A seismic survey has revealed a massive reservoir of methane and CO2 gas beneath the seabed off the coast of Japan, which could serve as a source of natural gas. However, a sudden opening caused by an earthquake could have devastating consequences, releasing the climate-damaging gas uncontrollably into the atmosphere. Scientists from Kyushu University used seismic imaging to discover a large gas reservoir filled with CO2 and methane in the Okinawa Trough, a tectonic rift zone between Japan and China. The reservoir is estimated to contain around 90 million tonnes of CO2 and methane, and if it is predominantly methane, it could be used as a source of natural gas. However, the risk of uncontrolled release of the gas into the atmosphere is a major concern.
The presence of methane and other gases in large quantities beneath the seabed has long been known to scientists. However, recent studies have shown that methane is released in large quantities to the surface and from there into the atmosphere, which is problematic given the impact of climate change. In addition to the seabed, large deposits of greenhouse gases are also present in the ice of the Antarctic and Arctic, which would be released if the ice melts. Theories suggest that bacteria living in the seabed produce methane.
The discovery of the gas reservoir in the Okinawa Trough is significant, as such gas reserves in rift zones are rare in geology. The scientists believe that similar gas reservoirs may exist in other back-arc basins worldwide. While the discovery of the gas reservoir could be a significant natural resource, the risk of uncontrolled release of the gas into the atmosphere is a major concern. The scientists warn that large gas reservoirs along rift zones could be another source of greenhouse gases that we need to keep an eye on.
