Earthquake reconnaissance report

Damage to the power generation and transmission facilities in the Loma Prieta earthquake of 17 October 1989

  • Tan Pham AC Power Group Ltd, Wellington, New Zealand


The magnitude 7.1 Loma Prieta earthquake, at 5.04 pm on 17 October 1989, caused deaths, damage to properties and disrupted transportation, utilities and communications. Electricity and gas in the area affected by the earthquake were supplied by Pacific Gas and Electric (PG&E) Company which served more than 10 million people in northern and central California. The company's 1988 annual report showed a total sale of 68537 GWh of electricity. The earthquake caused considerable damage to power generation facilities at Metcalf, San Mateo and Moss Landing. Facilities at Potrero and Hunter Points also experienced minor damage. Damage occurred to old items of equipment which were not designed to PG&E's current seismic specifications. Those which were located on sites near the epicentre of the earthquake suffered the most damage. According to PG&E's report, issued soon after the earthquake, about 1.4 million PG&E customers lost electric power, some for up to 48 hours, and a total cost of damage between US $30 millions and US $50 millions has been estimated. There were other smaller power generation plants in the area besides those owned by PG&E. Most were built recently and, to the author's knowledge, they suffered little damage during the earthquake.


Loma Prieta Earthquake Reconnaissance Report, Earthquake Spectra Vol 6, 1990.

CAE (1991) - Lifelines in Earthquakes - Wellington Study - Project Report

How to Cite
Pham, T. (1992). Earthquake reconnaissance report. Bulletin of the New Zealand Society for Earthquake Engineering, 25(1), 3-16.