Geochemistry, Mineralogy, Volcanology News

Taal Eruption and Ashfall Continue; Thousands Still at Risk

The Philippines’ volcanology institute warns that a hazardous eruption of Taal is imminent. In the past, Taal’s eruptions have lasted months and even years.

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Taal Volcano in the Philippines has been erupting since midday local time on 12 January. Since early on 13 January, Taal has experienced a continuous eruption of its main crater from magmatic and hydrovolcanic activity, including lava fountains 500 meters tall. Ash from these eruptions and from a 10- to 15-kilometer plume of steam and tephra has blanketed the surrounding area with a thick layer of wet ash, mud, and falling debris. Taal is about 65 kilometers south of the capital of the Philippines, Manila, and last erupted in 1977.

Taal—a complex volcano that includes stratovolcanoes, craters, and conical hills—is one of the smallest volcanoes in the world. But it is considered one of the most dangerous in the Philippines because of its high activity level and proximity to population centers.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) urged the evacuation of all people within a 14-kilometer radius of Taal because of continued risk of an explosive eruption, falling ash, and a potential volcanic tsunami. GMA News in the Philippines reported that more than 40,000 residents have evacuated because of the eruption and ashfall. An estimated 450,000 people live in the evacuation zone.


 

Lightning and Ash

PHIVOLCS started measuring an increase in seismic activity surrounding Taal in late December and has been closely monitoring the area since then. At 2:30 p.m. local time on 12 January, the agency raised the alert level from 1 to 2 because of increased steam activity, seismic activity, ground deformation, and sulfur dioxide emission.

By 7:30 p.m. Taal was at alert level 4, indicating that a hazardous explosive eruption was possible within hours to days. This alert status followed a few hours of continuous eruptions, multiple volcanic earthquakes, and a “tall 10–15 kilometer steam-laden tephra column with frequent volcanic lightning that rained wet ashfall on the general north as far as Quezon City.”

Heavy ashfall from this and later activity has fallen across municipalities surrounding the volcano and as far as Tagaytay City, north of Manila.


Ash poses the largest risk to people and animals. “The ash is what will kill you, not the lava,” Joseph Michalski, director of the Earth and Planetary Science Division at the University of Hong Kong, told CNN. “The ash flow from an exploding volcano can travel hundreds of kilometers an hour.” Sulfur dioxide emission from the volcano is also a large health risk.

The eruption also generated a lot of volcanic lightning within the cloud, from cloud to ground, and from ground to cloud. “These strikes are just as hazardous as lightning from regular thunderstorms,” Alexa Van Eaton tweeted. Van Eaton is a physical volcanologist at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Wash. “We’re seeing thousands of tiny flashes within the plume (as well as terrifying and hazardous cloud-to-ground strikes). This abundance of in-cloud lightning holds tantalizing clues about…the nature [and] movement of the charge-carries inside volcanic plumes.”


 

Eruption Likely to Continue for a While

On 13 January PHIVOLCS reported that new lateral vents opened along the northern flank of the volcano with 500-meter-tall lava fountains and 2-kilometer-tall steam plumes. As of 1:00 p.m. local time on 14 January, lava eruptions continue along the flank, and heavy ashfall still falls on the surrounding towns.

The agency has recorded 212 volcanic earthquakes in the Taal region, including 49 earthquakes in the span of 8 hours on 14 January. “The intense seismic activity coupled with fissuring on the caldera region likely signifies continuous magma intrusion beneath the Taal edifice, which may lead to further eruptive activity,” PHIVOLCS reported. Eos reached out to PHIVOLCS and other experts in the region but did not receive a response in time for publication.

PHIVOLCS chief of volcano monitoring Antonia Bornas told ABS-CBN News that on the basis of Taal’s past eruption patterns, these eruptions could continue for several months or even years.

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

Citation: Cartier, K. M. S. (2020), Taal eruption and ashfall continue; thousands still at risk, Eos, 101, https://doi.org/10.1029/2020EO138679. Published on 14 January 2020.
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