Other versions of the Great Shake Out are planned in other states and nations. The seismic education and training exercise began in southern California in 2008.
In Utah, students, teachers and staff of public schools accounted for nearly 540,000 participants, with colleges and universities adding another 104,000-plus. Federal, state and local governments signed up more than 75,000 registrants, with businesses coming in with about 34,000 and religious institutions some 31,000.
All told, the Wasatch Front, deemed overdue for a major earthquake by many seismologists, accounted for nearly 550,000 participants.
Great Utah Shakeout organizers ask that at 10:15 a.m. Thursday all participants practice dropping to the ground or floor, taking cover under a desk, table or against a wall with arms covering heads and necks; and then holding on for at least 60 seconds.
Many participating agencies, businesses and institutions plan more extensive drills. To learn more about what is scheduled, visit the Great Utah Shakeout website at www.shakeout.org/utah/.
Some Utah earthquake facts:
• Earthquake zones encompass areas where 90 percent of Utah's residents live and work.
• Utah has experienced damaging earthquakes in the past and geologic evidence indicates that earthquakes larger than any experienced locally in historical times are likely in the future.
• Large earthquakes are possible anywhere in Utah, but they are most likely in a "seismic belt" about 100 miles wide extending north to south along the Wasatch Front and through Richfield to Cedar City and St. George.
• Utah averages a magnitude 6 earthquake once every 15 to 20 years.