Anatahan calming down

The Emergency Management Office yesterday said that Anatahan volcano seemed calmer than it was in the last few days, even as it reported that the seismicity level on the island continues at about 80 percent of the highest level of the year, which was reached in late April.

Quoting the observation of U.S. Geological Survey employee Andy Lockhart, who visited the island on Sunday, EMO said the volcano’s eruption “appeared to be somewhat less vigorous than it was four days ago.”

But the agency added that strombolian explosions “continue to occur very frequently, sometimes accompanied by steam and ash and other times only by steam, alternating with periods of continuous ash emission.”

The explosions, EMO added, throw up mostly coarse material at intervals of tens of seconds.

EMO noted, however, that the volcano was less violent than it was during the past few days, when periods of continuous ash emission have become more frequent and sometimes lasted up to 40 minutes.

Despite this, the off-limits advisory on Anatahan will remain in place until further notice. All travels to the island are restricted, except for scientific expeditions. Aircrafts are urged to pass upwind of Anatahan or farther than 30 km downwind from the island, and exercise due caution within 30 to 50 km of the island.

“Although the volcano is not currently dangerous to most aircraft within the CNMI airspace, conditions may change rapidly,” EMO said.

Gov. Juan N. Babauta declared Aanatahan “off-limits” days after the volcano’s big eruption on May 10 last year. The volcanic activity eventually slowed down, but regained intensity last March 30.

According to EMO, a more energetic seismicity stage began on April 24, when a light ash cloud rose to a few thousand feet. Seismic activity peaked on April 28, then decreased slowly to about half that peak intensity during May.

In June, the seismicity level was higher, as a result of more frequent small explosions every few tens of seconds, and a 100-km-long, light-colored plume of steam and ash was occasionally visible. An active spatter cone has existed since at least June 10, from which continuous strombolian explosions were throwing material as high as 100 meters every few tens of seconds to minutes, EMO said.