More earth tremors possible in California

Officials warned Monday of the possibility of more tremors in the Sierra Nevada where four large earthquakes Sunday stopped ski lifts, knocked down power lines, and ruptured water mains. The earthquakes -- centered in the Mammoth Lakes area near Yosemite National Park -- ranged between 5.7 and 6 on the Richter scale and were followed by 12 aftershocks. Nine people were injured. Rescue parties searched Monday for 20 stranded hikers.