Tuesday, 10 January 2017

Sam Carana on the 5.8 quake in the Canadian Arctic

Sam Carana reports on yesterday’s earthquake in the Arctic. Since then there has been another.


Canadian Arctic Archipelago Hit By M5.8 Earthquake


An earthquake with a magnitude of 5.8 on the Richter scale hit the Canadian Arctic Archipelago on January 8, 2017.


Above image was created with USGS (United States Geological Survey) 
content. The image shows the epicenter of the quake (gold star). The earthquake hit Barrow Strait on January 8, 2017 at 23:47:12 (UTC), at 74.320°N 92.305°W and at a depth of 18.9 km.

This earthquake is important, given its magnitute and given that it hit an area without large faultlines (though earthquakes are not uncommon here, also see 
this discussion). Importantly, this earthquake occurred in an area prone to glacial isostatic adjustment, as illustrated by the image below.

From "http://grace.jpl.nasa.gov", (unfiltered version). Credit: A, G., J. Wahr, and S. Zhong (2013) "Computationsof the viscoelastic response of a 3-D compressible Earth to surface loading: an application to Glacial Isostatic
Adjustment in Antarctica and Canada", Geophys. J. Int., 192, 557–572, doi: 10.1093/gji/ggs030

Glacial isostatic adjustment as a phenomenon typically takes place over relatively long periods. Yet, extreme weather events can trigger earthquakes in areas that are already on the edge.

The extreme weather situation is depicted by the combination image below.

Similar to the 
M4.6 earthquake that hit Baffin Island on February 12, 2015, this earthquake occurred at a time when surface temperature anomalies over parts of North America and Greenland were at the bottom end of the scale. At the same time, temperature anomalies over the Arctic Ocean are at the top end of the scale, as illustrated by the left panel in above image. The right panel in above image shows pressure differences reaching the top and bottom ends of the scale.

Earthquakes in the Arctic Ocean are dangerous as they can destabilize methane hydrates. Huge amounts of methane are present in sediments under the Arctic Ocean in the form of free gas and hydrates. Earthquakes can send out strong tremors through the sediment and shockwaves through the water, which can trigger further earthquakes, landslides and destabilization of methane hydrates. The situation is especially dangerous when combined with extreme weather events that can cause cracks and movement in sediments.

As temperatures in the Arctic keep rising, the jet streams and polar vortex are changing their shape, in particular becoming more wavy, which can cause more extreme weather events such as the events described above.

The situation is dire and calls for comprehensive and effective action, as described at the 
Climate Plan.

Links

- Climate Plan
http://arctic-news.blogspot.com/p/climateplan.html

- Something had to give - Baffin Island hit by M4.6 earthquake

- High Methane Levels Follow Earthquake in Arctic Ocean




No comments:

Post a Comment