Stories tagged geological forces
Chinese earthquake location
Courtesy USGSThe Tangjiashan “quake lake”
formed by a landslide during China’s devastating May 12th earthquake is draining slowly thanks to a sluice constructed by engineers there. Fears of the lake bursting from its earthen dam pushed authorities to find a quick and effective way to release the pressure building from the backed-up water. More than a million people living in the area were under threat of being inundated with millions of cubic meters of water.
As work crews start construction of a second drainage channel, engineers are closely watching downstream riverbanks and bridges for any sign of stress from the surging waters.
The 7.9 magnitude earthquake killed over 60,000 people and more than 17,000 are still missing.
SOURCES AND LINKS
AP story
BBC report
Maps and photos of lake region
Tags : Geological processes don't always occur over long stretches of time. Landslides triggered by recent 7.9 magnitude earthquake in China have blocked rivers causing new - and perhaps unstable - lakes to form in the devastated landscape.
Satellite photos taken of the region around Beichuan County show formation of a lake in one of the worst hit areas. Twenty other lakes have formed in Beichuan because of the massive tremor and are being monitored closely according to a story in Chinese Daily.
Death estimates are nearing 60,000, and the quake is thought to have destroyed more than 5 million buildings.
Here today, gone tomorrow: Undated photo combination showing five acre lake that disappeared mysteriously in the southernmost region of Magallanes, Chile. Photo credit: CONAFA glacial lake in Chile has suddenly disappeared according to park rangers at Bernardo O’Higgins National Park in the southern Andes.
“In March we patrolled the area and everything was normal,” said Juan Jose Romero from CONAF Chile’s National Forestry Corporation. “We went again in May and to our surprise we found that the lake had completely disappeared. All that was left were chunks of ice and an enormous fissure.”
The fissure could mean an earthquake may be responsible for the disappearance, since the Magallanes region is known to experience lots of tremors, but the problem is there haven’t been any quakes recently in the park.
“No one knows what happened,” Romero said.
However, an earthquake hasn’t been completely ruled out as the cause. A recent quake in nearby Aysen last April could be the culprit. According to glacial specialist, Andres Rivera, the Magallenes area has seen interesting changes in the last few decades. He noted that the lake didn’t exist 30 years ago.
When the lake was there, it covered about 5 acres, (330 ft by 660 ft) and was about 100 feet deep. It’s not a huge lake, but it’s no backyard fish pond either. Here’s a link that will give you a better idea just how large an area 5 acres is.
Geologists and other experts are heading to the area 1250 miles south of Santiago to investigate so maybe they’ll come up with some answers.
In geological terms lakes are considered ephemeral events, and sometimes changes in the landscape happen gradually, sometimes they happen quite rapidly. This is a good example of the latter.
STORY LINKS
BBC Website Story
OttawaCitizen.com Story (Neat photo)
More on Bernardo O'Higgins National Park
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