Two deadly Mexico earthquakes not linked

This September, two devastating earthquakes struck Mexico in rapid succession. The first, a magnitude-8.2 temblor Sept. 7 near the southern state of Chiapas, killed an estimated 96 people and sent aftershocks shivering through the region. Just 12 days later and a few hundred miles away, a magnitude-7.1 quake shook central Mexico; hundreds more people died, including 19 children who were crushed when their elementary school collapsed.

The chance of the two tragedies occurring in such a short span of time by sheer coincidence was just one in 200, said seismologist Ross Stein. But there is no evidence to suggest that the quakes were connected.

Stein’s research suggests that the combination of temblors added to the stress along faults in the earthquake-prone country, possibly doubling the likelihood that another earthquake of magnitude 7 or greater will strike next year. “Another shoe could drop,” said Stein, a longtime U.S. Geological Survey scientist who is now chief executive of the earthquake awareness company Temblor, during a presentation of his findings last week at the annual meeting of the American Geophysical Union.

Earthquake prediction is notoriously difficult: Despite years of installing seismometers and sifting through data, scientists have found no reliable warning signals. Forecasting quakes is mostly a matter of weighing probabilities — and trying to convince the public to get prepared.

Scientists in Mexico had no warning for either of the two September earthquakes, and the second struck far away from the zone where aftershocks from the first still rocked the earth.

Xyoli Perez-Campos, a seismologist at the National Autonomous University of Mexico, said she agreed with Stein’s conclusion that the two quakes were unconnected.