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Re: Land rebound
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Posted by heartland chris on February 11, 2007 at 08:26:51:
Jane....yes, I'm sure this is being studied, but not sure by who, and don't have names of references handy. But, your question is too vague. There is a lot of interest in sea level rise, but in any one place a tide guage does not give global sea level rise because the land there may be going up or down. So, the effects of where ice caps were 20 to 10 thousand years ago is studied: Hudson's Bay and Sweden are still going up fast, but areas around the edges of where the ice sheets were are compensating for this uplift by subsiding: for example, Rhode Island may be going down at 1 1/2 mm/yr (old figure from about 1980 when I was a student there). You may or may not be talking about current melting of Greenland: it is, I think, small icequakes in the last few years that greatly increased that show the outlet glaciers in southern Greenland are now flowing about twice as fast in the last decade as before. Much of eastern US is under horizontal compression (maximum principle stress axis is horizontal, minimum is vertical) which favors thrust faulting. If you had a couple of km of ice melt, it would decrease the vertical stress and make thrust faults weaker. So, as the ice was melting 15,000 to 10,000 years ago there may have been a surge of earthquakes. But, I don't know if this has been documented by paleo-seismology. Whether that effect is still triggering quakes or not, I don't know, but there still are vertical motions so that must be perturbing stress fields. Chris
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