Northern coast of Chile rocked by a powerful 7.8-magnitude aftershock following Tuesday's earthquake

Chile's northern coast has been rocked a powerful 7.8-magnitude aftershock, the U.S. Geological Survey has reported, just days after the same area was hit by a powerful magnitude-8.2 earthquake. The aftershock caused buildings to shake in the port of Iquique, which saw some damage from the big quake on Tuesday. There are no immediate reports of new damage or injuries. The latest tremor came 45 minutes after a strong 6.4-magnitude aftershock shook the same area. The stronger aftershock's epicenter was 23 kilometers south of Iquique. The USGS said the aftershock had a depth of 20 kilometers. Hard-won expertise and a big dose of luck had helped Chile escape its latest magnitude-8.2 earthquake on Tuesday with surprisingly little damage and death. The country that suffers some of the world's most powerful quakes has strict building codes, mandatory evacuations and emergency preparedness that sets a global example. But Chileans weren't satisfied Wednesday, finding much room for improvement. And experts warn that a 'seismic gap' has left northern Chile overdue for a far bigger quake. Authorities on Wednesday discovered just six reported deaths from the previous night's quake. It's possible that other people were killed in older structures made of adobe in remote communities that weren't immediately accessible, but it's still a very low toll for such a powerful shift in the undersea fault that runs along the length of South America's Pacific coast. 'How much is it luck? How much is it science? How much is it preparedness? It is a combination of all of the above. I think what we just saw here is pure luck. Mostly, it is luck that the tsunami was not bigger and that it hit a fairly isolated area of Chile,' said Costas Synolakis, an engineer who directs the Tsunami Research Center at the University of Southern California. Chile is one of the world's most seismic countries and is particularly prone to tsunamis, because of the way the Nazca tectonic plate plunges beneath the South American plate, pushing the towering Andes cordillera ever higher. About 2,500 homes were damaged in Alto Hospicio, a poor neighborhood in the hills above Iquique, a city of nearly 200,000 people whose coastal residents joined a mandatory evacuation ahead of a tsunami that rose to only 8 feet (2.5 meters). Iquique's fishermen poked through the aftermath: sunken and damaged boats that could cost millions of dollars to repair and replace. Still, as President Michelle Bachelet deployed hundreds of anti-riot police and soldiers to prevent looting and round up escaped prisoners, it was clear that the loss of life and property could have been much worse. Mines in Chile, the world's No 1 copper producer, mostly said they were functioning normally, and oil refineries said they were normalizing operations. Local television showed images of smaller fishing vessels damaged and overturned in at least one northern port. Thousands of miles away in Hawaii, the Pacific Tsunami Warning Center cautioned residents that possible sea level changes and strong currents could pose a danger to swimmers and boaters.