Residents across southern California are set to take part in what organisers say will be America's biggest-ever earthquake drill.
Residents of southern California are taking part in what organisers say is the biggest-ever US earthquake drill.
Some five million people will be involved in the exercise, called "The Great Southern California Shake-out".
Some five million people were expected to become involved in the exercise, known as "The Great Southern California Shake-out".
Beginning at 1000 (1800 GMT), it is based on the hypothetical scenario of a magnitude 7.8 earthquake striking the southern San Andreas Fault.
The drill is based on the hypothetical scenario of a magnitude 7.8 earthquake striking the southern portion of the San Andreas Fault.
Schools, hospitals and businesses are taking part, as well as rescue workers.
Schools, hospitals and businesses are taking part, as well as rescue workers.
Organisers say 300 scientists have worked together on the scenario for the drill.
Organisers say 300 scientists have worked together on the scenario for the drill.
The imagined earthquake would, they say, cause 2,000 deaths, 50,000 injuries and $200bn (£134bn) in damage.
The imagined earthquake would, they say, cause 2,000 deaths, 50,000 injuries and $200bn (£134bn) in damage.
Search and rescue
Search and rescue
When it strikes at 1000 local time, millions of participants across the region will "drop, cover and hold on" - drop to the ground, take cover under a sturdy desk and hold on until the shaking stops.
Millions of participants across the region followed instructions to "drop, cover and hold on" - drop to the ground, take cover under a sturdy desk and hold on until the shaking stops.
The San Francisco quake of 1906 was also about 7.8 magnitude
The San Francisco quake of 1906 was also about 7.8 magnitude
This will kick off an emergency response exercise involving more than 5,000 people from local, state and federal agencies. The drill will include triage and search-and-rescue exercises.
This kicked off an emergency response exercise involving more than 5,000 people from local, state and federal agencies. The drill includes triage and search-and-rescue exercises.
California is one of America's most earthquake-prone states.
California is one of America's most earthquake-prone states.
The US Geological Survey says it faces a 46% chance of being hit by a magnitude 7.5 or higher earthquake in the next 30 years.
The US Geological Survey says it faces a 46% chance of being hit by a magnitude 7.5 or higher earthquake in the next 30 years.
The last major earthquake to strike California was in 1994, when a magnitude 6.7 strike left 57 people dead.
The last major earthquake to strike California was in 1994, when a magnitude 6.7 strike left 57 people dead.
The great San Francisco earthquake of 1906 was about 7.8 and caused some 3,000 deaths in collapsed buildings and fires.
The great San Francisco earthquake of 1906 was about 7.8 and caused some 3,000 deaths in collapsed buildings and fires.
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Have you been affected by issues covered in this story? Are you taking part in the quake drill? Send us your comments using the form below.
Have you been affected by issues covered in this story? Are you taking part in the quake drill? Send us your comments using the form below.
