In the M=7.1 Puebla, Mexico earthquake on September 19, which caused significant damage in Mexico City, the city’s earthquake early warning sirens went off approximately 12 seconds before the strongest ground shaking (See video below – sirens go off at the 37 second mark). While the onset of shaking appears to begin only a few seconds after the sirens, that should have been enough for people to take cover underneath tables or desks.
Houston offers a grim vision of Los Angeles after catastrophic earthquake.
For years, scientists have drawn up terrifying scenarios of widespread destruction and chaos that would come to Southern California when a catastrophic earthquake hits.
Their efforts to warn the public may get an unlikely boost from the unprecedented disaster unfolding in Houston, where Tropical Storm Harvey dumped trillions of gallons of rain across Texas and brought America’s fourth-largest city to its knees.