Actually, the chances of that happening are extremely, extremely, remote. But, a major earthquake occurred near Yellowstone in 1959. From www.yellowstone.net:
Centered near Hebgen Lake, just west of the park, it had a magnitude of 7.5. This quake caused $11 million in damage (equivalent to $70 million in 2005 dollars) and killed 28 people, most of them in a landslide that was triggered by the quake.With that in the back of their mind, the emergency services personnel at Yellowstone National Park have assembled an Incident Management Team for the earthquakes.
On a related note, a web site that popped up that impersonates the U.S. Geological Survey and warns people to evacuate the Yellowstone area because the Super Volcano could erupt, has garnered the attention of the USGS Solicitors Office, which is pursuing federal charges of impersonating a federal official as well as violation of the agency's trademark.