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What are my risks?
Kauai
has had a tsunami?!
 Click
to enlarge
A
tsunami's effect at the shoreline can be considerably
different within very short distances. The only general
rule is that runup heights tend to be greatest near where
the offshore bathymetry is steeper. Along gentle-sloping
coasts, wave energy is dissipated upon shoaling. Even
so, inundation can be significant and is usually greatest
along low-lying coastal plains.
An
important historical example that demonstrates the variability
of tsunami impact at the shoreline occurred during the
1965 tsunami on the north shore of Kauai. Despite the
same north-facing exposure at Haena and Hanalei, a runup
height of 35 feet was recorded at Haena, while only a
few miles away in Hanalei Bay, runup was a mere 3 feet.
In
some cases, the runup height has been nearly equal on
opposite sides of the island, suggesting that shoreline
orientation (i.e. facing the tsunami source) is not always
an important control. For example, during the 1960 tsunami,
generated by an earthquake in Chile far to the southeast,
a runup of 13 feet was recorded at Haena, only 1 foot
lower than the maximum of 14 feet for the entire island
reported at Hanapepe.
Despite
these variations, each side of Kauai has observed tsunami
runups of over 10 feet with significant damaging effects.
Written history records a tsunami damaging Kauai once
every 16.5 years. However, the last of these tsunamis
occurred in 1965, so looking at the time period between
1933 and 1965, the average recurrence interval was ~4.5
years. In light of the long-term frequency with which
tsunamis have adversely impacted Kauai (i.e., every 16.5
years), one might conclude a damaging tsunami is overdue.
Am
I at risk?
If you live
in a low-lying coastal area, you are at risk. All low-lying
coastal areas can be struck by tsunami.
To see Kauai
County’s Tsunami Evacuation Maps, go to the front section
of your phone book or click
here.
For more
information, contact the Kauai Civil Defense Agency.
Source:
Fletcher, Charles, Eric Grossman, Bruce Richmond. Atlas
of Natural Hazards in the Hawaiian Coastal Zone. 2000. |
