| UTC time | Doublet earthquake: |
|---|---|
| 1868-08-15 19:30 | |
| 1868-08-16 06:30 | |
| Local date | |
| 15 August 1868 | |
| 16 August 1868 | |
| Local time | |
| Afternoon | |
| 01:30 | |
| Magnitude | |
| 6.3Mw[1] | |
| 6.7 Mw [1] | |
| Depth | 20 km |
| Epicenter | 0°19′N78°11′W / 0.31°N 78.18°W /0.31; -78.18 |
| Areas affected | Ecuador,Colombia |
| Max. intensity | MMI VIII (Severe) MMI X (Extreme) |
| Casualties | 70,000[2] |
The1868 Ecuador earthquakes occurred at 19:30UTC on August 15 and 06:30 UTC on 16 August 1868. They caused severe damage in the northeastern part ofEcuador and in southwesternColombia. They had an estimatedmagnitude of 6.3 and 6.7[1] and together caused up to 70,000 casualties.[2] The earthquake of 15 August occurred nearEl Ángel,Carchi Province, close to the border with Colombia, while that of August 16 occurred nearIbarra inImbabura Province.[1] Reports of these earthquakes are often confused with the effects of the earthquake of 13 August atArica.[2]
The activetectonics of Ecuador is dominated by the effects of thesubduction of theNazca plate beneath theSouth American plate. The high degree of coupling across the plate boundary where theCarnegie Ridge is being subducted beneath northern Ecuador causes unusually intenseintraplate deformation.[3] Known faults within the area of the earthquake epicenters are the SSW-NNE trendingSan Isidro,El Ángel,Río Ambi andOtavalo 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.[4]
The towns ofEl Ángel and La Concepcion were severely shaken by the first earthquake and El Ángel was described as "ruined".[5]
Ibarra was devastated, with every building destroyed and only a few walls left standing. NearbyOtavalo was left without a single house standing and 6,000 people died. In Imbabura Province, there were 15–20,000 casualties.[6]
There was a minorforeshock the previous afternoon (possibly the 15 August event),[2] with the mainshock occurring at 01:30 local time early on the morning of 16 August. The shaking lasted for one minute.[7]
The relief efforts were organised byGabriel García Moreno, who had been appointed to that role by the federal government.[6]
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.[8]
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| Sources | Paris, Gabriel; Machette, Michael N.; Dart, Richard L.; Haller, Kathleen M. (2000).Map and Database of Quaternary Faults and Folds in Colombia and its Offshore Regions(PDF).USGS. pp. 1–66. Retrieved2017-06-20. Gómez Tapias, Jorge; Montes Ramírez, Nohora E.; Almanza Meléndez, María F.; Alcárcel Gutiérrez, Fernando A.; Madrid Montoya, César A.; Diederix, Hans (2015).Geological Map of Colombia.Servicio Geológico Colombiano. pp. 1–212. Retrieved2019-10-29. Various authors (2014).Enciclopedia de desastres naturales históricos de Colombia(PDF).Universidad del Quindío. pp. 1–21. Retrieved2017-06-20. | ||||||||||
