In northern Luzon, where the July 27 earthquake occurred, the subduction zone location and direction changes, with another trench (Manila Trench) located west of Luzon and the Sunda plate subducts eastward beneath the Philippine Sea plate.

The complexity of plate tectonics on and around Luzon is evidenced by the diversity of faulting mechanisms in large earthquakes.

Magnitude 7 or greater earthquakes in this region since 1970 have exhibited reverse, normal, and strike-slip faulting.

[10] A scientific journal published by Rimando and others in 2022 revealed the earthquake did not occur on any of the known faults in the area.

[15][16] It caused extensive damage to thousands of infrastructures including homes and roads, and left 139 people injured.

[3][17][18][19][20] Two days later, four soldiers giving aid to the affected area were attacked by the New People's Army, leaving two of them dead, another injured and one missing.

In Vigan, Sinait, Bantay, San Esteban (in Ilocos Sur), Laoac (in Pangasinan), and Baguio, shaking corresponding to intensity VI (Very strong) was reported.

[9] In an interview with a local radio station, Renato U. Solidum, the head of PHIVOLCS,[25] it was felt with "relatively moderate intensity" in Manila, the capital of the Philippines.

Due to the inland epicenter, the earthquake could not cause seafloor uplift and trigger large waves.

However, PHIVOLCS noted that shorelines and enclosed bodies of water may experience seiches due to oscillation from the earthquake.

[29] According to the National Grid Corporation of the Philippines (NGCP), power services in Manila and the surrounding provinces were uninterrupted.

[30] Commanders of the Philippine National Police (PNP) in Luzon were tasked to cooperate with the regional Risk Reduction and Management Office to maximize relief operations.

[32] President Bongbong Marcos conducted a press briefing addressing the disaster and was scheduled to fly to Abra.

[33] He was expected to coordinate with national and local government establishments in relief efforts,[33] but was "staying away" at the present.

[34] President Marcos has also called for telecommunication companies to give free communication to areas where transmission towers had collapsed.

[34] Local authorities stated that work and schools would be suspended in parts of Ilocos Norte to allow damage assessments to take place.

[35] In the Ilocos region, the Department of Social Welfare and Development (DSWD) said that it would be ready to serve the affected.

More than 17,410 family food packs and 9,291 non-food items had been prepared and stored at warehouses, ready for distribution.

[39] UNICEF said that emergency supplies were on standby to support government relief efforts and to assist affected children and families.

[52] In Bangued, a person died when the walls of a dormitory collapsed, and an additional 44 were injured due to falling debris.

The Shrine of San Lorenzo Ruiz in Bangued sustained major damage and one of its bell-towers was reduced to rubble.

[65] The earthquake was felt strongly in Metro Manila, where minor damage to a hospital and several other buildings were reported.

[65][66] The earthquake prompted the Manila Metro Rail Transit System to suspend service during rush hour.

[71] In Asipulo, Ifugao, a landslide partially buried an ambulance; four occupants including a pregnant woman escaped unhurt.

[72] There were two deaths in Benguet,[70] including one in La Trinidad, who died due to falling debris from a collapsed building.