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The researchers' documentation of inflation of the undersea volcanofrom gradual magma intrusion over a period of years led to thelong-term eruption forecast. But new analyses using data fromunderwater hydrophones also show an abrupt spike in seismic energyabout 2.6 hours before the eruption started, which the scientistssay could lead to short-term forecasting of undersea volcanoes inthe future. They also say that Axial could erupt again -- as soon as 2018 --based on the cyclic pattern of ground deformation measurements frombottom pressure recorders. Results of the research, which was funded by the National ScienceFoundation, the National Oceanic and Atmospheric Administration,and the Monterey Bay Aquarium Research Institute (MBARI), are beingpublished this week in three separate articles in the journal Nature Geoscience. Bill Chadwick, an Oregon State University geologist and lead authoron one of the papers, said the link between seismicity, seafloordeformation and the intrusion of magma has never been demonstratedat a submarine volcano, and the multiple methods of observationprovide fascinating new insights. "Axial Seamount is unique in that it is one of the few placesin the world where a long-term monitoring record exists at anundersea volcano -- and we can now make sense of itspatterns," said Chadwick, who works out of Oregon State'sHatfield Marine Science Center in Newport, Ore. "We've beenstudying the site for years and the uplift of the seafloor has beengradual and steady beginning in about 2000, two years after it lasterupted. "But the rate of inflation from magma went from gradual torapid about 4-5 months before the eruption," added Chadwick."It expanded at roughly triple the rate, giving a clue thatthe next eruption was coming." Bob Dziak, an Oregon State University marine geologist, hadpreviously deployed hydrophones on Axial that monitor sound wavesfor seismic activity. During a four-year period prior to the 2011eruption, there was a gradual buildup in the number of smallearthquakes (roughly magnitude 2.0), but little increase in theoverall "seismic energy" resulting from thoseearthquakes. 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. "The hydrophones picked up the signal of literally thousandsof small earthquakes within a few minutes, which we traced to magmarising from within the volcano and breaking through thecrust," Dziak said. "As the magma ascends, it forces itsway through cracks and creates a burst of earthquake activity thatintensifies as it gets closer to the surface. "Using seismic analysis, we were able to clearly see how themagma ascends within the volcano about two hours before theeruption," Dziak said. "Whether the seismic energy signalpreceding the eruption is unique to Axial or may be replicated atother volcanoes isn't yet clear -- but it gives scientists anexcellent base from which to begin." The researchers also used a one-of-a-kind robotic submersible tobounce sound waves off the seafloor from an altitude of 50 meters,mapping the topography of Axial Seamount both before and after the2011 eruption at a one-meter horizontal resolution. Thesebefore-and-after surveys allowed geologists to clearly distinguishthe 2011 lava flows from the many previous flows in the area. MBARI researchers used three kinds of sonar to map the seaflooraround Axial, and the detailed images show lava flows as thin aseight inches, and as thick as 450 feet. "These autonomous underwater vehicle-generated maps allowedus, for the first time, to comprehensively map the thickness andextent of lava flows from a deep-ocean submarine in highresolution," said David Caress, an MBARI engineer and leadauthor on one of the Nature Geoscience articles. "These newobservations allow us to unambiguously differentiate between oldand new lava flows, locate fissures from which these flows emerged,and identify fine-scale features formed as the lava flowed andcooled." 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 ofthe lava flows -- is important because over the next few yearsresearchers will be installing many new instruments and underwatercables around Axial Seamount as part of the Ocean ObservatoriesInitiative. These new instruments will greatly increase scientists'ability to monitor the ocean and seafloor off of the PacificNorthwest. "Now that we know some of the long-term and short-term signalsthat precede eruptions at Axial, we can monitor the seamount foraccelerated seismicity and inflation," said OSU's Dziak."The entire suite of instruments will be deployed as part ofthe Ocean Observatories Initiative in the next few years --including new sensors, samplers and cameras -- and next time theywill be able to catch the volcano in the act." The scientists also observed and documented newly formedhydrothermal vents with associated biological activity, Chadwicksaid. "We saw snowblower vents that were spewing out nutrients sofast that the microbes were going crazy," he pointed out."Combining these biological observations with our knowledge ofthe ground deformation, seismicity and lava distribution from the2011 eruption will further help us connect underwater volcanicactivity with the life it supports." Scientists from Columbia University, the University of Washington,North Carolina State University, and the University of Californiaat Santa Cruz also participated in the project and were co-authorson the Nature Geoscience articles. The e-commerce company in China offers quality products such as Ultra-clear Glass Manufacturer , Fire Rated Glass, and more. For more , please visit Tempered Safety Glass today!
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