Response of Fena Dam to the 1993 Guam Earthquake: Fid-Bau Portal

Response of Fena Dam to the 1993 Guam Earthquake

Mejia, Lelio H.

The potential for strength loss of cohesionless and clay-like soils during strong, long-duration earthquake shaking is a key consideration in the seismic evaluation of embankment dams located in regions where the hazard from large earthquakes is significant. Limited experience is available regarding the performance of dams underlain by fine-grained soils during large earthquakes. This paper presents a case history on the observed performance of Fena Dam during the magnitude 7.8, 1993 Guam Earthquake, which was generated by subduction of the Pacific Plate under the Philippine Plate. Located on the Island of Guam, the dam is an earth and rockfill embankment founded on deep, young alluvial and lacustrine deposits. The dam withstood the earthquake with limited damage that only required modest repairs. The dam’s good performance is ascribed to the low susceptibility of the foundation materials to liquefaction. The paper describes the observed performance of the dam during the earthquake, presents analyses of the dam’s seismic response, and discusses implications of the observed behavior for practice.