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 Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...

and in southwestern Colombia. They had an estimated

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 6.3 and 6.7 and together caused up to 70,000 casualties. The earthquake of 15 August occurred near

El Ángel The Angel of Independence, most commonly known by the shortened name ''El Ángel'' and officially known as ''Monumento a la Independencia'' ("Monument to Independence"), is a victory column on a roundabout on the major thoroughfare of Paseo de ...

Carchi Province Carchi () is a province in Ecuador. The capital is Tulcán. The Carchi River rises on the slopes of Chiles volcano and forms the boundary between Colombia and Ecuador near Tulcan. Rumichaca Bridge is the most important land route between Colom ...

, close to the border with Colombia, while that of August 16 occurred near Ibarra in

Imbabura Province Imbabura () is a province located in the Andes of northern Ecuador. The capital is Ibarra. The people of the province speak Spanish, and a large portion of the population also speaks the Imbaburan Kichwa variety of the Quechua language. The s ...

. Reports of these earthquakes are often confused with the effects of the earthquake of 13 August at

Arica Arica ( ; ) is a commune and a port city with a population of 222,619 in the Arica Province of northern Chile's Arica y Parinacota Region. It is Chile's northernmost city, being located only south of the border with Peru. The city is the capita ...

Tectonic setting

The active

tectonics Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...

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 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 ...

is being subducted beneath northern Ecuador causes unusually intense

intraplate deformation Intraplate deformation is the folding, breaking, or flow of the Earth's crust within plates instead of at their margins. This process usually occurs in areas with especially weak crust and upper mantle, such as the Tibetan Plateau (Figure 1). Int ...

. Known faults within the area of the earthquake epicenters are the SSW-NNE trending San Isidro,

, Río Ambi and Otavalo Faults, all considered to be dextral strike-slip faults, sometimes with reverse movement. All these faults are interpreted to have moved in the last 1.6 million years.

Damage

15 August

The towns of

and La Concepcion were severely shaken by the first earthquake and El Ángel was described as "ruined".

16 August

Ibarra 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 Province, there were 15–20,000 casualties.

Characteristics

There was a minor

foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) 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 full se ...

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 Moreno Gabriel Gregorio Fernando José María García Moreno y Morán de Butrón (24 December 1821 – 6 August 1875), was an Ecuadorian politician and aristocrat who twice served as President of Ecuador (1861–65 and 1869–75) and was assassinated d ...

, 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.

References

External links

El Terremoto de Ibarra del 16 de Agosto de 1868
page on this earthquake from the Instituto Geofísico, Ecuador (in Spanish)
El Retorno: La Historia del Terremoto, Éxodo y Resurrección de Ibarra
The Return: the story of the earthquake, the exodus of the population and the resurrection of Ibarra (in Spanish) {{Tectonism in Colombia, state=expanded Earthquakes in Ecuador Earthquakes in Colombia Ecuador Earthquakes, 1868 Ecuador Earthquakes, 1868 Ecuador Earthquakes, 1868 August 1868 events