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| USGS earthquake location. |
April 17, 2016 - ECUADOR - At least 77 people have been killed after a 7.8-magnitude earthquake hit Ecuador's central coast.
Tremors were recorded at 11:58 p.m. UTC time (02:58 MSK). According to the USGS, the epicenter of the quake was 17 miles away from the coastal town of Muisne and just over 100 miles away from the capital Quito.
Hazardous tsunami waves of up to one meter (3.2 feet) above the tide level are possible in Ecuador, the Pacific Tsunami Warning Center (PTWC) said in a forecast after a powerful earthquake shook the coast of the country.
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"Tsunami waves reaching 0.3 to 1 meters above the tide level are possible for some coasts of Ecuador," the PTWC said in a statement.
Officials have declared a state of emergency in six of the country's 24 provinces and the National Guard. The tremor destroyed homes and collapsed one major overpass.
President Rafael Correa urged the country's 16 million people to remain calm during the crisis.
"Our infinite love to the families of the dead," he said on Twitter. He also announced that he would cut short his trip to Italy to return home.
Vice President Jorge Glas also announced that the number of injured people were not currently available but he admitted that the death toll is expected to rise.
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People stand in the rubble of a collapsed building after an earthquake struck Manta, Ecuador. © REUTERS/PAUL OCHOA
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"It's very important that Ecuadoreans remain calm during this emergency," Vice President Glas announced in a televised address.
"We're trying to do the most we can but there's almost nothing we can do," said Gabriel Alcivar, mayor of Pedernales near the epicentre.
He pleaded for rescuers as dozens of buildings in the town were flattened, people trapped and looting broke out amid the chaos.
Images of the destruction caused by #EcuadorEarthquake. State of emergency declared. #Ecuador pic.twitter.com/v7NzE2AX0C— Natasha Fatah (@NatashaFatah) April 17, 2016
Car flattened by collapsed overpass after 7.8 magnitude #earthquake in #Ecuador. pic.twitter.com/Zbw5QGI9Xa— Scott McClellan (@bamasevere) April 17, 2016
That was the control tower Airport #Manta after earthquake in Ecuador pic.twitter.com/OzcUHnumvO— Airplane Pictures ✈️ (@iLove_Aviation) April 17, 2016
"This wasn't just a house that collapsed, it was an entire town."
On social media residents shared photos of homes collapsed, the roof of a shopping centre coming apart and supermarket shelves shaking violently.
In Manta, the airport was closed after the control tower collapsed, injuring an air force official. Hydroelectric dams and oil pipelines in the OPEC-member nation were shut down as a precautionary measure.
WATCH: Monumental Earth Changes.
Zoila Villena, a Quito resident said that she is in a current "state of panic."
"My building moved a lot and things fell to the floor," Villena told The Associated Press.
"Lots of neighbors were screaming and kids crying." The US Geological Survey said the shallow quake, the strongest since 1979 to hit Ecuador, was centred on south-southeast of Muisne, a sparsely populated area of fishing ports that is popular with tourists.
USGS Tectonic Summary
The April 16, 2016 M 7.8 earthquake, offshore of the west coast of northern Ecuador, occurred as the result of shallow thrust faulting on or near the plate boundary between the Nazca and Pacific plates. At the location of the earthquake, the Nazca plate subducts eastward beneath the South America plate at a velocity of 61 mm/yr. The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between these two major plates. Subduction along the Ecuador Trench to the west of Ecuador, and the Peru-Chile Trench further south, has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile.While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Events of the size of the April 16, 2016 earthquake are typically about 160x60 km in size (length x width).
Ecuador has a history of large subduction zone related earthquakes. Seven magnitude 7 or greater earthquakes have occurred within 250 km of this event since 1900. On May 14th, 1942, a M 7.8 earthquake occurred 43 km south of this April 16th, 2016 event. On January 31st, 1906 a M 8.3 earthquake (reportedly as large as M 8.8 in some sources) nucleated on the subduction zone interface 90 km to the northeast of the April 2016 event, and ruptured over a length of approximately 400-500 km, resulting in a damaging tsunami that caused in the region of 500-1,500 fatalities. The April 2016 earthquake is at the southern end of the approximate rupture area of the 1906 event. A shallow, upper crustal M 7.2 earthquake 240 km east of the April 2016 event on March 6th, 1987 resulted in approximately 1,000 fatalities.
USGS Seismotectonics of South America (Nazca Plate Region)
The South American arc extends over 7,000 km, from the Chilean margin triple junction offshore of southern Chile to its intersection with the Panama fracture zone, offshore of the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their descent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 65 mm/yr in the north. Although the rate of subduction varies little along the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic activity, crustal deformation, earthquake generation and occurrence all along the western edge of South America.Most of the large earthquakes in South America are constrained to shallow depths of 0 to 70 km resulting from both crustal and interplate deformation. Crustal earthquakes result from deformation and mountain building in the overriding South America plate and generate earthquakes as deep as approximately 50 km. Interplate earthquakes occur due to slip along the dipping interface between the Nazca and the South American plates. Interplate earthquakes in this region are frequent and often large, and occur between the depths of approximately 10 and 60 km. Since 1900, numerous magnitude 8 or larger earthquakes have occurred on this subduction zone interface that were followed by devastating tsunamis, including the 1960 M9.5 earthquake in southern Chile, the largest instrumentally recorded earthquake in the world. Other notable shallow tsunami-generating earthquakes include the 1906 M8.5 earthquake near Esmeraldas, Ecuador, the 1922 M8.5 earthquake near Coquimbo, Chile, the 2001 M8.4 Arequipa, Peru earthquake, the 2007 M8.0 earthquake near Pisco, Peru, and the 2010 M8.8 Maule, Chile earthquake located just north of the 1960 event.
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| USGS plate tectonics for the region. |
Large intermediate-depth earthquakes (those occurring between depths of approximately 70 and 300 km) are relatively limited in size and spatial extent in South America, and occur within the Nazca plate as a result of internal deformation within the subducting plate. These earthquakes generally cluster beneath northern Chile and southwestern Bolivia, and to a lesser extent beneath northern Peru and southern Ecuador, with depths between 110 and 130 km. Most of these earthquakes occur adjacent to the bend in the coastline between Peru and Chile. The most recent large intermediate-depth earthquake in this region was the 2005 M7.8 Tarapaca, Chile earthquake.
Earthquakes can also be generated to depths greater than 600 km as a result of continued internal deformation of the subducting Nazca plate. Deep-focus earthquakes in South America are not observed from a depth range of approximately 300 to 500 km. Instead, deep earthquakes in this region occur at depths of 500 to 650 km and are concentrated into two zones: one that runs beneath the Peru-Brazil border and another that extends from central Bolivia to central Argentina. These earthquakes generally do not exhibit large magnitudes. An exception to this was the 1994 Bolivian earthquake in northwestern Bolivia. This M8.2 earthquake occurred at a depth of 631 km, making it the largest deep-focus earthquake instrumentally recorded, and was felt widely throughout South and North America.
Subduction of the Nazca plate is geometrically complex and impacts the geology and seismicity of the western edge of South America. The intermediate-depth regions of the subducting Nazca plate can be segmented into five sections based on their angle of subduction beneath the South America plate. Three segments are characterized by steeply dipping subduction; the other two by near-horizontal subduction. The Nazca plate beneath northern Ecuador, southern Peru to northern Chile, and southern Chile descend into the mantle at angles of 25° to 30°. In contrast, the slab beneath southern Ecuador to central Peru, and under central Chile, is subducting at a shallow angle of approximately 10° or less. In these regions of “flat-slab” subduction, the Nazca plate moves horizontally for several hundred kilometers before continuing its descent into the mantle, and is shadowed by an extended zone of crustal seismicity in the overlying South America plate. Although the South America plate exhibits a chain of active volcanism resulting from the subduction and partial melting of the Nazca oceanic lithosphere along most of the arc, these regions of inferred shallow subduction correlate with an absence of volcanic activity. -
More information on regional seismicity and tectonics
- Independent | Sputnik | USGS.
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