7.8 Magnitude Undersea Earthquake Hits South Atlantic, No Tsunami Warnings Issued
By Esther Tanquintic-Misa | November 18, 2013 11:53 AM EST
A mighty 7.8 magnitude undersea earthquake has occurred in the Scotia Sea on Sunday, according to the U.S. Geological Survey. Scotia Sea is a distant region in the far south Atlantic near Antarctica.
Occurring at the boundary between the Antarctic tectonic plate and the Scotia Sea plate, the temblor struck at 0904 GMT in the ocean some 893 km southwest of Grytviken, South Georgia, and 1,140 km southeast of Ushuaia, Argentina.
Randy Baldwin, a geophysicist at the National Earthquake Information Center in Golden, Colorado, told AFP aftershocks will be felt surrounding the area "probably for weeks."
"They're sliding past one another horizontally, it's not a subduction zone," Mr Baldwin said.
With its 7.8 magnitude intensity, the Scotia Sea quake of Nov 17 could well be already described as "one of the most significant earthquakes of all time," almost parallel to the great San Francisco earthquake of 1906 which had a 7.9 magnitude intensity.
But since the Scotia Sea quake struck at a remote area where little or no human beings reside, the USGS no longer issued issue tsunami warnings. It was not considered a major catastrophe to endanger human lives.
"You couldn't pick a more remote area for an earthquake," Mr Baldwin said.
"This quake took place in a remote area (the closest inhabited land is almost 1500 km distant) which means that there is no immediate direct impact on human populations," according to Jennifer Young of www.decodedscience.com.
Ms Young further explained tsunamis remain a remote possibility for this particular 7.8 magnitude undersea earthquake because of the nature of its faulting.
"Geological phenomena generate tsunamis when they displace large volumes of seawater laterally, or in a side-to-side motion. Earthquakes are the primary cause of tsunamis, but other mechanisms such as landslides could have the same effect," she said.
"In this case, because there was no vertical movement, the quake could generate no large-scale tsunami, and any local tsunami would have disappeared before reaching land."
The quake's epicentre was recorded 10 kilometres deep. It was near the 6.8 magnitude undersea earthquake that occurred in the same sea 30 hours earlier.
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