In an MIT lab, a team of geophysicists created “lab quakes,” a series of miniature, controlled versions of real earthquakes to see where all that destructive energy actually goes and what it’s doing. If you think it all gets absorbed into the ground that it tears apart, or the man-made infrastructure that it crumbles, you’re wrong.
According to their study published in AGU Advances, only about 10 percent of an earthquake’s energy actually causes the shaking that sends us diving under desks and door frames. The majority of it, somewhere between 68 percent and 98 percent, just cooks the surrounding rock, generating heat at the fault line. Less than 1 percent is spent on the dramatic stuff like fracturing rock and creating new surfaces.
To figure this out, the researchers basically recreated the Earth’s crust in miniature. They ground up granite and mixed in magnetic particles to track temperature changes. Then they squeezed the whole thing under pressure that mimics the Earth’s seismogenic layer, which is the fault-ridden zone where earthquakes are born.
Daniel Ortega-Arroyo, one of the study’s authors, says that his team’s work shows that rocks have a “memory” of past deformations, and that memory changes how they break. Like humans in therapy, rocks remember their trauma, and it changes their behavior.
The goal of the research is to isolate the key physical processes that underlie every earthquake. The hope is that any knowledge gained will help refine earthquake prediction models and possibly even pinpoint which regions are sitting on fault lines ready to pop.
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