2001 – Criteria for Developing Seismic Loads for the Safety Evaluation of Dams of Two New Zealand Owners

Lelio Mejia, Murray Gillon, Jim Walker, Tom Newson

This paper describes the criteria for developing seismic loads for the safety evaluation of dams of two New Zealand owners. The criteria were constrained to satisfy the requirements of the NZSOLD Dam Safety Guidelines and to be consistent with international practice in countries with levels of seismicity and socio-economic development similar to New Zealand. In selecting the criteria, dam seismic load standards from several countries were surveyed and summarized. The selected criteria follow a standards-based approach to the seismic safety evaluation of dams. Guidelines for the use of deterministic and probabilistic procedures to develop seismic loads were formulated as a function of the Potential Impact Classification of a dam. In addition to the traditional deterministic definition of evaluation earthquakes, the selected criteria allow the use of a probabilistic definition in cases where the deterministic definition yields very low probability evaluation events.