The undersea temblor struck Monday at 11:49 a.m. local time in a narrow strait between the islands of Negros and Cebu at a depth of 12 miles, according to the U.S. Geological Survey.
The shaking triggered deadly landslides and caused buildings to collapse upon those inside.
“Many infrastructures were damaged and at least three main bridges are not passable so we cannot reach some areas,” civil defense chief Benito Ramos told reporters.
A local tsunami destroyed cottages at a beach resort near the town of La Libertad, but no significant changes in sea level were detected elsewhere.
A landslide in the mountain village of Plantas buried as many as 30 houses, trapping dozens of people inside.
Government seismologists said the jolt was centered along a newly discovered fault line and was followed by more than 100 aftershocks.
Negros was struck by an 8.2 magnitude quake in 1948, when the island was still recovering from the devastation left by World War II.