Major environmental events write their own headlines. With loss of life and crippling infrastructure damage, the aftershocks of earthquakes reverberate around the world — not only as seismic waves, but also in the photos and news stories that follow a major seismic event. So, it is no wonder that both scientists and the public are keen to understand the dynamics of faults and their hazard potential, with the ultimate goal of prediction.

To do this, William Frank and Camilla Cattania, assistant professors in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), have teamed up as EQSci@MIT to uncover hidden earthquake behaviors and fault complexity, through observation, statistics, and modeling. Together, their complementary avenues of research are helping to expose the fault mechanics underpinning everything from aseismic events, like slow slip actions that occur over periods of hours or months, to large magnitude earthquakes that strike in seconds. They’re also looking at the ways tectonic regions interact with neighboring events to better understand how faults and seismic events evolve — and, in the process, shedding light on how frequently and predictably these events might occur.

“Basically, [we’re] trying to build together a pipeline from observations through modeling to answer the big-picture questions,” says Frank. “When we actually observe something, what does that mean for the big-picture result, in places where we have strong heterogeneity and lots of earthquake activity?”

While there are many ways to investigate different types of earthquakes and faults, Frank takes a detailed and steady approach: looking at slow-moving, low wave frequency earthquakes — called slow slip — in subduction zones over long periods of time. These events tend to go unnoticed by the public and lack an obvious seismic wave signature that would be registered by seismometers. However, they play a significant role in tectonic buildup and release of energy. “When we start to look at the size of these slow slip events, we realize that they are just as big as earthquakes,” says Frank.

His group leverages geodetic data, like GPS, to monitor how the ground moves on and near a fault to reveal what’s happening along the plate interface as you descend deeper underground. In the crust, near the surface, the plates tend to be locked together along the boundary, building up pressure and then releasing it as a giant earthquake. However, below that region, Frank says, the rocks are more elastic and can deform and creep, which can be picked up on instrumentation. “There are events that are transient. They happen over a set period of time, just like an earthquake, but instead of several seconds to minutes, they last several days to months,” he says.