November 11, 1921 Earthquake: E, Mindanao, Philippines

Reference #414:

1921, November 7, 0:02 [local time]. There was an

earthquake with source off the southeastern coast of Mindanao Island in the form of sudden vertical shocks. The coast from 8o N, to Cape San Agustin, with center at Caraga, suffered most. The 6-degree (VI1 Rossi-Forel) isoseismal included an area of land 200 km long along the coast and almost 100 km wide inland. The 3-degree isoseismal was almost 400 km to the west of Caraga, and 600 km to the north, reaching the southeastern tip of Luzon Island and the Visayan Sea.

Many recurrent shocks occurred; their frequency markedly decreased by the 10th but began to increase again on the 11th. The main earthquake struck at night on the 12th, and was accompanied by a large number of aftershocks.

In the Caraga region, the force of the earthquake was 7 degrees (VIII). It did only slight damage to the few light structures there. The collapse of the roof of the church at Manay was reported. The church was a wooden building with a corrugated iron roof, which was in a very bad state of repair. Several pile huts were damaged, while other huts settled into cracked ground. Many cracks developed and collapses occurred on the step and abraded limestone cliffs and on the hillsides. The earthquake was felt as far as Manado (Sulawcsi Island) where it was estimated at 4 degrees (V).

After the main earthquake, a tsunami arose, which inundated the low-lying coasts of several bays, for example, at Manay, and did some damage to structures and plantations there. The tsunami was also observed at Manganitu on Sangihe Island.

Reference #88:

1921, Nov 11, 18:36:08 UTC, 8 N, 127 E, shallow depth, magnitude 7.5 MS.

Reference #1058:

1921, Nov 11. Intensity VIII. Davao. Destructive.

Reference #1187:

1921, Nov. 12, 12:25 a.m. W Luzon: Earthquake of Intensity IV-V felt through the mountainous eastern portion of La Union Province and the Baguio region. It was

repeated with less intensity two hours later. The epicentre

apparently lay in the vicinity of the Santo Tomas mountain block. Mindanao: Mati - tidal wave invaded the few bays with low lands existing there. Manay - sustained greater loss in structures and crops from the tidal wave. Caraga - subterranean rumblings and great disturbance in the sea.