What should you do if you get an earthquake early warning?
Would you know what to do if you felt an earthquake while at work? At home? At the gym?
Researchers that study earthquake safety want the answer to these questions to be “yes.”
Over the last few years, the U.S. has rolled out an earthquake early warning system for the West Coast called ShakeAlert. When an earthquake occurs, real time data from seismometers is used to determine how large an earthquake will be and which areas will be affected. Alerts are then automatically sent to individuals and facilities likely to experience strong shaking. The system is designed to give people a few seconds to protect themselves before seismic waves arrive, so all of this must happen very quickly for an alert to be useful.
But once people receive the warning, what should they do?
Building a rapid-fire warning system was a technological feat, but understanding how people react during an earthquake and what actions lower their risk of injury poses a whole new suite of challenges, as laid out by researchers in a recent study about the best guidance to pair with ShakeAlert.
A clear message
People that haven’t experienced an earthquake before are most likely to either freeze or flee, according to some studies. They may pause to see what others are doing. But during a large earthquake, a few seconds of hesitation could be costly. For an alert to be most effective, it needs to be accompanied by guidance.
“We know that the alert is going to be less effective if a warning goes out and doesn’t provide people with actionable information about what to do,” explains Sara McBride, a social scientist at the U.S. Geological Survey and lead author of the study. “Providing an alert with no advice is not really an option.”
The trouble is, how do you give clear guidance to 50 million people on the West Coast who are in different places, doing different things and have different abilities?
McBride and others collected data about injuries from a wide range of studies and locations. Between different earthquakes, the dangers vary depending on building construction, the type of earthquake and even the time of day or season when the earthquake happens. Earlier studies have noted that women are injured more often than men — possibly because they are more likely to be caretakers and may move around to try to help children during shaking.
One challenge to understanding what causes injuries during an earthquake is inconsistent data collection; after an earthquake, finding out what an injured person was doing isn’t as important as getting them help. Scientists must also follow ethical data collection standards and consider the impact of trauma. As such, this data can be sparse and collected over varying time periods, confounding simple interpretations.
Some of the most common causes of injuries during earthquakes in the U.S. have been from tripping and falling while moving, from objects falling and flying and from the collapse of building exteriors such as windows and facades. A common misconception is that a doorway is a good place to go, but in truth doorways are not a stronger part of the building, and don’t protect you from flying debris.
In their study, McBride and others conclude that the best message to accompany an alert is “Drop, Cover, Hold On.” Getting low to the ground and under a sturdy table or desk can protect people from falling objects.
This message is repeated every year during the largest international earthquake drill, the Great ShakeOut, held in October. It has also been adapted to consider varied ability levels — for example, a wheelchair user will probably not best be served by dropping, but should instead lock their wheels, cover their head and hold on.
Although there is no one perfect action that accounts for every scenario, thinking through and practicing your actions ahead of time gives you the best chance of survival.
Not a universal message
Japan and New Zealand have also embraced the “Drop, Cover, Hold on” message. In countries that have buildings more prone to collapse, such as Haiti, officials have decided that evacuation is a better bet. In Mexico City — home to the first earthquake early warning system, built in 1991 — the guidance depends on an individual’s location. First or second floor? Evacuate. Higher floors? Drop, cover, hold on.
Chris Goldfinger, a geologist at Oregon State University who was not involved with the study, emphasizes that it’s important for people to know the buildings they occupy. A lot of buildings in Oregon and Washington were built before stringent earthquake codes were enacted or even before the recognition that the Pacific Northwest is at risk of a large earthquake. If someone is in a building that is likely to collapse, and they’re close to a doorway, Goldfinger says that getting out is probably a better idea than “Drop, Cover, Hold On.”
McBride agrees that everyone needs to evaluate their own situation, and that educational campaigns and drills play a crucial role in this type of preparation, but said she hopes that a clear call to action during an earthquake will save lives and prevent injuries.