Santa Ana sits just 33 miles from the Newport-Inglewood fault, and at an elevation of 115 feet above sea level, the city's dense urban fabric amplifies the need for structural resilience. The 1933 Long Beach earthquake, which caused widespread damage across Orange County, remains a reference point for our approach to seismic isolation here. In our experience, base isolation design in this basin requires more than a standard spectrum—we account for site amplification in the alluvial soils that underlie much of downtown. For taller structures on softer profiles, we often pair isolation analysis with a seismic microzonation study to capture basin-edge effects, and we use CPT sounding to refine the shear wave velocity profile before selecting isolator properties.
In Santa Ana's basin, site amplification can push spectral ordinates well above the code minimum—isolation periods under 3.5 seconds rarely work here.
