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An submersed volcano gave off decipherable signals well before its outburst last year that it would erupt , findings that could help presage such eruptions in the future , researchers say .
Submarine eruptionsaccount for about three - quarters of all of Earth ’s volcanism . However , the superimposed sea and the bold vastness of the seafloor make detecting and monitoring them difficult .
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.
Now robot submersibles and a boniface of other scientific instruments are helping scientists learn more about these mysterious volcanoes . Their findings could lead to forgetful - term prediction of undersea eruption in the future .
blast clue
investigator concentrated on Axial Seamount , anundersea volcanoabout 250 miles ( 400 kilometers ) off the Oregon seacoast . The vent , located under more than 4,900 feet ( 1,500 measure ) of water , erupted April 6 , 2011 .
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.
" Axial Seamount is unequaled in that it is one of the few places in the world where a farseeing - terminus monitoring record subsist at an submarine vent , and we can now make sentiency of its rule , " said researcher Bill Chadwick , a geologist at Oregon State University in Newport .
The researchers used press detector on the seafloor to supervise its vertical motions . " Uplift of the seafloor has been gradual and unfluctuating beginning in about 2000 , two class after it last erupted , " Chadwick say . " But the rate of inflation from magma went from gradual to speedy about four to five months before the eruption . It expanded at roughly triple the rate , ease up a hint that the next eruption was coming . "
Less than an minute before the volcanic eruption , the seafloor see an abrupt uplift of 2.75 inches ( 7 centimetre ) . After the eruption , the seabed deflated by more than 6 feet ( 2 meters ) as the magma flowed into the pelagic crust and break out as lava .
A “snowblower” hydrothermal vent spews hot water and white bits of bacterial mat that are blooming in the chemical-rich hot-spring water, showing that the lava flow that was erupted in 2011 at Axial Seamount is still cooling.
" This variety of trend has been discover in volcanic areas on land before , but not this effectively in the ocean , " say marine geologist Neil Mitchell at the University of Manchester in England , who did not take part in this research .
seismal signals
Seismic data fromunderwater microphonesalso gave clues to the volcano ’s behaviour , showing a gradual buildup in the turn of small earthquakes ( roughly magnitude 2 ) in the four years prior to the 2011 eruption . Then researchers detected an abrupt spike in seismic vigour about 2.6 hours before the eruption .
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.
" The hydrophones picked up the signal of literally G of small temblor within a few minutes , which we trace to magma rising from within the volcano and breaking through the cheekiness , " say researcher Bob Dziak , an Oregon State University shipboard soldier geologist . " As the magma ascends , it forces its way through crack and creates a burst of seism activity that intensifies as it get close to the surface . "
" Using seismal depth psychology , we were able to clearly see how the magma ascends within the volcano about two hour before the eruption , " Dziak added . " Whether the seismal energy signal preceding the eruption is alone to Axial or may be double at other volcanoes is n’t yet clean , but it gives scientists an excellent base from which to begin . "
Mitchell told OurAmazingPlanet , " If we can tell these volcanic drove asunder from normal architectonic temblor , we have one way of monitor volcanism in the ocean . "
Robot submarines
The investigators also used a robot submarine toscan the seafloorwith intelligent waves , map out the topography of the volcano from about 165 feet ( 50 m ) above the bill before and after the 2011 eruption . These surveys enabled geologists to clearly distinguish the 2011 lava flows from the many previous flows in the area and locate the scissure from which these flow emerge , say research worker David Caress , an engineer at Monterey Bay Aquarium Research Institute in Moss Landing , Calif. The detailed image show lava flows as thin as 8 in ( 20 cm ) and as thick as 450 foot ( 137 m ) .
The scientists also saw biologic natural action at newly formedhydrothermal vent .
" We picture snowblower volcano that were spit out nutrients so fast that the microbes were going crazy , " Chadwick enjoin . " Combining these biologic observance with our knowledge of the ground deformation , seismicity and lava distribution from the 2011 eruption will further help us connect underwater volcanic activeness with the life it supports . "
The researchers sound out Axial Seamount could push through again , perhaps as soon as 2018 , based on the cyclical pattern of ground deformation they see .
" 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 rising prices , " Dziak said .
The scientists detailed their findings online June 10 in three theme in the journal Nature Geoscience .
This story was provided byOurAmazingPlanet , a sister website to LiveScience .
