Hawaii to California: How often have tsunamis hit the US and how bad do they get

Indian Express

3 days ago

Waves have begun to hit California shores in the US, after tsunami alerts were issued for nations across the Pacific when a strong 8.8 magnitude earthquake struck off Russia's far eastern coast on Wednesday morning.
The US National Weather Service has warned people from venturing along the coast looking for tsunami waves. 'This will NOT be a single wave. Do NOT try to go to the coast to take photos,' the NWS San Francisco Bay Area office posted on X.
In 1946, Hawaii, an archipelago of islands in the US was hit by a massive tsunami originating in the Pacific Ocean. An earthquake thousands of kilometres away, sent 55-foot waves barreling toward the islands. By the time they crashed into Hilo, 159 people were dead, and much of the town's downtown lay in ruins.
It was a brutal reminder of a truth the United States has confronted since at least 1737: tsunamis, though rare, are among the most relentless forces of nature. Over nearly three centuries, 77 have struck American shores, with an average of two destructive ones every decade
These waves are overwhelmingly a Pacific problem. The geology of the region, where tectonic plates clash against each other, makes southern Alaska, Hawaii, and the West Coast prime targets.
Alaska sits on one of the planet's most volatile fault lines, a tectonic powder keg. Hawaii, caught in the crosshairs of both local quakes and far-off 'tele-tsunamis' from across the Pacific Rim, has suffered more deaths from tsunamis than from all other natural disasters combined, according to the Pacific Disaster Center.
Most tsunamis start with an undersea earthquake but underwater landslides can also churn up devastating waves, as can volcanic eruptions.
In 1883, Alaska's Augustine Volcano sent a surge of water outward after erupting. Far earlier, some 1,00,000 years ago, a massive volcanic landslide in Hawaii triggered one of the largest tsunamis ever to hit the islands.
Alaska's history is littered with such extremes. In 1958, an earthquake in Lituya Bay sent 90 million tons of rock crashing into the water, creating a wave that surged 1,700 feet high becoming the tallest tsunami ever recorded. As the location was relatively remote, few lives were lost. However, scientists argue that rising temperatures could cause mighty Alaskan glaciers to melt, sparking the potential for even more tsunamis in the future.
The continental US hasn't escaped the toll. In 1964, a 9.2-magnitude earthquake—the strongest ever recorded in North America—ruptured the Gulf of Alaska, sending waves all the was to California, where 11 people died in Crescent city.
Even modest waves, under 10 feet, can generate currents strong enough to destroy ports. In the worst cases, waves topping 100 feet can erase entire coastal communities.
Local tsunamis, triggered by nearby quakes or landslides, can hit within minutes, leaving little time for warnings to reach those in harm's way. Despite being rare, tsunamis represent one of the most powerful and unpredictable natural forces affecting the United States.