Yellowstone Is Shaken by More Quakes

More earthquakes are rattling Yellowstone National Park. The small quakes include three more that measured stronger than magnitude 3.0. The University of Utah Seismic Stations said the strongest was 3.5. Several hundred quakes centered under the northern end of Yellowstone Lake have occurred since Dec. 26. No damage has been reported. Earthquake swarms happen fairly often in Yellowstone. But scientists say it is unusual for so many earthquakes to happen over several days. Scientists have not concluded what is causing the earthquakes.