MANILA, Philippines – A magnitude 5.7 earthquake struck off Balut Island in Sarangani, Davao Occidental on Saturday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.  In its earthquake bulletin, Phivolcs said that this was an aftershock of the magnitude 7.8 earthquake that hit off the coast of Maasim, Sarangani on June 8. Phivolcs