The epicenter of the quake, which struck at 8:33 GMT at a depth of 15.7 kilometers (9.8 miles), was located 25 kilometers west of Muisne and 73 kilometers west-southwest of Propicia, the US Geological Survey said.
No tsunami warning has been issued.
The USGS indicated on its website that shaking was weak to light in the country's capital Quito and its biggest city Guayaquil.
Late Saturday, a 7.8-magnitude quake struck Ecuador's Pacific coast in a zone popular with tourists. The death toll from that quake currently stands at 480 but was set to rise sharply as after authorities warned that 1,700 people were still missing.
International rescuers and aid groups rushed to help victims as searchers dug for families trapped in the debris of homes, hotels and businesses.