Earthquake Preparedness Never Stops: How to Pack an Emergency Bag

Mexico records more than 15,000 earthquakes over the course of a year, meaning the ground moves more than 40 times a day. Most events measure below magnitude 4 and remain imperceptible to residents, according to the Institute of Geophysics at the National Autonomous University of Mexico, or UNAM.

Because seismographs detect movement only after it occurs, the National Center for Disaster Prevention, CENAPRED, says earthquakes cannot be predicted. Specialists therefore focus on constant preparation at home.

UNAM mathematician Saraí Hernández Torres said the impression that earthquakes cluster on the same dates can be explained through probability and psychology, in a way similar to the birthday paradox. In a group of 23 people, there is a probability greater than 0.5 that two share a birthday because the group contains 253 possible pairs.

But fixing one particular date changes the calculation sharply. Hernández Torres cautioned, “We are not taking into account all the possible ways in which a coincidence can happen, and we call it a coincidence after it has already happened.” She added that the emotional memory of the 1985 and 2017 tragedies reinforces the public’s focus on particular dates.

CENAPRED recommends preparing an emergency bag with basic supplies, including a flashlight and battery-powered radio with spare batteries, bottled water, nonperishable food that can cover at least 24 to 48 hours, and a first-aid kit.

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We are not taking into account all the possible ways in which a coincidence can happen, and we call it a coincidence after it has already happened.