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For example, sinkholes can be human induced:

New sinkholes have been correlated to land-use practices, especially from groundwater pumping and from construction and development practices. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created. The substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.

We have been pumping oil out of the ground, fracking, extracting natural gas, mining, etc. for a long time now and in some instances to the point that we completely deplete such reserves. What is the long term impact of anthropogenic removal of material from the underground on the ability of the foundational soil to support our ever expanding population and associated infrastructure?

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  • $\begingroup$ Can you clarify what you mean by 'long term impact'? It seems to me that impacts will be short term, in that the ground surface will stabilize when the removal ends. $\endgroup$ – haresfur Jan 1 '15 at 23:32
  • $\begingroup$ @haresfur It does not appear that extraction of material from the earth will stop anytime soon. So I am wondering if, over a long time there is the possibility that the widespread weakening of the foundational soil due to extraction will have a catastrophic impact on human infrastructure over large areas (ex:cities), rather than the local example I gave of human induced sinkholes. $\endgroup$ – Isopycnal Oscillation Jan 1 '15 at 23:53
  • $\begingroup$ @haresfur: stabilisation will be a long and slow process that starts after the removal ends. Could take decades or centuries in some cases. $\endgroup$ – naught101 Jan 2 '15 at 1:08
  • $\begingroup$ @naught101 to geologists decades and even centuries can be considered short term. That's why I asked the question - to put bounds on the question and possible answers. In my neighbourhood there is still occasional small-scale subsidence over mine shafts from the gold rush that started in the 1850s but it only affects small areas (still bad if under your house, though). $\endgroup$ – haresfur Jan 2 '15 at 1:49
  • $\begingroup$ @haresfur: Yeah, fair enough. I just though "the ground surface will stabilize when the removal ends" sounded somewhat ... instantaneous :) $\endgroup$ – naught101 Jan 2 '15 at 3:04
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The answer to your question will depend on the type of material and the depth. I will restrict this answer to groundwater withdrawal to focus the discussion. Of course there can be effects from other extractive industries.

Groundwater pumping can lead to large scale subsidence, with the Central Valley of California being one of the best described examples. According to that website, "More than 80 percent of the identified subsidence in the United States is a consequence of human impact on subsurface water."

Approximate location of maximum subsidence in the U.S., identified by research efforts of Dr. Joseph F. Poland (pictured).

Overall, the extreme subsidence shown may cause damage to foundations, etc. but is spread over a large area and is pretty even, unlike your classic sink-hole. It is the differential settling that causes the most damage.

There are several types of sink holes (also called dolines), they may be related to failure of indurated rock above cavities or by failure of soft soils/sediments. The most common natural sinks occur through the dissolution of limestone in 'karst' terrain and they can be kilometers across. This can lead to the creation of water or air filled caves. In some cases a cavity forms in sediments above the limestone and can subsequently collapse. Cavities can also be formed in sediments where they are removed through pipe erosion but that tends to be a shallow phenomenon (but can still be damaging).

The description, above, talks about natural processes but these can be enhanced by groundwater pumping. The water supports some of the overburden and removing it weakens the structure and can lead to collapse. Flow systems can change, enhancing subsurface soil erosion as water tables decline. And of course, building over a cavity may exceed the load bearing capacity.

So the long term impacts will depend on both the geologic setting and the severity of water level decline. Will this have a major effect on global infrastructure and economies? I suspect not but the damage we have seen in certain areas is likely to continue and perhaps spread.

A somewhat old but good reference on the subject sinkholes and caves that discusses the land-use issues is Geomorphology and Hydrology of Karst Terrains. White, William B. (1988). Oxford University Press.

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