Scientists studying massive earthquakes finally found evidence to confirm a link between earthquakes and bursts of underwater methane – a potent greenhouse gas. While studying the site of a huge 8.1 magnitude earthquake that struck Pakistan in 1945, the researchers found mud rich with methane and shore sand. With help from the evidence found in the Arabian Sea, researchers were able to connect unexpectedly large releases of methane gas to the 1945 quake.
Methane seeps have been found in the ocean in various places, but their sources haven’t been clear. These gasses and other minerals such as barite and sulfate were found just below the seafloor surface near the Makran subduction zone, an area where two tectonic plates collide.
David Fischer, who took part in the study, suggests that the volume coming from this particular methane burst is worth considering in the overall greenhouse gas total worldwide. Ken Caldeira, climate scientist at Stanford University’s Carnegie Institution for Science, suggests that, while this is a significant amount of methane, when put into perspective against the current natural global methane flux it doesn’t amount to enough to have a likely impact on the climate.
Carolyn Ruppel, chief of the U.S. Geological Survey’s Gas Hydrates Project in Woods Hole, Massachusetts points out that the gasses are likely to simply dissolve into the water or be oxidized by microbes in the water, since they are released so deep in the ocean. She says that although we can see the connection between this earthquake and a methane burst, we still don’t know if only a quake of this magnitude that would cause a methane burst.
Even if a significant amount of this methane does not reache the surface, it is still an important discovery for understanding the source of this methane in the ocean, and subsequently understanding what impact it may have on the overall carbon levels of the ocean, since methane is converted to carbon dioxide in the ocean and in the atmosphere. This gives us another piece of the puzzle of understanding the ecology of our oceans.