Anatahan’s volcano erupts again—USGS, EMO

Anatahan’s rumbling volcano erupted again for the third time this year, spewing clouds of ash into the air, just days after a scientific mission had collected rock samples and measured emissions of sulfur dioxide, a major air pollutant.

The U.S. Geological Survey and the CNMI Emergency Management Office said the third volcanic eruption on Anatahan broke out last Friday afternoon.

These agencies said, though, that the third eruption seemed short-lived, after seismicity level dropped significantly about seven hours after the eruption that was recorded to have occurred at about 3:44pm Friday.

“The third eruption of the year at Anatahan apparently began according to seismicity recorded by the two seismic station[s] operating on the island. Seismicity levels reached about 10-20 percent of the maximum reached at the end of January during the first eruption of the year,” the EMO and the USGS said in a joint report released on Sunday.

When the volcano erupted for the first time during the year, the activity escalated, with pyroclastic rocks with diameters of about a meter and over being thrown from the crater to hundreds of feet in the air.

That eruption, which was considered as Anatahan’s third historical eruption, peaked on Jan. 26 and Feb. 2, during which time the volcano sent ash as high as 15,000 to 20,000 feet locally and as far as 100 miles downwind, and vog—volcanic smog—nearly 600 miles downwind.

Fresh lava covered the entire crater floor by up to about a kilometer in diameter some two weeks later, according to the USGS and the EMO.

The Washington Volcanic Ash Advisory Center said that ash plume at elevations below 13,000-ft extended about 50-85 nautical miles from the volcano early Sunday morning. Later that day, the VAAC said the ash plume was moving west and southwest from Anatahan, which is located north of Saipan.

Before last week’s eruption, the EMO and scientists from the private sector—Dave Hilton, PhD. and Tobias Fischer, PhD.—flew to Anatahan last Monday to gather rock samples and measure the amount of sulfur dioxide being emitted from the volcano.

EMO geophysical seismic technician Juan Takai Camacho, who flew with the team to Anatahan, said the rocks samples have been sent to the USGS laboratory in Hawaii for study.

Camacho said he has yet to obtain the results of the assessment on the volcano’s sulfur dioxide emissions. The EPA considers sulfur dioxide as one of the six common air pollutants, which causes a wide variety of health and environmental impacts.

Sulfur dioxide in the air can cause temporary breathing difficulty, especially for people with asthma and other respiratory ailments. “When these are breathed, they gather in the lungs and are associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death,” the EPA said.

It also reacts with other substances in the air to form acids, which fall to earth as rain, fog, snow or dry particles, according to the EPA. Sulfur dioxide may be carried by the wind far from the place of emission.

Anatahan’s volcano first erupted after centuries of dormancy on May 10, 2003, with ash plume rising to an altitude of over 30,000 feet that covered over 1-million-square kilometers of airspace above the Pacific Ocean and reached Philippine jurisdiction. That eruption, which ceased by mid-June that year, deposited about 10 million cubic meters of material over Anatahan Island and the sea. The second batch of volcanic eruptions happened from April to June 2004.