Phoebe DeVries

Small earthquakes are a common occurrence, but every few years, a seismic event of greater magnitude devastates a region and captures international attention—take, for instance, Nepal in 2015 or Japan in 2011, which triggered a disastrous tsunami.

In some cases, these large earthquakes may trigger other large earthquakes years later, due to the redistribution of stresses in the crust over time. Phoebe DeVries, PhD candidate in Earth and planetary sciences, develops models that identify how stresses in the crust may evolve after large earthquakes.

DeVries’ work looks specifically at the earthquakes that occurred along the North Anatolian Fault (NAF) in Turkey between the years of 1939 and 1999. According to DeVries, when an earthquake displaces the upper crust of the Earth’s surface, the lower crust may act something like silly putty: It is solid rock, but it can also flow slowly from years to decades in response to stresses. Her model allows her to input information about previous earthquakes in a region and watch how the stresses may change over time. A slow build-up of stress at a faraway location may trigger another earthquake down the line, and indeed the NAF could represent an exceptional case of this. “It’s a remarkably linear sequence of earthquakes,” DeVries says.

DeVries works on models of time-dependent stress changes in the crust due to the eight major earthquakes that have occurred along the NAF since 1939. The models are informed by GPS data from before and after the 1999 Izmit earthquake in Turkey. As DeVries explains, “If scientists can understand the events here, we can perhaps understand them elsewhere as well.”