(CNN)- A 6.5-magnitude earthquake shook the ocean floor about 100 miles off the northern California coast Thursday morning, causing weak to light shaking in near coastal communities in parts of that state and Oregon, the US Geological Survey said.
The quake, centered about 102 miles west of Ferndale, California, happened around 6:50 a.m. PT.
Light shaking was reported from east central Oregon to areas a few dozen miles south of San Francisco, the USGS said.
No tsunami threat is expected from the quake, the Pacific Tsunami Warning Center said.
There were no immediate reports of injuries or serious damage.
The USGS initially said the magnitude was 6.8, but later revised it.