High Quality Content by WIKIPEDIA articles! The Luzon earthquake occurred on Monday, July 16, 1990, at 4:26 PM local time in the Philippines. The densely populated island of Luzon was struck by an earthquake with a 7.8 Ms (surface-wave magnitude). The earthquake produced a 125 km-long ground rupture that stretched from Dingalan, Aurora to Cuyapo, Nueva Ecija as a result of strike-slip movements along the Philippine Fault and the Digdig Fault within the Philippine Fault System. The earthquake epicenter was placed at 15° 42` N and 121° 7` E near the town of Rizal, Nueva Ecija, northeast of Cabanatuan City.