Undersea volcano gave off eruption signal

An undersea volcano located about 250 miles off the Oregon coast produced clear seismic signals hours before an eruption, researchers say.

Last year, researchers at Oregon State University correctly forecast the eruption of Axial Seamount in advance.

Documentation of inflation of the undersea volcano from gradual magma intrusion over a period of years led to the eruption forecast, but new analyses of data from underwater hydrophones also show an abrupt spike in seismic energy about 2.6 hours before the eruption started, an Oregon State said in a release Sunday.

The researchers say such a finding could lead to short-term forecasting of undersea volcanoes in the future.

The link between seismicity, seafloor deformation and the intrusion of magma can provide new insights into eruption patterns, they said.

"Axial Seamount is unique in that it is one of the few places in the world where a long-term monitoring record exists at an undersea volcano -- and we can now make sense of its patterns," researcher Bill Chadwick said.

"We've been studying the site for years and the uplift of the seafloor has been gradual and steady beginning in about 2000, two years after it last erupted.

"But the rate of inflation from magma went from gradual to rapid about 4-5 months before the [2011] eruption. It expanded at roughly triple the rate, giving a clue that the next eruption was coming."

Meanwhile, hydrophones on Axial monitoring sound waves for seismic activity recorded a burst of small earthquakes just hours before the eruption.

"Now that we know some of the long-term and short-term signals that precede eruptions at Axial, we can monitor the seamount for accelerated seismicity and inflation," researcher Bob Dziak said, noting the researchers hope next time to "catch the volcano in the act." (UPI)

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‘부글부글’ 해저화산 폭발의 비밀 밝혀져!

해저화산이 폭발하기 직전에 활발히 지진활동이 일어나는 것으로 밝혀짐에 따라 해저화산의 분화를 더욱 정확히 예측할 수 있을 것으로 보인다.

미국 오레건 주립대의 연구진은 작년 해저화산 엑시얼 시마운트의 분화를 정확히 예측할 당시의 자료를 분석한 결과, 분화 약 2.6 시간 전에 지진 에너지가 급격히 증가했다고 10일 (현지시간) 밝혔다.

수중 청음기 자료를 분석한 결과 오레건 주 해변에서 서쪽으로 약 400 킬로미터 정도 떨어진 곳에 위치한 이 화산이 분화하기 몇 시간 전부터 작은 지진들이 산발적으로 발생했다고 한다.

연구진은 지진활동과 해저변형, 마그마 유입량 등을 종합하여 분화의 일정한 패턴을 알아냄으로서, 미래에 해저화산 폭발을 예견할 수 있을 것으로 기대하고 있다.