Showing posts with label fault. Show all posts
Showing posts with label fault. Show all posts

Saturday, November 9, 2013

Norwegian Sea hit by 4.6M Earthquake

In the early morning of November 9, 2013, the Norwegian Sea was hit by an earthquake with a magnitude of 4.6 on the Richter Scale. Earlier (on October 28, 2013), an earthquake with a 5.3 magnitude hit the Greenland Sea closer to Svalbard.

These earthquakes come at a time when huge amounts of methane are rising from the seabed of the Arctic Ocean, from areas on or close to the fault line that crosses the Arctic Ocean. The location of the earthquake that hit the Norwegian Sea is indicated on the map below with a white circle.

[ click on image to enlarge ]

Related

- Greenland Sea hit by M5.3 Earthquake
http://arctic-news.blogspot.com/2013/10/greenland-sea-hit-by-m53-earthquake.html

- Methane, Faults and Sea Ice
http://arctic-news.blogspot.com/2013/11/methane-faults-and-sea-ice.html

- Earthquake hits waters off Japan
http://arctic-news.blogspot.com/2013/10/earthquake-hits-waters-off-japan.html

- Earthquake hits Laptev Sea
http://arctic-news.blogspot.com/2013/09/earthquake-hits-laptev-sea.html

- Methane Release caused by Earthquakes
http://arctic-news.blogspot.com/2013/09/methane-release-caused-by-earthquakes.html

- Earthquake M6.7 hits Sea of Okhotsk
http://methane-hydrates.blogspot.com/2013/10/earthquake-m67-hits-sea-of-okhotsk.html

- Sea of Okhotsk
http://methane-hydrates.blogspot.com/2013/06/sea-of-okhotsk.html



Monday, September 30, 2013

Earthquake hits Laptev Sea

An earthquake with a magnitude of 4.6 on the Richter scale hit the Laptev Sea on September 28, 2013.

[ click on image to enlarge ]
This follows a number of earthquakes on or close to the fault line that crosses the Arctic Ocean and extends into Siberia, as shown on above map and on the map below.

[ click to enlarge ]
Furthermore, as earlier discussed in the post Methane release caused by earthquakes, there has been a lot of seismic activity in the Aleutian Islands region all the way up into Alaska, including an earthquake with a magnitude of 7 on the Richter scale on August 30, 2013, and several more recent earthquakes with a higher magnitude than 6 on the Richter scale.

This is a lot of seismic activity for the Arctic, given that this is a relatively quiet part of the globe in terms of earthquakes.

[ click on image to enlarge ]
As above map shows, there were 1250 earthquakes with a magnitude of 2.5 or higher over the past 30 days globally. About 90% of the world's earthquakes occur along the Ring of Fire, on the edges of the Pacific Ocean.

The fault line that crosses the Arctic Ocean marks the boundery between the North American Plate and the Eurasian Plate. Along this fault, huge amounts of methane are held in sediments, in the form of free gas and hydrates. The danger is that earthquakes along this fault will destabilize methane, causing it to rise abruptly in large amounts and enter the atmosphere.

As the top image shows, a lot of methane is currently present in the atmosphere along this fault line. Methane has shown up there repeatedly, indicating that methane there has been prone to release for some time and warning that even larger releases could occur soon.

Related posts

- Methane release caused by earthquakes (2013)
http://arctic-news.blogspot.com/2013/09/methane-release-caused-by-earthquakes.html

- North Hole (2013)

- Sea of Okhotsk (2013)
Methane-hydrates.blogspot.com/2013/06/sea-of-okhotsk.html

- Seismic activity, by Malcolm Light and Sam Carana (2011)
Arctic-news.blogspot.com/p/seismic-activity.html

- Thermal expansion of the Earth's crust necessitates geoengineering (2011)
Arctic-news.blogspot.com/p/thermal-expansion.html


Sunday, September 15, 2013

Methane Release caused by Earthquakes


Methane hydrates can become destabilized due to changes in temperature or pressure, as a result of earthquakes and shockwaves accompanying them, severe storms, volcanic activity, coastal collapse and landslides. As an example, an earthquake followed by methane release was discussed in the post Sea of Okhotsk a few months back. Such events can be both primed and triggered by global warming, particularly in the Arctic, as follows:
  • As more ice melts away on Greenland and more water runs off into the sea, there is less weight on the Earth’s crust under Greenland. The crust and mantle can bounce back during a large melt, an effect that is called 'isostatic rebound'. This rebound can not only trigger earthquakes and landslides, it can also suck up the magma in the Earth’s crust to the surface and trigger volcanic eruptions.
  • The added weight of water from melting glaciers stresses the Earth’s crust underneath the sea, which can cause earthquakes. This is especially the case for coastal waters, where the impact of the water that flows into the sea is huge, not only in terms of weight, but also in terms of the currents they cause. 
  • As the permafrost melts, mountain ranges, soil and submarine sediments all become less robust. Where the permafrost previously held things together, we can now expect more coastal collapse, avalanches and landslides, which can send shockwaves through the sea that in turn trigger earthquakes and hydrate destabilization.
  • Methane hydrates that are on the edge of stabilization can be disturbed by global warming in two additional ways, temperature and pressure: Warming of the Earth's crust as heat penetrates sediments on the seafloor. Thermal expansion of the Earth's crust means that the crust will expand slightly in volume, resulting in expansion of the cavity that holds the hydrates. 
  • Finally, there's the additional impact of methane itself. Permafrost previously kept methane stable in sediments. Methane converting from hydrates into free gas will expand some 160 times in volume; this explosive process can trigger further destabilization. Once released into the atmosphere, the methane has a huge local warming potential, adding to the threat that further methane releases will occur locally.   


Back in 2006, Bill McGuire said: "A particular worry is that this in turn will contribute to large-scale releases of methane gas from the solid gas hydrate deposits that are trapped in marine sediments. Gas hydrates have been identified around the margins of all the ocean basins, and outbursts of gas may occur as sea temperatures climb or as rising sea levels trigger underwater quakes in the vicinity."

For more than a decade, Malcolm Light, contributor to the Arctic-news blog, has been warning about the danger of methane hydrate destabilization due to earthquakes (see the poster at the bottom of the page on seismic activity).

With this in mind, let's take a look at the most recent picture of Earth.

September 13, 2013, 3am - Sep 14, 2013 1am    [ click on image to enlarge ]

The large number of yellow spots in the top left corner are related to the flooding in the Basin of the Amur River (Heilong Jiang). Such extreme weather events are becoming ever more prominent, due to global warming and the feedbacks such as methane releases. Similarly, extreme weather events such as droughts and heatwaves lead to wildfires that also produce large amounts of methane.

The image only shows the Northern Hemisphere, but on the Southern Hemisphere, high levels of methane have been recorded for a long time on Antarctica. While huge amounts of snow fall on Antartica, the amount of snow and ice that melts each year is even larger, widening the difference between the weight the snow and ice exercize between periods. This difference in weight could similarly cause rebounds of the Earth's crust, sucking up the magma and causing methane hydrates to be destabilized, as described in the earlier post Antarctic methane peaks at 2249 ppb.

The image also shows fault lines. Several yellow spots are present on the fault line over the Arctic, including some that point at the coast of Norway; they appear to be caused by seismic activity along the fault line, as discussed in the recent post Methane reaches 2571 ppb.

Meanwhile, methane readings peaked at 2416 ppb on September 14, 2013. Very worrying are also the high methane readings close to the Gakkel Ridge, the fault line at the center of the Arctic Ocean, and the spots closer to the Laptev Sea.

Finally, there are high readings along the Aleutian Islands, Alaska. The islands, with their 57 volcanoes, are in the northern part of the Pacific Ring of Fire and they have experienced a lot of seismic activity lately, including an earthquake with a magnitude of 7 on the Richter scale on August 30, 2013, and several more recent earthquakes with a higher magnitude than 6 on the Richter scale.

[Editor: The images below, added September 24 and 26, 2013, show high methane releases at a spot just north of Greenland that was hit by an earthquake with a magnitude of 4.5 on the Richter scale on September 1, 2013, as also discussed in the post Methane reaches 2571 ppb. The two bottom images also show the magnitude 5 earthquake that hit Russia on September 24, 2013.]

September 20, 2013, 11am - Sep 22, 2013 3pm    [ click on image to enlarge ]

Sept. 25, 2013 am - the orange spot just north of Greenland indicates a recent earthquake [ click on image to enlarge ]

Map specifying details of two recent earthquakes. Size of spots indicating earthquakes on the map is relative. [ click image to enlarge ]

References and related posts

- Climate Change: Tearing the Earth Apart, by Bill McGuire (2006)

- Seismic activity, by Malcolm Light and Sam Carana (2011)
Arctic-news.blogspot.com/p/seismic-activity.html

- Thermal expansion of the Earth's crust necessitates geoengineering (2011)
Arctic-news.blogspot.com/p/thermal-expansion.html

- Runaway Warming (2011)
Arctic-news.blogspot.com/p/runaway-warming.html

- Methane reaches 2571 ppb (2013)

- Sea of Okhotsk (2013)

- Is Global Warming breaking up the Integrity of the Permafrost? (2013)

- Antarctic methane peaks at 2249 ppb (2013)