August 1, 1968 Earthquake: Manila, Luzon, Philippines

Reference #414:

1968, Aug 2, 4:20 [local time], 16.5 N, 122.2 E, depth 36 km, magnitude 7.7. There was a destructive earthquake with source off the east coast of Luzon Island. It was preceded by at least four shocks which were felt at Casiguran during the 24 hours before the earthquake.

The radius of perceptibility was more than 600 km. At Casiguran, loose ground settled 1-2 m. The channel which connects the Casiguran and Casalogan Rivers dried up. Numerous cracks 10-500 m long and 0.3-1.0 m wide appeared in the ground, here and there ejecting water, sand and mud.

In the city, several buildings made of wood and concrete suffered damage. A bridge shifted. The people ran from their homes in panic. Posts and various subjects fell.

Near Dinadyavan, numerous avalanches and landslides occurred along the coast of Casiguran Sound and in the valley of the Jagdauan River. At Baler, the damage was slight: a bridge shifted out of place near the city. In the middle reaches of the Casiguran River, near Manglad and Maddela, large mudflows and landslides descended. In the upper reaches of the Manglad River, a part of the river bed 2.5 m wide and 0.5 m deep dried up. At Quezon City, according to the accelerograph record, the acceleration of the ground was estimated at 50 +- gal.

At Manila, homes situated at the mouth of the Pasig River on young alluvium more than 20 m thick suffered heavy damage. The "Ruby," a six-story reinforced concrete building, completely collapsed, as a result of which 268 people died and 260 people were injured. Up to another 10 such buildings almost collapsed and had to be demolished. Non-structural damage to buildings occurred in many, though hardly all, regions of the city.

In addition to the above-mentioned victims, another two dead and one injured were registered in the country. The material losses have been estimated at at least 8 million dollars. Many recurrent shocks were registered. Their epicenters approximately outline the source of the main earthquake.

The earthquake caused a tsunami.

Reference #45:

1968, Aug 1, 20:19:21.9 UTC, 16.5 N, 122.2 E, depth 36 km, magnitude 7.3. An estimated 207 residents were killed, many were injured, and widespread property damage occurred. The greatest loss of life was sustained in Manila when a six-story apartment building collapsed into a pile of rubble. A river was blocked at Maddela in the province of Nueva Vizcaya. Ground fissures were noted between Casiguran and Baker; some were reported to be 7 or more km long. Damage to private buildings in Manila was extensive with six structures of six to eight floors severely damaged. Fire ignited by the shock caused an estimated $7.5 million damage in the harbor area.

Reference #150:

1968, Aug 2, 04:19 [local time], 16.5 N, 122.2 E, depth 36 km, magnitude 7 MS. Considerable damage, 207 more deaths, at Manila by quake.

Reference #1250:

1968, Aug 2. 271 deaths, 261 injured, $5 million damage.