The Municipal Water Department for Guatemala City is dreaming, when they should be having nightmares. Eddy Sanchez, the director of the Institute of Seismology, Volcanology, Meteorology and Hydrology, is concerned that the recent rain of ash and sand from the nearby Pacaya volcano might accumulate and further damage the city's aging sewer systems.
It's more serious than that. The recent appearance of a 60x100 hole in a city intersection that engulfed a furniture factory and demolished an entire intersection of city streets, is only the beginning. There was another sinkhole incident two years ago, not far from the recent event. That older hole was not only wider but deeper. They say that the hole has been sealed and the city is thinking of allowing new development there. This is nothing more than pouring sand down a rat hole and as useless.
"with this review, the Water Department will know with certainty what the damage of the collector is and thus make the repairs, because so far we have not been able to do." Prensa Libre /6/12/2010
The giant sinkhole that opened beneath downtown Guatemala City last week?
There's a small problem: it isn't a sinkhole.
"Sure, it looks a lot like a sinkhole," geologist Sam Bonis is quoted as saying. Instead, Bonis prefers the term "piping feature" but that's in important distinction, he maintains, because "sinkholes" refer to areas where bedrock is solid but has been eaten away by groundwater.
The situation beneath the country's capital is different and far more dangerous.
Most of the city is built on volcanic debris or pumice. Mud, sand and ash flows made up of loose particles have been deposited during over millions of years. In some places, the debris is piled over 600 feet thick, filling up what would otherwise be a v-shaped valley of unstable bedrock.
Two years ago, after a sewage pipe broke off just a few blocks from this latest disaster, Bonis was part of a team of geologists and engineers brought in to investigate and advise officials on what went wrong.
"Our recommendation was that this could happen again," he recalled. "When you have water flowing from storm water runoff, a sewage pipe, or any kind of strong flow, it eats away at the loose material. We don't know how long it has to go on before it collapses. But once it starts collapsing, God help us." (Discovery News Channel)
The Guatemala City metro area is home to nearly 3 million people. Perhaps a third to half of them live on the fill. Bonis worked for the Gautemalan government's National Geographic Institute for sixteen years and he's familiar with the underlying problems.
Eddy Sanchez is dreaming, when he should be having nightmares. This is a city build on sand and with more rain, more hydrologic action, they can kiss their ash goodbye.
"I'd hate to have to be in the government right now," Bonis, "There is an excellent potential for this to happen again. It could happen almost anywhere in the city."
Source: Guatemala News-El
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