How do earthquake early warning systems work?

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Would you know what to do if an earthquake struck while you were at work?  at home? at gym?

Earthquake safety researchers want the answer to these questions to be "yes."

Over the last few years, the United States has implemented ShakeAlert, an earthquake early warning system for the West Coast. When an earthquake happens, real-time data from seismometers is used to assess the magnitude of the earthquake and the locations that will be affected. Individuals and facilities that are likely to experience strong shaking are then automatically notified. The system is intended to provide individuals with just a few seconds to defend themselves before seismic waves arrive; thus everything must happen rapidly for an alarm to be meaningful.

But what should people do once they've received the warning?

Creating a rapid-fire warning system was a technological marvel, but understanding how people react during an earthquake and what behaviors reduce their chance of damage presents a whole other set of issues, as researchers detailed in a recent study regarding the best recommendations to pair with ShakeAlert.

A concise message

According to several research, people who have never experienced an earthquake are more inclined to freeze or run. They may take a break to observe what others are doing. However, in the event of a big earthquake, a few seconds of uncertainty could be costly. To be most effective, an alert must be followed with guidance.

"We know that if a warning is issued without providing people with actionable information about what to do, the alert will be less effective," says Sara McBride, the main author of the study and a social scientist at the US Geological Survey. "Providing an alert with no advice is not really an option."

The problem is determining how to provide clear direction to 50 million individuals on the West Coast who are in different places, doing different things, and have varied talents.

McBride and colleagues gathered injury data from a variety of research and locales. The dangers of earthquakes vary based on building construction, earthquake type, and even the time of day or season when the earthquake occurs. Previous research has found that women are more likely to be hurt than men, probably because they are more likely to be carers and may move around to help children during shaking.

Inconsistent data collecting is one difficulty to determining what causes injuries during an earthquake; after an earthquake, figuring out what an injured person was doing isn't as vital as providing them treatment. Scientists must also adhere to ethical data-gathering norms and take trauma into account.

As a result, this data can be unavailable and acquired over a wide range of time periods, complicating easy conclusions.

Tripping and falling while moving, things falling and flying, and the collapse of building exteriors such as windows and facades have been among the most prevalent causes of injury during earthquakes in the United States. A widespread misperception is that a doorway is a good location to go; however, entrances are not a stronger section of the building and do not shield you from flying debris.

According to McBride and colleagues' research, the best phrase to accompany an alarm is "Drop, Cover, Hold On." Getting low to the ground and under a strong table or desk can shield people from falling objects.

This message is repeated every year during the Great ShakeOut, the world's largest earthquake drill, conducted every October. It has also been modified to account for different skill levels; for example, a wheelchair user should presumably not drop, but rather lock their wheels, cover their head, and hold on.

Although there is no one perfect solution for every event, planning and practicing your actions ahead of time gives you the best chance of surviving.

It is not a universal message.

The "Drop, Cover, Hold On" warning has also been adopted by Japan and New Zealand. In countries with more susceptible buildings, such as Haiti, officials have decided that evacuation is a better bet. The guidance in Mexico City, which developed the first earthquake early warning system in 1991, is location-based. Is living on the first or second floor preferable? Evacuate. Greater levels? Drop, cover, and hang on.

A geologist at Oregon State University who was not involved in the study emphasizes the importance of individuals knowing the buildings in which they live. Many buildings in Oregon and Washington were constructed before strict earthquake rules were implemented, or perhaps before the Pacific Northwest was recognized as being at risk of a big earthquake. If someone is in a building that is about to collapse and is close to a doorway, Goldfinger believes that getting out is a better option than 'Drop, Cover, Hold On'.

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