Methane as recorded by IASI* reached levels of up to 2571 parts per billion (ppb) on September 11, 2013.
The image below shows the peak levels that have been reached recently, as well as the highest mean methane level for each day.
Where did the methane come from?
IASI data do not identify locations, other than that all locations where methane is present in concentrations higher than 1950 ppb show up in yellow.
Yet, there are some ways to further examine where these high levels came from. To create the top image, only four layers were selected. The yellow spots on the image show locations where methane is present at the selected layers (695-766 mb) at concentrations of 1950 ppb and higher. At these relatively low altitudes, yellow spots will show up at fewer locations than at some of the higher altitudes, yet one can assume that the largest sources will be included among those showing up; and indeed, peak methane levels at these altitudes ranged from 2193 ppb to 2328 ppb, which are extremely high levels.
On the top image, there are several locations that look suspicious, including a large spot north of the New Siberian Islands, while the Kara Sea and the Barents Sea, and many locations around Greenland all feature suspicious yellow spots.
Most worrying are the numerous spots clustered off the coast of Norway, which show up quite prominently at many altitudes. The situation is reminiscent of the Storegga Slides, the underwater landslides that occurred at the edge of Norway's continental shelf thousands of years ago. The latest incident occurred some 8,000 years ago.
Seismic Activity
Earthquakes can cause tremors over long distances, especially along fault lines.
There has been some seismic activity close to Greenland that could have triggered one or more landslides off the cost of Norway, since the fault line points that way. An earthquake with a magnitude of 4.5 on the Richter scale occurred occured on September 1, 2013, 08:49:19 UTC, at a location 214km NE of Nord, Greenland, as illustrated by above image and the image below.
* IASI (Infrared Atmospheric Sounding Interferometer) is a hyperspectral infrared sounder residing on the European Space Agencys (ESA) MetOp series of polar orbiting satellites.
