Ecuador has been hit by a 6.0 magnitude earthquake less than a week after a huge 7.8 magnitude quake devastated the area and killed 587 people.
The latest quake struck at 3am, 20 miles off the Ecuadorian coastline near the city of Bahía de Caráquez.
According to the USGS, the tremor occured at a depth of six miles, 100 miles from Portoviejo where the quake on Saturday had the biggest impact.
Ecuador's security minister, Cesar Navas, went on Twitter just before 5am to reassure Ecuadorians there was no threat of a tsunami.
Following three aftershocks during the night, Ecuador's President Rafael Correa tweeted that such tremors were expected and called on the country to "have strength".
Following the 7.8 quake, hundreds are still reported missing and thousands more injured in the aftermath.
Saturday's earthquake was the largest the South American country has experienced since March 1987, when a 7.2-magnitude earthquake killed 1,000 people, according to the USGS.
