Voçoroca

In Brazil, a voçoroca or boçoroca is a geological phenomenon that consists of a sudden collapse of a large area of land caused by rain and windstorms. This occurs on ground where surface vegetation is scarce and cannot protect the ground from runoff. The phenomenon somewhat resembles a combination of a sinkhole (though without the normal surface vegetation, such as a large tree in the center) and soil liquefaction.

Voçorocas can be prevented by planting trees in the side of the small ruts and areas which attract water flow, which will protect the ground from rain and wind erosion and restrain the flow of sediment with their root structure.

It is a harmful, typically man-made phenomenon which destroys farmland and causes river sedimentation and sewer system clogging. These also collect ground debris, and contribute to urban flooding.

"A more complete article is available in Portuguese, [http://pt.wikipedia.org/wiki/Vo%C3%A7oroca here] ; please replace or extend this article with a translation of that article if you are able."

References

http://www.playfuls.com/news_10_17846-Twelve-Houses-Cars-Swallowed-By-Giant-Crater-In-Brazil.html (Note: this appears to be a reprint; if you know of a root source, please replace this with it.)

http://www.apadescalvado.cnpm.embrapa.br/erosivo.html