This is not an "all of a sudden" situation for Siberia so far as I know as it happens every spring and fall. The entire northwestern portion of Siberia is an out wash plain where all the rivers( 9-10-11?-- everyone!)--run north to the Arctic Ocean. So as it is, a few hundred miles southward the water, still liquid, keeps flowing to the north,only it keeps hitting ice dams that froze up in the days and weeks before. The water is diverted out of channel over to the next ice dam etc until it freezes in large ice sheets. This is not a Yazoo river drainage pattern but probably the closest cousin. The braided terrain there, I believe is the only region so patterned that the course of rivers flow seasonally:backwards for freeze and forward for thaw and over the banks in between . This is a weather/seasonal plus geology/ geographical cycle with nothing to do with climate--be it remembered that even the IPCC now admits they were wrong and that we've been in a 16 year cooling cycle, expected to go on for at least 4 more years, but I digress.
It goes on every year--just this year we have photos to share. It will exist so long as the region lies below the permafrost circle. There was actually a discussion to take the Eastern most two rivers and channel them southwards but something about the Sturgeon and caviar industry stopped that. The diversion of fresh water would create an are of higher salinity in the breeding grounds in the Arctic marshlands.
Building on this ground was one of those Moscow/USSR Central committee projects by people who didn't want to be confronted by facts. I stand in awe that the engineers tasked with building major cities on such terrain did as well as they did. They did not concentrate the buildings shoulder to shoulder but in wide spaced blocks and I assume that has an effect on terminal gradients and permafrost melting. Not perfect but a good idea.
Eman
From: Lin Kerns <linkerns@gmail.com>
To: Geology2 <geology2@yahoogroups.com>
Sent: Wednesday, April 10, 2013 4:37 PM
Subject: Re: [Geology2] Samara, the Russian city being 'eaten alive' by giant sinkholes
You're right, Peter, and this was the same thing that Vic stated when he sent me this article. I'm so glad that someone here initiated this conversation, as you'll notice that some of the bedding below those sinkholes is composed of sandy sediments instead of an organically based bedrock. The type of sinkholes generated from permafrost thaw will only continue to worsen, given the melting that is occurring due to global warming.
A couple of other points here is that an article like this does not go into any depth to explain if any mining has occurred beneath that layer of sediment or how high the water table is. So the public is led to believe that karst topography is the only reason that sinkholes happen, which is not true.
LinOn Wed, Apr 10, 2013 at 5:47 AM, Peter Land <peter@pland.org> wrote:
Surely this article is mixing up karst areas with thawing permafrost?
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