Nobody has to be more aware of tsunami dangers than fishermen and mariners.
Tsunamis that have zero threat of causing damage on land can still destroy a marina and the boats it holds — as seen in Crescent City Harbor in 2011.
And the way that boat owners and captains have to react for each particular tsunami can be very different.
During a Friday meeting with fishermen and mariners, emergency response planners were alarmed at the fact that most in attendance thought they should always take their boat out to sea after an earthquake to avoid the carnage of a pending tsunami.
Not the case, said Troy Nicolini of the National Weather Service, who advised the boat-owners at the meeting and those he met on the docks that there will be no time to hit the sea during a near-source earthquake.
“There is no time to take your boat to deep water,” said Nicolini, adding that a tsunami could arrive in less than ten minutes if the earthquake shakes for longer than 30 seconds.
If a long earthquake occurs when a boat is already at sea, the boat should stay out in the deep water until the tsunami danger passes, which could be up to 24 hours.
“There’s no time to get back and tie your boat up, so you’re better off going out into deeper water,” Nicolini said.
Going out to sea to avoid damage “worked great in 2006, it worked great in 2011, and worked OK in ’64, but it won’t work when the earthquake is right under us,” Nicolini said.
‘Playbook’ for tsunamis
Also on Friday, state and federal scientists and emergency managers gave details about a project focused on creating maps that identify the specific tsunami danger posed in and around harbors in California.
The maps will be the basis of tsunami response “playbooks” that harbor personnel can turn to during tsunami threats, according to a press release on the project.
Crescent City is one of only five pilot ports for which maps have already been created, but the plan is to expand the project to all California harbors. The other pilot harbors are in Santa Cruz, Ventura, northern San Diego Bay, and the small boat marinas within the ports of Los Angeles and Long Beach.
“Every tsunami is unique,” said Rick Wilson, who manages the California Geological Survey tsunami program. “The height and frequency of the tsunami surges and the ports that are impacted vary with the source. We’re calling our project a ‘playbook’ because we want to give the harbormasters multiple options depending on the situation. In the last couple of tsunamis that have impacted California’s coast, the harbormasters have been on their own. Now they’ll have a course of action to follow in advance.”
These maps are for more-common, distant-source tsunamis like 1964, 2006 and 2011.
For a near-source tsunami, like one produced by an earthquake on the Cascadia Subduction Zone, vessels will not have time to make it to deeper water.
The maps and playbooks should provide some guidance to boaters who decide to take their vessels out to sea by showing them how to avoid tsunami damage, where they will be safe and whether or not they should risk going to sea.
Nicolini pointed out that the playbooks will be most useful when the ocean conditions are dangerous, like 45-knot winds offshore, unlike in 2011 when ocean conditions were fine.
“Is this tsunami going to cause enough damage to hurt boats in port? Because we know there’s a lot of damage possibility out at sea,” Nicolini said about a possible scenario.
Planning past worst-case
Emergency managers have often made a habit of planning specifically for the worst-case scenarios.
The harbor tsunami playbooks are designed to provide more guidance for smaller tsunamis where it is more difficult to predict the threat, like in 2010 when emergency managers were caught off guard by a Chilean earthquake that caused $3 million in damage in California.
Videos and eye-witness observations from the 2010 and 2011 tsunamis validated numerical modeling that had already been created, giving emergency managers the ability to model other scenarios, Wilson said.
Some of the information learned during those events will be used to create models for how deep the ocean needs to be before a boat is safe.
“We are working with each one of the harbors to develop a safe-zone offshore,” Wilson said.
“Offshore safety areas are important,” said Kevin Miller, tsunami lead at California Office of Emergency Services. “But it is equally important for boaters to understand that they may have to stay offshore for up to 24 hours until tsunami activity dies down.”
When the 2011 tsunami was heading towards Crescent City, then-harbormaster/CEO Richard Young and Nicolini were doing back-of-the-envelope calculations on what effect could be predicted from the tsunami’s planned arrival at low-tide.
They were able to be fairly confident that the tsunami would not cause damage on land.
Nicolini said that those “in the moment” calculations for Crescent City were one of the main motivations for the harbor playbook project.
Another project pioneered in Crescent City is the tsunami-resistant harbor that was completed this year, which emergency managers said on Friday will be used to establish a standard for harbors moving forward.
“I think Crescent City is going to be a great example for other coastal communities to look at when they are addressing these risk levels in their hazard and mitigation process,” said Ed Curtis, a civil engineer with FEMA Region IX in Oakland.
If a tsunami spurred by a large earthquake in Alaska’s Aleutian islands like in 1964 were to happen today, Wilson of CGS said that California might lose one-third of its ocean vessels statewide and two-thirds of the state’s marinas.
The 50th anniversary of that 1964 event is next Thursday, and with a tsunami-resistant harbor and a strong county emergency planning and response program in place, Crescent City and Del Norte County are looking like one of the most prepared communities on the West Coast.