Performance of Two Reservoirs during 1994 Northridge Earthquake

Abstract

The 1994 Northridge Earthquake affected two geotechnical structures of the Van Norman Complex, the Los Angeles Reservoir (LAR) and the Power Plant Tailrace, in different ways. Both the Los Angeles Dam and North Dike of the LAR slightly moved and settled, and sustained small superficial cracks. The North Dike underwent a noticeable increase in seepage, without significantly impeding normal reservoir operations. The Northridge Earthquake uplifted and shifted the foundation of the LAR by 30 cm, and provided us with a unique example of tectonic effects on embankments. In contrast to the LAR, which performed well, the nearby rolled fill dike of the Power Plant Tailrace slowly failed by piping due to transverse cracks and differential lateral spreading induced by liquefaction. Both case studies yield valuable information about the response of embankments subjected to near-source ground motion.