Anatahan eruptions intensify anew

The ongoing volcanic activity on Anatahan abruptly changed after subsiding in the past days, with eruptions intensifying anew since late Saturday.

Shortly before noon yesterday, the eruptions resumed to peak levels, with the volcano displaying strong explosions, according to the Emergency Management Office and the U.S. Geological Survey.

The third historical eruption of Anatahan’s volcano, which began on January 5, had big pyroclastic rocks thrown hundreds of meters in the air from the crater. In a joint report, the EMO and the USGS said strombolian explosions resumed late Saturday and have been going on yesterday.

Before this, the volcanic activity subsided abruptly last Thursday. The EMO and the USGS said seismicity dropped significantly, indicating that explosions had ceased. The volcano, however, continued to emit gas.

The volcano has spewed out ashes and smog several thousands of feet in the air. With winds blowing southerly several days ago, ash plume and haze being blown from Anatahan to Saipan prompted the EMO and the Department of Public Health to issue a health advisory that advised residents to stay indoors. Inhalation of sulfur dioxide may have adverse health effects, especially to those who have respiratory problems.

An overflight conducted by the EMO right after the new batch of eruptions began saw ash plume rising to about 10,000 feet. The EMO’s overflight team observed pyroclastic rocks to have diameters of one meter or greater.

The volcano’s activity intensified after months of extremely low seismic activities, which followed the second batch of eruptions from April to June last year.

The volcano on Anatahan 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 eruptions began about April 9, 2004, after more than a week of increasing seismicity. The second eruption consisted of passive extrusion during mid-April, which later developed to strombolian explosions every minute or two on April 24, the agencies said. The strombolian explosions continued every minute or two through mid-July, often sending a thin plume of gas and ash upward a few thousand feet and 100 km downwind.

According to the agencies, the second eruption essentially ended on July 26, although visitors to the island three months later could still see very small amounts of steam and ash rising 100-200 ft above the crater rim and could smell sulfur dioxide near the crater.

Anatahan remains off-limits to the public, except for government and approved scientific missions, pursuant to a continuing emergency declaration by Gov. Juan N. Babauta.

The Babauta administration has been asking for federal funding for the installation of early warning devices and the implementation of volcano hazards assessment in the Northern Islands.