A magnitude 7.5 earthquake struck Mindanao, Philippines, triggering a tsunami warning. The US Geographic Survey reported the earthquake as magnitude 7.6 with a depth of 32km. The waves could hit the Philippines by midnight, according to the Philippine Seismology Agency Phivolcs. The U.S. Tsunami Warning System warned of waves up to 3 meters above tide level along some Philippine coasts. A tsunami is a series of ocean waves with extremely long wavelengths and high energy.