Tsunami warning puts disaster response to the test
- Kevin Hessel
- Dec 11, 2024
- 9 min read
Updated: May 21
The Tiburon Peninsula was briefly under the highest-level tsunami warning last week after a 7.0-magnitude earthquake struck off Humboldt County’s Cape Mendocino, with many residents taking to higher ground, local first responders visiting low-lying areas to issue warnings and dozens of parents retrieving their kids from Reed Elementary School, where the district ordered all schools to evacuate lower levels.
But other residents, including those in mapped tsunami inundation zones, were left in the dark about the local response as Tiburon and Belvedere relied in part on AlertMarin for public outreach. Just 37% of 94920 residents have signed up, county officials say, and for those who have, some notifications were significantly delayed.
“This was an actual exercise” that could in theory have been devastating, said Belvedere’s Tom Cromwell, a disaster-response champion who’s chair of both the Block Captains Committee and the Belvedere-Tiburon Joint Disaster Advisory Council. “It reminds us we might need to crank up efforts.”
At 10:49 a.m. Dec. 5, just five minutes after the quake, millions of cellphones across Northern California received a notice from the National Oceanic and Atmospheric Administration’s National Tsunami Warning Center in Palmer, Alaska. The warning was the highest-level alert, above an information statement, watch or advisory, for possible “dangerous coastal flooding and powerful currents,” with instructions to move to high ground or inland.
“Coasts facing all directions are threatened because the waves can wrap around islands and headlands and into bays.”
The bulletin included surge-start times for several cities to the north and south of the quake epicenter, including San Francisco at 12:10 p.m., meaning Marin was predicted to be first hit about noon.
But with the bulletin covering an 800-mile stretch between central Oregon and Santa Cruz, it was up to local authorities to assess the threat and reach their own residents.
According to Marin Director of Emergency Services Steven Torrence, the county pushed out its AlertMarin notice at 11:19 a.m., but delays were caused by third-party vendor Everbridge, with emails, texts and phone calls not delivered to some residents for nearly half an hour. Barely a third of Tiburon and Belvedere residents are signed up for alerts, Torrence said, and while the service can reach landlines and cellphones listed as the emergency contact on utility bills, renters can be harder to reach if they’re not the contact. The alert for many of those numbers is limited to phone calls.
For several members of The Ark staff, where the office is in the inundation zone at The Boardwalk shopping center, the AlertMarin phone call to evacuate to higher ground was delayed the most, not arriving until 11:50 a.m., more than an hour after the national alert but just minutes before the tsunami had been predicted to first hit Marin’s northern coastal areas.
“If you are on a beach or very near the coast, evacuate immediately. If unable to go to higher ground, go to a second floor. Stay away from harbors, coastal and low-lying areas until further notice,” the messages said.
Representatives from Everbridge did not return a request for comment by The Ark’s press time, but Torrence said the county is investigating the issue. San Francisco press officials said SFAlert, which also uses Everbridge, did not suffer any significant delays.
In the meantime, other coastal communities were taking significant actions following the federal alert, including those south of the peninsula or further into the inner bay. Disaster sirens were sounded and helicopters were dispatched to Stinson Beach, where evacuations were ordered. Sirens were also used in Bonny Doon in Santa Cruz County, at the southern end of the federal alert area. Berkeley issued “immediate danger … must evacuate now” orders for Aquatic Park and parts of Interstate 80 and West Berkeley. San Rafael patrolled shorelines. Vallejo issued alerts that kids could be picked up from schools. First-responders in San Francisco took to beaches with megaphones to get people away, BART suspended all underground service, some Market Street and Treasure Island Muni service was canceled and the zoo was evacuated.
At the Reed Union School District, where only Reed Elementary School is in the inundation zone, the superintendent ordered principals to create a plan to move students to higher ground. That was activated about 11:50 a.m., according to Reed Elementary Principal Mary Niesyn. She said all children on the lower floor there joined kids in predetermined buddy classrooms on the upper portion of the tiered campus, and everything was back to the status quo by lunchtime.
Niesyn said about 50 children were picked up by parents who were notified of the tsunami warning. The school had quickly implemented a vehicle pickup line with staff acting as runners to retrieve students from class and record them as having joined their parents, she said.
But during the same period, the local public-safety response was considerably cooler.
The warning system’s supplemental forecast timeline predicted Sausalito would be hit at 12:15 p.m., meaning the Tiburon Peninsula would potentially be struck moments later.
It was a maximum-velocity, level-3 alert, Tiburon Peninsula Emergency Services Coordinator Laurie Nilsen of the Tiburon Police Department said.
A few minutes after the initial AlertMarin notice went out, the National Tsunami Warning Center issued a followup notice, at 11:24 a.m., which included that the coastal warning was still fully in effect. About the same time, however, the U.S. Geological Survey was hosting a conference call in which state and county officials learned the warning could be called off about noon.
Tiburon Police Chief Michelle Jean said that local authorities learned at about 11:30 a.m. that there was a chance the warning could be canceled and chose to not sound the peninsula’s six emergency-warning sirens “until we had more clarity.”
Under the Tiburon Peninsula Emergency Operations Plan for Tiburon and Belvedere, where the latest update was developed and approved by Tiburon in late 2021 and Belvedere in September, the joint Emergency Operations Center at the Tiburon Police Department is supposed to be “hot” and activated for a tsunami warning — on level 1, standby with one of the city or town managers acting as director with the emergency services coordinator to monitor developments; on level 2, a partial response for a potential widespread emergency, adding planning/intelligence and logistic coordinators; or on level 3, a full response for a major event with obvious damage, bringing in all the positions required to cover 24 responsibilities from the city or town manager’s office, police, fire, public works, planning and finance.
Jean said that while the center wasn’t activated, representatives from public works and administrative staff, alongside the Belvedere Police Department and Tiburon Fire Protection District, were at the department to monitor the event as it unfolded. They also worked with the Reed Union School District as they collectively got updates at the county and state levels, Jean said.
In addition to the sirens, peninsula disaster responders have access to 840 AM radio and to Genasys Protect, formerly Zonehaven, to create neighborhood-specific alerts, though those are also relayed to residents either through the AlertMarin system or the mobile app with low local participation rates.
By Ark estimates, there are roughly 1,000 homes, businesses and public facilities in Tiburon’s and Belvedere’s combined tsunami inundation zones as mapped by the California Geological Survey, though that’s for an extreme event — a 9.3 Alaskan quake that would send a 13-foot wall of water to the peninsula.
Such a quake could inundate the entire downtown Tiburon Boulevard corridor, including the Point Tiburon Bayside and Marsh condos plus coastal homes along Paradise Drive and Mar East Street; Main Street and downtown businesses up to The Boardwalk shopping center; public agencies like the downtown fire station, Town Hall, the Belvedere-Tiburon Library, the Police Department, Reed Elementary School and the Richardson Bay Sanitary District wastewater station; several homes off Rock Hill and Hawthorne drives; plus dozens more homes deep into in the Bel Aire, Reedlands and Belveron neighborhoods.
For Belvedere, the zone includes all homes on the lagoon and on West Shore Road, as well as low-lying areas of Beach Road, Corinthian Island and San Rafael Avenue — including the lower levels of City Hall that house the Police Department and Community Center — plus the Corinthian and San Francisco yacht clubs and their harbors.
While an Alaskan quake would give residents about five hours to react, modeling shows a 7.3 at the Point Reyes thrust fault would bring a 4-foot swell within minutes. The expanded inundation maps were updated after the 2011 Tohoku-Oki earthquake and tsunami in Japan, which caused $100 million in damage to California harbors, much in Crescent City and Santa Cruz.
The peninsula saw a 3-foot swell after a volcanic eruption in Tonga on Jan. 15, 2022, that caused little local damage, though boats washed ashore and a floating dock broke away at The Cove at Tiburon apartments, temporarily stranding a resident there.
In limbo last week after the Humboldt quake, Tiburon and Belvedere each dispatched a handful of staff to certain low-lying areas to issue warnings in person. Jean said four to five staff went to The Cove shopping center and to downtown commercial areas “where we expected a higher density of people at the time of day this event occurred,” but no homes were visited or warned.
Robert Zadnik, Belvedere’s city manager and emergency-preparedness coordinator, said three public works staff and one police officer knocked on doors on West Shore and Peninsula roads and on San Rafael Avenue to warn residents to evacuate to higher ground and that council chambers in City Hall were open as an evacuation center.
He said they didn’t have time to alert residents along Lagoon Road.
Zadnik said that while some residents who answered chose to move to higher ground, others thought the severity was overstated and still others chose to shelter in place and wait for more information.
Cromwell said that he saw people walking and driving to higher ground and called City Hall about activating the block captains group, but that Zadnik didn’t feel it was necessary.
Zadnik said in an interview that, like Jean, he was also made aware through communications with the county that the tsunami likely wouldn’t be as severe as initial federal warnings indicated.
Broader community outreach was limited. There was no central coordination for public or media messaging, making the local response unclear until after the threat had passed.
Tiburon issued notices on Instagram and Nextdoor about 11:30 a.m. — “evacuate inland or to higher ground,” the latter said, directing residents to tsunami.gov for more information — while Jean said the town has gotten away from using the Tiburon Talk newsletter as a real-time alert system.
Belvedere also didn’t send out a Belvedere Blast newsletter, and it doesn’t have a presence on social media, including on Nextdoor. Instead, it updated the city website to notify residents, with Zadnik saying he was worried about mixed messaging when notifications are also coming from AlertMarin.
Meanwhile, Nilsen, the emergency services coordinator, is also the Tiburon police spokesperson. Historically, however, her duties as coordinator have required precedence in an emergency, limiting her ability to also act as a central media liaison. Last week, The Ark was referred to Tiburon police Capt. Jarrod Yee for details about Tiburon’s response, to Belvedere Police Chief Jason Wu about Belvedere’s response and to the Tiburon and Southern Marin fire protection districts about their own individual responses.
Belvedere also requires all media inquiries, including permission for the police chief to provide comment for The Ark on any matter, to first run through Zadnik, frequently delaying access to information on public-safety and other issues.
Jean said that communications will be a critical part of the town’s post-incident review, while Zadnik said he’d like to explore integrating the media in its response plan to get the word out.
The Ark previously participated in Emergency Operations Center activation drills, the last time in 2015.
Ultimately, the tsunami never materialized.
Experts had initially thought the quake, near the Cascadia subduction zone, was a 7.3 with the potential of triggering a massive tsunami at a fault where plates collide. With no land or buoys between the epicenter and the nearest coastline, there was no way to monitor the surge without putting residents at risk.
That magnitude revised down to a 7.0 at 11:24 a.m., though the tsunami warning remained in full effect.
Analysts later determined the quake was on the Mendocino fault zone, a northern extension of the San Andreas strike-slip fault, where side-to-side action is less likely to produce tsunamis, as the first buoy 130 miles southwest also registered only a 1 centimeter sea rise.
The federal alert was called off at 11:54 a.m., shortly before any potential tsunami’s predicted noon arrival on Marin’s northern Pacific coast, with the AlertMarin notification of cancellation sent at 12:14 p.m., after the potential northern threat had passed and about as the wave would have hit the peninsula. Notifications were delayed again, however; for the only Ark staff member to receive the cancellation call, it came at 12:59 p.m.
The Humboldt quake was the strongest earthquake in California since the 7.1 near the Kern County city of Ridgecrest in July 2019.
Reach Executive Editor Kevin Hessel at 415-435-2652. Reach public-safety reporter Naomi Friedland at 415-944-4627.
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