Foam rubber modeling of topographic and dam interaction effects at Pacoima Dam
Foam rubber modeling of topographic and dam interaction effects at Pacoima Dam
Bulletin of the Seismological Society of America (October 1989) 79 (5): 1347-1360
- accuracy
- aftershocks
- body waves
- California
- dams
- earthquakes
- elastic waves
- engineering geology
- Fourier analysis
- ground motion
- Los Angeles County California
- models
- numerical models
- Pacoima Dam
- physical models
- polarization
- S-waves
- San Fernando earthquake 1971
- scale models
- seismic response
- seismic waves
- seismology
- SH-waves
- signal-to-noise ratio
- three-dimensional models
- topography
- two-dimensional models
- United States
Dam-topographic interaction effects for the Pacoima Dam accelerograph were three-dimensionally modelled with foam rubber for the 1971 San Fernando earthquake. Assuming B (sub e) = 2 km/sec, for vertically incident SH-waves, spectral ratio of ridge ground acceleration to flat surface indicates 60% amplification around 6.5 Hz on the N76 degrees W component whereas motion on the S14 degrees W component is unaffected by topography. Nonvertically incident SH-waves results show that topographic effect is seismic energy direction of approach dependent. Either amplification or de-amplification will result depending whether canyon is on raypath or not. Dam-ridge dynamic interaction shows coupling less than 2% at 10 Hz and less than 12% at 15 Hz.--Modified journal abstract.
