Anatahan's volcanic eruption has produced a thick ash plume that has reached Philippine airspace, even as explosive activity declined after intensifying last weekend.
Although the eruptive activity has significantly declined since Sunday, the U.S. Geological Survey and the Emergency Management Office said several long-period earthquakes have been occurring on Anatahan since Monday. The strongest quake had a magnitude of 2.0.
Citing information obtained from the Washington Volcanic Ash Advisory Center, the agencies said yesterday that ash and steam rose to altitudes of 20,000 feet and 13,000 feet and extended in different directions.
At 20,000 feet in the air, volcanic ash and steam reportedly extend about 110 nautical miles to the northeast. Another plume that rose to an altitude of about 13,000 feet extends over 250 nautical miles to the west-northwest.
“The vog plume extends 1,325 nautical miles to the west, reaching the Philippines, and also extends 500 nautical miles to the north of Anatahan,” the USGS and the EMO said in a joint report.
The VAAC reportedly monitored significant ash emissions yesterday morning, less than an hour after ash production ceased during the wee hours before dawn.
As of noontime yesterday, the VAAC said ash emissions rose to about 22,000 feet in the air. It said that a large area of dispersed ash at an altitude of 15,000 feet extends approximately 300 miles west-northwest of the volcano.
Before nighttime, the ash plume reached an altitude of 15,000 feet near the volcano and about 10,000 feet further west. The EMO reported no ashfall on Saipan, located several miles south of Anatahan.