Earthquake hits waters off Japan

An earthquake with a magnitude of 7.3 on the Richter scale hit the waters 231 miles (371 kilometers) east of Japan on October 25, 2013, reports rt.com, adding that the quake prompted an evacuation at the devastated Fukushima Daiichi plant and that strong tremors could be felt on Japan’s main Honshu Island, as well as on the northern island of Hokkaido.

USGS.gov reported the quake as having a magnitude of 7.1 followed up by several smaller quakes, as indicated on the image below, which also indicates the location of Fukushima.

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The image below shows that methane readings of 1950+ were recorded on and around the location where the earthquake hit. The image merely shows methane that did enter the atmosphere. More methane will have escaped from the seabed, but much of it will have oxidized in the water.

The occurence of this earthquake is very worrying, due to the situation at the Fukushima Daiichi nuclear plant. It is also relevant to the situation in the Laptev Sea, north of Siberia, for a number of reasons, including: 

1. As the above image clearly shows, earthquakes can trigger methane releases from the seabed, as previously discussed in the post Methane Release caused by Earthquakes.
2. Global warming is contributing to the occurance of earthquakes. For years, geophysical hazard specialist Bill McGuire has studied this impact of global warming, in particular the Earth's crust bouncing and bending in response to the melting of the great ice sheets and the filling of the ocean basins—dramatic geophysical events that triggered earthquakes, spawned tsunamis, and provoked a series of eruptions from the world's volcanoes. Bill McGuire warns that staggering volumes of melt water poured into the ocean basins, warping and bending the crust around their margins. The resulting tossing and turning provoked a huge resurgence in volcanic activity, seismic shocks, and monstrous landslides—the last both above the waves and below.
   
   According to calculations posted by Doyle Doss in January 2012, the increase in weight of the Pacific Ocean over the last 50 years due to freshly introduced water from land ice melt is 10 Trillion 331 Billion 125 Million 200 Thousand TONS. In conclusion, global warming is making methane releases triggered by seismic activity worse. 
3. The fault lines around Japan are interconnected with other fault lines, as illustrated by the image below, from the post High Methane Levels over Laptev Sea, showing methane readings on October 20, 2013 pm. Earthquakes can trigger further earthquakes, especially along the same or interconnected fault lines. 

The image below shows methane readings on October 25, 2013 pm, indicating that high methane readings continue to be recorded over the Laptev Sea.

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The above image also shows that the Laptev Sea was hit by an earthquake with a magnitude of 4.6 on the Richter scale on September 28, 2013. Earlier, on August 7 and on September 9, earthquakes with similar magnitudes had hit the Laptev Sea closer to land, as described in the post Earthquake hits Laptev Sea.

For more than a month, large amounts of methane have been present over the Arctic Ocean, in particular over the Gakkel Ridge and, more recently, also over the Laptev Rift.

Sediments under the Arctic Ocean contain huge amounts of methane in the form of hydrates and free gas. Some areas, such as the Gakkel Ridge and the Laptev Rift are prone to earthquakes, volcanoes and landslides, as they are part of a tectonic fault line that crosses the Arctic Ocean.

The danger is that, as the permafrost retreats and the snow and ice cover declines rapidly, methane in the Arctic is on the brink of being released abruptly and in large quantities from the seabed. A single earthquake, perhaps even outside of the Arctic Ocean could set this off. There are many more factors that influence seismic activity, such as the position of sun, moon and stars, and the depth at which seismic activity occurs, as tremors can be felt far away from earthquakes that occur at greater depth. Anyway, the danger is that earthquakes will trigger abrupt release of methane from the seabed of the Arctic Ocean, and since methane is a powerful greenhouse gas, such a release could further accelerate local warming, triggering further destabilization of methane in the seabed, escalating into abrupt climate change across the globe.

The depth of the seabed is also important in this regard, since shallow seas can warm up rapidly, while methane that escapes from the seabed has less chance to get oxidized in shallow seas. Large parts of the Arctic Ocean are very shallow, in particular the Laptev Sea, as further descibed in the post methane hydrates.