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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 1776
Tsunamis Recorded on the Pacific Coast of Canada: 1994-2007
Mr. Fred Stephenson
Fisheries and Oceans Canadian Hydrographic Service IASPEI
Alexander B. Rabinovich
In the last 15 years there have been 14 tsunami events recorded at tide stations on the Pacific Coast of
Canada. Ten of these events were from distance sources covering almost all regions of the Pacific, as
well as the December 26, 2004 Sumatra tsunami. Three of the tsunami events were from local or nearfield
earthquakes and one was a meteorological tsunami. The earliest four events, which occurred in the
period 1994 - 1996, were recorded on analogue recorders, and these tsunami records were recently reexamined,
digitized and analysed. The other 10 tsunami events were recorded using digital
instrumentation with one minute sampling intervals. Each of these tsunamis was recorded at two or
more of the tide gauge stations, and all 14 of the events were recorded at Tofino and Bamfield on the
outer B.C. coast. The tide station at Tofino has been in operation for 100 years and these recent
observations add to the dataset of tsunami events compiled previously by S. Wigen for the period 1906-
1980. For each of the tsunami records statistical and spectral analysis was carried out to determine the
arrival times, amplitudes, frequencies and wave train structure. As a result of these observations, and
the resulting analyses, it was confirmed that significant background noise at one key station creates
serious problems in detecting tsunami waves. As a result, the station has now been moved to a new
location with better tsunami response. The number of tsunami events observed in the past 15 years
also justified re-establishing a tide gauge at Port Alberni, where large tsunami wave amplitudes were
measured in March 1964. The data obtained at Port Alberni during future tsunami events will increase
our understanding of tsunami response at this location, as well as other similar locations at the heads
coastal inlets.
Keywords: observations, canada, pacific