The 7.2 magnitude quake struck the central Philippines today at 8:12am near the town of Carmen in Bohol province, about 40 miles across the Cebu Strait from Cebu City, said the U.S. Geological Survey and Philippine emergency authorities.
Some of the Philippines oldest and most hallowed churches were severely damaged in the quake.
At least two aftershocks of a 5.0 magnitude or greater followed.
Of the 20 dead, 15 were killed in Cebu province, four in Bohol province, and one in Siquijor province.
Power was reportedly out across Cebu City and Bohola and Masbate provinces, said the official Philippine Information Agency.
The Philippine Red Cross has asked people in the region to use their cell phones only for emergencies so rescue operations are not hampered.
People in the region are worried about the possibility of a tsunami, but the Pacific Tsunami Warning Center has issued no warning and said the data indicates little chance of one.