It’s the holy grail of seismology, but researchers now think they could have a new tool in predicting major earthquakes. New research suggests that as the Earth’s rotation periodically slows, it leads to more magnitude-7 quakes within the following five years. If this is true, then it could be a powerful predictor for the natural disasters.
The researchers came about the intriguing link after they noticed two patterns in the frequency and intensity of earthquakes, which they published earlier this year in the journal Geophysical Research Letters. They found that earthquakes appeared to cluster in time, but not in location, and that earthquakes that measured over magnitude-7 seemed to cluster every 32 years.
What lured the two seismologists was the idea that earthquake cycles, in which fault lines build up stress and then release it, were oscillators not unlike heart muscles or metronomes. This spurred them on to wonder whether or not, as in these other well-known oscillating systems, earthquakes have a tendency to synchronize their activity. Remarkably, it turns out that earthquakes do indeed show signs of such synchronization.
What it is that causes this, however, is not quite so clear. But speaking at the annual meeting of the Geological Society of America in Seattle last week, the researchers think they may have figured it out. And they suggest that the next five years might prove them right or wrong.
It all comes down to the Earth’s rotation. The researchers argue that when it slows down, it correlates with periods of increased magnitude-7 earthquakes. They think that this change in the flow of the molten iron at the core of the planet may be influencing not only the length of the day but also the Earth’s magnetic field, which in effect “ripples”.
It is this mismatch in the speed of the iron circulating at the center of the Earth and the solid crust on the outside that could be creating enough force to alter both the length of day – by several milliseconds every three decades or so – and the magnetic field. The researchers suggest that when this happens, maybe a bit of outer core sticks to the mantle above to cause these effects.
As Science reports, the researchers are in no way certain about any of this, but many other seismologists have commented on the research, saying is compelling and worth considering.
And perhaps we won’t have to wait long. The Earth entered its periodic slow down around four years ago, meaning that over the next few years the researchers will be able to observe whether or not their predictions are indeed right.