Hawaii's tsunami history - A destructive and deadly past

Aftermath of the 1960 Chilean tsunami in the Waiakea area of
Hilo, Hawaii. Parking meters were bent by the force of the debris-
filled waves. Photograph Credit: U.S. Navy. Source: National
Geophysical Data Center.

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With a massive 8.8 earthquake striking near Chile and sending a tsunami across the Pacific, Hawaii readies itself for what could be a devastating strike. The island state has a history of being stricken by tsunamis, some generated locally but many from far off areas.

According to the U.S. Geological Survey (USGS), 50 tsunamis have been reported in Hawaii since the early 1800’s. Of those seven caused major damage. Five of those were generated from areas outside the state.

The worst tsunami to strike Hawaii in modern history occurred in 1946 and was caused by an earthquake in the Aleutian Islands. The tsunami struck without warning and claimed the lives of 170 people, mainly near Laupahoehoe and Hilo. Wave heights near Hilo reached 30 feet while the maximum height was 55 feet at the northern tip of the island near the Pololu Valley.

In 1960, the world’s largest recorded earthquake struck Chile, not far from where the earthquake that struck today occurred. That massive 9.5 temblor generated a tsunami that struck Hawaii but technology allowed a warning to go out beforehand.

Waves as high as 35 feet struck Hilo, Hawaii and caused 61 deaths and $75 million in damage. Hilo Bay itself was struck the worst where 600 acres of land inland were inundated and only the most reinforced buildings survived. On Maui, the Kahului area was struck the worst where a warehouse and some houses were destroyed.

Tsunamis caused closer to the epicenter of a quake are often more deadly as there is less warning. Two locally generated tsunamis have also caused damage in Hawaii, one in 1868 and another in 1975. The 1868 tsunami destroyed two villages while waves from the 1975 tsunami claimed two lives.

As the wave approaches land, it slows but they increase in height
and the distance between them shrinks. (Wikipedia)

A tsunami is typically generated by the movement of tectonic plate boundaries that move abruptly causing an earthquake. As one of the plates moves upward, it pushes the water up and outwards.

On the surface, tsunamis are difficult to detect and may only cause a rise in the surface of 12 to 36 inches. These waves can travel at 600 mph and as they reach shallower waters near land the waves slow but they increase in height and the distance between them shrinks.

Downtown Hilo, Hawaii, was left devastated by the 1960 tsunami. (USGS / The Honolulu Advertiser)

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