Since the tidal gauge was installed in Crescent City’s harbor in 1934, the town has been hit by 34 tsunamis. This time, the waves raced into the boat basin, ripping up docks, sinking 11 boats, damaging 47 others, killing one man and causing millions of dollars in damage.
Tsunamis are different from stormy seas. A storm wave is generated by the wind, moving only the top of the water.
A tsunami, however, is generated by an upheaval on the ocean floor. To a ship at sea, it’s not even noticeable — three to four feet high — a bump in the ocean.
This tsunami was generated by one tectonic plate slipping violently underneath the other in a zone 350 miles long and 150 miles wide. The wave raced across the ocean at the speed of 500 to 600 mph.
A factor that saved the harbor from even more damage was the surge hit at low tide, keeping it within the breakwater. Plus a network of deep-sea warning sensors alerted the entire West Coast hours in advance of the surges from the magnitude 9.0 earthquake in Japan.
The town wasn’t forewarned on Good Friday, 1964, however when a magnitude 9.2 earthquake in Alaska’s Prince William Sound sent bigger surges down the coast. Crescent City bore the brunt, due to its offshore geography, position relative to the earthquake’s strike-line, underwater contours such as the Cobb Seamount, and the position of rivers near the city.
Within a two hours, four waves washed over Crescent City.
When finished, 289 buildings and businesses had been destroyed; 1000 cars and 25 large fishing vessels crushed; 11 people were confirmed dead, over 100 were injured, and numbers were missing; 60 blocks had been inundated with 30 city blocks destroyed in total.
Although most of the missing were later accounted for, not all were found. Authorities estimate the city received more damage from the tsunami on a block-by-block basis than did Anchorage from the initial earthquake.
It took the city years to recover from the 1964 Tsunami, with the help of Congressman Don Clausen, who secured federal aid for the ravaged town. There are also some who claim,Crescent City has never recovered and still others who say it never will.
This a matter of person opinion on those people’s part.
Another earthquake, measuring magnitude 8.2 rumbled in the Pacific Ocean, west of Eureka, November 8, 1980. A number of Del Norte residents report being able to walk out to Whaler’s Rock, jus’ off Pebble Beach in Crescent City, as the waters had receded that far, but they didn’t report seeing surge waves.
This event was followed years later by a magnitude 6.5 and 6.6 aftershock April 25, 1992 off Cape Mendocino. Again the ocean recede into itself, and again there was lack of surge waves.
Then the city’s preparedness was tested June 14, 2005 when an earthquake measuring magnitude 7.0 occured 90 miles offshore. Reportedly, much of the city was evacuated in a matter of 20 minutes when a tsunami warning was issued, but no waves were reported.
Then on November 15, 2006, a magnitude 8.3 earthquake struck off Simushir Island in the Kuril Islands, in the western Pacific. A tsunami warning was issued but rescinded hours later. However, a surge from that quake did hit the harbor at Crescent City causing damage to three docks and several boats.
As this recent tsunami moved east, the wave’s energy bounced off a huge underwater ridge extending out from Mendocino, deflecting part of its energy toward Crescent City.
The deflection slowed the wave, but made it grow higher. And by moving into shallower water, its energy built even more.
The first surges to hit the shore were small. But by bouncing back, they made the next surge bigger and so on.
When the biggest of the surges hit the tidal gauge, it measured 8.1 feet.
That bouncing amplification is what caught Dustin Weber at the mouth of the Klamath River. He and two friends thought the tsunami
was over after the first surge.
Weber was caught in the bigger surge that hit a couple of hours later. His body has not yet been found.