July 16, 1990, an earthquake with epicenter near Cabanatuan City jolted a wide area of Luzon.
The earthquake struck at 4:26 p.m., July 16, 1990. It registered at magnitude 7.7 on the open-ended Richter scale, and intensity 8 on the Rossi-Forel scale, near the epicenter. The impact of the quake approximated the explosion of some 45 atomic bombs similar to those dropped on Nagasaki and Hiroshima in 1945.
After 45 seconds, nine cities and 39 municipalities in 15 provinces lay damaged; some, almost totally devastated.
Included in the list of damaged areas were: the provinces of Ilocos Norte, Ilocos Sur, La Union, and Pangasinan in Region 1; Nueva Vizcaya, Quirino, and Aurora in Region 2; Benguet, Ifugao, Kalinga-Apayao, and Abra in the Cordillera Administrative Region; Tarlac, Nueva Ecija, Pampanga, Bulacan, and Bataan in Region 3. Portions of some provinces in Region 4-A were also slightly damaged.
Government buildings in the National Capital Region also suffered heavy damage.
The affected major urban centers included: Dagupan City which suffered the worst physical damage; Cabanatuan City which saw one of the most tragic human dramas in a collapsed schoolbuilding; Baguio City which was transformed overnight from a tourist haven to a massive disaster area; and Agoo, La Union where treasured centuries-old structures crumbled.
A state of calamity was declared in the cities of Cabanatuan, Baguio, Dagupan, San Carlos, Palayan and San Jose and in the provinces of Nueva Ecija, Benguet and Pangasinan.
Baguio City was isolated for days after the major highways to the mountain resort collapsed and cut for a timetrapping thousands of people, including local and foreign tourists, within its confines.
Thus, For a time, these major arteries were cut. These included two historic roads: Kennon, which linked Rosario, La Union to the Summer Capital; and Dalton Pass, the gateway to the Cagayan Valley. Carmen Bridge in Rosales, Pangasinan—Luzon’s longest span—also collapsed into the dry Agno riverbed looking like an ostrich with its head in the sand, hampering travel to the north.
Major landmarks were either seriously damaged or totally wrecked. Hyatt Terraces, the famous Baguio watering hole, caved in at the height of the temblor; so did nearby Nevada Hotel. The roof and ceiling of the famed Cathedral of Agoo, La Union crashed down on its marble floors.