PERFORMANCE OF 2 RESERVOIRS DURING 1994 NORTHRIDGE EARTHQUAKE

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 super ficial cracks. The North Dike underwent a noticeable increase in seepa ge, without significantly impeding normal reservoir operations. The No rthridge Earthquake uplifted and shifted the foundation of the LAR by 30 cm, and provided us with a unique example of tectonic effects on em bankments. In contrast to the LAR, which performed well, the nearby ro lled fill dike of the Power Plant Tailrace slowly failed by piping due to transverse cracks and differential lateral spreading induced by li quefaction. Both case studies yield valuable information about the res ponse of embankments subjected to near-source ground motion.