Probable Geohazards in PNOC-EDC's Proposed North Luzon Wind Power Projects in Ilocos Norte, Philippines

Abstract

Two development blocks are intended for PNOC-EDC's 120 MW wind farm development in the province of llocos Norte. The first block is in Burgos and the other one is in the municipality of Pagudpud. Block 1 (Burgos) comprised of Barangays Bayog, Pagali-Saoit, Bantoc, Agaga and Cungon-dungon (affregate area = 6,990 has) while Block 2 (Pagundpud) covered Balaoi, Subrec, Caparispisan and Ayoyo barangays (aggregate area = 4, 125 has). The northern coastal strip of llocos Norte is mantled by a sedimentary layer of Pliocene Laoag Formation which is unconformably underlain by Miocene volcanics of the Bojeador Formation. Highly serpentinized ultramafic peridoitites and schists formed the basement in the region. A major geologic structure called the Vigan-Aggao Fault defines the major regional structural feature in the project areas. The probable geologic and /or natural hazards identified in the area are the following: landslides, soil erosion, seismic, tsunami/surge, and sinkholes. Detailed engineering geologic mapping and geotechnical investigations were already undertaken in the vicinity of Saoit and Bantoc.