Undersea volcano gave off signals before eruption in 2011
Baku, June 11 (AZERTAC). A team of scientists that last year created waves by correctly forecasting the 2011 eruption of Axial Seamount years in advance now says that the undersea volcano located some 250 miles off the Oregon coast gave off clear signals just hours before its impending eruption.
The researchers` documentation of inflation of the undersea volcano from gradual magma intrusion over a period of years led to the long-term eruption forecast. But new analyses using data from underwater hydrophones also show an abrupt spike in seismic energy about 2.6 hours before the eruption started, which the scientists say could lead to short-term forecasting of undersea volcanoes in the future.
They also say that Axial could erupt again -- as soon as 2018 -- based on the cyclic pattern of ground deformation measurements from bottom pressure recorders.
Results of the research, which was funded by the National Science Foundation, the National Oceanic and Atmospheric Administration, and the Monterey Bay Aquarium Research Institute (MBARI), are being published this week in three separate articles in the journal Nature Geoscience.
Bill Chadwick, an Oregon State University geologist and lead author on one of the papers, said the link between seismicity, seafloor deformation and the intrusion of magma has never been demonstrated at a submarine volcano, and the multiple methods of observation provide fascinating new insights.
Bob Dziak, an Oregon State University marine geologist, had previously deployed hydrophones on Axial that monitor sound waves for seismic activity. During a four-year period prior to the 2011 eruption, there was a gradual buildup in the number of small earthquakes (roughly magnitude 2.0), but little increase in the overall "seismic energy" resulting from those earthquakes.
That began to change a few hours before the April 6, 2011, eruption, said Dziak, who also is lead author on one of the Nature Geoscience articles.
MBARI researchers used three kinds of sonar to map the seafloor around Axial, and the detailed images show lava flows as thin as eight inches, and as thick as 450 feet.
The researchers also used shipboard sonar data to map a second, thicker lava flow about 30 kilometers south of the main flow -- also a likely result of the 2011 eruption.
Knowing the events leading up to the eruption -- and the extent of the lava flows -- is important because over the next few years researchers will be installing many new instruments and underwater cables around Axial Seamount as part of the Ocean Observatories Initiative. These new instruments will greatly increase scientists` ability to monitor the ocean and seafloor off of the Pacific Northwest.
The scientists also observed and documented newly formed hydrothermal vents with associated biological activity, Chadwick said.
Scientists from Columbia University, the University of Washington, North Carolina State University, and the University of California at Santa Cruz also participated in the project and were co-authors on the Nature Geoscience articles.
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