Magnitude 7.1 - ECUADOR
2010 August 12 11:54:16 UTC
Earthquake Details
* This event has been reviewed by a seismologist.
Magnitude 7.1
Date-Time
* Thursday, August 12, 2010 at 11:54:16 UTC
* Thursday, August 12, 2010 at 06:54:16 AM at epicenter
* Time of Earthquake in other Time Zones
Location 1.260°S, 77.312°W
Depth 211 km (131.1 miles) set by location program
Region ECUADOR
Distances 145 km (90 miles) E of Ambato, Ecuador
155 km (95 miles) ENE of Riobamba, Ecuador
155 km (95 miles) SSW of Nueva Loja, Ecuador
175 km (110 miles) SE of QUITO, Ecuador
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http://www.google.com/hostednews/afp/article/ALeqM5iOk0igRKX72pYpBSO4LiKjlMb9XA
Powerful quake rattles Ecuador, Peru
(AFP) – 9 hours ago
WASHINGTON — A strong 7.1-magnitude earthquake rocked Ecuador and parts of Peru Thursday, but its epicenter was deep underground in a remote Amazonian region and only one injury and light damage was reported.
The quake, which experts from the US Geological Survey said hit at 6:54 am (1154 GMT), 110 miles (175 kilometers) southeast of Quito, lasted for about 40 seconds and was felt around the country and in neighboring Peru.
One person in a southwestern fishing port was injured by a crumbling wall, Ecuador Red Cross spokesman Jorge Arteaga told AFP.
"So far that is the only victim," he said, adding that a handful of buildings including a firehouse had their walls crumble as a result of the quake.
The epicenter of the quake was deep, some 210 kilometers under the Amazonian jungle, which Ecuadoran officials said was the reason for the lack of damage above ground. No tsunami was generated.
The USGS said the nearest urban center was some 145 kilometers to the west -- Ambato -- an Ecuadoran city high in the Andes mountains which is home to a volcano of the same name and suffered a devastating quake back in 1949.
The Geophysical Institute of Peru said Thursday's quake was also felt by Peruvians along the border in the Amazonian jungle regions.
Sandro Vaca, an expert from the Geophysical Institute of Ecuador, said no aftershocks had been detected during the morning.
The USGS revised its estimate of the quake's magnitude several times, from 6.9 to 7.2 and then back to a 6.9 before finally settling on 7.1.
Ecuadoran experts first put the quake at 6.9 on the Richter scale before revising the magnitude upwards to 7.2.
The USGS uses the moment magnitude scale, which measures the amount of movement on the underground fault and the area of the fault that ruptured.
Many seismologists now use that system rather than the Richter scale, which measures the size based upon the amount of ground shaking.
According to the USGS, the quake was the largest involving Ecuador since a 7.2-magnitude temblor off the coast in 1998. Ecuador's deadliest was the 6.8-magnitude quake in 1949 in Ambato which killed more than 5,000 people.
The Ecuadoran Andes are part of the Pacific Ring of fire, where most of history's deadliest quakes, tremors and volcanic explosions have occurred.
The weak line in the Earth's crust stretches along the western coast of the Americas and through the island nations of the South Pacific and on through Southeast Asia.
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http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010zwa5.php#summary
Tectonic Summary
This major earthquake occurred within the lithosphere of the Nazca plate. The earthquakes of Ecuador and most of western South America are due to strains generated by ongoing subduction of the Nazca plate beneath the South America plate. At the latitude of the earthquake, the oceanic Nazca plate moves east relative to the South America plate at a rate of about 7 cm per year. It is overridden by the South America plate at the Peru-Chile trench, west of the Ecuadoran coast, and sinks into the earth's mantle beneath the South America plate. The subducted Nazca plate is seismically active to depths of about 650 km. This earthquake occurred as normal faulting within a segment of the subducted plate that has produced frequent earthquakes with focal depths of 160 km to 200 km beneath the earth's surface. A magnitude 6.7 earthquake in 1971 was situated 60 km to the southwest of the August 12, 2010, earthquake at a depth of 170 km.
Earthquakes that have focal-depths between 70 and 300 km are commonly termed "intermediate-depth" earthquakes, as distinguished from "shallow-focus" earthquakes, having depths less than 70 km, and "deep-focus" earthquakes, having depths greater than 300 km. Intermediate-depth and deep-focus earthquakes represent deformation within subducted plates, rather than deformation at plate boundaries. Intermediate-depth and deep-focus earthquakes typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth and deep-focus earthquakes may be felt at great distances from their epicenters.
