NGDIR News Section--THERE'S BEEN A lot of volcanic news lately from places you wouldn't think of as having volcanoes. Like, say, Taiwan.
The Tatun Group cluster of about 20 andesitic volcanoes sits just 20 kilometers (about 13 miles) or so from Taipei. More than 6.7 million people live within 30 kilometer (18.5 miles) of this volcanic group, which last erupted around 650 AD. Researchers from the Academia Sinica's Institute of Earth Sciences found seismic evidence for magma about 20 kilometers under the Tatun Group, supporting the idea that people should consider it potentially active.
The study in Nature Scientific Reports suggests that the magma body is a single lens of magma or a series of sills that might mean the full magmatic system (liquid magma and mush) could be as large as 350 cubic kilometers, depending on what percentage of the system is molten. However, even if this magma has been imaged seismically, it doesn't mean an eruption will happen soon. By some estimates, as little as 14 percent of it might be molten, well below the well below the threshold of approximately 60 percent required before the viscosity of the magma would allow it to erupt.
Eruptions have occurred in Taiwan and local officials have established a monitoring system for the Tatun Group given its proximity to Taipei and the fact it's been active more recently than previously thought. In what could be the understatement of the week, Lin Cheng-horng, a geologist from this study, says, "it could happen in a few years, 10 years, or many decades later, it will require much more research to be better understood." Now, I don't think Lin means an eruption is likely in the next decade, but that the possibly exists. It could be centuries before anything happens at the Tatun Group, but this study shows there is magma down there right now.
Oh, that drone footage of what some called a "submarine eruption" off the coast of Taiwan in 2015 was more likely steam or gas vents off the coast of Kueishantao Island.
India has just one potentially-active volcanoes, in the Andaman Sea on Barren Island. This remote island is uninhabited, but around 600 people live within 5 kilometers of a volcano that has erupted numerous times over the last few hundred years. That makes headlines about the most recent eruption especially odd, as people have called it something of a surprise after years of quiet, which is definitely not true.
The island has seen eight periods of eruption since 1991, the most recent ending just one year ago. The current activity is ash emissions and lava flows from a small cone within the larger volcanic crater, although past eruptions have produced impressive lava fountains. This eruption was notable because a research vessel happened to be in the area. However, Barren Island doesn't pose much of a threat to people and property unless you happen to be a bit too close when it has its next eruption.