Underwater volcano offered warnings ahead of eruption

Charles Q. Cho -

An underwater volcano gave off clear signals well before its outburst last year that it would erupt, findings that could help forecast such eruptions in the future, researchers say.

Submarine eruptions account for about three-quarters of all of Earth's volcanism.

However, the overlying ocean and the sheer vastness of the seafloor make detecting and monitoring them difficult.

Now robot submersibles and a host of other scientific instruments are helping scientists learn more about these mysterious volcanoes.

Their findings could lead to short-term forecasting of undersea eruptions in the future.

Researchers concentrated on Axial Seamount, an undersea volcano about 250 miles (400 kilometers) off the Oregon coast.

The volcano, located under more than 4,900 feet (1,500 meters) of water, erupted April 6, 2011.

"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," said researcher Bill Chadwick, a geologist at Oregon State University in Newport.

The researchers used pressure sensors on the seafloor to monitor its vertical motions.

"Uplift of the seafloor has been gradual and steady beginning in about 2000, two years after it last erupted," Chadwick said.

"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."

Full story...

Posted via http://maritime-news.posterous.com Maritime-News posterous