These days, we can predict just about anything – from foreseeing political trends, forecasting the weather fairly accurately to tracking asteroids that might swing near the Earth.
But for all of our technological savvy, we can’t predict when an earthquake like the one that just rocked Chile might occur.
“We will probably not be able to ever tell, ever predict with any real precision when a future earthquake will occur on the order of minutes-to-days,” says Andrew Newman, a Georgia Institute of Technology professor who worked on a study that used GPS technology to predict the size and location of a 2012 earthquake in Costa Rica’s Nicoya Peninsula.
Unlike weather systems, earthquakes do not provide warnings or scientifically-reliable data before they occur. Scientists can tell how and when an earthquake started. But when that information becomes available, it “usually means that you will have on the order of about 30 seconds’ warning,” said Newman.
That doesn’t seem like much. But Newman argues that 30 seconds might be enough to get someone out of a precarious situation.
An early warning system to mitigate some of the immediate effects of earthquakes is currently being developed and tested in California and other parts of the United States.
“We’re working on an earthquake early warning system whereas seismometers closest to the instruments can record an earthquake and get a very early estimate of how big an event is and send out warnings before … the seismic waves travel to the populations that will be most affected,” Newman said.
Early warning systems already exist for tsunamis that sometimes follow earthquakes in coastal areas. “Once a larger earthquake occurs,” says Newman,” we send out very, very early warnings that … there is a tsunami potential. And for the most part, we can do this very, very early warning before the tsunami ever hits.”
Developing countries lacking proper infrastructure sometimes rely on Western monitoring systems for early warnings. In the 2004 Sumatra, Indonesia earthquake and tsunami, which claimed more than 100,000 lives, Newman says “even if we were to give early warning to the government, at that time there wasn’t infrastructure locally developed to actually disseminate the warning along coastlines.”
Social media, cellular phones and cellular data communications can play an important part in passing along crucial information when an earthquake occurs, provided that the local infrastructure exists. In the case of Chile’s recent earthquake, Newman says that infrastructure wasn’t there.
“But using Twitter is one possible mechanism to develop early dissemination,” he says. “Whether or not we can do it sufficiently well for earthquake early warnings – you know I am talking about 30 seconds.”
Why does my cat seem to know when an earthquake is coming?
Anecdotal evidence suggests pets and livestock sometimes become agitated shortly before an earthquake begins. So why do animals seem to be able to sense an earthquake before it occurs? Newman says this behavior is typically associated with a sampling bias, meaning that people might attribute strange behavior in pets to a particular incident, even though it might not necessarily relate to it.
Seismic slips, where parts of a fault might shift for days or weeks, change the stress patterns of the earth and create changes such as raising or lowering ground water levels. “We see actually changes in the electric response of the earth, even maybe an effect on the ionosphere above the earth,” he said. “All of these things and … probably the changes in well levels will have an effect on some animals.”
Recalling an incident in the 1970s in China, when snakes were coming out of a well in the middle of winter after water levels changed, Newman cautions that these things often occur when there is no earthquake.
So even if the scientific community were able to predict when an earthquake might occur and sufficiently warn affected populations, he says “we have to be very careful of the boy who cried wolf effect.”
The first warnings might cause panic. After that, “if we start warning of a potential and … no earthquake occurs, very quickly the population becomes desensitized,” said Newman.
There are no easy answers. But understanding how faults shift allows scientists to map areas with the greatest potential for earthquakes. So even if they were unable to say that “an earthquake is coming tomorrow,” Newman says “we can probably say … within the next 20 years, you have a probability of an earthquake than a certain magnitude occurring in your environment.”
That probably provides little consolation for the victims of Chile’s earthquake. But until technology finds a better way, Newman says it is more important to develop understanding of earthquakes and enforce building codes that can minimize damage and casualties when an earthquake occurs.