CHICAGO They heard things were going to be shaking, so they decided to join in.
Emergency officials in Ohio said on Tuesday their state would participate in next week's Great Central U.S. ShakeOut -- a massive, multi-state emergency drill designed to teach proper earthquake survival skills.
Ten other states -- Illinois, Missouri, Kentucky, Tennessee, Arkansas, Oklahoma, Mississippi, Alabama, Georgia and South Carolina -- will be participating in the April 28 drill, which is coordinated by the Federal Emergency Management Agency and several other government agencies.
Organizers say that more than 2.4 million people have signed up here so far to participate in the day's big event: a mass "Drop, Cover and Hold On" drill scheduled next Wednesday morning.
When an earthquake hits, experts suggest people should drop to the ground, take cover under a desk or table, and hold on until the ground stops shaking -- hence the drill.
Although California is more commonly associated with temblors, the central U.S. is home to at least two historically active seismic zones, including the New Madrid Fault.
This year marks the 200th anniversary of a series of earthquakes on the New Madrid, which remain among the largest ever in North America's recorded history.
They caused little death or damage to man-made structures at the time because the region was sparsely populated. But a 2008 report from the U.S. Federal Emergency Management Agency warned that a similar sized quake today could result in "widespread and catastrophic physical damage" and trigger "the highest economic losses due to a natural disaster in the United States."
Scientists say there is as much as a 40 percent probability of a big earthquake in the central United States some time over the next 50 years.