Thanks to a new modeling technique and study of geothermometry of fault lines, researchers now have a better understanding of earthquakes.
Researchers at the University of Massachusetts Amherst recently re-created a fault line in a lab using china clay confined in a box. Using this, they studied how the shape of a fault affects the earthquakes that result from it.
The researchers' fault resembled that of California's San Andreas fault, which has one geologic plate sliding past or over another plate. The team was particularly interested in how faults evolve and affect earthquakes near areas where the fault lines bend.
They used something called fault efficiency as their measurement. This is basically a measurement of how effectively a fault converts energy from plates' movement into earthquakes. A straight fault, for example, is efficient because it is better at dealing with the strain of movement than a fault along a bend or curve.
However, researchers discovered that over time, as faults grow and connect to others, their curves change and they become more efficient, although never as efficient as straight fault lines. These bends also often restrain earthquakes, though, which means that the bend might have smaller earthquakes that stop there rather than a longer earthquake that might accompany a longer and straighter fault line movement.
The results from the models correlated what they already knew about the San Andreas fault, proving their experimental method accurate. These results could help determine particular areas along fault lines most at risk of earthquakes, thanks to a new understanding of how bends in the faults affect tremors.
"Because the experiments scale to crustal lengths and strengths, we can extrapolate from the experiments to kilometer-scale systems," write the researchers. "The models show progressive deformation by the successive outboard growth of dipping faults in some cases and persistence of vertical fault in others."
This is the first time researchers have used a clay experiment inside a box to represent fault lines. The results of this research could lead to new studies that can not only help us better understand earthquakes, but possibly even predict their likelihood at certain locations. It could even lead to techniques that eventually can constrain earthquakes.
The United States Geological Survey (USGS) estimates that at least several million earthquakes happen worldwide every year, although most are small or undetected because they happen in remote regions. However, when large ones hit, they are often deadly, as demonstrated in 2011 when an earthquake triggered a massive tsunami that devastated parts of Japan.