Humboldt County got a good jolt Sunday night when an earthquake struck off the coast, west of Ferndale, but the chances of a large aftershock striking the area are diminishing by the minute.
Folks throughout northern California reported feeling the 6.8 quake that hit about 10:18 p.m. some 48 miles off the coast. Most reported feeling a gentle rolling that lasted more than 30 seconds. Humboldt State University Geology Associate Professor Mark Hemphill-Haley said the quake occurred on the Gorda Plate, an oceanic plate that is crumbling as its being subducted under North America and which accounts for 85 to 90 percent of the seismic activity felt on the North Coast.
While Hemphill-Haley said it is true there was a 90 percent chance the area would experience an aftershock of 5.0 or higher in the week following the quake, he said that’s based on a statistical formula and the probability of experiencing such a quake is steadily decreasing. Still, a total 16 aftershocks measuring 3.0 or greater were recorded in the area between the time of the quake and 8:30 a.m. Monday, according to the United States Geological Survey.
No tsunami warning was issued after the temblor, but Hemphill-Haley said some folks evacuated from low-lying areas, which he said was smart. The recommendation, he said, is that folks leave low-lying areas for higher ground any time they feel more than 15 seconds of strong motion. People hanging on the coast, he said, should get moving toward higher elevation as soon as they feel any shaking at all.
Sunday night’s quake should serve as a wake-up call, Hemphill-Haley said, urging people to check their quake kits and emergency plans.
The earthquake trumped news that Sunday’s rainfall broke a 30-plus year record. Scott Carroll, a meteorologist with the National Weather Service, said Eureka recorded 2.58 inches of rain Sunday, smashing March 9’s previous record of 1.17 inches in 1983. The precipitation onslaught brings the area up to 52 percent of normal rainfall levels for the current water year, which runs July 1 through June 30. This week’s forecast looks pretty dry, Carroll said.