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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Oral Presentation 1766
Tsunami wave characteristics in Alberni Inlet, British Columbia, Canada
Dr. Josef Cherniawsky
Isaac Fine, Alexander Rabinovich, Fred Stephenson
Spectral analysis of sea level records of recent tsunami events and calculations with numerical models
are used to study tsunami wave propagation and resonance characteristics on the southwest shelf and
coast of Vancouver Island, British Columbia, and in particular, inside Alberni Inlet. This 45-km long fjord
has experienced significant tsunami waves in the past. The town of Port Alberni, located at the head of
the fjord, was severely affected by the March 27 (Good Friday) 1964 tsunami that originated from a
magnitude 9.2 earthquake in Prince William Sound, Alaska. Property damage in Port Alberni was
estimated at more than 8 million dollars. Tsunami-alert sirens warned the residensts to move to higher
ground and helped to avoid fatalities. Tide gauges in Port Alberni and at two locations on the Pacific
Coast, Bamfield and Tofino, recorded clearly the incoming tsunami waves. However, the Port Alberni
maximum wave heights of up to 5 m were by a factor of 4 larger than in Bamfield, or Tofino, exhibiting
relatively strong amplification inside the inlet. We use spectral analyses of observed tide gauge records
and compare these to spectra of time series generated by two numerical models, a nested-grid finitedifference
model initialized with scenaria from nearby and remote earthquakes and a local finitedifference
model that is forced at its open boundary with red-noise signal.
Keywords: tsunami wave, propagation, resonance