July 29, 2013
Methane Release From Earthquakes Feeds Global Warming
Michael Harper for redOrbit.com - Your Universe Online
In 1945 an 8.1 magnitude earthquake hit the northern Arabian Sea which released 7.4 million cubic meters of methane into the ocean and atmosphere.Now a team of scientists from the MARUM Institute at the University of Bremen, the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, and the ETH Zurich have concluded a study on this earthquake and believe similar temblors are also adding to the release of greenhouse gases. These heat-trapping gases (along with other factors) are said to play a significant role in the climate change affecting ecosystems all over the world.
According to the researchers, while there is more carbon dioxide affecting climate conditions, methane is a more potent and harmful gas. First author Dr. David Fischer from MARUM and his team published their findings in the online journal Nature Geoscience.
When earthquakes occur, large shifts in the ocean floor create tears and openings by which methane is released. Supporting this hypothesis required some digging and an instance of an earthquake that occurred many years ago.
"We started going through the literature and found that a major earthquake had occurred close by, in 1945," explained Fischer in a statement to the AFP.
The 8.1 magnitude earthquake of 1945 is the largest ever recorded in the northern Arabian Sea.
"Based on several indicators, we postulated that the earthquake led to a fracturing of the sediments, releasing the gas that had been trapped below the hydrates into the ocean," noted Fischer.
The gas in question was released from a shallow gas reservoir called "Nascent Ridge." Following this powerful earthquake, Nascent Ridge was opened up and therefore began spewing methane into the ocean. According to their research, the equivalent of 10 gas tanker's worth of methane was spewed into the ocean over several decades.
To better understand this reaction and prove their hypothesis, the team shipped out to the Arabian Sea in 2007 to dig for sediment core samples, which were later analyzed in the lab.
"First, we examined the pore water, which is the water between sediment grains in the core," said Fischer, explaining the team's research on the MARUM website.
One of the cores obtained from the 2007 dig contained methane hydrates -- solid icy structures which contain both methane and water.
"At two separate coring sites, one with hydrates the other without, we found unusual pore water sulfate profiles indicating a substantial increase in upward methane flux in the recent past," he said.
This led the scientists to believe the 1945 earthquake was responsible for leaking so much dangerous gas into the ocean and subsequently the atmosphere.
Though methane traps heat in the earth's atmosphere and is therefore blamed as a partial cause for global warming, another geological occurrence has been found to slow down the pace of global warming by actually cooling the atmosphere.
Earlier this year researchers from the University of Colorado Boulder and the National Oceanic and Atmospheric Administration (NOAA) claimed global warming slowed between 2000 and 2010 thanks to the gasses spewed by volcanoes.