Indeed, some scientists, such as Robert Geller from the University of Tokyo, think that prediction is outright impossible. In a 1997 paper, starkly titled Earthquakes Cannot Be Predicted, he argues that the factors that influence the birth and growth of earthquakes are so numerous and complex that measuring and analysing them is a fool’s errand. Nothing in the last 15 years has changed his mind. In an email to me, he wrote: “All serious scientists know there are no prospects in the immediate future.”
Finding fault
Earthquakes start when two of the Earth’s tectonic plates – the huge, moving slabs of land that carry the continents – move around each other. The plates squash, stretch and catch against each other, storing energy which is then suddenly released, breaking and shaking the rock around them.
Those are the basics; the details are much more complex. Ross Stein from the United States Geological Survey explains the problem by comparing tectonic plates to a brick sitting on a desk, and attached to a fishing rod by a rubber band. You can reel it in to mimic the shifting plates, and because the rubber band is elastic, just like the Earth’s crust, the brick doesn’t slide smoothly. Instead, as you turn the reel, the band stretches until, suddenly, the brick zips forward. That’s an earthquake.
If you did this 10 times, says Stein, you would see a huge difference in the number of turns it took to move the brick, or in the distance the brick slid before stopping. “Even when we simplify the Earth down to this ridiculous extreme, we still don’t get regular earthquakes,” he says. The Earth, of course, isn’t simple. The mass, elasticity and friction of the sliding plates vary between different areas, or even different parts of the same fault. All these factors can influence where an earthquake starts (which, Stein says, can be an area as small as your living room), when it starts, how strong it is, and how long it lasts. “We have no business thinking we’ll see regular periodic earthquakes in the crust,” he says.
That hasn’t stopped people from trying to find “anomalies” that reliably precede an earthquake, including animals acting strangely, radon gas seeping from rocks, patterns of precursor earthquakes, and electromagnetic signals from pressurised rocks. None of these have been backed by strong evidence. Studying such “anomalies” may eventually tell us something useful about the physics of earthquakes, but their value towards a predictive test is questionable.
by Ed Yong, Not Exactly Rocket Science | Read more:
