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Andrew Alden

Pakistan Quake Pushes Up New Land

By September 25, 2013

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mud volcanoThe magnitude-7.7 earthquake of 24 September in Pakistan's remote western province Baluchistan destroyed many structures and caused deaths in the epicentral area. With information coming in slowly, the U.S. Geological Survey's PAGER model suggested that several thousand deaths are likely.

One unusual effect of the earthquake was to trigger what I can only call eruptions of land: small islands, bubbling with methane gas, burst out of the Arabian Sea near the towns of Gwadar and Ormara. These show the basic features of large mud volcanoes. The next day, satellite images showed the new island as a round dot of land off an otherwise featureless coast.

The seacoast east of the Persian Gulf is being squeezed and folded as the Arabia plate pushes into southern Asia. This compresses the hydrocarbons in the seafloor sediment and makes them liable to erupt on occasion, either spontaneously or when earthquake shaking disturbs them. If the distant, low-frequency shaking of this earthquake was enough to do this, we might expect more widespread disturbances along the Arabian Sea coast. It's plausible that slump landslides triggered by the distant shaking have pushed up the seafloor in some of these places. That would certainly produce mud volcanism in the uplifted land, but the volcanism would be secondary to the true cause.

Temporary islands have been documented along this coast in the past, most recently in 2011. They tend to erode away within months, so there may not be time enough for a proper geological expedition to study the newest ones. Such a study would involve detailed mapping of the surrounding seafloor, collecting lots of samples, installing seismeter networks, and making repeated surveys. What strikes me about the story is that these events are understood in such different ways by people, over the full range from divine acts to familiar natural phenomena.
Mud volcano — courtesy Pakistan National Institute of Oceanography


September 30, 2013 at 5:42 am
(1) sohrab says:

If hydrocarbons erupts, then it will desturb deep oceanic enviornment.

September 30, 2013 at 4:00 pm
(2) Jeff says:

This is one of the coolest things I’ve heard of in a long time! Why hasn’t there been any media coverage of it? Thank you Andrew Alden.

September 30, 2013 at 4:32 pm
(3) Geology Guide says:

Jeff, there’s lots of coverage if you do a bit of searching. LiveScience, Discovery News, Earth Magazine and other sources cover this kind of thing all the time, and I recommend that you add them to your media stream.

October 1, 2013 at 4:17 am
(4) subhashree says:

why do such islands disappear soon?

October 1, 2013 at 1:28 pm
(5) Geology Guide says:

Subhashree, they are weak structures consisting only of mud, no more substantial than the sand castles that children make on the beach.

October 2, 2013 at 10:27 am
(6) Michael says:

So…….. I guess, Ghod’s not done building his ‘perfect’ world, Eh? ;-O

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