专家解读天坑的出现原因

Residents of an urban neighborhood in Guatemala City experienced the opening up of a giant sinkhole in May 2010. It swallowed a three-story building and left a deep hole. EarthSky spoke with Dan Doctor, a geologist at the U.S. Geological Survey, who studies sinkholes.

今年5月危地马拉城市区内出现了一次地陷，它吞噬了一幢三层房屋，留下一道深坑。记者就此采访了美国地质调查局地质学家、研究地陷现象的专家丹·多科特。

Dan Doctor: We wouldn’t consider this to be a type of terrain which would be vulnerable to these types of sinkholes.

丹·多科特：危地马拉城并不是容易发生此类地陷的地方。

Doctor said that sinkholes are created when the ground collapses into a void beneath the surface. This usually happens in places where water dissolves away rocks like limestone and gypsum. But that’s not Guatemala City. It’s built on volcanic rock and ash. Heavy rains from Tropical Storm Agatha might have stressed the city’s human infrastructure – water mains or sewer systems – to help create the May 2010 sinkhole.

多科特说，地陷是由地表陷入地下空洞造成的。这种现象通常发生在地质为石灰石、石膏的岩溶地带。而危地马拉城并不属于这样的地质带。该城建立在火成岩与火山灰上。热带风暴“阿加莎”可能破坏了城内的总水管、污水排放系统这类基础设施，导致今年5月这次地陷的发生。

Dan Doctor: In some cases, you can have rather significant voids formed in the subsurface that later will collapse if they reach the surface.

丹·多科特：有时地表以下会出现巨大的空洞，它们扩张到地面就会造成塌陷。

This sinkhole is just 5 kilometers – or 3 miles – from where another sinkhole in Guatemala City opened in 2007. Local authorities and geologists are still investigating what caused the sinkhole. Doctor added that in the U.S. Florida is the only state he knows that requires sinkhole insurance for homes.

危地马拉城2007年也出现过相似塌陷，与此次塌陷地点相距仅5千米（3英里）。当地官员及地质学家仍在调查此次地陷发生的原因。多科特进一步指出，就他所知，福罗里达州是美国各州唯一要求家家户户办理溶岩塌陷保险的地方。