The tremor occurred in a very sparsely populated region of the Amazon rainforest, some 45 kilometres northwest of the city of Barranca, the Euro-Mediterranean Seismological Centre (EMSC) said.
While it was extremely strong, at a depth around 110km it was also relatively deep underground – which typically limits damages and casualties but results in tremors being felt in a larger area.
The EMSC received multiple accounts from people living in parts of Ecuador more than 250km away from the epicentre who said they had experienced strong shaking – and some who felt minor quakes in Colombia.
The US Tsunami Warning System said there was no tsunami expected after the quake, and there were no reports of injuries.
But local media and eyewitnesses reported some damage to buildings, including a church tower forming part of a 16th century complex considered to be the oldest Catholic temple in the Amazonas region – which was reduced to rubble.
Social media posts also showed damage in other locations, including in a church in southern Ecuador.
The earthquake took place within the Nazca plate at the Peru-Chile trench, where large earthquakes at this depth “are reasonably common”, the US Geological Survey said.
Over the past century, there have been five other intermediate-depth earthquakes within 250km of the epicentre of Sunday’s tremor with a magnitude of 7 or greater, according to the US government agency.
The most recent of these was a magnitude 8 earthquake which struck on 26 May 2019 and, according to the government, killed two people and injured 15 others while damaging hundreds of homes, leaving many families homeless.