During the second field survey to the epicentral area, a 3.4 meters offset of the shoreline in Barrio Cabong,
Guinayangan was observed. Ground displacement was laso left lateral.

Other Geologic Features:

The strong shaking of the ground during the Ragay Gulf Earthquake caused two areas along the Calauag-Guinayangan municipal road between kms 236-238 to subside. One of the resulting depressions was 225 meters long while the other was 95 meters long. The longer depression was 2 kms. NW from the first.

A fissure, 15 cms. Wide with 2 unknown lenth, lies along the foothills some 200 meter nw of the PNR terminal in Calauag. Its orientation is N80W. In Lopez, two fissures were observed along Lopez-Jaena St. These may be due to settlement of the bank of Talolong River.

Close to the eastern bank of the Calauag River in Barrio Sumulong and Mabini, several sand boils were found. Mudboils are formed when water- laden sediments are subjected to compressional forces thereby causing the water and fine sands and muds to be injected into the air through fissures or to just upwellm towards the surface.

References:

Southeat Asia Association of Seismology and Earthquake Engineering; Volume IV, Philippines, 1985

Journal of the Geological Society of the Philippines; Volume XXVIII, June, 1974

Summarized by: Erlinda Q. Amin