New assessment of tsunami hazards in San Diego Bay

We assess tsunami hazards in San Diego Bay, California, using newly identified
offshore tsunami sources and recently available high resolution bathymetric/topographic
data. We simulate locally, regionally and distant-generated tsunamis.
Local tsunami source models use more realistic fault and landslide data than previous
efforts. With the exception of the Alaska-Aleutian Trench, modeling results suggest
that local sources are responsible for the largest waves within the San Diego Bay and
Mission Bay. Because San Diego Bay is relatively well protected by North Island and the
Silver Strand, the wave heights predicted are consistently smaller inside the harbor than
outside. However, historical accounts, recent tsunamis and our predictions show that San
Diego Bay is vulnerable to strong tsunami induced currents. More specifically, large
currents are expected inside the harbor for various distant and local tsunami sources with
estimated flow velocities exceeding 100 cm/s. Such currents have been damaging to harbor
facilities, such as wharves and piers, and may cause boats to break from moorings and ram
into adjacent harbor structures, as observed in recent historic tsunamis. More recently,
following the Mw 8.8 February 27, 2010 Chile earthquake, tsunami-currents damaged
docks/piers in Shelter Island confirming our findings.

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