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An early earthquake warning system may be coming to the West Coast. The system will issue a warning ten seconds before an earthquake—enough time to shut down transportation networks, critical infrastructure, dangerous activities (e.g., surgery), and hopefully allow people to take necessary precautions. Information about the quake’s location and magnitude will be gathered by detecting the initial release of P-waves (primary waves), a relatively harmless seismic event. The familiar violent tremors we associate with large earthquakes come from S-waves (shear waves), which are generated afterwards.

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Though the technology has been around for decades, implementing a system for P-wave detection has been a challenge in the United States. Several other countries, most notably Japan, have had warning systems in place for years. Fifteen seconds before the 2011 magnitude-9 earthquake struck near Fukushima, cell phones, TVs, and radios sounded the alarm in nearby Sendai. It was just enough time for the city to take emergency precautions. Areas further from the epicenter, however, received incomplete information and were insufficiently prepared.

Truth be told, warnings can only mitigate potential damage. A more proactive tactic would involve predicting a quake in advance. Unfortunately, according to a 1996 study in PNAS, predictions may be impossible. Theoretically, given the geological processes at work, anticipating the development of an earthquake should be possible. But these processes are so inconsistent and their magnitudes vary so widely that they’ve proven to be unsatisfactory metrics. Even short-term predictions—having a few days notice—have produced too many false positives to be useful.

However if we take a much longer view, anticipating an earthquake in an specific area over the next twenty years, for example, our ability to deal with it is much stronger. In such cases, authorities will be able to strengthen building codes and develop emergency response plans far in advance. Such prosaic measures aren’t flashy, but they do save lives.

In many ways, the West Coast alert system is an upgrade over the Japanese one. It relies on multiple algorithms to ensure accuracy and minimize possible false positives. Its enhanced processing speed ensures a faster response time. But it’s not perfect. For those living close to a potential earthquake’s epicenter, the warning and the quake will feel almost simultaneous. Nonetheless, this kind of system is long overdue.


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Science News, Vol. 185, No. 8 (APRIL 19, 2014), pp. 16-20
Society for Science & the Public
Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, No. 9 (Apr. 30, 1996), pp. 3726-373
National Academy of Sciences