Sunday, June 17, 2012

Signs From the Underwater Volcano Eruptions

Underwater volcanoes still save a lot of mystery. Therefore, the location and the wide spread it difficult for researchers to study it. Though the intensity of the underwater volcanic eruption reached 75 percent of all volcanic eruptions on Earth.

In Indonesia, of the 129 volcanoes, there are five which are underwater volcano, including Mount Sub Marine, which erupted in 1922, and Mount Banuawalu, erupted in 1919. Both are located in North Sulawesi waters.

In addition, in the waters of Banda there Mount Niuwewerker (erupted in 1927) and Mount Emperor of China. the others underwater volcano are Hobal (erupted 1999) in East Nusa Tenggara waters.

Now, the experts find the information that an underwater volcano gave a very clear signal before it erupted. The research was carried out geological team from Oregon State University in Newport, United States, and published in the journal Nature Geoscience issue of June 10, 2012.

The team is using underwater robots to install the instrument at Axial Seamount, an underwater volcano located about 400 kilometers off the coast of Oregon. The volcano is located at depths greater than 1,500 meters and has erupted on 6 April 2011.

"Axial Seamount is unique because it is one of the few places in the world with a record of long-term monitoring of underwater volcanoes. We can now understand the pattern," said Bill Chadwick, a geologist at Oregon State University, Newport, United States.
A 'snowblower' hydrothermal vent spews hot water and white bits of bacterial matter showing that the lava flow that was erupted in 2011 at Axial Seamount is still cooling. (Picture from:
The researchers used a pressure sensor on the seabed to monitor the vertical movement of the volcano. "The appointment of the ground floor of the sea has begun gradually and began to stabilize about two years after the last eruption," said Chadwick.

However, the inflation rate has gradually changed into magma rapidly around 4-5 months before the eruption. A three-fold increase, thus giving hints that the next eruption will come.

Less than one hour before the eruption, the sea floor suddenly rose as high as 7 inches. After the eruption ended, the sea floor dropped by more than 2 meters due to the flow of magma into the ocean and the lava erupted.

"Such a movement has also been detected previously in the area around the volcano on land. But not as effective as existing in the ocean," said marine geologist, Neil Mitchell, from the University of Manchester in U.K, who did not take part in this study.

A chain still attached to an ocean-bottom
hydrophone (OBH) comes directly out of
the seafloor at Axial Seamount where a
lava flow erupted in 2011 has buried the 
instrument to a depth of about 1.5 meters
(5 feet). The front of the Jason remotely
operated vehicle is in the lower right and its 
manipulator arms are visible in the upper
left and right. (Picture from:
Seismic data from an underwater microphone (hydrophone) also provide clues about the behavior of volcanoes. These data suggest a gradual buildup of a small number of earthquakes (average of 2 on the Richter scale) in the four years before the eruption in 2011.

The researchers then detected a sudden jump in seismic energy of about 2.6 hours before the eruption occurred. Hydrophone picks up signals from thousands of small earthquakes for a few minutes. "When we browse, these earthquakes caused by magma rising from the volcano that broke into the Earth's crust," said Bob Dziak, a marine geologist at Oregon State University.

Magma rises to the surface through cracks and creates an explosion seismic activity greater strength. Seismic analysis can be used to see the rising of magma from the volcano about two hours before the eruption.

Whether the seismic energy signal before the eruption is only unique to Axial or may be replicated to other volcanoes, remains unclear. "But these findings are the basis to start another similar study," said Dziak.

According to Mitchell, if this volcanic phenomenon separate from ordinary tectonic earthquake, "We have a way to monitor volcanic activity in the ocean," he told OurAmazingPlanet. *** [LIVESCIENCE | MAHARDIKA SATRIA HADI | KORAN TEMPO 3909]

Assisted Robot Submarine
The manipulator arm of the Jason
remotely operated vehicle (upper left)
prepares to sample the new lava flow
that was erupted in 2011 on the
seafloor at Axial Seamount.
(Picture from:
The researchers in marine geology from Oregon State University, United States, have to use a robot submarine to investigate Axial Seamount.

David Caress, researcher and engineer from the Monterey Bay Aquarium Research Institute in Moss Landing, California, said the collection of data in a submarine robot allows them to distinguish between the eruption of lava flows in 2011 and the eruption in previous years.

The survey also enabled the researchers to map the gap which is the location of the release of lava. "The detailed description is taken from a submarine robot was able to show lava flows as thick as thin as 20 centimeters to 137 meters," Caress said.

Submersible robot is also able to see the biological activity of the newly formed hydrothermal vent after the eruption. Bill Chadwick, other researchers, see the holes that spew nutrients so quickly.

To find out the terms of volcanic activity under the sea life it supports, the researchers combined biological observations with knowledge about the distribution of ground deformation, seismicity, and the distribution of lava from the eruption of 2011.

The researchers say the Axial Seamount is likely meietus again. Based on soil deformatinn patterns are repeated, they predict an eruption will occur soon after 2018. *** [LIVESCIENCE | MAHARDIKA SATRIA HADI | KORAN TEMPO 3909]
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