Saturday, May 14, 2005
Seismecity is not link to volcanic activity
Friday, May 13, 2005 U.S. Geological Survey geophysicist Dr. Andy Lockhart, who is currently working with the Emergency Management Office to repair and install seismic monitoring stations on Anatahan, stressed yesterday that seismic monitoring is critical for the northern volcano.Lockhart said, though, that the Anatahan volcano's ongoing eruption is not directly linked to its seismicity.
"It would be really critical except that right now the activity of the volcano is such that it kind of comes and goes without a very strong relationship to the seismicity," he said. "In other words, the volcano right now is kind of an open pipe and it can erupt fairly vigorously without providing a very strong seismic signature"Lockhart said that, because of Anatahan's "open-pipe" situation, satellite images are currently providing majority of the minute-to-minute data."The seismicity doesn't correlate as strongly to the size of the eruptions as we would like, so the seismic monitoring is important but I think right now, the satellite monitoring is providing most of the really important minute to minute monitoring," he said.
Lockhart is currently stationed at the Cascades Volcano Observatory in Vancouver, Washington and is tasked with working on instrumentation for monitoring volcanoes."My mission comes as a result of the damage on the monitoring equipment on Anatahan," he said. "The situation with the one remaining station looked tenuous enough that I just decided to come out and get the job done."Lockhart and a team from EMO will travel to Anatahan tomorrow and possibly Monday to replace and repair the stations.
Very low amplitude tremors continue at Anatahan after an intensity surge on May 5, with two quakes registering a magnitude 1.5 on the Richter scale on May 9 and 10.A joint report by the EMO and the USGS showed a dense plume of ash rising to about 10,000 feet in the air and extending 350 nautical miles to the northwest and 500 nautical miles to the west. Thinner ash extends beyond that to 550 nautical miles northwest and 800 nautical miles west of Anatahan.
A broad swath of vog extends beyond that over the Philippine Sea north and west of the ash. Anatahan's larget eruption occurred on April 6 and expelled roughly 50 million cubic meters of ash.