Three earthquakes rumbled through Northern California late Wednesday and early Thursday, but the temblors probably weren't connected, geologists said.
A magnitude 4.0 quake hit around 9:19 p.m. Wednesday roughly 85 miles southwest of Eureka. The quake was 1.2 miles below the ocean floor, geologists said. Then just before 2 a.m. Thursday, a 3.3-magnitude quake struck about 25 miles north of Santa Rosa in The Geysers, where geothermal energy reaches the surface. Roughly seven hours later, at 9:16 a.m., a magnitude 3.4 quake hit 25 miles south of Eureka - 60 miles from where the Wednesday night earthquake was centered. No damage was reported in any of the temblors.
The collection of quakes was probably nothing more than coincidence, said David Schwartz, an earthquake geologist with the U.S. Geological Survey. "It is very hard to say that there is any cause and effect between them," Schwartz said. "In any 24-hour period, you could get quite a number of earthquakes in California." A major earthquake can set off a chain reaction, Schwartz said. But "these quakes are so small and their effects are so local, that I have trouble believing that they are related."