The earthquake was centered 30 miles west of the CA coast in the Pacific Ocean.
Ferndale, a small city in coastal Humboldt County, which is located approx. 130 miles from the Oregon border, was the nearest city, 62 miles from the epicenter. In San Francisco, about 270 miles away, residents said the quake produced a rolling motion for several seconds.
It is state protocol to issue tsunami warnings whenever a quake with a magnitude of more than 5.0 strikes in a coastal region. The warning was canceled an hour later.
From the NY Times:
Why wasn’t there more damage?
Dr. DeLong said the earthquake was a “largely horizontal motion,” meaning that two faults had slid past each other. It was also not particularly deep, and it struck offshore. “If the earthquake happens farther away, there’s less shaking,” Dr. DeLong said at the news briefing, adding, “We just don’t anticipate the humanitarian effects that we see from these earthquakes that occur under the land.”
Robert de Groot, an operations team leader for the U.S.G.S.’s ShakeAlert system, which detects earthquakes, described the motion of the quake as akin to slicing a cup of water with a knife. “Nothing really moves,” he said. “The knife just goes through.”
Still, the earthquake struck during what experts said could be a period of increased seismic activity in the state, after decades of relative quiet. Seismologists have long warned that an overdue “Big One,” which California has not experienced since 1906, could happen at any point.
I live in the EBay hills, NE of San Francisco. We didn't notice anything.
