A large sinkhole, some 70m deep, has appeared in the ground, swallowing two buildings, during a heavy storm in Guatemala City. Following more than 1000mm of rainfall in a single storm event, many instances of flooding and local landslides were also reported. It is likely that the sinkhole, formed from dissolution of limestone over thousands of years, was infilled with sediment which was washed away as a result of the storm. The link above goes to a clip of the sinkhole on the BBC web site.The image is from http://www.blindloop.com/wp-content/uploads/2010/04/Sinkhole.jpg. There are some other spectacular images at http://tinyurl.com/2942est.
2 comments:
A Guardian report on 3 June suggests "An investigation of the 2007 disaster blamed the city's drainage system, which experts believe also caused the more recent one." They refer to "porous volcanic ground" and ash from a nearby volcano. So there is ambiguity: this might be washing away of volcanic ash causing collapses/"sinkholes". Alternately it might be collapse of surficial volcanic ash deposits into (presumed) underlying limestone cavities - more information needed!
Clearer information on the "sinkhole" shows the underlying geology does not include any limestone of gypsum, hence this is not the usual type of sinkhole related to solution of bedrock. (see: http://earthsky.org/earth/dan-doctor-on-the-guatemala-city-sinkhole-of-may-2010). It seems that washing away of volcanic ash is the likely cause, with sewer/storm drain leakage being a very likely factor.
Post a Comment