1949 Ambato earthquake

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1949 Ambato earthquake
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PACIFIC OCEAN
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ECUADOR
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PERU
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COLOMBIA
1949 Ambato earthquake (Ecuador)
UTC  time1949-08-05 19:08:52
ISC  event 896736
USGS-ANSS ComCat
Local dateAugust 5, 1949 (1949-08-05)
Local time14:08:52
Magnitude6.4 Ms [1]
Epicenter 1°30′S78°12′W / 1.5°S 78.2°W / -1.5; -78.2 Coordinates: 1°30′S78°12′W / 1.5°S 78.2°W / -1.5; -78.2
Areas affected Ecuador
Max. intensity XI (Extreme) [2]
Casualties5,050

The 1949 Ambato earthquake was the deadliest earthquake in the Western Hemisphere in five years. On August 5, 1949, it struck Ecuador's Tungurahua Province southeast of its capital Ambato and killed 5,050 people. Measuring 6.4 on the Ms scale, [1] it originated from a hypocenter 15 km [3] beneath the surface. The nearby villages of Guano, Patate, Pelileo, and Pillaro were destroyed, and the city of Ambato suffered heavy damage. [4] The earthquake flattened buildings and subsequent landslides caused damage throughout the Tungurahua, Chimborazo, and Cotopaxi Provinces. It disrupted water mains and communication lines and opened a fissure into which the small town of Libertad sank. Moderate shaking from the event extended as far away as Quito and Guayaquil. [4]

Contents

Earthquakes in Ecuador stem from two major interrelated tectonic areas: the subduction of the Nazca Plate under the South American Plate and the Andean Volcanic Belt. The 1949 Ambato earthquake initially followed an intersection of several northwest-southeast-trending faults in the Inter-Andean Valley which were created by the subduction of the Carnegie Ridge. Strata of rock cracked as the earthquake ruptured the faults, sending out powerful shock waves. Today threats exist throughout the country from both interplate and intraplate seismicity. [5]

Background

Earthquakes are common in Ecuador. Near the Nazca subduction zone the recorded history of interplate earthquakes spans 80 years. [5] At the time it struck the 1949 Ambato earthquake was the second-worst earthquake in Ecuador's modern history topped only by the 1797 Riobamba earthquake, [6] and the most devastating earthquake in the Western Hemisphere since the 1944 San Juan earthquake. [7] Several major and deadly earthquakes have occurred throughout the country since 1949, including the 1987 Ecuador earthquakes and the 2016 Ecuador earthquake. [8] The 2007 Peru earthquake also affected the country. [9]

Geology

The Nazca Plate is being subducted under the South American Plate, generating volcanism and extensive seismicity. South American plates.png
The Nazca Plate is being subducted under the South American Plate, generating volcanism and extensive seismicity.

Much of South American seismic activity and volcanism originates from subduction of the oceanic Nazca Plate under the continental South American Plate and subduction of the Pacific's lithosphere under the South American continent. This seismicity extends for 6,000 km (3,728 mi) along the continent's western edge and probably stems from a region of northeast-trending faulting near the Ecuadorian Trench. The region of faulting may actually function as its own microplate. [5]

The Carnegie Ridge is sliding under Ecuadorian land, causing coastal uplift and volcanism. The ridge's movement may also have changed the type of faulting along the coast, causing strike-slip faults (faults that move horizontally past each other). Evidence of this subduction altering the course of faulting is found at the Yaquina fault, which, unlike the rest of the Panama Basin faults, trends to the west instead of north-south, indicating that the Carnegie Ridge may be colliding with the continental mass of Ecuador. This collision created northwest-southeast and northeast-southwest-trending faults in the region, and with that, caused strong earthquakes in Riobamba in 1797 and Alausi in 1961. Several of the northwest-southeast-trending faults converge in the Inter-Andean Valley where the 1949 Ambato earthquake took place. [5]

The hypocenter of the earthquake occurred 40 km (25 mi) beneath the surface, under a mountain 72 km (45 mi) from Ambato. Nearby faults ruptured, breaking rock strata and sending shock waves to the surface capable of bringing down entire buildings. Life reported that local seismologists first placed the earthquake's magnitude at 7.5, [7] but the official measurement was later revised to 6.4 Ms . [1]

Damage and casualties

The ruins of homes in Pelileo after the earthquake Ambato Earthquake - Pelileo Ruins.jpg
The ruins of homes in Pelileo after the earthquake

The earthquake was preceded by a foreshock, which, although modest, was strong enough to cause chaos and force people to flee from their homes into the streets. The main shock originated southeast of Ambato. [9] When the primary shock hit Ambato's main cathedral and military barracks collapsed, as did most of the city's buildings, scores of young girls preparing for their First Communion perished in the cathedral. [10] The shaking ruptured water mains, disabled communication lines, opened cracks in the earth, reduced bridges to rubble, [10] and derailed a train. [11] The earthquake demolished buildings in rural hamlets; closer to the nearest mountains of the Andes, landslides destroyed roads and blocked rivers. [6] The village of Libertad near Pelileo sank 460 m (1,509 ft) into a huge hole about 800 m (2,625 ft) in diameter with all of its 100 inhabitants. [12] Shaking up to intensity IV extended as far away as Quito and Guayaquil. [4]

Initial reports (around August 7) estimated the death toll at 2,700 people. [13] The cities of Patate and Pelileo suffered the most with 1,000 and 1,300 dead respectively. In Ambato reports of the death toll ranged from 400 to 500, and the Ecuadorean Embassy in Washington, D.C., estimated that 1,000 to more than 2,000 people were injured. [13] The town of Pillaro, destroyed by the quake, had more than 20 dead, and in Latacunga, 11 were killed and 30 injured; 50 homes, two churches, and the local government building were also ruined. [13] Fifteen other towns and cities were also badly affected, [13] including Guano which was devastated. [4]

Later counts assumed around 3,200 casualties in Pelileo; the total death toll estimates were adjusted to around 4,000 people. Officials reported that many of the dead had been inside buildings as they buckled or were killed by flooding brought about by the blockage of a drainage canal. Others were crushed by landslides from nearby mountains. No homes in the city of Pelileo were left standing, many buildings were flattened, and large cracks formed in the ground. In Ambato alone 75 percent of the homes still standing had to be demolished. [14] On August 8, an aftershock with "considerable strength" struck near Ambato. [15]

The final death toll according to the United States Geological Survey was 5,050. [4] The earthquake severely affected some 30 communities and left approximately 100,000 people homeless. [14]

Relief efforts

Ecuador's President Galo Plaza Lasso flew to Ambato to take personal charge of the primary relief efforts. Plaza directed rescue efforts for two days as airlifts from Quito dropped supplies. A group of Red Cross volunteers and medical supplies were sent on American aircraft. [6] The United States Army sent two relief teams equipped with serum and blood plasma. The mayor of Miami along with seven other politicians began a fund-raising campaign for medical needs and clothing and coordinated the distribution of 69 kg (152 lb) of Rexall drugs. [16] Several nearby countries sent airplanes carrying medicine and food. [17] A local fund-raising effort collected 250,000  Ecuadorian sucres (approximately US$14,815 1949) within two hours of its launch. [10] Plaza said "We have not lost our courage. Neither Ambato nor Ecuador shall cry any more, but begin to work." [6]

On August 7 a plane carrying 34 rescue workers from the Shell Oil Company crashed 32 km (20 mi) from Ambato leaving no survivors. [18] Disease began to spread in Pelileo within days of the earthquake, which prompted a team of American soldiers, acting as relief workers, to order water purification devices and DDT airdrops to cleanse the area of airborne agents. Sick victims were quarantined and prevented from leaving the city. [17]

Aftermath

A hospital ruined by the earthquake in Ambato; almost 75 percent of the city's remaining buildings had to be demolished. Ambato Earthquake - Ruined Hospital.jpg
A hospital ruined by the earthquake in Ambato; almost 75 percent of the city's remaining buildings had to be demolished.

The earthquake considerably impacted a number of cities: it destroyed Guano, Patate, Pelileo, Pillaro, and one-third of Ambato. [4] The city of Ambato was a "scene of anguish and pain" described by "scores of little funerals winding their way through the debris". [18] The brand-new hospital had been reduced to four walls, and most of the buildings in town were demolished. [18] In Pelileo relief workers found victims feeding buried people through holes in the ground. In the days following the earthquakes aftershocks occurred and torrential rains ensued. [19]

In an effort to help the inhabitants a festival of fruit and flowers was held on June 29, 1950. The festival was a success and became an annual event that is celebrated each year during Carnaval and is now an important tourist attraction. [20] [21] Ambato was completely rebuilt after the earthquake. The city's main church, the Iglesia Matriz de Ambato, was replaced by a new cathedral known as Iglesia La Catedral in 1954. [22] Pelileo was rebuilt on a new site 2 km (1.2 mi) from its previous location. [23]

Current situation

Ambato is frequently visited by tourists traveling on the Pan-American Highway. The city is well known for its extensive market, which sells a wide array of items, including local delicacies and flowers, and for its quintas — old estates that serve as historic parks — some of which pre-date the earthquake. [24]

Ecuador is still at risk from earthquakes: Both intraplate (such as those in March 1987) and interplate earthquakes are possible. Intraplate seismicity poses a more formidable threat, as it can be much more powerful than interplate seismicity and is usually associated with landslides, subsidence, and even soil liquefaction. [5]

See also

Related Research Articles

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Ambato, Ecuador City in Tungurahua, Ecuador

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Pelileo

Pelileo is a city located at the center of the Andean region of Ecuador called La Sierra. It is the seat of Pelileo Canton, and forms part of Tungurahua Province.

Carnegie Ridge Aseismic ridge on the Nazca Plate that is being subducted beneath the South American Plate

The Carnegie Ridge is an aseismic ridge on the Nazca Plate that is being subducted beneath the South American Plate. The ridge is thought to be a result of the passage of the Nazca Plate over the Galapagos hotspot. It is named for the research vessel Carnegie, which discovered it in 1929.

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The Nazca Ridge is a submarine ridge, located on the Nazca Plate off the west coast of South America. This plate and ridge are currently subducting under the South American Plate at a convergent boundary known as the Peru-Chile Trench at approximately 7.7 cm (3.0 in) per year. The Nazca Ridge began subducting obliquely to the collision margin at 11°S, approximately 11.2 Ma, and the current subduction location is 15°S. The ridge is composed of abnormally thick basaltic ocean crust, averaging 18 ±3 km thick. This crust is buoyant, resulting in flat slab subduction under Peru. This flat slab subduction has been associated with the uplift of Pisco Basin and the cessation of Andes volcanism and the uplift of the Fitzcarrald Arch on the South American continent approximately 4 Ma.

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1997 Punitaqui earthquake Earthquake in Chile

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The 1797 Riobamba earthquake occurred at 12:30 UTC on 4 February. It devastated the city of Riobamba and many other cities in the Interandean valley, causing between 6,000–40,000 casualties. It is estimated that seismic intensities in the epicentral area reached at least XI (Extreme) on the Mercalli intensity scale, and that the earthquake had a magnitude of 7.6–8.3, the most powerful historical event known in Ecuador. The earthquake was studied by Prussian geographer Alexander von Humboldt, when he visited the area in 1801–1802.

The 1998 Bahía de Caráquez earthquake occurred on August 4 at 13:59 local time with a magnitude Mw 7.2. The epicenter was located at 10 km north of Bahía de Caráquez, about 190 km NNW of Guayaquil, and about 215 km W of Quito, Ecuador. The intensity in Bahía de Caráquez reached MM VIII. In Bahía de Caráquez, electricity, telephone, and water services disrupted, and many buildings were damaged. It was felt strongly in Guayaquil and Quito and could be felt in much of Ecuador and in Cali, Colombia. An Mw  5.4 foreshock occurred 1 hour and 24 minutes before the main shock and hence alerted many people. The Nazca Plate is subducting beneath the South American Plate near the Ecuadorian coast. This earthquake was a shallow thrust earthquake in this subduction zone.

The 1953 Tumbes earthquake occurred on December 12 at 12:31:29 local time near the border between Peru and Ecuador. The shock had a moment magnitude of 7.5, a maximum Mercalli Intensity of VIII (Severe), and occurred in the northwestern offshore area of Tumbes, Peru.

The 1953 Concepción earthquake occurred on May 6 at 17:16 UTC. The epicenter was located offshore Biobío Region, Chile. It had a magnitude of Ms 7.6, or ML 7.6. Twelve people were reported dead in this earthquake.

The 1992 Murindó earthquake occurred on October 18 at 15:11 UTC with an epicenter in the Department of Chocó, northern Colombia. The shallow magnitude 7.2 earthquake struck northwest of the town of Murindó, killing ten and injured more than a hundred. Thirty-three municipalities were severely damaged.

An earthquake measuring Mw 8.0 struck Peru and the surrounding areas on 26 May 2019 at 02:41 local time. It had a maximum perceived intensity of VII on the Modified Mercalli intensity scale in the towns of Yurimaguas and Lagunas. Two people died and a further 30 were injured. It was the strongest earthquake in 2019 by magnitude.

The 1965 Valparaíso earthquake struck near the city of La Ligua in the Valparaíso Region, Chile, about 140 kilometers from the capital Santiago on Sunday, March 28 at 12:33 p.m. (UTC−03:00). The moment magnitude Mw  7.4–7.6 temblor killed an approximate 500 people and caused damages amounting to some US$1 billion. Many of the deaths were from El Cobre, a mining location that was wiped out after a series of dam failures caused by the earthquake spilled mineral waste onto the area, burying hundreds of residents. The shock was so powerful that it could be felt throughout the country and even across the continent to the Atlantic coast of Argentina.

The 1940 Lima earthquake occurred on May 24 at 11:35 a.m. PST with a magnitude of Mw 8.2 on the moment magnitude scale. Shaking from this powerful earthquake was felt throughout the country, and in Ecuador and Chile. An estimated 179 to 300 Peruvians lost their lives while 3,500 left injured by the earthquake. The earthquake was centered near the coastal cities of Huacho and Huaura, about 150 km north of the Peruvian capital, Lima. A tsunami of up to two meters was generated without major damage.

Chile Ridge Submarine oceanic ridge in the Pacific Ocean

The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca Plate and the Antarctic Plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates to the Southern coast of Chile. The Chile Ridge is easy to recognize on the map, as the ridge is divided into several segmented fracture zones which are perpendicular to the ridge segments, showing an orthogonal shape toward the spreading direction. The total length of the ridge segments is about 550–600 km.

References

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  3. ISC-EB Event 896736 [ IRIS ]
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  14. 1 2 "100,000 Homeless In Ecuadorian Earthquake". The Telegraph . Terrence Williams. August 9, 1949. Retrieved August 5, 2010.
  15. "Another Earthquake Strikes in Ecuador". The Southeast Missourian. August 9, 1949. Archived from the original on April 28, 2016. Retrieved August 5, 2010.
  16. "Florida East Coast Cities Head Drive to Supply Relief to Stricken Ecuador". Evening Independent . August 12, 1949. Archived from the original on May 5, 2016. Retrieved September 11, 2010.
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  18. 1 2 3 "Latest Reports on Earthquake". The Sydney Morning Herald . August 8, 1949.
  19. "Ecuador Victims Homeless in Downpour". The Sydney Morning Herald. August 10, 1949.
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