On November 15, 2006 a tsunami, originating from a magnitude 8.3 subsea earthquake, impacted Crescent City and caused $9.2M of damage to the marina located within the inner boat basin of the harbor. Gerwick provided the detailed planning and the structural, hydrodynamic, and coastal engineering design required for rehabilitation of the damaged marina. The work includes optimization of the layout of floats and finger piers in the marina, location of access ramps and ADA-compliant access points, design of rock-socketed pilings, floats, and wave attenuators.

As part of the work, we performed a tsunami study, which includes review of available background information and acquisition of data required for numerical modeling of tsunami waves within the harbor and inner boat basin. The data utilized for the analyses includes seabed bathymetry, layout of the harbor and inner boat basin, landside topography, offshore wave data, currents, tides, and data on seismic sources around the Pacific Rim. The focus is on establishing the effects of wave action, water surface elevations, runup, currents, wave agitation, and loads incurred to moored vessels, floats, and pilings within the marina and port basin, in order to investigate ways of reducing tsunami effects and potentially improving water quality and circulation within the port and marina.

Gerwick is using the time-domain Boussinesq wave model (BOUSS-2D) and the phase-resolving elliptic mild-slope model (CGWAVE) from Aquaveo’s Surface wave Modeling Software (SMS). As a time-domain, finite-difference code, BOUSS-2D handles complex phenomena including wave-wave and wave-current interactions, wave breaking, bottom friction and reflection.