At 11:22 a.m. Thursday, as some Bay Area emergency officials rushed to ensure that residents evacuated to safety from a possible tsunami less than an hour away, a San Mateo County official pressed send on a social media post through the agency’s X account.

“UPDATE: National Weather Service reports that there is now no tsunami warning, advisory, watch or threat.”

It was wrong.

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Scientists still believed at that time it was possible that a wave triggered by the magnitude 7.0 earthquake off the coast of Humboldt County could barrel into the Bay Area around 12:10 p.m.

Ryan Reynolds, program services manager with San Mateo County’s department of emergency management, said in an interview Friday that the X post may have resulted from a glaringly simple mistake: someone in his office acted on a weather service tsunami bulletin that had ended the alert for Hawaii, not California.

“I think that’s a distinct possibility,” Reynolds said. “I cannot say for sure. I don’t know. These things are happening very quickly. And that’s why we’re continuing to push that and get that information correct.”

San Mateo County’s error was not the only perplexing response to the tsunami warning by a Bay Area agency.

In one county, an emergency tsunami alert only went out after the weather service had already canceled it, and after the wave had been predicted to arrive. Other jurisdictions decided not to sound their tsunami sirens, while regional ferry systems and airports carried on with business as usual despite their proximity to water and potential inundation areas.

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The upshot was clear: Even as federal officials advised people to move away from the coast across Northern California on Thursday morning, it was up to local officials at municipalities, counties and other entities — who sometimes relied on different sources of information — to decide what actions to take regarding evacuations and disruptions of service.

In the Bay Area, that meant a patchwork of responses that ranged from mandatory evacuations to delayed communication with the public to no action at all, with halts in some transit services but not others. In some cases, mistakes were made during the tsunami warning that was in effect for a little over an hour.

In Berkeley, city officials ordered and enforced mandatory evacuations across the western swath of the city, including several blocks east of Interstate 80. BART halted trains passing through the Transbay Tube while Muni closed downtown stations and rerouted vehicles away from coastal zones.

In other places, little to nothing was done.

The earthquake hit 45 miles off the coast of Eureka at 10:44 a.m. Five minutes later, the National Tsunami Warning Center issued a warning for the California and Oregon coast. Minutes later, the agency sent out “information statements” for Hawaii and Guam and other areas in the Pacific Ocean, saying it was analyzing if there would be a threat.

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At 10:55 a.m., the center issued a bulletin that there would be no tsunami threat to Hawaii. “A tsunami threat exists for parts of the Pacific located closer to the earthquake,” it said.

San Mateo County issued its first warning to residents at 11:16 a.m. on its X account. Six minutes later, it mistakenly issued the threat cancellation.

Reynolds told the Chronicle that his agency had called the Monterey office of the weather service, which said it did not expect San Mateo County to get hit hard by a potential tsunami because it had few low-lying coastal areas and the worst waves were expected to hit farther north.

After someone likely mistakenly read the wrong message from the tsunami center website, the department double-checked on a phone call with the Governor’s Office of Emergency Services, known as Cal OES, to determine whether the office could verify the tsunami warning had been cancelled.

“The exact wording they used is, ‘That’s what we’re hearing,’” Reynolds said.

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After the mistaken X post, Reynolds’ office called the Monterey branch of the weather service, which said the warning was still in effect.

At 11:31 a.m., San Mateo County corrected its error: “UPDATE AGAIN: National Weather Service has reissued the tsunami warning. Expected arrival at 12:10 p.m. AVOID beaches and coastlines. Move to high ground immediately! Updates to follow.”

The federal agency had not “reissued” the warning — it had never canceled it to begin with. Reynolds said that at this point, the mistake had been made and we “used the term reissuance to try and avoid conflicting information.”

A county spokesperson, Michelle Durand, said, “We used the term ‘re-issue’ because at that point in time it appeared to be just that, and also we felt it might be less confusing for residents who might not realize this was a new post.”

Finally, at 12:08 p.m., San Mateo County correctly alerted the public that the tsunami warning had been canceled. In retrospect, Reynolds saw learning opportunities.

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“I think that it’s critical in this business, to really take a lot of reflection and self-examination anytime anything happens,” he said. “I think a little bit of a pause. We talked about maybe a two-minute or a five-minute (delay) or something before we push that.”

The county also chose not to blare its tsunami warning sirens during the hour-long alert. Reynolds called the decision a “balancing act,” and said his office sought guidance from Marin County officials, who also have sirens at their disposal and decided against using them.

The decision was prompted by local weather service officials saying that San Mateo County was unlikely to be impacted significantly. Sounding the sirens might have caused panic and produced gridlock traffic, Reynolds said.

In San Francisco, where an alert to the public advising people to move away from the coast went out 48 minutes after the federal warning, no sirens went off because the system is broken.

In Contra Costa County, the Community Warning System did not notify the public of the tsunami warning until 12:20 p.m., according to posts on X that were later deleted. That was more than an hour and a half after the warning was issued, 16 minutes after the warning was canceled and 10 minutes after the first wave had been predicted to hit the Bay Area.

The Contra Costa Sheriff’s Office, which operates the Community Warning System, did not respond to questions Friday.

Supervisor John Gioia, whose district includes Richmond, which has areas in tsunami inundation zones, criticized the tsunami center’s quick trigger and confusing updates, and local jurisdictions, including his own county for their handling of the quake aftermath.

“The notices provoked a lot of fear. … The public was left confused and not knowing what to do,” he said. “We need to get the Tsunami Warning Center and we need to get public agencies to review their practices. Crying wolf is never a good thing; if you cry wolf every time people will start to not believe the message.”

In Santa Cruz County, the sheriff’s office did not post anything on its X account. At 11:30 a.m., 41 minutes after the warning was issued, the sheriff’s office posted on its Facebook page that a warning had been issued. Automated calls alerting residents of the warning reached some residents around 12:15 p.m., more than 20 minutes after the alert was canceled and after the wave had been expected to hit the area.

A Santa Cruz County sheriff’s spokesperson did not return requests for comment.

Oakland Airport, which lies in a potential flooding area in the event of a massive tsunami, did not adjust its operations Thursday during the warning period.

Spokesperson Kaley Skantz said the airport has an emergency plan related to flooding, including tsunami surges.

“That being said, unless tides are exceptionally high on a given day, the surge created by a tsunami is unlikely to have any material impact on OAK,” Skantz said. “Our airport team monitored the situation and did not make any operational changes during this event due to the assessed risk being almost zero.”

She said Port of Oakland officials, upon learning of the warning, assessed the risk to the airport and coordinated with officials at the Federal Aviation Administration, who were not concerned and did not reroute flights.

Denis Mulligan, general manager of the Golden Gate Bridge, Highway and Transportation District, which runs the Golden Gate Ferry, said their vessels operated as usual based off U.S. Coast Guard guidance. The federal agency instructs marine traffic over VHF Channel 14 during natural disasters, He said the agency activated its emergency operations center and coordinated with the Coast Guard and Water Emergency Transportation Authority.

He did not answer questions about safety on the water or loading areas during a potential tsunami.

Lamont Bain, science operations officer at the weather service office in Monterey, said predicting inundation can be tricky, but that’s what inundation maps are for.

“At that point in terms of evacuation orders, that’s when you really have to rely on your local jurisdiction and officials to direct you on what to do,” he said. “Generally speaking, if you’re along the coast, the recommendation is going to be to get away from the coast.”

It was high tide when the tsunami wave was predicted to hit, which would have worsened any potential wave.

On Friday morning, Bain participated in a post-event call with the San Francisco Department of Emergency Management. In San Francisco, the first text alerting residents about the warning went out at 11:37 a.m., 48 minutes after the warning was first issued.

“I have no doubt that we’ll be talking about this with all of our partners and stakeholders for quite some time,” Bain said. “We’re fortunate that in this case there weren’t substantial impacts. … I think we’ll look at this event, ‘What worked well, what didn’t work well? ' and then just try to improve together as a society.”