I have a Question:
It melts a lot of ice from glaciers.
Can you calculate the weight?
I found an estimation for the total volume of water frozen as ice on Earth excluding sea ice: about 12,7*10¹⁵m³ (equating to 12,7 million gigatons, calculated from
these findings).
The weight of all glaciers spread new to the earth's surface.
In some places pressure is released and in other places of the earth pressure is increased.
Can be generated by the displacement of the weight, a new movement of the continental plates?
1. Can produce an acceleration of earthquakes?
Yes, movement is caused by this. At the end of the last ice age Scandinavia was buried under several thousand meters of ice. The weight caused the Earth's crust to sink deeper into the mantle that behaves plastically on geological timescales. After the ice melted, the land started "popping up" like a swimming mattress on water when you get off it. Because of the huge masses involved, that "popping up" process takes a very long time, in fact Scandinavia is still rising today at a rate of about one centimeter per year. Like the two sides of a scale, the coast of northern Germany is sinking at the same time, but only at about one centimeter per decade. You can see nice pictures explaining the process at
http://de.wikipedia.org/wiki/Postglaziale_Landhebung (German, the pics are missing from the English page).
Earthquakes? I don't think so. This might be the case if fault lines / subduction zones would experience a pressure release due to melting ice, but as far as I know there are no such zones near any large ice caps. In theory, yes, of course - when large amounts of mass move, stress on the crust changes, and in unlucky cases that might destabilise fault lines, causing them to move (that would be the cause of an earthquake). But I'd say that's very unlikely. The masses of glaciers in geologically active mountain ranges are too small to really make a difference (the Earth has a high inertia), and those glaciers and ice caps that are large enough to cause movement (see above) are all in geologically inactive areas (Antarctica and Greenland, mostly).
Added to this is the total amount of coal and oil in the last 200 years. This total weight is partially in air and partially in the sea. Also causes a certain pressure redistribution on the tectonic plates.
2. Is there geological investigations that take into account the weight distribution?
I searched for scientific publications, but couldn't find anything. I would also say that these masses are too small to cause any significant movement. They do change the isotopic composition of atmosphere and oceans, though, but that's only interesting because you can measure it, it doesn't have any impact on life, even less on tectonics. Until now, about 300 gigatons of carbon (from all fossil sources combined) have been burned and about 5000 gigatons are thought to exist in total (
source). Compare to the amount of ice mentioned above, and you'll see that this mass can be disregarded when talking about tectonic balances.
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Of course local mishaps can happen, when you extract fluids from the pores of a rock. Tiny earthquakes associated with oil and gas exploration are
known to happen, and collapsing coal mines can also destroy buildings above ground.