Monitoring Structural Deformation at Pacoima Dam, California Using Continuous GPS

Agencies responsible for dam safety have long used conventional surveying methods to measure the displacements of benchmarks as part of dam monitoring programs. Such surveys have provided infrequent though precise estimates of a dam’s motions. With the development of high precision GPS methods to monitor plate tectonic motions and crustal deformation rates, an alternative method for monitoring such structural motions became available. While highprecision GPS approaches the horizontal positioning capability of conventional surveying methods, its great benefit lies in a much higher temporal resolution and nearly unattended continuous