A powerful aftershock has struck off the northern coast of Chile, a day after the region was struck by an 8.2-magnitude quake that killed six people.
The U.S. Geological Survey said a 7.8-magnitude earthquake was detected late Wednesday night about 23 kilometers south of Iquique, at a depth of 20 kilometers below sea level. The aftershock prompted authorities to issue a new tsunami alert along the Chilean coast and order the evacuation of thousands of coastal residents.
Tuesday's quake struck about 100 kilometers off the country's sparsely populated northwest coast, triggering tsunami warnings as far away as Japan. The warnings were canceled several hours later.
Police and soldiers patrolled northern coastal areas of Chile to prevent looting, as television footage showed damaged homes and shopping centers in the port city of Iquique, 1,800 kilometers north of Santiago.
Chilean President Michelle Bachelet toured the area Wednesday, declaring it a disaster zone. To the north, the quake triggered power outages in Peru, and evacuations in some southern towns there. But there were no reports of serious damage or injuries.
Chilean Interior Minister Rodrigo Penailillo said about 300 inmates escaped a woman's prison in Iquique. But hours later, authorities said more than 100 of the escapees had voluntarily returned or had been captured.
In 2010, an 8.8-magnitude quake rocked central Chile, killing more than 500 people and destroying 220,000 homes.
The region hit by Tuesday's quake also experienced several smaller temblors in recent days, including a 6.0-magnitude earthquake on Sunday.