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Poor H Dog.
The docks closest to the port, designed to bear the brunt of surge energy, pounded when a four-foot tsunami hit Crescent City Harbor in rural Northern California last week.
Protem Mike McGuire, the state Senate president who represents the North Coast, is known as the H-Dock and the “Sacrificial Lamb.” The Crescent City Harbour district said in a statement that the dock “worked as it was designed and sacrificed to protect other infrastructure.”
But despite state and local officials’ relief for how well the docks worked during the storm, the damage to the port of Del Norte County, known as “comeback town,” due to its history with the tsunami, appears to be worse than the original review.
Harbor officials now estimate that on July 30, the throbbing wave caused $1 million in damage to the port. It was destroyed by the 2011 tsunami and was rebuilt as “tsunami resistant.”
“On the first glance, the damage seemed modest,” the Harbor district said in a statement Tuesday. However, further evaluations showed serious sub-water lines impacts on infrastructures that “support ports’ safe and functional operations.”
Added Harbormaster Mike Rademaker: “The visible damage tells only part of the story.”
The tsunami, which followed the 8.8 magnitude earthquake off the sparse east coast of Russia on July 29, sparked alerts along Japan, Canada and the entire West Coast of the United States. In the end, it caused little damage outside of Northeast Russia, and almost destroyed the floating pier at the submarine base.
Crescent City, a town where the tsunami of about 6,200 people was born, appears to have had the most impact in California.
According to the Harbour area, at about 2:40am on July 30 and at about 2:40am on July 30, Surging Waves stacked and lifted the H Dock floating concrete deck.
As the water continued to rise, the structure could not support the deck. It was temporarily submerged, “resulting in segment separation and progressive structural failures,” the Harbor district said in a statement last week.
In a statement Tuesday, Harbor officials said the incident illuminated “new vulnerabilities in floating dock designs: Previously unrecognized hydrodynamic impairment mechanisms.”
Video footage and data modeling starting July 30th will include “Fluid dynamic effects on docks that are rarely captured in video.”
The tsunami accelerated the current below the floating deck of the H-dock, creating a low-pressure zone that “produces a force strong enough to overcome the buoyancy of the dock, pulling the structure downward into the water.”
“This is similar to the way an airplane’s wings generate lifts, but the opposite,” Harbormaster Rademaker said. “Instead of lifting up the structure, the rapidly moving water under the dock actually covered it. It’s a dramatic and underrated mode of failure.”
Crescent City Harbor suffered major tsunami-related damage, primarily affecting H-Dock.
(Courtesy of Crescent City)
Port officials believe that the electrical conduits passing through the center of the H-Dock deck are as badly damaged as drinking waterways. The fire extinguishing pipelines have fallen apart.
The tsunami also deposited large amounts of sediment and debris throughout the port basin. Harbor officials added that restoring the safe depth of boat navigation requires extensive dr removal work, adding that repairs are “more expensive than comparable land-based jobs” due to the required specialized labor.
Port authorities said Tuesday they are working on a tight deadline to assess the damage. California law requires city and county governments to declare a local emergency within 10 days of a disaster as a prerequisite for requesting state or federal assistance.
The Del Norte County Board of Supervisors said: “We will issue such a declaration later this week,” a statement from the Harbor District read.
The boat was not damaged in the storm last week and no injuries were reported.
In 2011, the tsunami that followed a catastrophic earthquake in Japan caused $50 million in damage to Crescent City Port. The storm damaged many boats and was repeatedly pounded by docks and each other.
The inner boat basin has been completely rebuilt to allow for more tsunamis to resuscitate.
According to the Harbour area, the 16-inch stakes used in the previous dock structure were replaced by the 16-inch stakes used in the previous dock structure, driven to bedrock compared to just 10 feet in the previous design.
The H-dock is designed to withstand the brunt of a storm and is closely spaced, designed to absorb and consume energy before it reaches the interior dock.
State and local officials said the design hampered the impact from the much worsening tsunami last week.
“Infrastructure built since 2011 saved ships and lives,” writes Rademaker. “Now we have the opportunity to take our design to the next level. We are not asking for blank checks to return to the status quo. We are taking advantage of the opportunity to build smarter what we have learned.”
Crescent City is susceptible to tsunamis for many reasons, including exposure, which is lowlands and protrudes into the Pacific Ocean – and the shape of a bowl on the continental shelf that traps the energy of the tsunami and exchanges waves.
42 tsunamis have been recorded in Crescent City since the first tide gauge was installed in 1933, including last week’s surge.
Crescent City earned the nickname Comeback Town in 1964 after the tsunami killed 11 people, destroyed 29 city blocks, and changed downtown forever.
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