about 20,000 years ago’.

Overall, it is not news that there is risk of potential activity at Tatun. An article in the Journal of Volcanology and Geothermal Research in 2007 described the Tatun Volcano Group as ‘a potentially active Quaternary volcano’ and noted that ‘Because of lack of any activity in historical times it has been classified as an extinct volcano, even though more recent studies suggest that TVG might have been active during the last 20 ka’ (in any case, when assessing whether a volcano is extinct or dormant, ‘activity in historical times’ is no guide). The article went on to observe that seismic studies ‘indicate that a magma chamber may still exist beneath TVG and that a future eruption or period of unrest should not be considered unlikely’.

There’s nothing wrong in waking up the people of northern Taiwan to the risks posed by their local volcano, but (as ever) sensationalized press reports are perhaps not the best way to do it.

UPDATE. Taiwan News Online quotes Chaing Chung-jung of the Taiwan Central Geological Survey: ‘Chiang said that the possibility of the mountain erupting again is “extremely low”. “Besides, volcanic eruptions can be predicted”, he said, urging that there is no need for people to panic over the matter’. This story still claims, erroneously, that the ‘last eruption of Datun Mountain occurred 200,000 years ago’, however.

Information
Global Volcanism Program: Tatun Group – information on the Tatun Volcano Group (0801032A)
Yangmingshan National Park: Datun Mountain – information from the Yangmingshan National Park website

News
Datun Mountain is active, can devastate Taipei: study – The China Post, 2 November 2009
Volcano near Taiwan’s capital is still active, scientists warn – My Sinchew, 2 November 2009