A collapsed building is seen in Pedernales, after an earthquake struck off Ecuador's Pacific coast, April 22, 2016. Reuters/Guillermo Granja
April 24, 2016 - ECUADOR - Hovering over collapsed buildings and piles of debris, a drone
has captured a scary panorama of the Ecuadorian city of Manta struck by
the country’s latest deadly earthquake.
The drone flies around
what seems to be a badly damaged block of flats, and then a hotel with
broken windows, and curtains blown into the empty rooms by the wind.
There is a skewed building of a hotel that is almost collapsing, with very few people or cars in the empty streets.
The death toll from Ecuador's devastating 7.8 magnitude earthquake last week has risen to 654 people, the country's emergency management authority said on Saturday.
Last Saturday's quake, the worst in nearly seven decades, injured around 16,600 people and left 58 missing along the country's ravaged Pacific coast. One hundred and thirteen people were rescued from damaged buildings.
"These have been sad days for the homeland," President Rafael Correa said during his weekly television broadcast earlier on Saturday. "The country is in crisis."
The aftershocks have been striking almost daily, with the latest a
5.8-magnitude tremor that hit in the early hours of Saturday and 6.0
tremor that hit Friday.
RT Ruptly
Residents receive food from volunteers at the Reales Tamarindos airport which is used as a shelter. Reuters/Henry Romero
A girl is pictured next to a line of clothes hung out to dry outside a tent at the Reales Tamarindos airport which is used as a shelter. Reuters/Henry Romero
A resident is pictured as clothes are hung out to dry outside a tent at the Reales Tamarindos airport which is used as a shelter. Reuters/Henry Romero
A resident rests outside his damaged home in Portoviejo, after an earthquake struck off Ecuador's Pacific coast, April 22, 2016. Reuters/Henry Romero
Several strong tremors and more than 700 aftershocks have continued to shake the country since the major quake, sparking momentary panic but little additional damage. Tremors are expected to continue for several weeks.
With close to 7,000 buildings destroyed, more than 25,000 people were living in shelters. Some 14,000 security personnel were keeping order in quake-hit areas, with only sporadic looting reported.
Survivors in the quake zone were receiving food, water and medicine from the government and scores of foreign aid workers, although Correa has acknowledged that bad roads delayed aid reaching some communities.
WATCH: Drone footage reveals scale of destruction by Ecuador quake.
Correa's leftist government, facing mammoth rebuilding at a time of greatly reduced oil revenues for the OPEC country, has said it would temporarily increase some taxes, offer assets for sale and possibly issue bonds abroad to fund reconstruction. Congress will begin debate on the tax proposal on Tuesday.
Correa has estimated damage at $2 billion to $3 billion. Lower oil revenue has already left the country of 16 million people facing near-zero growth and lower investment.
The country's private banking association said on Saturday its member banks would defer payments on credit cards, loans and mortgages for clients in the quake zone for three months, to help reconstruction efforts.
April 23, 2016 - ECUADOR - A 5.8-magnitude earthquake has struck off the coast of Ecuador, about 16
miles west of Muisne, a town in the northwestern Esmeraldas province,
the US Geological Survey (USGS) reports.
The earthquake occurred at 01:24 GMT on Saturday (20:24 p.m. local time
on Friday). There were no immediate reports of damages or casualties.
On April 16, Ecuador was hit by a 7.8-magnitude earthquake, with its
epicenter located near the town of Pedernales in Manabi province, which
is situated south of Esmeraldas province. Over 600 people died as a
result and more than 8,000 were injured.
According to the UN Office for the Coordination of Humanitarian Affairs
(OCHA), over 300 aftershocks have been registered after the quake.
USGS earthquake location.
More than 1,100 buildings have been destroyed in Ecuador and
over 800 have been damaged, including more than 280 schools, according
to OCHA.
Ecuador and the United Nations have launched a $72.7 million appeal to
assist the country in dealing with the consequences of the 7.8-magnitude
earthquake. The World Bank has agreed to allocate $150 million to
Ecuador.
According to Ecuador's President Rafael Correa, the damage caused by the 7.8-magnitude earthquake is estimated at $3 billion.
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.
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. -
April 22, 2016 - ECUADOR - A 6.0-magnitude earthquake has struck off the coast of Ecuador,
the US Geological Survey (USGS) has reported.
The new tremblor
comes just days after a devastating 7.8 quake killed at least 587 people
in the South American country and amid internationally-assisted
recovery efforts.
The earthquake was centered some 33.0
kilometers (20.5 miles) north-northwest of Bahia de Caraquez and some
100 kilometers (62 miles) from the city of Portoviejo. It hit at a depth
of 10 kilometers.
USGS shakemap intensity.
The latest tremblor came just days after a strong 7.8 magnitude quake hit the country on Saturday, whose death toll has already climbed to over 580 victims, the government reported on Thursday. With 155 people still unaccounted for, the death toll is expected to rise even further, however.
Soldiers stand guard next to a collapsed buildings at the village of
Manta, after an earthquake struck off Ecuador's Pacific coast, April 21,
2016.
Henry Romero / Reuters
The damage to the country’s infrastructure appears unprecedented, with over 23,500 people left without homes. The quake was followed by two aftershocks of 6.1 and 6.3 magnitudes. The country’s president, Rafael Correa, said that the damages inflicted by the disaster are estimated at a staggering $3 billion.
He has consequently announced plans to raise taxes in order to rebuild the affected areas.Correa said on Twitter that three aftershocks were registered on Thursday night, two of which were “fairly strong.” He called on residents to “keep calm”.
WATCH: Cape Verde - Russian humanitarian aid aircraft en route to Ecuador .
“We should expect about ten aftershocks of that magnitude,” he added.Russia’s Emergency Ministry has sent an airplane carrying 30 tons of humanitarian aid to Ecuador, including food, tents, and mobile electric stations on order of Russian President Vladimir Putin.
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.
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. -
April 20, 2016 - JAPAN -
A magnitude 6.1 earthquake struck off Japan's north-eastern coast on
Wednesday (April 20), the US Geological Survey said. There was no
immediate tsunami warning, or reports of damage or casualties.
A series of strong quakes struck the south of Japan late last week
killed at least 58 people. On Wednesday, survivors struggled with
shortages of food and water.
USGS shakemap intensity.
The USGS said Wednesday's quake was centred 104km east south-east of
Sendai, Honshu, near where a devastating quake and tsunami struck in
March 2011. It was 51km deep.
Seismotectonics of Japan and Vicinity
The
North America plate, Pacific plate, Philippine Sea plate, and Eurasia
plate all influence the tectonic setting of Japan, Taiwan, and the
surrounding area. Some authors divide the edges of these plates into
several microplates that together take up the overall relative motions
between the larger tectonic blocks, including the Okhotsk microplate in
northern Japan, the Okinawa microplate in southern Japan, the Yangzee
microplate in the area of the East China Sea, and the Amur microplate in
the area of the Sea of Japan.
The seafloor expression
of the boundary between the Pacific and North America plates lies 300
km off the east coasts of Hokkaido and Honshu at the Kuril-Kamchatka and
Japan trenches. The subduction of the Pacific plate beneath the North
America plate, at rates of 83-90 mm/yr, generates abundant seismicity,
predominantly as a result of interplate slip along the interface between
the plates. The 1958 M 8.4 Etorofu, 1963 M 8.6 Kuril, 2003 M 8.3
Tokachi-Oki, and the 2011 M 9.0 Tohoku earthquakes all exemplify such
megathrust seismicity. The 1933 M 8.4 Sanriku-Oki earthquake and the
1994 M 8.3 Shikotan earthquake are examples of intraplate seismicity,
caused by deformation within the lithosphere of the subducting Pacific
plate (Sanriku-Oki) and of the overriding North America plate
(Shikotan), respectively.
USGS plate tectonics for the region.
At the southern terminus of the
Japan Trench the intersection of the Pacific, North America, and
Philippine Sea plates forms the Boso Triple Junction, the only example
of a trench-trench-trench intersection in the world. South of the triple
junction the Pacific plate subducts beneath the Philippine Sea plate at
the Izu-Ogasawara trench, at rates of 45-56 mm/yr. This margin is
noteworthy because of the steep dip of the subducting Pacific plate (70°
or greater below depths of 50 km depth), and because of its
heterogeneous seismicity; few earthquakes above M 7 occur at shallow
depths, yet many occur below 400 km. The lack of large shallow
megathrust earthquakes may be a result of weak coupling at the plate
interface, or simply a reflection of an incomplete earthquake catalog
with respect to the length of typical seismic cycles.
The
northernmost section of the Philippine Sea plate shares a 350 km
boundary with the North America plate that runs approximately east-west
from the Boso Triple Junction towards the Izu Peninsula. This short
boundary is dominated by the subduction of the Philippine Sea plate
beneath Japan along the Sagami Trough, but also includes small sections
of transform motion.
The subduction of the Philippine
Sea plate under the Eurasia plate begins at the Suruga Trough,
immediately southwest of the Izu peninsula. In the northern Tōkai,
Tonankai and Nankai sections of this subduction zone, historical data
indicate M 8+ earthquake recurrence intervals of 100-150 years. The
Tonankai and Nankai sections last ruptured in M 8.1 earthquakes in 1944
and 1946, respectively, while the Tōkai section last broke in 1854. In
the 1980's studies began to forecast the imminence of a large earthquake
in the Tōkai region, and warned of its potential impact on the cities
of Tokyo and Yokohama (the two largest cities in Japan); to date, the
expected event has not occurred.
The boundary between
the Philippine Sea and Eurasia plates continues south and southwestwards
from the Suruga Trough, extending 2000 km along the Nankai and Ryukyu
trenches before reaching the island of Taiwan. Along the Ryukyu Trench,
the Philippine Sea plate exhibits trench normal subduction at rates
increasing from 48 mm/yr in the northeast to 65 mm/yr in the southwest.
Convergence and the associated back-arc deformation west of the oceanic
trench creates the Ryukyu Islands and the Okinawa Trough. The largest
historic event observed along this subduction zone was the M 8.1 Kikai
Island earthquake in 1911.
In the vicinity of Taiwan
the structure of the Philippine Sea: Eurasia plate boundary and the
associated pattern of seismicity becomes more complex. 400 km east of
Taiwan a clockwise rotation in the trend of the margin (from NE-SW to
E-W), paired with an increase in subduction obliquity creates a section
of the plate boundary that exhibits dextral transform and oblique
thrusting motions. South of Taiwan the polarity of subduction flips; the
Eurasia plate subducts beneath the Philippine Sea plate. Debate
surrounds contrasting models of the plate boundary position between the
zones of oppositely verging subduction, and the boundary's relation to
patterns of seismicity. Many studies propose that crustal thickening
causes the majority of regional seismicity, while others attribute
seismicity to deformation associated with subduction. Another resolution
proposes a tear in the Philippine Sea plate and a complex assortment of
subduction, transform, and collisional motion. All the models concede
that seismicity around the island of Taiwan is anomalously shallow, with
few earthquakes deeper than 70km.
While there are no
instances of an earthquake Magnitude greater than 8 in the modern
record, Taiwan and its surrounding region have experienced eight
Magnitude greater than 7.5 events between 1900 and 2014. The dominance
of shallow Magnitude less than 8 earthquakes suggests fairly weak plate
boundary coupling, with most earthquakes caused by internal plate
deformation. The 1935 M 7.1 Hsinchu-Taichung earthquake and the 1999 M
7.6 Chi-Chi Earthquake both exemplify the shallow continental crust
thrust faulting that dominates regional seismicity across the island. A
major tectonic feature of the island is the Longitudinal Valley Fault,
which ruptures frequently in small, shallow earthquakes. In 1951, the
Longitudinal Valley Fault hosted twelve Magnitude greater than or equal
to 6 events known as the Hualien-Taitung earthquake sequence.
Large
earthquakes in the vicinity of Japan and Taiwan have been both
destructive and deadly. The regions high population density makes
shallow earthquakes especially dangerous. Since 1900 there have been 13
earthquakes (9 in Japan, 4 in Taiwan) that have each caused over 1000
fatalities, leading to a total of nearly 200,000 earthquake related
deaths. In January 1995 an earthquake that ruptured a southern branch of
the Japan Median Tectonic Line near the city of Kobe (population 1.5
million) killed over 5000 people. The 1923 Kanto earthquake shook both
Yokohama (population 500,000, at that time) and Tokyo (population 2.1
million), killing 142,000 people. The earthquake also started fires that
burned down 90% of the buildings in Yokohama and 40% of the buildings
in Tokyo. Most recently, the M9.0 Tohoku earthquake, which ruptured a
400 km stretch of the subduction zone plate boundary east of Honshu, and
the tsunami it generated caused over 20,000 fatalities.
April 20, 2016 - ECUADOR - Magnitude 6.2 and 6.0 earthquakes struck off the coast of Ecuador this morning,just days after a major quake hit the country, killing nearly 500 people.
This morning's quakes was centred 70km west-southwest of Esmeraldas at a shallow depths of 10km and 14km, the Pacific Tsunami Warning Center said, not far from the epicentre of Saturday's 7.8 magnitude quake.
Reuters witnesses in the zone said two strong tremors of about
30 seconds each were felt, waking people up and sending them racing them
into the streets.
It was not felt in the highland capital of Quito.
There was no immediate word from authorities on the impact of this morning's quake.
USGS shakemap intensity.
More than 100 people are still missing from the weekend disaster, with rescuers losing hope of finding more survivors.
It was Ecuador's worst earthquake in decades.
It destroyed or damaged about 1,500 buildings, triggered mudslides and
left about 20,500 people sleeping in shelters, according to the
government.
Rescue teams had been using dogs, their bare hands and excavators to
hunt through debris of flattened homes, hotels and shops in the
hardest-hit Pacific coastal region.
More than 100 people are still missing from the weekend earthquake
Supervising rescue work in the disaster zone, Ecuador's President Rafael
Correa said Saturday's quake inflicted $2bn to $3bn of damage to the
oil-dependent economy.
"Let's not kid ourselves, it will be a long struggle. Reconstruction for
years, billions [of dollars] in investment," said Mr Correa.
"In the short term, we're going to need tens of millions of dollars," he said from the quake-hit town of Tarqui.
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.
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. -
April 20, 2016 - INDIA - A subduction process similar to the one that caused the Ecuadorean quake
is happening under the Himalayan region as well, where the Indian plate
is getting inside the Chinese landmass.
This northward push has been creating a huge amount of tectonic strain
in the region, making it particularly prone to earthquakes.
Scientists believe there is so much energy stored in the area
that an earthquake of magnitude greater than 8, possibly even 9, would
be needed to release it. This earthquake can come at any time.
The Nepal earthquake was a result of this same process, but it was relatively weak in magnitude.
Interestingly, historical data from the US Geological Survey
shows that on an average only one earthquake of magnitude 8 or above,
called as 'great earthquakes', takes place in a year anywhere in the
world. This year there hasn't been a 8-plus quake so far.
There have been aberrations. The year 2007, for example, witnessed as
many as four 8-plus earthquakes - in Kuril Islands in north Pacific,
Soloman Islands near Australia, central Peru, and in Sumatra in
Indonesia. The years 1920, 1923, 1946, 1960 and 1995 each had three of
these big events.
On the other hand, in recent memory, 2002, 2008 and 2013, did not have any 8-plus earthquake.
Still,
the period after 2000 has been one of the most frequent for 'great
earthquakes'. As many as 20 of these events have happened in these 15
years.
The frequency of earthquakes every year increases exponentially as we
look at smaller magnitudes. Earthquakes of magnitude between 7 and 7.9
happen 15 times on an average every year, while 134 instances of
earthquakes between 6 and 6.9 are recorded every year.
WATCH: Explained - The Afghanistan Earthquake That Rocked North India.
April 19, 2016 - MEXICO - The Popocatépetl volcano in Mexico erupted overnight, sending lava flying as far as a mile away from the mountain.
The Puebla airport, directly east of the volcano, has been
closed and officials are urging residents to wear masks and avoid
inhaling ash covering the city.
There are approximately 25 million people who live within 62 miles, or 100 kilometers, of the active volcano.
The eruption of the 17,797-foot stratovolcano, the second highest peak
in Mexico, began around 2:30AM, sending ash almost two miles into the
sky.
Popocatépetl is the most active volcano in the country, with documented
eruptions dating back to the arrival of the Spanish in 1519.
WATCH: Popocatepetl erupts.
It has been
active since 1991, after being dormant for approximately half a
century.
Since 1993, smoke has constantly billowed from the crater.
The most recent eruption was April 3, just 15 days ago.
The name Popocatépetl is derived from the Nahuatl words popōca 'it
smokes' and tepētl meaning 'mountain,' translating to Smoking Mountain.
Among locals, it is commonly referred to as El Popo. - Sputnik.
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.
USGS shakemap intensity.
"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.
"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.
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. -
April 5, 2016 - MEXICO - A video has emerged of the spectacular eruption of Mexico’s Popocatepetl
volcano, Sunday, showcasing the explosion as it lit up the night sky,
throwing lava and ash high into the air.
The Popocatepetl volcano, located in central Mexico, erupted at
20:31 p.m. local time, with smoke and ash rising to a height of 2,000
meters (6,562ft), according to Mexico’s National Disaster Prevention
Center.
— Webcams de México (@webcamsdemexico) April 4, 2016
A large dome of lava, formed in January, was destroyed during the recent explosions, leaving a new inner crater in its place.Rocks were also swept into the sky to an altitude of 3,500 meters (11,483ft).
Popocatepetl,
also known as “Don Goyo”, located about 80km (50 miles) southeast of
Mexico City, is one of the country's most-active volcanoes, erupting 15
times since records began.
WATCH: Extraordinary eruption of the Popocatepetl volcano.
Situated in the eastern half of the
Trans-Mexican volcanic belt, the volcano is the second highest peak in
Mexico, standing at more than 5,181 meters (17,000ft). - RT.
April 1, 2016 - PAPUA NEW GUINEA - A strong 6.1-magnitude earthquake struck off Papua New Guinea's
northern coast on Saturday (Apr 2), the US Geological Survey said, with
no immediate tsunami warning issued.
The shallow quake hit at
5.24am local time (1924 GMT Friday) about 120 kilometres (75 miles)
northeast of Angoram and over 700 kilometres from the island's capital
Port Moresby, USGS said.
No damage or injuries were immediately reported.
USGS shakemap intensity.
The Hawaii-based Pacific Tsunami Warning Center had no alerts on its website following the quake.
Quakes
are common on the island nation that lies on the 4,000-kilometre-long
Pacific Australia plate, which forms part of the "Ring of Fire", a
hotspot for seismic activity due to friction between tectonic plates. - Channel News Asia.
Seismotectonics of the New Guinea Region and Vicinity
The Australia-Pacific plate boundary is over 4000 km long on the northern margin, from the Sunda (Java) trench in the west to the Solomon Islands in the east. The eastern section is over 2300 km long, extending west from northeast of the Australian continent and the Coral Sea until it intersects the east coast of Papua New Guinea. The boundary is dominated by the general northward subduction of the Australia plate.
Along the South Solomon trench, the Australia plate converges with the Pacific plate at a rate of approximately 95 mm/yr towards the east-northeast. Seismicity along the trench is dominantly related to subduction tectonics and large earthquakes are common: there have been 13 M7.5+ earthquakes recorded since 1900. On April 1, 2007, a M8.1 interplate megathrust earthquake occurred at the western end of the trench, generating a tsunami and killing at least 40 people. This was the third M8.1 megathrust event associated with this subduction zone in the past century; the other two occurred in 1939 and 1977.
USGS plate tectonics for the region.
Further east at the New Britain trench, the relative motions of several microplates surrounding the Australia-Pacific boundary, including north-south oriented seafloor spreading in the Woodlark Basin south of the Solomon Islands, maintain the general northward subduction of Australia-affiliated lithosphere beneath Pacific-affiliated lithosphere. Most of the large and great earthquakes east of New Guinea are related to this subduction; such earthquakes are particularly concentrated at the cusp of the trench south of New Ireland. 33 M7.5+ earthquakes have been recorded since 1900, including three shallow thrust fault M8.1 events in 1906, 1919, and 2007.
The western end of the Australia-Pacific plate boundary is perhaps the most complex portion of this boundary, extending 2000 km from Indonesia and the Banda Sea to eastern New Guinea. The boundary is dominantly convergent along an arc-continent collision segment spanning the width of New Guinea, but the regions near the edges of the impinging Australia continental margin also include relatively short segments of extensional, strike-slip and convergent deformation. The dominant convergence is accommodated by shortening and uplift across a 250-350 km-wide band of northern New Guinea, as well as by slow southward-verging subduction of the Pacific plate north of New Guinea at the New Guinea trench. Here, the Australia-Pacific plate relative velocity is approximately 110 mm/yr towards the northeast, leading to the 2-8 mm/yr uplift of the New Guinea Highlands.
Whereas the northern band of deformation is relatively diffuse east of the Indonesia-Papua New Guinea border, in western New Guinea there are at least two small (less than 100,000 km²) blocks of relatively undeformed lithosphere. The westernmost of these is the Birds Head Peninsula microplate in Indonesia's West Papua province, bounded on the south by the Seram trench. The Seram trench was originally interpreted as an extreme bend in the Sunda subduction zone, but is now thought to represent a southward-verging subduction zone between Birds Head and the Banda Sea.
There have been 22 M7.5+ earthquakes recorded in the New Guinea region since 1900. The dominant earthquake mechanisms are thrust and strike slip, associated with the arc-continent collision and the relative motions between numerous local microplates. The largest earthquake in the region was a M8.2 shallow thrust fault event in the northern Papua province of Indonesia that killed 166 people in 1996.
The western portion of the northern Australia plate boundary extends approximately 4800 km from New Guinea to Sumatra and primarily separates Australia from the Eurasia plate, including the Sunda block. This portion is dominantly convergent and includes subduction at the Sunda (Java) trench, and a young arc-continent collision.
In the east, this boundary extends from the Kai Islands to Sumba along the Timor trough, offset from the Sunda trench by 250 km south of Sumba. Contrary to earlier tectonic models in which this trough was interpreted as a subduction feature continuous with the Sunda subduction zone, it is now thought to represent a subsiding deformational feature related to the collision of the Australia plate continental margin and the volcanic arc of the Eurasia plate, initiating in the last 5-8 Myr. Before collision began, the Sunda subduction zone extended eastward to at least the Kai Islands, evidenced by the presence of a northward-dipping zone of seismicity beneath Timor Leste. A more detailed examination of the seismic zone along it's eastern segment reveals a gap in intermediate depth seismicity under Timor and seismic mechanisms that indicate an eastward propagating tear in the descending slab as the negatively buoyant oceanic lithosphere detaches from positively buoyant continental lithosphere. On the surface, GPS measurements indicate that the region around Timor is currently no longer connected to the Eurasia plate, but instead is moving at nearly the same velocity as the Australia plate, another consequence of collision.
Large earthquakes in eastern Indonesia occur frequently but interplate megathrust events related to subduction are rare; this is likely due to the disconnection of the descending oceanic slab from the continental margin. There have been 9 M7.5+ earthquakes recorded from the Kai Islands to Sumba since 1900. The largest was the great Banda Sea earthquake of 1938 (M8.5) an intermediate depth thrust faulting event that did not cause significant loss of life.
March 31, 2016 - JAPAN - A magnitude 6.0 earthquake struck south west Japan on Friday (Apr 1), 56
kilometres from Shingu city, according to the US Geological Survey.
The quake hit at a depth of 10 km just before midday local time and was felt throughout Wakayama prefecture.
Local media reported the quake initially at magnitude 6.1 with NHK
saying Tokaido Shinkansen services were suspended temporarily as a
precaution.
No tsunami alert was issued. Although there may be slight sea-level
changes in coastal regions, no damage was expected, the Japan
Meteorological Agency said.
USGS shakemap intensity.
Earthquakes are common throughout Japan; more than 750 have been registered in the past year.
Japan sits at the junction of four tectonic plates and experiences around 20 percent of the world's most powerful earthquakes.
But rigid building codes and strict enforcement mean even powerful tremors frequently do little damage.
A massive undersea quake that hit in March 2011 sent a tsunami
barrelling into Japan's northeast coast, leaving 18,500 people dead or
missing, and sending several reactors into meltdown at the Fukushima
nuclear plant in the worst atomic accident in a generation. - Channel News Asia.
Seismotectonics of Japan and Vicinity
The North America plate, Pacific plate, Philippine Sea plate, and Eurasia plate all influence the tectonic setting of Japan, Taiwan, and the surrounding area. Some authors divide the edges of these plates into several microplates that together take up the overall relative motions between the larger tectonic blocks, including the Okhotsk microplate in northern Japan, the Okinawa microplate in southern Japan, the Yangzee microplate in the area of the East China Sea, and the Amur microplate in the area of the Sea of Japan.
The seafloor expression of the boundary between the Pacific and North America plates lies 300 km off the east coasts of Hokkaido and Honshu at the Kuril-Kamchatka and Japan trenches. The subduction of the Pacific plate beneath the North America plate, at rates of 83-90 mm/yr, generates abundant seismicity, predominantly as a result of interplate slip along the interface between the plates. The 1958 M 8.4 Etorofu, 1963 M 8.6 Kuril, 2003 M 8.3 Tokachi-Oki, and the 2011 M 9.0 Tohoku earthquakes all exemplify such megathrust seismicity. The 1933 M 8.4 Sanriku-Oki earthquake and the 1994 M 8.3 Shikotan earthquake are examples of intraplate seismicity, caused by deformation within the lithosphere of the subducting Pacific plate (Sanriku-Oki) and of the overriding North America plate (Shikotan), respectively.
USGS plate tectonics for the region.
At the southern terminus of the Japan Trench the intersection of the Pacific, North America, and Philippine Sea plates forms the Boso Triple Junction, the only example of a trench-trench-trench intersection in the world. South of the triple junction the Pacific plate subducts beneath the Philippine Sea plate at the Izu-Ogasawara trench, at rates of 45-56 mm/yr. This margin is noteworthy because of the steep dip of the subducting Pacific plate (70° or greater below depths of 50 km depth), and because of its heterogeneous seismicity; few earthquakes above M 7 occur at shallow depths, yet many occur below 400 km. The lack of large shallow megathrust earthquakes may be a result of weak coupling at the plate interface, or simply a reflection of an incomplete earthquake catalog with respect to the length of typical seismic cycles.
The northernmost section of the Philippine Sea plate shares a 350 km boundary with the North America plate that runs approximately east-west from the Boso Triple Junction towards the Izu Peninsula. This short boundary is dominated by the subduction of the Philippine Sea plate beneath Japan along the Sagami Trough, but also includes small sections of transform motion.
The subduction of the Philippine Sea plate under the Eurasia plate begins at the Suruga Trough, immediately southwest of the Izu peninsula. In the northern Tōkai, Tonankai and Nankai sections of this subduction zone, historical data indicate M 8+ earthquake recurrence intervals of 100-150 years. The Tonankai and Nankai sections last ruptured in M 8.1 earthquakes in 1944 and 1946, respectively, while the Tōkai section last broke in 1854. In the 1980's studies began to forecast the imminence of a large earthquake in the Tōkai region, and warned of its potential impact on the cities of Tokyo and Yokohama (the two largest cities in Japan); to date, the expected event has not occurred.
The boundary between the Philippine Sea and Eurasia plates continues south and southwestwards from the Suruga Trough, extending 2000 km along the Nankai and Ryukyu trenches before reaching the island of Taiwan. Along the Ryukyu Trench, the Philippine Sea plate exhibits trench normal subduction at rates increasing from 48 mm/yr in the northeast to 65 mm/yr in the southwest. Convergence and the associated back-arc deformation west of the oceanic trench creates the Ryukyu Islands and the Okinawa Trough. The largest historic event observed along this subduction zone was the M 8.1 Kikai Island earthquake in 1911.
In the vicinity of Taiwan the structure of the Philippine Sea: Eurasia plate boundary and the associated pattern of seismicity becomes more complex. 400 km east of Taiwan a clockwise rotation in the trend of the margin (from NE-SW to E-W), paired with an increase in subduction obliquity creates a section of the plate boundary that exhibits dextral transform and oblique thrusting motions. South of Taiwan the polarity of subduction flips; the Eurasia plate subducts beneath the Philippine Sea plate. Debate surrounds contrasting models of the plate boundary position between the zones of oppositely verging subduction, and the boundary's relation to patterns of seismicity. Many studies propose that crustal thickening causes the majority of regional seismicity, while others attribute seismicity to deformation associated with subduction. Another resolution proposes a tear in the Philippine Sea plate and a complex assortment of subduction, transform, and collisional motion. All the models concede that seismicity around the island of Taiwan is anomalously shallow, with few earthquakes deeper than 70km.
While there are no instances of an earthquake Magnitude greater than 8 in the modern record, Taiwan and its surrounding region have experienced eight Magnitude greater than 7.5 events between 1900 and 2014. The dominance of shallow Magnitude less than 8 earthquakes suggests fairly weak plate boundary coupling, with most earthquakes caused by internal plate deformation. The 1935 M 7.1 Hsinchu-Taichung earthquake and the 1999 M 7.6 Chi-Chi Earthquake both exemplify the shallow continental crust thrust faulting that dominates regional seismicity across the island. A major tectonic feature of the island is the Longitudinal Valley Fault, which ruptures frequently in small, shallow earthquakes. In 1951, the Longitudinal Valley Fault hosted twelve Magnitude greater than or equal to 6 events known as the Hualien-Taitung earthquake sequence.
Large earthquakes in the vicinity of Japan and Taiwan have been both destructive and deadly. The regions high population density makes shallow earthquakes especially dangerous. Since 1900 there have been 13 earthquakes (9 in Japan, 4 in Taiwan) that have each caused over 1000 fatalities, leading to a total of nearly 200,000 earthquake related deaths. In January 1995 an earthquake that ruptured a southern branch of the Japan Median Tectonic Line near the city of Kobe (population 1.5 million) killed over 5000 people. The 1923 Kanto earthquake shook both Yokohama (population 500,000, at that time) and Tokyo (population 2.1 million), killing 142,000 people. The earthquake also started fires that burned down 90% of the buildings in Yokohama and 40% of the buildings in Tokyo. Most recently, the M9.0 Tohoku earthquake, which ruptured a 400 km stretch of the subduction zone plate boundary east of Honshu, and the tsunami it generated caused over 20,000 fatalities.
