MANILA, Philippines — A magnitude 7.8 earthquake shook part of the southern Philippines early Monday, and a tsunami was possible on some regional coasts. Power outages were reported and people were urged to go to higher ground. No further information on damage or casualties was immediately available. The epicenter was 13 kilometers (8 miles) southwest of General Santos city on the island of Mindanao and had a depth of 10 kilometers (6.2 miles), according to the Philippine Institute of