New station installed, another repaired at Anatahan

A new seismic and acoustic station was installed while another was repaired on Anatahan Saturday, according to the latest joint report from the Emergency Management Office and the U.S. Geological Survey.

USGS geophysicist Dr. Andy Lockhart and Juan Camacho of EMO traveled to Anatahan early Saturday morning in hopes of bolstering the seismic monitoring efforts there, and according to the report released yesterday, were successful in doing so.

The report indicated that Camacho and Lockhart installed the new station about two kilometers west of the active vent.

Before the expedition, only one of the three stations on the island was functional. Lockhart said one station that is down may not be accessible for repair due to its proximity to the erupting crater, resulting in the need to install a new station.

Lockhart and Camacho flew over the station, located a kilometer west of the active vent, and reported that it is buried under a meter of ash from the February and April eruptions.

The third station, located at the center of the island and high on the western rim of the crater, was repaired.

The stations are thought to have been hampered by lost power due to ash covering its solar panels.

Lockhart earlier said that batteries with a life span of one year will be added along with the solar panels to ensure continuous monitoring despite the ash.

Equipment for the stations include a metal box with batteries, electronics, and radio that will relay data to Saipan. A sensor used to measure ground vibration is also buried and a piece of pipe is used for the antenna mast for the radio to send signals.

Equipment for each station, according to Lockhart, costs about $7,500.

Lockhart and Camacho also reported that they heard a continuous roaring sound from two to three kilometers west of the East Crater vent.

“They saw ash and steam rising by pure convection, not explosively, to 10,000 feet,” the report stated.

Released yesterday, the report also indicated that seismicity continues to be very low.

“The records show continuous very low amplitude low-frequency tremor,” USGS and EMO said.

Meanwhile, the ash plume has been continuous and moderately thick, moving at 5 knots northwestward. The plume extends out 35 nautical miles from northwest through northeast of Anatahan.

The broad swath of vog—volcanic smog—is less extensive than the previous days, now extending only 900 nautical miles west and 460 nautical miles northeast of Anatahan.

The vog was earlier limiting visibility of a passing ship to just 2.5 miles.

Anatahan experienced its largest eruption on April 6, expelling roughly 50 million cubic meters of ash. Ash and haze as a result of the eruption darkened the skies over Saipan and Tinian.

For more information, contact EMO geophysical seismic technician Juan Takai Camacho at 322-9528 or email at juantcamacho@hotmail.com; geophysical instrument specialist Ramon Chong at 322-9528 or email at rcchongemo@hotmail.com; or USGS geologist Frank Trusdellat (808) 967-8812, fax: (808) 967-8890, or email at trusdell@usgs.gov.