February 9, 2016 - CHILE - A strong earthquake with a preliminary magnitude of 6.3 has struck off the coast of central Chile, centered off Tongoy and La Serena, seismologists say. No tsunami warnings have been issued.
The earthquake, which struck at 9:33 p.m. local time on Tuesday, was
centered in the ocean about 48 kilometers southwest of the coastal town
of Tongoy, or 89 kilometers southwest of La Serena. It struck about 19
kilometers deep, making it a shallow earthquake, according to Chile's
national seismological agency.
USGS shakemap intensity.
Moderate shaking was felt in the Coquimbo Region, according to Chile's
National Office of Emergency of the Interior Ministry (ONEMI). "The
characteristics of the earthquake do not meet the conditions necessary
to generate a tsunami off the coast of Chile," ONEMI said in an alert.
No tsunami warnings have been issued.
Citizens on the streets of La Serena. In some
localities power outages were reported , but no major damage has been
reported so far
Other details were not yet available, but there were no immediate reports of damage or casualties.
Chile and the wider region are on the so-called 'Pacific Ring of Fire'
which is regularly struck by large earthquakes, including the Great
Chilean earthquake that struck the coast of central Chile on May 22,
1960. The 9.5-magnitude earthquake, the largest earthquake ever
instrumentally recorded, left between 490 and 5,700 people killed.
- BNO News.
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.
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. - USGS.
November 10, 2015 - CHILE - A 6.9 magnitude earthquake has struck off the coast of Chile, some 100 kilometers west of Coquimbo, according to USGS.
The epicenter of the
earthquake was located at a depth of just 10 kilometers (6.2 miles),
according to the United States Geological Survey, which initially
reported it as having a magnitude 6.6.
The Pacific Tsunami Warning Center said that based on all available data they have received, there is no threat of a tsunami.
There were no immediate reports of any injuries or damage having
occurred to local buildings. Chile’s Navy confirmed that the parameters
of the quake did not suggest a possible threat of a tsunami occurring.
USGS earthquake shakemap intensity map.
The
quake affected the same region as the deadly 8.3-magnitude earthquake
in September, which killed at least 15 and forced over one million
people to evacuate their homes, triggering tsunami warnings in
California and Hawaii.
Chile
has a long history of major quakes, including the strongest recorded in
recent history. At least 1,655 people were killed and 3,000 injured in
the Great Chilean Earthquake of 1960. - RT.
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.
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. - USGS.
April 6, 2015 - ATACAMA DESERT, CHILE - Dramatic footage of cars, trucks and whole buildings being washed away in muddy water has emerged online after thunderstorms and abnormal rainfall in Chile’s desert Atacama region caused the Copiapo River to break its banks last week.
At least 25 people were killed and 125 others are missing as the floods ravaged the area known as one of the driest places on Earth.
WATCH: Freak rainfall and floods devastate the driest desert in Chile.
The authorities evacuated thousands from their homes in what was described as “the worst rain disaster to fall on the north [of Chile] in 80 years.”
About 2,700 people are currently being housed in emergency accommodation, with around 30,000 people affected by the disaster, the National Emergency Office said.
President Michelle Bachelet was forced to cancel a trip to an international summit to travel to flood-hit Atacama on Sunday.
"We stand with you, as we have from the beginning, and we will rebuild," Bachelet is cited by AFP. "It pains me to see my country in such a state ... we will find a solution."
The president also warned of high risk of disease outbreaks in the area, saying that government is sending thousands of doses of vaccines against flu, tetanus and hepatitis A.
The heavy rains in Chile came after several days of high temperatures and a drought that caused massive wildfires in the south-central regions. - RT.
Flooding caused by abnormally heavy rains cut roads, knocked out electricity and threatened several communities
in the usually bone-dry Atacama desert region this week.
April 3, 2015 - CHILE - The death toll from heavy rains and flooding that battered Chile last week has risen to 23, with another 57 still missing, and President Michelle Bachelet said on Wednesday she would cancel upcoming trips to lead ongoing reconstruction efforts.
The freak torrential downpours in the Atacama desert, normally
the driest in the world, destroyed homes and bridges, cut off roads, and
left thousands stranded as rivers broke their banks and flash floods
dramatically filled dry valleys.
Although the rains ceased by the end of last week, the clear-up
operation continues, with emergency office Onemi saying on Wednesday
around 4,000 people were still in temporary housing and a night-time
curfew remained in place for the worst affected areas, where looting has
been reported.
The Chilean air force said on Wednesday that it was looking for a
helicopter that had disappeared in the Copiapo area. It was not
immediately clear who was on board, although media reported that the
helicopter was privately owned and carrying out rescue operations.
Rescuers say it is highly probable that the death toll will rise
as more victims are found buried under tons of mud and rubble strewn
over the worst-hit areas in northern Chile.
Mines in Chile, the world's top copper exporter, have not reported any
serious damage, although blocked roads forced operations to halt at some
projects.
WATCH: Monumental deluge in Chile.
BACHELET REACTION
Center-left Bachelet has been keen to show she has learnt lessons after
her government came under heavy fire in 2010 for a perceived slow
response to a massive earthquake and tsunami.
"I have instructed the government to keep working non-stop until
people's lives have returned to normal," she said on Wednesday, adding
that she was cancelling international trips scheduled for next week.
She had planned to attend the Summit of the Americas, a gathering of
leaders from the Western Hemisphere, in Panama and visit Ecuador.
Chile was praised for its fast reaction to a quake in the north last year.
But the government has been criticized by some Chileans for a too-slow
response to the developing crisis after the floods. After a torrid month
of natural and political disasters, the president's popularity rating
has hit an all-time low. - Reuters.
Flood rescue in Copiapó. Photo: Carabineros de Chile
March 26, 2015 - CHILE - Floods in northern Chile have killed at least 2 people, with a further 24 still missing.
Torrential
rain and overflowing rivers have caused widespread flooding in the
normally dry regions of Atacama and Antofagasta, northern Chile. A state
of emergency has been called by the government in Chile for both
regions. The region of Coquimbo has also been affected by heavy rain and
floods. Further heavy rain is expected, particularly in Atacama.
The
latest assessments (as of 26 March 2015) indicate that 760 people are
homeless and 5,576 people are housed in 23 shelters that have been set
up in the affected areas.
35 homes have been completely destroyed,
142 have suffered major damage and 799 minor damage, according to the
latest government reports. Victims – Death Toll Increases
The
two deaths reported yesterday occurred in the coastal commune of
Chañaral in the Atacama Region. Wide areas of the town were under around
1.5 metres of water yesterday. UPDATE:
Two further deaths have since been reported by the government. The
deaths occurred in the town of Antofagasta in Antofagasta Region.
About
30 km away from Chañaral, the small village of El Salado has been
completely inundated after the Salado river overflowed, according to
local emergency services. At least 40 people had to be rescued from the
village.
Several other areas, in particular the commune of Taltal, have also been affected by the floods. Copiapó City
The
region’s capital city, Copiapo, has also seen major floods as a result
of the overflowing Copiapo river. Local observers said the streets were
turned to rivers. Copiapó River Dry for 17 Years
Red
alerts have been issued for the municipalities of Tocopilla, Taltal,
Alto de Carmen and Antofagasta province over the last 24 hours. Evacuations
Fear
of mudslides as well as floods prompted 1000s of evacuations. Rescue
and relief operations have been hampered by blocked roads. Chilean
military and rescue teams have used helicopters to carry out
evacuations.
Floods in Chanaral, Chile, March 2015. Photo: Cristhian Acori @ Twitter
Raging floods in El Salado, Chile, March 2015. Photo: Bomberos de Chile
In Atacama, over 400 houses have been damaged or
destroyed and around 2,000 families have been evacuated. Power outages
caused by the floods and rain in the 3 affected regions have left over
50,000 without electricity. Thousands have also been left without
drinking water. Missing People
There are currently at least 24 people missing in the floods. Google have set up a “Google Person Finder” for the floods here. Chile Fighting Disasters on Several Fronts
The
floods in the north came as southern Chile battled devastating
wildfires exacerbated by a severe drought. Earlier this month the
Villarrica volcano in southern Chile erupted, forcing more than 3,000
people from their homes. Peru’s Floods and Landslides
April 10, 2014 - CHILE - A 6.0 magnitude earthquake has struck Chile, says the US Geological Survey.
USGS earthquake location map.
The epicenter of tremor was located 84 kilometers to the south-west of the port city of Iquique in the north of Chile, the same area of northern Chile
where a massive 8.2 earthquake struck on couple weeks ago. The earlier quake,
which caused a tsunami, killed six people and forced almost one million
others to evacuate.
Two powerful 7.6 and 6.4 magnitude aftershocks were also recorded following that quake.
Today's 6.0 quake nested at a depth of 17.5 kilometers (11 miles). There have been no official reports of damage or injury in Chile or Peru, according to Reuters.
USGS earthquake intensity map.
There is no threat of tsunami after the earthquake.
Hundreds of earthquakes have occurred along Chile's far-northern
coast in the past two weeks, starting with a 6.7 magnitude quake that hit on March
16, causing the brief evacuation of 100,000 people in low-lying
areas. No tsunami followed.
An 8.8 magnitude quake and accompanying tsunami hit central Chile
in 2010, killing over 500 people and destroying 220,000 homes,
among other damage.
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.
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. - USGS.
April 04, 2014 - CHILE - A 6.1 magnitude earthquake has struck Chile, says the US Geological Survey.
USGS earthquake location map.
The epicenter of tremor was located 76 kilometers to the south-west of the port city of Iquique in the north of Chile, the same area of northern Chile
where a massive 8.2 earthquake struck on Tuesday. The earlier quake,
which caused a tsunami, killed six people and forced almost one million
others to evacuate.
Two powerful 7.6 and 6.4 magnitude aftershocks were also recorded on Wednesday.
USGS earthquake shakemap intensity map.
The 6.1 quake nested at a depth of 20 kilometers. There have been no official reports of damage or injury in Chile or Peru, according to Reuters.
There is no threat of tsunami after the earthquake.
Hundreds of earthquakes have occurred along Chile's far-northern
coast in the past two weeks, starting with a 6.7 magnitude quake that hit on March
16, causing the brief evacuation of 100,000 people in low-lying
areas. No tsunami followed.
An 8.8 magnitude quake and accompanying tsunami hit central Chile
in 2010, killing over 500 people and destroying 220,000 homes,
among other damage.
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.
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. - USGS.
April 03, 2014 - CHILE - A 7.6-magnitude aftershock has rocked the same area of northern Chile
where a massive 8.2 earthquake struck on Tuesday. The earlier quake,
which caused a tsunami, killed six people and forced almost one million
others to evacuate.
USGS earthquake location map.
The Wednesday quake occurred just before 23:43 local time off the northern coast of Chile, 19 km (14 miles) south of Iquique, according to the US Geological Survey (USGS). The epicenter of the latest quake was located at a shallow depth of 40 km (24.9 miles).
Chile’s emergency ministry has ordered a preventative evacuation along the northern Chilean coastline.
However there have been no official reports of damage or injury in Chile or Peru, according to Reuters.
USGS earthquake shakemap intensity map.
USGS earthquake uncertainty ratio map.
A tsunami warning is now in effect for Chile and Peru following the 7.8 quake, according to the Pacific Tsunami Warning Center. “An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines in the region near the epicenter within minutes to hours,” the PTWC reported.
“Based on all available data a destructive Pacific-wide tsunami is not expected,” it added.
Chilean President Michelle Bachelet has been evacuated from the Arica coast, local media has reported.
A cameraman records near cars caught under rubble after an earthquake
and tsunami hit the
northern port of Iquique April 2, 2014. (Reuters /
Ivan Alvarado)
Aftershocks measuring magnitudes of 5.6 and 5.8 occurred after the 7.6 quake, according to the USGS. Both were located around 70 to 75 km (43 to 46 miles) southwest of Inquique.
Another strong aftershock, measured at magnitude 6.4, also struck 47 km (29 miles) west of Iquique at around 21:00 local time Wednesday evening.
This comes one day after an 8.2 magnitude quake hit 95 km (59 miles) northwest of the same area, around Iquique.
After Tuesday’s quake, tsunami warnings spurred the evacuation of 900,000 people and 11 hospitals along the coastline, government officials said.
At least six people died following the quake, Chile's Interior Minister Rodrigo Penailillo said. Many of the victims died from heart attacks or falling debris. - RT.
This is rolling coverage. Updates will follow as soon as more information is available. Stay tuned.
Tectonic Summary.
The April 3, 2014 M 7.6 earthquake off the west coast of northern
Chile occurred as a result of thrust motion at a depth of approximately
40 km, 23 km south of the city Iquique. The location and mechanism of
the earthquake are consistent with slip on the plate boundary interface,
or megathrust, between the Nazca and South America plates. At the
latitude of the event, the Nazca plate is subducting beneath South
America at a rate of ~73 mm/yr.
This earthquake is an aftershock of the M 8.2 subduction zone
earthquake that occurred April 1, 2014. The M 8.2 event triggered a
tsunami with measured heights near 2 meters along the northern Chile and
southern Peru coasts. Since the M8.2 event, 47 aftershocks ranging from
M 4.2 to this M 7.8 event have occurred, including a M 6.4 on April 2.
The current seismic sequence was preceeded by a foreshock sequence that
began on March 16, 2014, with a M 6.7 earthquake close to the epicenter
of the April 1 M 8.2 event. This segment of the subduction zone, known
as the Iquique or Northern Chile seismic gap, last ruptured during the
1877 M8.8 Iquique earthquake. Other recent large plate boundary ruptures
bound the possible rupture area of the April 1 event, including the
2001 M 8.4 Peru earthquake adjacent to the south coast of Peru to the
north, and the 2007 M 7.7 Tocopilla, Chile and 1995 M 8.1 Antofagasta,
Chile earthquakes to the south.
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.
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. - USGS.
Chile's Magnitude 8.2 Earthquake May Be A Forewarning Of A Larger Event.
Chile is beginning to dig out from a massive 8.2 magnitude earthquake
that struck the region at 8:46 p.m. local time Tuesday evening about 52
miles northwest of the mining town of Iquique, according to the USGS. At
least six people are confirmed dead and tens of thousands have been
evacuated from their homes.
The earthquake touched off tsunami warnings and, according to the BBC,
waves up to six feet battered the shoreline in some areas. Widespread
power outages, fires and landslides were also complicating rescue
efforts. As well, numerous aftershocks were felt throughout the night,
including a 6.2 tremor.
Several regions have been declared disaster areas by the government in hopes of "avoiding instances of looting and disorder."
Shortly after the quake, President Michelle Bachelet promised troops and
police reinforcement would be sent to maintain public order during
rebuilding and repair.
"We're leaving with the children and what we can, but everything is
clogged up by people fleeing buildings by the beach," said 32-year old
Liliana Arriaza, who was driving away with her three children, according
to a Reuters report.
Bachelet said the country had "faced the emergency well" and called on
those in the affected regions "to keep calm and follow instructions from
the authorities."
The country's interior minister told Chilean TV that
the quake allowed 300 woman inmates to escape from a prison in Iquique.
Officials later said that 26 had been recaptured.
WATCH: Chile 8.2 magnitude earthquake blackout terror - Screams, panic as power dies.
At press time, the government said that 50 percent of the power has been restored to affected regions.
While this was already considered a massive earthquake, geologists say
that an even bigger temblor may be lurking in the region's future.
"This magnitude 8.2 is not the large earthquake that we were expecting
in this area," Mark Simons, a geophysicist at Caltech in Pasadena,
California, told CNN. "We're expecting a potentially even larger earthquake."
"We do not know when it's going to occur," he maintained.
To give a better idea why geologists believe a larger quake is in Chile's forecast, a little science is needed.
Chile sits on an arc of volcanoes and fault lines that circles the
Pacific Ocean. This circle, known as the "Pacific Ring of Fire," sees
frequent earthquakes and volcanic eruptions. And Chile is no stranger to
frequent tremors.
Since 1973, more than a dozen magnitude-7.0 or larger quakes have struck Chile. In more recent years, an M8.8 temblor
killed 500 people when it rocked the region in 2010. The quake was so
violent, it moved the whole city about 10 feet to the west.
Simons said Tuesday's quake was of much interest because the fault line
along Chile's coast has been in constant shift for the past 140 years.
NOAA's Pacific Tsunami Warning Center's near real-time animation for the
tsunami from northern Chile on 1 April 2014 resulting from an offshore
8.2 magnitude earthquake in the region. The animation shows simulated
tsunami wave propagation for 30 hours followed by an "energy map"
showing the maximum open-ocean wave heights over that period.
WATCH: Tsunami Animation - 8.2 Magnitude Earthquake In Chile On April 1-2, 2014 .
In recent weeks, as many as 100 smaller quakes have been recorded. But
late last month the region was affected by two larger tremors - a 6.7-
and a 6.1-m.
Simons explains that when a quake occurs the surface can rupture and the
two sides of the fault slip past each other. However, he said that no
surface rupture occurred in the latest quake. And, he added, it "hasn't
ruptured in 140-odd years."
He said it is only a matter of time, however, until an earthquake causes surface rupture.
"We expect another 8.8-8.9 earthquake here sometime in the future,"
Simons told CNN. "[But,] it may not occur for many, many years."
As for last night's temblor, the Pacific Tsunami Warning Center issued
an initial warning for Chile, Peru, Ecuador, Colombia and Panama.
However, all warnings were later lifted except for Chile and Peru.
Tsunami watches were also issued for Costa Rica, Nicaragua, El Salvador,
Guatemala, Mexico and Honduras. As well, a tsunami advisory was issued
for Hawaii, although no disaster was expected to hit the island state.
WATCH: Tsunami observed in Japan.
"Sea level changes and strong currents may occur along all coasts that
could be a hazard to swimmers and boaters as well as to persons near the
shore at beaches and in harbors and marinas," the PTWC said in a
statement.
Japan's Meteorological Agency said that a tsunami of up to three feet
might hit Japan's Pacific Coast about 5:00 a.m. Thursday. After
collecting more data it said it may issue a tsunami advisory early
Thursday.
Patrick Moore, a British expatriate living in Antofagasta, Chile told
the BBC that there had been several tremors since the last quarter of
2013.
"But this earthquake, even with the increased distance, seemed to last a
lot longer," Moore said. "I knew it was bad so I immediately went
online to see what had happened and saw a tsunami warning that's been
put in place which confirmed my fears that it was a big one."
The largest earthquake to hit Chile in recent memory was the 1960
9.5-magnitude event that caused about 1,655 deaths as well as a tsunami
that hit Hawaii and Japan. By comparison, the 2011 Japan earthquake that
killed 15,000 people and caused a nuclear disaster was a 9.0-magnitude
temblor.
- Red Orbit.
April 02, 2014 - CHILE- A massive 8.2 magnitude quake has struck off the coast of northern
Chile, killing 5 people and displacing around 80,000. Damages and fires
have been reported throughout the region and many have lost power
because of the quake.
USGS earthquake location map.
The quake occurred Tuesday, 95 km (59 miles) northwest of the
mining area of Iquique near the Peruvian border. The epicenter
was located at a shallow depth of about 20 km (12 miles) below
the seabed.
The Chilean navy said the first sign of the tsunami hitting the coast was within 45 minutes of the quake. The US Pacific Tsunami Warning Center (PTWC) said a tsunami measuring almost two meters (6.56 feet) had been generated.
Firefighters try to extinguish a fire on a restaurant by the sea shore
after a powerful 8.0-magnitude earthquake
hit off Chile's Pacific coast,
on April 1, 2014 in Iquique. (AFP Photo / Aldo Solimano)
Chile’s emergency ministry ONEMI said there have been reports of landslides causing some blockage on roads and highways.
At least five people have died following the quake, Chile's Interior Minister Rodrigo Penailillo said.
WATCH: Deadly 8.2 earthquake hits Chile.
Complicating any government response to the quake in Chile were reports that 300 female prisoners had escaped. According to The Guardian newspaper, the armed forces was being used to track down the escapees and had recaptured less than 50.
The country’s president, Michelle Bachelet, has declared the
region around the epicenter a “disaster zone” and
praised Chile’s emergency services for their swift response to
the crisis.
Chile's National Seismological Centre upgrades magnitude of earthquake to 8.3.
USGS earthquake shakemap intensity map.
Electricity is out in Iquique, and partially lost in the Peruvian
cities of Tacna, Moquegua, and Arequipa, Reuters reports.
Several aftershocks - ranging from magnitude 5 to 6.2 - were
detected in the area following the earthquake.
WATCH: Aftershocks shake Chile.
Two major fires have been reported in Iquique following the
quake, according to Publimetro. There have also been reports of
looting in the city.
USGS earthquake uncertainty ratio map.
All of the Latin American Pacific coast is under threat for
tsunami activity, according to the US Geological Survey (USGS).
In addition to Chile, a tsunami warning has been issued for Peru,
the Pacific Tsunami Warning Center said. Tsunami watches for
Colombia, Panama, Costa Rica, and Nicaragua have been cancelled.
Aleuy said the tsunami alert for Chile’s coast will last for at
least another six hours after the quake, Reuters reported.
A tsunami energy map released by the National Tsunami Warning Centre after the quake.
“Sea level readings indicate a tsunami was generated," the Pacific Tsunami Warning Center said in a bulletin. "It may have been destructive along coasts near the earthquake epicenter and could also be a threat to more distant coasts.”
The Chile National Office of Emergency of the Interior Ministry (ONEMI) ordered a preventative evacuation for the coastal areas of Arica, Parinacota, and Tarapacá, La Tercera reported.
An estimated tsunami time travel map resulting from the Chilean quake
Chile President Michelle Bachelet suspended all of her scheduled
activities for Wednesday and is evaluating travel to the impacted
region, according to La Tercera.
Peruvian authorities have begun evacuating areas in the southern
coastal region of Ica, RPP radio reported. About 200 people left
the seaside town of Boca del Rio, Peru, according to AP. No
injuries or major damage occurred, said Col. Enrique Blanco,
regional police chief in Tacna, a city of 300,000 on the Chilean
border.
People evacuate buildings in the Chilean port city of Antofagasta
Chile's main mining companies said there was no serious damage to
their operations.
The PTWC said it does not expect a major tsunami to hit the state
of Hawaii.
Map of all seismic activity from the past 2 weeks. iris.edu/seismon/
Hundreds of earthquakes have occurred along Chile's far-northern
coast in the past two weeks. A 6.7 magnitude quake hit on March
16, causing the brief evacuation of 100,000 people in low-lying
areas. No tsunami followed.
An 8.8 magnitude quake and accompanying tsunami hit central Chile
in 2010, killing over 500 people and destroying 220,000 homes,
among other damage.
The Pacific Tsunami Warning Centre has cancelled the tsunami warning for most of countries. A tsunami advisory continues to be in effect in Hawaii
The April 1, 2014 M8.2 earthquake in northern Chile occurred as the
result of thrust faulting at shallow depths near the Chilean coast. The
location and mechanism of the earthquake are consistent with slip on the
primary plate boundary interface, or megathrust, between the Nazca and
South America plates. At the latitude of the earthquake, the Nazca plate
subducts eastward beneath the South America plate at a rate of 65
mm/yr. Subduction along the Peru-Chile Trench to the west of Chile has
led to uplift of the Andes mountain range and has produced some of the
largest earthquakes in the world, including the 2010 M 8.8 Maule
earthquake in central Chile, and the largest earthquake on record, the
1960 M 9.5 earthquake in southern Chile.
The April 1 earthquake occurred in a region of historic seismic
quiescence – termed the northern Chile or Iquique seismic gap. Geodetic
modeling indicates that the subducting and overriding plates are
partially to fully-locked, implying that large earthquake are possible
along the plate boundary megathrust. Historical records indicate a M 8.8
earthquake occurred within the Iquique gap in 1877, which was preceded
immediately to the north by an M 8.8 earthquake in 1868.
A recent increase in seismicity rates has occurred in the
vicinity of the April 1 earthquake. An M6.7 earthquake with similar
faulting mechanism occurred on March 16, 2014 and was followed by 60+
earthquake of M4+, and 26 earthquakes of M5+. The March 16 earthquake
was also followed by three M6.2 events on March 17, March 22, and March
23. The spatial distribution of seismicity following the March 16 event
migrated spatially to the north through time, starting near 20oS and moving to ~19.5oS.
The initial location of the April 1 earthquake places the event near
the northern end of this seismic sequence. Other recent large plate
boundary ruptures bound the possible rupture area of the April 1 event,
including the 2001 M 8.4 Peru earthquake adjacent to the south coast of
Peru to the north, and the 2007 M 7.7 Tocopilla, Chile and 1995 M 8.1
Antofagasta, Chile earthquakes to the south. Other nearby events along
the plate boundary interface include an M 7.4 in 1967 as well as an M
7.7 in 2005 in the deeper portion of the subduction zone beneath onland
Chile.
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.
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. - USGS.
"A big earthquake could strike in a number of years or it could strike sooner - the only thing we can be certain of is that it will strike."
March 25, 2014 - CHILE - Chile's northern coast has been hit
by more than 300 earthquakes in the past week in what seismologists
warned Tuesday could be the precursor to a long-overdue disaster.
A screenshot of a United States Geological Survey (USGS) map showing
earthquakes in the past seven
days stronger than magnitude-4.5 off the
northern coast of Chile.
Most of these quakes have been too small to be felt on land, but people living near the city of Iquique have experienced the rumbling of up to a dozen tremors per day.
Experts analyzing this flood of data are worried the increased seismic activity could be a sign the region is about to experience its first devastating quake in 137 years. The last event, a magnitude-8.5 quake in 1877, killed thousands of people and created a deadly tsunami that reached Hawaii and Japan.
"It is very unusual activity and we are trying to find out what is causing it," said Mario Pardo, deputy head of the seismology center at the University of Chile.
"We usually get around 10
earthquakes per day in this area [many of them very small], but now we
have been getting up to 100 per day," he told NBC News via telephone
from the country's capital Tuesday.
Pardo told NBC News that seismologists are particularly concerned about this cluster of quakes because press reports following the 1877 event said there was a similar "swarm" of tremors beforehand.
"We have been waiting for a big one in this area for some time - this is a place where we are expecting an earthquake of over 8.5 magnitude," he said.
Residents in Chile gather at the Tsunami Safety Zone after a powerful earthquake hit the northwestern coast last week.
Paulina Gonzalez, an expert at the University of Santiago, backed up this analysis. "The latest string of quakes is noteworthy because the last one happened in this seismic zone more than 130 years ago. It's a zone where quakes should happen more often, and they haven’t in a very long time," she told The Associated Press.
Janan Purstey, a geophysicist at the National Earthquake Information Center, part of the USGS in Denver, said seismologists in Chile would be better placed than anyone to assess the threat of the current activity.
Chile is one of the world's most earthquake-prone countries, with its 2,500-mile coastline tracing where the Nazca tectonic plate meets the South American plate.
In 1960 it was hit by the largest earthquake ever recorded: The Valdivia earthquake, also known as the Great Chilean Earthquake, was a catastrophic magnitude-9.5 event that killed up to 6,000 people and created an 80-foot tsunami that reached as far as Hong Kong.
But this, along with a magnitude-8.8
earthquake in 2010, hit much farther south than the region affected by
the current cluster. The major worry for northern Chile is that the 1877
quake created what is known as a seismic gap - a fault line likely to
produce earthquakes because it has been quiet for some time.
Men and women on a main street in Concepcion, Chile, look up toward
building tops as
an earthquake hits the country on May 21, 1960.
The recent northern flurry began on March 16 with a magnitude-6.7 tremor off of Iquique, home to 180,000 people. People living in low-lying areas evacuated their homes to higher ground (shown in the full-bleed image above) but no tsunami materialized.
Since then, Pardo and his peers have seen the needles on their seismographs barely take a rest. They are still unsure of what it means, but they have given a series of hypothetical situations to state and government officials.
"We are working with all our authorities and they now have immediate access to our information in real time," he said. "We just want to make sure people are prepared."
"A big earthquake could strike in a number of years or it could strike sooner," he added. "The only thing we can be certain of is that it will strike." - NBC News.
