An earthquake with a preliminary magnitude of 6.7 struck Ecuador early Wednesday, rattling an area still recovering from last month's disastrous quake but causing only limited damage.
The epicenter was 36 miles south of Esmeraldas at a depth of about seven miles, the USGS said.
No tsunami alert was issued and Ecuador's president Rafael Correa said there were no reports of major damage from the quake, which struck at 3 a.m. local time (4 a.m. ET).
"It was a big shake and all of us were scared but there are no major problems at the moment," said Jorge Zambrano, mayor of the coastal city of Manta.
Wednesday's quake struck the same area hit by a 7.8-magnitude earthquake last month, Ecuador's worst disaster in nearly seven decades. That temblor killed 661 people, including one American, and injured around 16,600. Further tremors were expected for several weeks after that quake, which destroyed 7,000 buildings and left more than 25,000 people living in shelters.
In a televised address after Wednesday's aftershock, Correa called on residents in Quito, where some residents poured into the streets, to return to their homes.
The quake was strong enough to trigger a national disaster alert, but Correa deactivated the emergency response a few hours later when local authorities reported the situation was calm.
"These sort of aftershocks are normal but that doesn't mean they're not scary and can cause damage," Correa said in a televised address, adding that aftershocks of this magnitude were normal for up to two months after a major quake.