Last week I sent in an e-mail to the geologist interviewed a few weeks ago, regarding the possibility of subsidence or sink holes occurring in Colorado due to fracking.
Subsidence of soil is a gradual lowering of the earth due to the removal of particles underground. This can cause a dramatic lowering in elevation over several years and is seen though cases of sub-surface mining.
Sink holes, which have been making a lot of news in Florida (after a mans home caved into the ground), is a form of subsidence which usually occurs when underground limestone in karst areas are exposed to water. The water eats away at the limestone creating voids which eventually cave in, bringing anything on the surface with them. These holes can reach up to hundreds of meters deep.
In an e-mail I received back from the geologist he wrote:
“according to my research: ‘subsidence is not directly caused by (fracking) but may occur after considerable production of oil or groundwater. Subsidence occurs over reservoirs whether they have been subject to fracking or not because it is a result of producing fluids from the reservoir and lowering the reservoir pore pressure. The subsidence process is also associated with seismic activity.’ Therefore, according to this quote, subsidence cannot be directly linked to fracking.”
He also followed with this comment on sink holes:
“It’s not surprising that these sinkholes are developing in Florida, SE Ohio, West Virginia, and Pennsylvania – Limestone is the major bedrock unit underlying these areas. There are some sites on the internet that are trying to directly link sinkholes to fracking. However, I reviewed these sources and came to the conclusion that they are not that reliable. There really is no conclusive science that backs up their claims. There is no reliable evidence to back the claim.”
So as for now it appears Colorado is in the clear from suffering any of these major land shifts. That is until we have more evidence and studies done on the process. Another reason for the US government to do their homework before allowing drastic changes to our land.