A 3.5-magnitude earthquake shook the southern end of the two fault lines that run parallel with the Oregon Coast at Cape Mendocino in Northern California Sunday, Dec. 31. According to the U.S. Geological Survey, the quake was located in the Pacific Ocean west to southwest of Petrolia, CA. A 3.8-magnitude quake followed later that day in the same area, but on land, west to southwest of Hayfork, CA.