Wondering what a tsunami could do to our coast?
After the recent tsunami alert, I went looking for some history.
It didn’t take long to find a couple of photos.
The top photo shows a tsunami washing ashore on Laie Point in 1957 following an earthquake in the Aleutian Islands.
[credit: NOAA/NGDC/Henry Helbush]
The second photo was taken right here in Kaaawa. It shows damage to Kamehameha Highway from the April 1, 1946 tsunami that devastated Hilo. It appears to be the stretch of highway between what is now Polinalina Road and Puakenikeni Road.
[credit: NOAA/NGDC Natural Hazards Photo Archive/Orville T. Magoon]
According to the U.S. Geological Survey, Kaaawa experience a 7 foot wave during the 1946 tsunami, while nearby in Punaluu it was 12 feet, and in Kahuku 27 feet.
The USGS commentary below will have to be amended following the damage from the tsunami of March 11-12, but the main point is still well taken. We’re overdue for a damaging tsunami along our windward coast.
Between 1945 and 1975, a total of 7 large tsunamis hit the Hawaiian Islands, or one every 3.3 yr, and a damaging tsunami hit Oahu every 6 yr. However, since 1976 not one large tsunami has been recorded in all of Hawaii (1986 and 1994 had 2 small events that were less than 3 ft). The historical record suggests that a damaging tsunami is overdue to reach Oahu’s shores. Ironically, it has been during this last 20 years that development within the Hawaiian coastal zone has proliferated.
If wave runups like those of the 1957 or 1960 tsunamis occurred today, there exists a high probability that low-lying coastal areas such as Waikiki, Waimanalo, Kaaawa, Punaluu, and Nanakuli would suffer damage, primarily because of the risk that has been taken by developing within these inundation zones.
“The source of the photographs is the COMET® Website at http://meted.ucar.edu/ of the University Corporation for Atmospheric Research (UCAR), sponsored in part through cooperative agreement(s) with the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce (DOC). ©1997-2010 University Corporation for Atmospheric Research. All Rights Reserved.”
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The revised Tsunami maps for Kailua pushed the inundation zone from Kalaheo Ave to Kainalu St the street where my home is located. Seeing the damage in Japan, I’m convinced that a 23 meter wave could easily reach Kawainui Marsh with the river of debris, buildings, cars, etc.