A pair of moderate earthquakes, both registering a magnitude 4.5, struck the Southern California town of Yorba Linda on Tuesday night and Wednesday, rattling the region twice within 10 hours, but no damage or injuries were reported. The latest quake was recorded shortly after 9:30 a.m. (12:30 p.m. EDT) 2 miles northeast of Yorba Linda, an affluent Orange County community southeast of Los Angeles that was the birthplace of the late former President Richard Nixon and houses his presidential library and museum.