Volcanic activity felt on Pagan

Two monitoring agencies have detected volcanic activity on Pagan, even as the earthquake swarm being recorded on Sarigan has topped 460 since Tuesday.

The Emergency Management Office and the U.S. Geological Survey disclosed those developments, as Anatahan’s volcano continues to erupt.

“The portable seismograph indicated that there are activities going on,” said EMO geophysical instrument specialist Ramon Chong.

The problem, though, is that no seismic equipment is currently stationed on Pagan to constantly monitor seismic activities on the inhabited island, according to Chong.

“Since there’s no monitoring such as seismograph, it’s hard to tell if there’s a need to evacuate the people,” Chong said. Only Sarigan and Anatahan have seismic stations.

Chong disclosed that a team composed of EMO and USGS representatives went on a 10-day mission to Pagan several weeks ago to monitor the island’s volcanic activity. He said long-period earthquakes were recorded on Pagan, but added that no strombolian explosion was detected until the team left the island.

On Sarigan, the EMO and the USGS said yesterday that the seismic swarm continues and has now reached at least 460. They said quakes have been occurring at a rate of 30 events per hour as recorded on Sarigan’s seismometer.

“If Sarigan volcano erupts, we already have a plan,” Chong said, adding, though, that the plan has yet to be finalized. But unlike Pagan, Sarigan is uninhabited, he said. The plan addresses concerns by the airline industry about an ash outbreak should a volcanic eruption on Sarigan happen.

The National Earthquake Information Center also recorded a 4.5-intensity quake at about 8:01pm Thursday and located the temblor at about 20 miles northwest of Agrihan, 65 miles north-northwest of Pagan, and 260 miles north of Saipan.

The NEIC recorded a 5.4-intensity quake at about 1:10am Thursday and located it at about 30 miles north-northwest of Anatahan, 95 miles south of Pagan, and 105 miles north of Saipan.

Meanwhile, the EMO and the USGS said long-period earthquakes continue to be sporadic on Anatahan. Tremor levels generally ranged between 40 and 60 percent of the peak levels observed for the period June 17-26.

Citing satellite monitoring by the Air Force Weather Agency, they said an ash plume extends west and then turns north and northwest Thursday afternoon. The ash measured 600 nautical miles northwest of the volcano. They said a mixture of volcanic smog and smoke from Asian fires was detected beyond the plume.

The agencies said yesterday morning that any plume rising above 30,000 feet is projected to move easterly.