Underwater Volcano Gave Warning Before Eruption
An underwater volcano gave a clear indication before it erupted in April 2011, according to a new study, published in the journal Nature Geoscience on Monday. The findings may help predict underwater eruptions in the future, researchers said.
The study focused on Axial Seamount, a submarine volcano that resides almost 5,000 feet (1,500 meters) under the Pacific Ocean, just off the Oregon Coast. The volcano erupted on April 6, 2011, and covered the sea floor in lava up to 12-feet (4-meters) thick.
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Researchers said Axial Seamount is unique because it is one of the few places where a long-term monitoring record exists at an undersea volcano. The team said they can now make sense of its patterns to predict future eruptions.
"Uplift of the seafloor has been gradual and steady beginning in about 2000, two years after it last erupted," Bill Chadwick, study coauthor and a geologist at Oregon State University, said in a statement. "But the rate of inflation from magma went from gradual to rapid about four to five months before the eruption. It expanded at roughly triple the rate, giving a clue that the next eruption was coming."
An hour before the volcano erupted, the seafloor rose by almost 3 inches. After the eruption, it deflated by more than 6 feet.
"This kind of movement has been detected in volcanic areas on land before, but not this effectively in the oceans," Neil Mitchell, a marine geologist at the University of Manchester in England, who was not involved in the study, told MSNBC.
Researchers also noted an uptick in small earthquakes in the area in the years prior to the eruption, culminating in a spike in tectonic activity 2 hours before the event.
"The hydrophones picked up the signal of literally thousands of small earthquakes within a few minutes, which we traced to magma rising from within the volcano and breaking through the crust," Bob Dziak, study coauthor and Oregon State University marine geologist, told MSNBC. "As the magma ascends, it forces its way through cracks and creates a burst of earthquake activity that intensifies as it gets closer to the surface."
Dziak said that by studying earthquakes in the areas surrounding underwater volcanoes, scientists can get a better feel for when they will blow.
"Using seismic analysis, we were able to clearly see how the magma ascends within the volcano about two hours before the eruption," he told MSNBC. "Whether the seismic energy signal preceding the eruption is unique to Axial or may be replicated at other volcanoes isn't yet clear, but it gives scientists an excellent base from which to begin."
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