1868 Ecuador earthquakes
Encyclopedia
The 1868 Ecuador earthquakes occurred at 19:30 UTC
on August 15 and 06:30 UTC on 16 August 1868. They caused severe damage in the northeastern part of Ecuador
and in southwestern Colombia
. They had an estimated magnitude
of 6.3 and 6.7 and together caused up to 70,000 casualties. The earthquake of 15 August occurred near El Angel, Carchi Province
, close to the border with Colombia, while that of August 16 occurred near Ibarra
in Imbabura Province
. Reports of these earthquakes are often confused with the effects of the earthquake of 13 August at Arica
.
of Ecuador is dominated by the effects of the subduction
of the Nazca Plate
beneath the South American Plate
. The high degree of coupling across the plate boundary where the Carnegie Ridge
is being subducted beneath northern Ecuador causes unusually intense intraplate deformation. Known faults within the area of the earthquake epicenters are the SSW-NNE trending San Isidro, El Angel, Río Ambi and Otavalo Faults, all considered to be dextral strike-slip faults, sometimes with reverse movement. All these fault are interpreted to have moved in the last 1.6 million years.
was devastated, with every building destroyed and only a few walls left standing. Nearby Otavalo
was left without a single house standing and 6,000 people died. In Imbabura, there were 15–20,000 casualties.
the previous afternoon (possibly the 15 August event), with the mainshock occurring at 01:30 local time early on the morning of 16 August. The shaking lasted for one minute.
, who had been appointed to that role by the federal government.
On 26 April each year, in the 'El Retorno' festival, Ibarra celebrates the return of the inhabitants in 1872 after a four-year absence following the earthquake.
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on August 15 and 06:30 UTC on 16 August 1868. They caused severe damage in the northeastern part of Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
and in southwestern Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
. They had an estimated magnitude
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
of 6.3 and 6.7 and together caused up to 70,000 casualties. The earthquake of 15 August occurred near El Angel, Carchi Province
Carchi Province
- Economy :The provincial economy is based on industrial, and agriculture productions. Carchi produces food, drinks, tobacco, and dairy products. The agriculture sector produces potatoes, maize, etc. - Cantons :The province is divided into 6 cantons...
, close to the border with Colombia, while that of August 16 occurred near Ibarra
Ibarra, Ecuador
Ibarra is a city in northern Ecuador and the capital of the Imbabura Province. It lies at the foot of the Imbabura Volcano and on the left bank of the Tahuando river. It is about northeast of Ecuador's capital Quito....
in Imbabura Province
Imbabura Province
Imbabura is a province in Ecuador. The capital is Ibarra. The people of the province speak Spanish and the Imbaburan Quechua language.Imbabura Volcano is located in the province. Best reached from the town of La Esperanza, the 4,609-meter-high mountain can be climbed in a single day.- Cantons...
. Reports of these earthquakes are often confused with the effects of the earthquake of 13 August at Arica
1868 Arica earthquake
The 1868 Arica earthquake was an earthquake that occurred on August 13, 1868, near Arica, then part of Peru, now part of Chile, at 21:30 UTC. It had an estimated magnitude between 8.5 and 9.0...
.
Tectonic setting
The active tectonicsTectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
of Ecuador is dominated by the effects of the subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
beneath the South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....
. The high degree of coupling across the plate boundary where the Carnegie Ridge
Carnegie Ridge
The Carnegie Ridge is an aseismic ridge on the Nazca Plate that is currently 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...
is being subducted beneath northern Ecuador causes unusually intense intraplate deformation. Known faults within the area of the earthquake epicenters are the SSW-NNE trending San Isidro, El Angel, Río Ambi and Otavalo Faults, all considered to be dextral strike-slip faults, sometimes with reverse movement. All these fault are interpreted to have moved in the last 1.6 million years.
15 August
The towns of El Angel and La Concepcion were severely shaken by the first earthquake and El Angel was described as "ruined".16 August
IbarraIbarra, Ecuador
Ibarra is a city in northern Ecuador and the capital of the Imbabura Province. It lies at the foot of the Imbabura Volcano and on the left bank of the Tahuando river. It is about northeast of Ecuador's capital Quito....
was devastated, with every building destroyed and only a few walls left standing. Nearby Otavalo
Otavalo
Otavalo, capital of Otavalo Canton, is a largely indigenous town in the Imbabura Province of Ecuador. The town has about 50,000 inhabitants and is surrounded by the peaks of Imbabura 4,630m, Cotacachi 4,995m, and Mojanda volcanoes.- The market :...
was left without a single house standing and 6,000 people died. In Imbabura, there were 15–20,000 casualties.
Characteristics
There was a minor foreshockForeshock
A foreshock is an earthquake that occurs before a larger seismic event and is related to it in both time and space. The designation of an earthquake as foreshock, mainshock or aftershock is only possible after the event....
the previous afternoon (possibly the 15 August event), with the mainshock occurring at 01:30 local time early on the morning of 16 August. The shaking lasted for one minute.
Aftermath
The relief efforts were organised by Gabriel García MorenoGabriel García Moreno
Gabriel Gregorio Fernando José María García y Moreno y Morán de Buitrón was an Ecuadorian statesman who twice served as President of Ecuador and was assassinated during his second term, after being elected to a third term...
, who had been appointed to that role by the federal government.
On 26 April each year, in the 'El Retorno' festival, Ibarra celebrates the return of the inhabitants in 1872 after a four-year absence following the earthquake.