April 11, 2014 - NICARAGUA - A magnitude-6.6 earthquake shook Nicaragua
on Friday afternoon, sending people running frightened into the streets
less than 24 hours after a magnitude-6.1 quake rattled the country, the
United States Geological Survey said.
The government raised the number of people injured in the Thursday evening quake from 23 to 200. It also said that a 23-year-old woman had died of an apparent heart attack after the quake.
In the capital city of Managua, 300 homes were damaged and at least 20 were destroyed by the Thursday quake, said one of the mayor's deputies, Fidel Moreno.
Authorities ordered the demolition of two old buildings that had withstood the earthquake of 1972 that killed 10,000 people. Hospitals began discharging patients with minor illnesses so they could have beds available in the event of injuries from an aftershock or new quake.
On Thursday night, officials took 155 people out of neighborhoods northeast of the capital city due to risk of landslides. One of the shelters was still housing 22 families on Friday.
Schools closed in the capital and also in the northwestern city of Leon.
The government said roughly 800 homes were damaged in the town of Nagarote and surrounding areas, about 30 miles (50 kilometers) northwest of the capital.
Friday's quake struck at 3:29 p.m. local time (20:29 GMT), and was centered about 6 miles (11 kilometers) east-southeast of the town of Nandaime. It had a depth of 85 miles (138 kilometers).
The USGS said Thursday's quake struck at 5:27 p.m. local time (23:27 GMT), and was centered about 11 miles (18 kilometers) southeast of the city of Larreynaga. It had a depth of 6.2 miles (10 kilometers). - AP.
Along the northern margin of the Caribbean plate, the North America plate moves westwards with respect to the Caribbean plate at a velocity of approximately 20 mm/yr. Motion is accommodated along several major transform faults that extend eastward from Isla de Roatan to Haiti, including the Swan Island Fault and the Oriente Fault. These faults represent the southern and northern boundaries of the Cayman Trench. Further east, from the Dominican Republic to the Island of Barbuda, relative motion between the North America plate and the Caribbean plate becomes increasingly complex and is partially accommodated by nearly arc-parallel subduction of the North America plate beneath the Caribbean plate. This results in the formation of the deep Puerto Rico Trench and a zone of intermediate focus earthquakes (70-300 km depth) within the subducted slab. Although the Puerto Rico subduction zone is thought to be capable of generating a megathrust earthquake, there have been no such events in the past century. The last probable interplate (thrust fault) event here occurred on May 2, 1787 and was widely felt throughout the island with documented destruction across the entire northern coast, including Arecibo and San Juan. Since 1900, the two largest earthquakes to occur in this region were the August 4, 1946 M8.0 Samana earthquake in northeastern Hispaniola and the July 29, 1943 M7.6 Mona Passage earthquake, both of which were shallow thrust fault earthquakes. A significant portion of the motion between the North America plate and the Caribbean plate in this region is accommodated by a series of left-lateral strike-slip faults that bisect the island of Hispaniola, notably the Septentrional Fault in the north and the Enriquillo-Plantain Garden Fault in the south. Activity adjacent to the Enriquillo-Plantain Garden Fault system is best documented by the devastating January 12, 2010 M7.0 Haiti strike-slip earthquake, its associated aftershocks and a comparable earthquake in 1770.
Moving east and south, the plate boundary curves around Puerto Rico and the northern Lesser Antilles where the plate motion vector of the Caribbean plate relative to the North and South America plates is less oblique, resulting in active island-arc tectonics. Here, the North and South America plates subduct towards the west beneath the Caribbean plate along the Lesser Antilles Trench at rates of approximately 20 mm/yr. As a result of this subduction, there exists both intermediate focus earthquakes within the subducted plates and a chain of active volcanoes along the island arc. Although the Lesser Antilles is considered one of the most seismically active regions in the Caribbean, few of these events have been greater than M7.0 over the past century. The island of Guadeloupe was the site of one of the largest megathrust earthquakes to occur in this region on February 8, 1843, with a suggested magnitude greater than 8.0. The largest recent intermediate-depth earthquake to occur along the Lesser Antilles arc was the November 29, 2007 M7.4 Martinique earthquake northwest of Fort-De-France.
The southern Caribbean plate boundary with the South America plate strikes east-west across Trinidad and western Venezuela at a relative rate of approximately 20 mm/yr. This boundary is characterized by major transform faults, including the Central Range Fault and the Boconó-San Sebastian-El Pilar Faults, and shallow seismicity. Since 1900, the largest earthquakes to occur in this region were the October 29, 1900 M7.7 Caracas earthquake, and the July 29, 1967 M6.5 earthquake near this same region. Further to the west, a broad zone of compressive deformation trends southwestward across western Venezuela and central Columbia. The plate boundary is not well defined across northwestern South America, but deformation transitions from being dominated by Caribbean/South America convergence in the east to Nazca/South America convergence in the west. The transition zone between subduction on the eastern and western margins of the Caribbean plate is characterized by diffuse seismicity involving low- to intermediate-magnitude (Magnitude less than 6.0) earthquakes of shallow to intermediate depth.
The plate boundary offshore of Colombia is also characterized by convergence, where the Nazca plate subducts beneath South America towards the east at a rate of approximately 65 mm/yr. The January 31, 1906 M8.5 earthquake occurred on the shallowly dipping megathrust interface of this plate boundary segment. Along the western coast of Central America, the Cocos plate subducts towards the east beneath the Caribbean plate at the Middle America Trench. Convergence rates vary between 72-81 mm/yr, decreasing towards the north. This subduction results in relatively high rates of seismicity and a chain of numerous active volcanoes; intermediate-focus earthquakes occur within the subducted Cocos plate to depths of nearly 300 km. Since 1900, there have been many moderately sized intermediate-depth earthquakes in this region, including the September 7, 1915 M7.4 El Salvador and the October 5, 1950 M7.8 Costa Rica events.
The boundary between the Cocos and Nazca plates is characterized by a series of north-south trending transform faults and east-west trending spreading centers. The largest and most seismically active of these transform boundaries is the Panama Fracture Zone. The Panama Fracture Zone terminates in the south at the Galapagos rift zone and in the north at the Middle America trench, where it forms part of the Cocos-Nazca-Caribbean triple junction. Earthquakes along the Panama Fracture Zone are generally shallow, low- to intermediate in magnitude (Magnitude less than 7.2) and are characteristically right-lateral strike-slip faulting earthquakes. Since 1900, the largest earthquake to occur along the Panama Fracture Zone was the July 26, 1962 M7.2 earthquake. - USGS.
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| USGS earthquake location map. |
There were no
immediate reports of new casualties or serious damage, but the USGS said
the quake was felt in El Salvador and neighboring Costa Rica.
The government raised the number of people injured in the Thursday evening quake from 23 to 200. It also said that a 23-year-old woman had died of an apparent heart attack after the quake.
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| USGS earthquake shakemap intensity. |
In the capital city of Managua, 300 homes were damaged and at least 20 were destroyed by the Thursday quake, said one of the mayor's deputies, Fidel Moreno.
Authorities ordered the demolition of two old buildings that had withstood the earthquake of 1972 that killed 10,000 people. Hospitals began discharging patients with minor illnesses so they could have beds available in the event of injuries from an aftershock or new quake.
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| A woman walks inside a home that was damaged by an earthquake in Nagarote, Nicaragua, Thursday, April 10, 2014. Photo By Esteban Felix/AP |
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| Two men talk outside a home damaged by an earthquake in Nagarote. Photo By Esteban Felix/AP |
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| A girl passes by in a bicycle, in front a home damaged by an earthquake
in Nagarote, Nicaragua.
Photo By Esteban Felix/AP |
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| A girl walks in front a home damaged by an earthquake in Nagarote. Photo By Esteban Felix/AP |
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| A painting of a Nicaragua lake is seen hanging from a wall inside a home damaged by an earthquake in Nagarote. Photo By Esteban Felix/AP |
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| A man carries the remains of the wall of his home, damaged by an earthquake in Nagarote. Photo By Esteban Felix/AP |
"We're trying to take
as many preventive measures as possible to prevent more deaths," said
government spokeswoman and First Lady Rosario Murillo.
President
Daniel Ortega said that he raised the country's alert level to red,
meaning government officials were evacuating everyone at risk of harm
from aftershocks or new quake.
On Thursday night, officials took 155 people out of neighborhoods northeast of the capital city due to risk of landslides. One of the shelters was still housing 22 families on Friday.
Schools closed in the capital and also in the northwestern city of Leon.
The government said roughly 800 homes were damaged in the town of Nagarote and surrounding areas, about 30 miles (50 kilometers) northwest of the capital.
Friday's quake struck at 3:29 p.m. local time (20:29 GMT), and was centered about 6 miles (11 kilometers) east-southeast of the town of Nandaime. It had a depth of 85 miles (138 kilometers).
The USGS said Thursday's quake struck at 5:27 p.m. local time (23:27 GMT), and was centered about 11 miles (18 kilometers) southeast of the city of Larreynaga. It had a depth of 6.2 miles (10 kilometers). - AP.
Tectonic Summary Seismotectonics of the Caribbean Region and Vicinity
Extensive diversity and complexity of tectonic regimes characterizes
the perimeter of the Caribbean plate, involving no fewer than four
major plates (North America, South America, Nazca, and Cocos). Inclined
zones of deep earthquakes (Wadati-Benioff zones), ocean trenches, and
arcs of volcanoes clearly indicate subduction of oceanic lithosphere
along the Central American and Atlantic Ocean margins of the Caribbean
plate, while crustal seismicity in Guatemala, northern Venezuela, and
the Cayman Ridge and Cayman Trench indicate transform fault and
pull-apart basin tectonics.Along the northern margin of the Caribbean plate, the North America plate moves westwards with respect to the Caribbean plate at a velocity of approximately 20 mm/yr. Motion is accommodated along several major transform faults that extend eastward from Isla de Roatan to Haiti, including the Swan Island Fault and the Oriente Fault. These faults represent the southern and northern boundaries of the Cayman Trench. Further east, from the Dominican Republic to the Island of Barbuda, relative motion between the North America plate and the Caribbean plate becomes increasingly complex and is partially accommodated by nearly arc-parallel subduction of the North America plate beneath the Caribbean plate. This results in the formation of the deep Puerto Rico Trench and a zone of intermediate focus earthquakes (70-300 km depth) within the subducted slab. Although the Puerto Rico subduction zone is thought to be capable of generating a megathrust earthquake, there have been no such events in the past century. The last probable interplate (thrust fault) event here occurred on May 2, 1787 and was widely felt throughout the island with documented destruction across the entire northern coast, including Arecibo and San Juan. Since 1900, the two largest earthquakes to occur in this region were the August 4, 1946 M8.0 Samana earthquake in northeastern Hispaniola and the July 29, 1943 M7.6 Mona Passage earthquake, both of which were shallow thrust fault earthquakes. A significant portion of the motion between the North America plate and the Caribbean plate in this region is accommodated by a series of left-lateral strike-slip faults that bisect the island of Hispaniola, notably the Septentrional Fault in the north and the Enriquillo-Plantain Garden Fault in the south. Activity adjacent to the Enriquillo-Plantain Garden Fault system is best documented by the devastating January 12, 2010 M7.0 Haiti strike-slip earthquake, its associated aftershocks and a comparable earthquake in 1770.
Moving east and south, the plate boundary curves around Puerto Rico and the northern Lesser Antilles where the plate motion vector of the Caribbean plate relative to the North and South America plates is less oblique, resulting in active island-arc tectonics. Here, the North and South America plates subduct towards the west beneath the Caribbean plate along the Lesser Antilles Trench at rates of approximately 20 mm/yr. As a result of this subduction, there exists both intermediate focus earthquakes within the subducted plates and a chain of active volcanoes along the island arc. Although the Lesser Antilles is considered one of the most seismically active regions in the Caribbean, few of these events have been greater than M7.0 over the past century. The island of Guadeloupe was the site of one of the largest megathrust earthquakes to occur in this region on February 8, 1843, with a suggested magnitude greater than 8.0. The largest recent intermediate-depth earthquake to occur along the Lesser Antilles arc was the November 29, 2007 M7.4 Martinique earthquake northwest of Fort-De-France.
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| USGS plate tectonics map for the region |
The southern Caribbean plate boundary with the South America plate strikes east-west across Trinidad and western Venezuela at a relative rate of approximately 20 mm/yr. This boundary is characterized by major transform faults, including the Central Range Fault and the Boconó-San Sebastian-El Pilar Faults, and shallow seismicity. Since 1900, the largest earthquakes to occur in this region were the October 29, 1900 M7.7 Caracas earthquake, and the July 29, 1967 M6.5 earthquake near this same region. Further to the west, a broad zone of compressive deformation trends southwestward across western Venezuela and central Columbia. The plate boundary is not well defined across northwestern South America, but deformation transitions from being dominated by Caribbean/South America convergence in the east to Nazca/South America convergence in the west. The transition zone between subduction on the eastern and western margins of the Caribbean plate is characterized by diffuse seismicity involving low- to intermediate-magnitude (Magnitude less than 6.0) earthquakes of shallow to intermediate depth.
The plate boundary offshore of Colombia is also characterized by convergence, where the Nazca plate subducts beneath South America towards the east at a rate of approximately 65 mm/yr. The January 31, 1906 M8.5 earthquake occurred on the shallowly dipping megathrust interface of this plate boundary segment. Along the western coast of Central America, the Cocos plate subducts towards the east beneath the Caribbean plate at the Middle America Trench. Convergence rates vary between 72-81 mm/yr, decreasing towards the north. This subduction results in relatively high rates of seismicity and a chain of numerous active volcanoes; intermediate-focus earthquakes occur within the subducted Cocos plate to depths of nearly 300 km. Since 1900, there have been many moderately sized intermediate-depth earthquakes in this region, including the September 7, 1915 M7.4 El Salvador and the October 5, 1950 M7.8 Costa Rica events.
The boundary between the Cocos and Nazca plates is characterized by a series of north-south trending transform faults and east-west trending spreading centers. The largest and most seismically active of these transform boundaries is the Panama Fracture Zone. The Panama Fracture Zone terminates in the south at the Galapagos rift zone and in the north at the Middle America trench, where it forms part of the Cocos-Nazca-Caribbean triple junction. Earthquakes along the Panama Fracture Zone are generally shallow, low- to intermediate in magnitude (Magnitude less than 7.2) and are characteristically right-lateral strike-slip faulting earthquakes. Since 1900, the largest earthquake to occur along the Panama Fracture Zone was the July 26, 1962 M7.2 earthquake. - USGS.


























