25 de abril de 2014
Good Friday Quake in Mexico City Tested Region’s Preparations for Bigger One
The city’s unusual geology allows engineers and seismologists to rely upon exceptional safety measures
Scientists can’t be sure exactly how much of a threat the Guerrero Gap poses to the hemisphere’s largest city. But they can begin to prepare.
Last week’s 7.2-magnitude Good Friday earthquake in Mexico City sent people scurrying out into the streets as chandeliers and other objects spun wildly in houses. The quake wasn’t Earth’s biggest Good Friday temblor (that was the Great Alaskan Earthquake of 1964), nor was it the biggest to hit on an April 18th (that was the Great 1906 San Francisco Earthquake). In some ways, however, it was more unusual than either of those, because Mexico City’s earthquakes are unique. Unlike other shaky cities, such as San Francisco or Tokyo, Mexico City is nowhere near a major fault. The nearest one is 200 miles away on the coast. Still, Mexico’s unusual rock and soil allow its residents to experience potentially powerful shaking. And while this has led to catastrophic events, it also provides unique opportunities to study earthquakes and prepare for the future.
Japan has a similar system in operation and California has tried for a decade to create its own (a new state law recently provided money for it). But because of Mexico City’s distance from its threatening fault, no other city offers as much of an opportunity for warnings. The signal on April 18 went out to 60,000 classrooms and the subway shut down before the quake arrived (and was running again just three minutes later). “It was a complete success,” says Juan Manuel Espinosa-Aranda, general director of SASMEX.