CAUQUENES, Chile — A magnitude-6.8 earthquake struck central Chile Friday, centered in almost exactly the same spot where last year's magnitude-8.8 quake spawned a tsunami and devastated coastal communities.Rodrigo Ubillo, the vice interior minister, said they had no reports of damage or injuries, and the navy had "totally discounted any risk of a tsunami."Still, the strong earthquake frightened many Chileans, especially along the coast, where people quickly moved to higher ground."There was a preventive self-evacuation," said Vicente Nunez, who directs the National Emergency Office, ONEMI. But he said Chileans could safely return home.