SAN FRANCISCO (KRON) — A 7.0-magnitude earthquake that struck Thursday morning in Humboldt County prompted a tsunami warning across the Northern California coast into Oregon. In the San Francisco Bay Area, evacuations were made as communities braced for a tsunami that ultimately never came. Officials clarified Friday why a tsunami warning was issued when no tsunami threat ever developed.

“We understand the confusion and disruption this warning caused,” National Weather Service Bay Area said in a social media post. Officials said there were a “lot of questions, frustration, and even some anger about how it all unfolded.”

According to the weather agency, there are two ways in which a tsunami warning will be triggered. One is for distant trigger events that allow scientists the time to analyze and confirm data that shows a tsunami has developed prior to issuing the warning. While scientists work toward confirmation, a tsunami watch may be issued in the interim.

The second way a tsunami warning is triggered is what happened in Northern California on Thursday, NWS said. Local trigger events that occur close to the coast do not have the luxury of time. “The warning must be issued with more uncertainty in order to allow the maximum possible evacuation window,” officials said.

At 10:44 a.m., the 7.0M quake struck 45 miles southeast of Eureka. Five minutes later, the National Tsunami Warning Center issued a tsunami warning that included the Bay Area. The alert impacted 5 million people and blared on countless cell phones.

Tsunami waves in the deep ocean can travel as fast as 500 miles per hour, NWS said, and for the safety of millions, officials cannot wait to confirm using coastal observations or deep ocean buoys.

After the tsunami warning alert was sent at 10:49 a.m., scientists continued to receive data. Considerations were made for the strength of the earthquake and its faulting mechanism. Measurements and possible signs of tsunami waves were also analyzed.

In the end, the quake generated only a “small” tsunami, according to NWS. “All incoming data after the earthquake pointed to no damaging tsunami threat,” the agency said.

Seventy minutes after the quake struck Northern California, at 11:54 a.m., the tsunami warning was deactivated.

“We were fortunate yesterday, but don’t assume the next warning will play out the same way,” the weather agency said. Officials urged coastal community members to familiarize themselves with the preparations and actions that should be taken in the event of tsunami warnings.