Sink or Swim

We've probably all experienced minor damaging effects of a natural disaster at some point in our lives, (if not, you're very fortunate!) For some living in California, it might have been an earthquake. For me personally, it was a bit of minor flooding in my garage. While soggy floorboards and broken vases can be replaced, what do you do if the earth swallows up your house?

Subsidence

According to the British Geological Survey, subsidence is defined as ground failure when the earth shrinks downward. When water wears bedrock down, the earth above it collapses into either a big circular pit or a long depressed line. When water, either from under or above ground percolates through the bedrock, the rock (like limestone) can easily be dissolved. We call this process dissolution. (Keller and Devecchio, 258)

Sink hole in a back garden, St. Alban's, UK

The British Geological Survey maps out
hazardous areas based on ground stability.
Source: BGS

Recently I read a 2014 article from a British online magazine asking why there were so many sinkholes popping up in the UK. The fact that the author of the article was surprised about there being excess moisture in the ground in England of all places was a bit funny. The UK is known for being very rainy, and crowded cities with poor drainage provide perfect conditions for subsidence issues.

Certain parts of Britain have proven to be more susceptible to subsidence due to the types of rock found there. Places like Cheshire and the Vale of York in the south east of England, for example is chock full (haha) of gypsum, which is basically chalk, and soft clay.

To decrease hazards, the British Geological survey is constantly working to create maps indicating places where the ground is weak and likely to collapse, and predicts places where the ground is likely to sink in or erode.