A strong 6.4-magnitude earthquake has struck Bougainville Island in Papua New Guinea, with strong shaking felt across the area, according to seismologists. There was no immediate word on possible damage. The earthquake, which struck at 7:13 a.m. local time on Monday, was centered near Tokuaka on the southern coast of the island, about 178 kilometers (111 miles) southeast of Buka. The U.S. Geological Survey (USGS) said the earthquake had a magnitude of 6.4, down from an initial estimate of 6.6. It struck at a depth of about 41 kilometers (25 miles), making it a relatively shallow earthquake. An…