In many ways, the magnitude 7.0 earthquake that struck about 60 miles west of Petrolia and rattled Humboldt at 10:44 a.m. on Dec. 5 was entirely typical.
It occurred on the Mendocino Fault, a submarine fracture zone that runs more than 2,500 miles west from Cape Mendocino, separating the Pacific and Gorda plates.
“That fault, we can count on it to always be pumping out earthquakes,” says Lori Dengler, a Cal Poly Humboldt geology professor and world-renowned earthquake expert, adding that the Mendocino Fault is the most active fault in California for quakes registering magnitude 5.0 and above.
And while shaking from the temblor was reportedly felt from Medford, Oregon, to Southern California, and as far east as Carson City, Nevada, it was not particularly violent, with Dengler saying most described it as a kind of “rolling,” “round motion.” As such, reports of significant damage have been minimal, with the only known injury occurring in Ferndale, where someone reportedly fell and broke their arm while attempting to run outside before the shaking stopped.
What was entirely atypical about the quake was that it was the first to result in a tsunami warning issued by the National Oceanic and Atmospheric Association (NOAA) through the Wireless Emergency Alert system in a partnership between cellular companies and the federal government. And because of the complexities of an alert system not specifically designed for tsunamis, the alert went out to 5.3 million people in California, as well as some in Oregon, with the alarms on their phones sounding and advising, “You are in danger,” setting off widespread confusion and, in some cases, panic.
Here on the North Coast, experts say the quake, warning and associated alerts also laid bare how ill-prepared many residents are for a large-scale earthquake and tsunami, which are daily threats in Humboldt County.
Ryan Aylward, a warning coordination meteorologist with the National Weather Service, says most people are now accustomed to the earthquake warning system set up by the United States Geological Society, which sends out warnings to those in geographic areas expected to experience a certain degree of shaking in an earthquake. The alerts are designed to arrive just as the quake starts, if not a second or two prior, ideally giving people a warning to drop, cover and hold.
Tsunamis are a relatively recent addition to the Wireless Emergency Alert system, and Aylward says it’s the National Tsunami Warning Center in Palmer, Alaska, that makes the call as to when a warning should be issued. Dengler notes that while other countries — including Japan — have more detailed gradations of tsunami advisories, they come in two levels in the United States: an “advisory,” which is issued when a tsunami generating waves 3 feet or shorter is projected, and a “warning” for anything larger.
Aylward says the folks at the national warning center have set a threshold that any quake larger than magnitude 7.0 within a certain distance of the coast triggers a warning. The thinking is that an earthquake of that size close to the coast has the potential to trigger a devastating tsunami that will arrive on shore within minutes, so it’s better to act in an abundance of caution.
Dengler says if this had registered as a 6.9 earthquake, no warning would have been issued, noting it was the “worst possible type of tsunami situation” for a first test of the Wireless Emergency Alert system, as it demanded a quick decision with limited information. Complicating matters, Dengler says, is NOAA’s alert system, which is built for weather events and is based on “break points,” or geographic areas. There are only seven of them in place between San Diego and the Canadian border, Dengler says, adding that there’s one in Mendocino County and the next one south is by Santa Cruz, south of the Bay Area. Consequently, when the tsunami warning center saw potential danger a little south of the one in Mendocino, its only option was to issue the warning all the way down to Santa Cruz.
“We’re using the weather warning for tsunami, and it’s just not a good fit,” she says. “We all knew there was no way this tsunami was going to impact within San Francisco Bay. There’s just no way a magnitude 7 is going to do that.”
Dengler says the break-point system is something she’s sure is going to be addressed, “the question is how long it will take.” But there’s an urgency to getting it right, she says, pointing out that in addition to the economic impacts the flawed warning had in the Bay Area but stressing the major issue is “you want people to really trust the tsunami warning systems,” and needless warnings can have a boy-who-cried-wolf effect.
There are also more tangible impacts, too. Dengler says locally the warning resulted in ambulance companies declining to drive through a tsunami zone when a warning is in place, delaying emergency medical service for at least five calls.
The Humboldt Office of Emergency Services also issued its own alert relaying the tsunami warning, which came at 11:37 a.m. — 53 minutes after the quake — and was canceled about 45 minutes later.
While some residents have been critical of the delay, Emergency Services Manager Ryan Derby says the local alert system is not automated and needs to be initiated by his staff, which first needs to “confirm” the federal earthquake and tsunami warning alerts.
“We have a staff of four in the office of emergency services, and we’re impacted by earthquakes just like everybody else,” Derby says. “There’s going to be a delay, specifically with local earthquakes. I think the key takeaway there is that the shaking is your notification.”
Dengler and Aylward underscore this point, too, saying that while it’s important for residents to sign up for all available notifications from government agencies and cell phone apps, it’s unclear which — if any — would work in the event of a massive magnitude 9.0 earthquake, the kind local tsunami maps were created with in mind.
“There’s going to be a big earthquake with a big tsunami someday, and we’re not even sure the alerting systems will work,” Aylward says. “The earthquake — that’s your real alert. If you’re in the tsunami zone and you feel that earthquake, start evacuating.”
While Dengler stresses this is the first time the Wireless Emergency Alert system has been used for a tsunami warning, and there are plenty of lessons to be learned and improvements to be made. She says the Dec. 5 event also served as a kind of test of community readiness. If that’s the case, we failed.
First, Dengler says she’s already seen too many videos of people reacting to the onset of shaking by trying to run outside, noting that’s how people most typically get hurt in quakes, while the correct response is to drop, cover and hold on until the shaking stops.
There’s also a clear lack of preparation, experts say.
Dengler, Derby and Aylward all stressed the importance of households taking the time to really look at and consider the local tsunami zone maps, which, again, were created with a magnitude 9.0, 1,000-year tsunami in mind. (Find the official map at rctwg.humboldt.edu/tsunami-hazard-maps.) Derby and Aylward say outdated or unofficial maps were circulating on social media in the immediate aftermath of the quake, leading to widespread confusion.
“You need to know where you work, where you recreate, where your kids go to school and where your home is,” Aylward says. “And if you’re not in the tsunami zone, you don’t need to do anything. Just stay put.”
Dengler also stresses that people should trust the zone, noting they were prepared for an event 1,000-times stronger than what Humboldt experienced on Dec. 5 that occurs at high tide with high surf. There’s no need to run to Kneeland or Humboldt Hill, she says, noting folks will be just fine on the Arcata Plaza or in most of downtown Eureka.
Derby reminds folks to take note of those tsunami zone signs throughout the county, saying they’re not just for tourists.
“They placed those conservatively outside the tsunami inundation zone, meaning anyone who is on the eastern side of those signs would be in a safe position, at least in a 1,000-year event,” he says.
And if people frequent places in the tsunami zone, people should develop a plan for safely getting out of the tsunami zone on foot as quickly as possible.
Dengler, Aylward and Derby all note backed up traffic became a problem in some areas of the county following the warning, when much of the tsunami zone locally is within just a few blocks of safer ground. And if you live or work in the tsunami zone, Aylward says it’s a good idea to put together a go-bag you can grab on your way out the door, noting a large-scale tsunami may inundate the coast with waves for 24 hours or more, necessitating prolonged evacuations.
Aylward says the most important thing is to have a plan, to talk about it and to practice it, noting that a school in Manila that sits squarely in the tsunami zone practices tsunami drills monthly and, consequently, had all students safely on higher ground on Dec. 5 before the official tsunami warning was issued just five minutes after the quake.
Dengler also says it’s a good opportunity to remind the community of the need to plan to be resilient.
“I always like to emphasize the importance of talking to your family, talking to your neighbors,” she says. “In a really large event, it’s you and your neighbors who are going to be the first responders. Talk to your family, talk to your kids’ schools, talk to your workplace. What can we do to be more resilient?”
Thadeus Greenson (he/him) is the Journal’s news editor. Reach him at (707) 442-1400, extension 321, or thad@northcoastjournal.com.
This article appears in Sculpting Community.
The fact remains; the county response was awful and more life-threatening than the event, and the local media will give a pass to local incompetence, because it’s local.