Earthquake Science for Kids
I am really enjoying this science (fiction-y at times) blog called io9: We Come From the Future. Given the massive quake in Japan, this might be a great time to talk about geological science including how earthquakes hapen and why we can’t predict them. I’ve excerpted it below but you can see the full post here.
It’s clear that the science of predicting earthquakes has a long way to go. If your child finds earthquakes fascinating, perhaps he or she will be one of the scientists to bring this science further. You never know what will spark a life long interest. How about you? Are your kids interested in learning more about earthquakes after hearing about the big one in Japan? Will an education on earthquakes also help to quell fears about earthquakes happening to them? Please chime in!
by Alasdair Wilkins
In the wake of the massive 9.0-magnitude earthquake that has devastated Japan, an obvious question arises…why didn’t we see it coming? The fact is that earthquake prediction has long baffled scientists, and the current consensus is that it’s actually impossible.
Seismologist Yan Kagan of UCLA said a few years ago, “It may require the development of completely new mathematical and theoretical tools. We should not expect significant progress in this direction in the near future.”
So earthquake prediction depends on answering a crucial question: how do you predict the next sudden release of energy? To a certain extent, that’s easy enough to answer. After all, there are about 500,000 earthquakes a year, and about 100,000 of these cause tremors that can be felt on the surface. That means there’s practically an earthquake every minute, and most of these are clustered in the various regions that find themselves on active fault lines.
Myths and Failed Explanations
Unfortunately, as former U.S. Geological Survey employee and current geology science writer Andrew Alden explains, there’s nothing to any of this:
- Do earthquakes correlate with the phase of the Moon? No they don’t.
- Do they tend to occur during a particular type of weather? No they don’t.
- What about time of year? No effect. Previous seismic events? Outside of aftershocks, no.
- Sunspots and solar cycles? Nope, nope.
- Not even psychics do better than chance. Every prediction method makes lucky hits, but none of them really work.
But it gets worse. Alden goes on to explain that even seemingly scientific theories do no better at predicting when the next big earthquake will hit than the ideas put forward by the general public, something that geologists themselves will readily admit:
- It doesn’t matter, for instance, how long it has been since the last earthquake along a particular stretch of geologic fault.
- It doesn’t matter what fluid pressures underground are doing-rising, falling, or fluctuating.
- It doesn’t matter what the electrical conductivity of the ground is doing.
- The behavior of earthquake faults is a stubborn mystery.
The Importance Of Chaos
Now, all is not lost. Yes, earthquakes are naturally chaotic, which means there isn’t much hope of ever predicting the specific time and location of the next severe earthquake, or when a particular area is going to be hit next. But chaos theory has some pretty rigorous mathematics behind it, and it’s possible to model the overall chaotic system with great precision.
We can use the mathematics of chaos to determine the overall energy release for the various tectonic plates, and with that we can know which areas of the world are at the greatest long-term risk from earthquakes. Short-term predictions remain a pipe dream, but this at least gives us long-term forecasts. These can include assessments of how many earthquakes of varying magnitudes a region can expect over a given time period, and it can also provide a probable upper limit for just how severe the earthquakes in that area are likely to get.
We can’t know when the big one will hit, but just the knowledge that it will likely happen at some point in the future gives city and building planners and emergency services a chance at being as prepared as possible for the eventual earthquake.
What It Would Take To Go Further
Part of the problem is that, even if we can confidently identify the limits of seismology, we’re still not even particularly close to that. Even after a hundred years, the science remains in relative infancy. Andrew Alden explains by comparing seismology to predicting the weather:
Before weather predictions became widely accepted, we had to spend decades learning about climatology, fluid dynamics and the physical laws that govern the ocean and the atmosphere at all scales. We also had to collect immense amounts of historical data and set up satellites to monitor the ocean-atmosphere system. If earthquake predictions are to become as effective as weather predictions are today, we must take seismology to a comparable level. Today’s research is aimed at that more fundamental goal, and the nearest that scientists will come to issuing predictions is making long-term and medium-term forecasts on a strictly experimental basis.
Right now, seismology is still only taking baby steps in that direction. A lot of research is built around the mechanical concept of stress and trying to apply the behavior of objects like stressed beams to seismic activity. Researchers Chung-Han Chan and Ross S. Stein demonstrated how a transfer of stress caused by one earthquake to another region precipitated the next earthquake, which might allow us to zero in on the location of the next big earthquake, even if its timing still eludes us. But these methods have only very weak forecasting ability, and it’s too early to really know what, if anything, these methods will actually amount to.
What We’re Left With
It’s not fun to admit that science has fundamental limits on what it can do, particularly when so many human lives potentially hang in the balance. But it’s crucial that we understand those limitations and recognize all the things that we can do. Earthquake prediction is, in all likelihood, a scientific dead end, a distraction that keeps our focus off something that’s actually tangible and important, and that’s preparedness.
Earthquake preparedness – particularly when aided by long-term forecasting of likely problem areas – can at least give us the best possible chance of minimizing the extent of the destruction in the event of disaster. That may seem like rather hollow consolation, particularly in the wake of the current crisis in Japan. And yes, frankly, it is. But it’s still the preferable alternative to the false promise of pseudoscience.