HONG KONG (AP) - An intense undersea earthquake with an estimated magnitude of 6.8 has  shaken the Solomon Islands in the South Pacific, the Hong Kong Observatory reported Thursday. The quake late Wednesday was centered near the Santa Cruz Islands, a chain of islets about 384 miles southeast of Honiara, the capital of the Solomon Islands archipelago, the observatory reported. There were no immediate reports of damage or casualties. A magnitude 6.1 earthquake can cause severe damage when centered on land under heavily populated areas.