Wednesday, June 30, 2010

Sinkhole Explanation

Ten days ago I wrote an article explaining how these sinkholes in Guatemala City are forming. Today's issue of Nuestro Diario has an article showing geologists descending into the big sinkhole in Zone 2 to examine it and take photos. The article also shows a diagram confirming what I said in my previous post.

At the bottom center of the sinkhole, 100 feet down, is a 6 foot by 9 foot storm drain / sewer gallery that collapsed. The high pressures and flow rates during Tropical Storm Agatha then escavated the sinkhole by erosion from the bottom up. Once the underground cavity became large enough that the "roof" of the cavity could no longer support the weight of the buildings above, it collapsed and everything fell into the cavity. It's very simply once you understand how it happens, no mystery.

I'd like to provide a link to the online article in Nuestro Diario but their web site's Flash software is not working correctly and I cannot link to today's article. However you can navigate to the article yourself here Go to the June 30, 2010 issue and turn to page 5.