Thursday, August 11, 2011

Surprise! U.S. Under Water Volcano Erupts. The Seafloor Has Changed.

Surprise! Underwater volcano has erupted

Scientists going back to pick up monitoring equipment find a changed seafloor

By Andrea Mustain
updated 8/9/2011 5:36:28 PM ET

An undersea volcano has erupted off the coast of Oregon, spewing forth a layer of lava more than 12 feet thick in some places, and opening up deep vents that belch forth a cloudy stew of hot water and microbes from deep inside the Earth.

Scientists uncovered evidence of the early April eruption on a routine expedition in late July to the Axial Seamount, an underwater volcano that stands 250 miles off the coast of Oregon.

The discovery came as a surprise, as researchers attempted to recover instruments they'd left behind to monitor the peak a year earlier. When the researchers hefted a seafaring robotic vehicle overboard to fetch the instruments, the feed from the onboard camera sent back images of an alien seafloor landscape.

"At first we were really confused, and thought we were in the wrong place," said Bill Chadwick, a geologist with Oregon State University. "Finally we figured out we were in the right place but the whole seafloor had changed, and that's why we couldn't recognize anything. All of a sudden it hit us that, wow, there had been an eruption. So it was very exciting."

In addition to producing hardened lakes of blobby lava, in places more than a mile across, the eruption changed the architecture of the region's seafloor hot springs.

"There are more vents, they're higher temperature, and there are microbes living in them that are usually deep in the crust that come up to the surface in these events," Chadwick told OurAmazingPlanet.

Eruption predicted
The Axial Volcano rises 3,000 feet above the seafloor, the most active of a string of volcanoes along the Juan de Fuca Ridge, a plate boundary where the seafloor is slowly pulling apart.

Chadwick and colleagues have been keeping tabs on the peak since it last erupted in 1998. Thanks to a monitoring system they developed to measure the mountain's minute movements, the team predicted the volcano was due for another eruption sometime between 2011 and 2014.

"So for me, it's a very exciting thing that this worked!" Chadwick said.

The instruments kept track of the movement of the seafloor, which very gradually inflates and deflates like a giant, magma-filled balloon, Chadwick said, collapsing suddenly after an eruption, and rising, in this case, by about 6 inches a year in the lead-up to an eruption.

First long-term picture
Scientists have long known about the existence of subsea volcanoes, but information on their behavior is relatively sparse. Eruptions were first observed in the 1990s, and, although technology has improved, getting to the underwater peaks to study them is difficult.

Data from the Axial Seamount's recent eruption will provide the first long-term picture of a subsea volcano from one eruption to the next.

Chadwick said scientists are still trying to figure out how seafloor volcanoes differ from their terrestrial counterparts.

It could be it's easier to predict ocean eruptions, Chadwick said. It's possible that because the crust is thinner there, and magma is in ready supply, the mountains' slow inflations provide a good analogue for knowing when eruptions will occur. However, he cautioned that a single successful prediction wasn’t enough to forecast what the future holds.

"At Axial, we've only seen this once, so we don't know for sure it's going to be reliable," Chadwick said. "So we'll certainly keep making these measurements, and hopefully be around to see what happens next."

OSU geologist part of team that predicted underwater volcano eruption

Font Size:
Default font size
Larger font size
The manipulator arm of the remotely operated robotic vehicle named Jason prepares to sample the new lava flow that erupted in April 2011 at Axial Seamount, located off the northern Oregon coast. (photo courtesy of Bill Chadwick, Oregon State University; copyright Woods Hole Oceanographic Institution)
OSU geologist has helped monitor area for 13 years
An undersea volcano off the Oregon coast that has been monitored for nearly 13 years recently erupted, making it the first submarine volcano whose eruption had been forecasted.
A team of scientists, including an Oregon State University geologist, made the initial forecast and then found their forecast had come true during an expedition to the volcano late last month.
Bill Chadwick, an Oregon State University geologist at Hatfield Marine Science Center, and Columbia University’s Scott Nooner have studied the Axial Seamount volcano — located about 250 miles off the northern Oregon coast — since its most recent eruption in 1998. They used precise bottom-pressure sensors to study how belowground magma affected the ocean floor’s depth, because both the ocean floor and dry land “inflates” when it prepares to erupt and “deflates” after an eruption in the case of many volcanoes.
They found the caldera at the ocean floor had subsided 3.2 meters, or 10.5 feet when magma exited during eruption in 1998.
Comparing measurements of the ocean floor surrounding Axial Seamount with measurements taken after the 1998 eruption, Chadwick and Nooner forecast that the volcano again would erupt before 2014. Their prediction was published in a 2006 Journal of Volcanology and Geothermal Research article.
When Chadwick, Nooner and research colleagues traveled to the area above Axial Seamount in late July, they discovered new lava flows and other indications of eruption and removed the sensors and other instruments to discover that their forecast was in fact true: the volcano had erupted in early April.
Initial research indicates that lava flows are about 1.2 miles wide. The eruption also impacts the chemistry of this portion of the seafloor, creating new hot springs that attract different organisms to the area.
“Already, animals are colonizing the new lava flow,” Chadwick said.
Geologists have been able to forecast some on-land volcanic eruptions with similar sensor-style monitoring, but since the tools that work on land don’t always work deep underwater, no other researchers have monitored and successfully forecasted an undersea volcano’s eruption.
“It’s remarkable to me since we went out on a limb to see if that sort of forecasting would be possible on the seafloor,” Chadwick said, adding that his doctoral dissertation research was on the ground movements relating to the 1980 Mount St. Helens eruption.
The July expedition was sponsored by the Woods Hole Oceanographic Institution.

1 comment:

muebles en rivas said...

This can't have effect in actual fact, that's exactly what I think.