There were two earthquakes early Wednesday morning with magnitudes over 5.0 that rumbled under the Pacific Ocean off the Northern California coast.

The first of the quakes, with a magnitude of 5.7 on the Richter Scale, struck at 3:53 am about 95 miles due west of the California-Oregon border. The USGS puts the epicenter at 154 kilometers WSW of Pistol River, Oregon.

The second earthquake, 5.1M, occurred at 5:45 am and its epicenter was further south, off the coast of Eureka. Its epicenter was about 40 miles off the coast, or 64 kilometers west of Petrolia, California, in Humboldt County.

This earthquake's depth was relatively shallow, just about a half-mile below the seafloor.

There was subsequently a 4.5M aftershock in the same area at 6:11 am.

Some shaking was likely felt in and around Humboldt County from the latter two quakes, but no damages have been reported. At least one or two people on Xitter in Humboldt County reported the shaking.

This area off the NorCal coast is known to be highly tectonically active, and the latter two earthquakes occurred near what's called a triple-junction, where the northern end of the San Andreas Fault intersects with the Mendocino Fracture Zone  and the Cascadia Subduction Zone. The earlier, larger quake appears to have occurred along the Cascadia Subduction Zone.

The most recent earthquakes off the San Francisco coast occurred on April 25, and had magnitudes of 3.0 and 2.7.