MIT Study Reveals Mechanism of 'Boomerang Earthquakes' on Straight Faults
A new study from the Massachusetts Institute of Technology (MIT) has identified a unique type of earthquake dubbed "boomerang earthquakes." These seismic events differ from conventional quakes by briefly reversing along the same fault path, as detailed in research published in AGU Advances. The study indicates that even simple, straight faults could exhibit this reversal under specific conditions.
"Boomerang earthquakes differ from conventional quakes by briefly reversing along the same fault path."
Challenging Previous Assumptions
Boomerang earthquakes are rare occurrences, with notable instances including a 2016 Atlantic Ocean quake and observations during Japan's 2011 Tohoku earthquake and the recent Turkey-Syria quake. Earlier theories often attributed these events to complex networks of intersecting faults. However, the new MIT study suggests that this phenomenon can also occur on straight faults, challenging prior assumptions.
Simulating Seismic Dynamics
Researchers utilized computer models to simulate an elastic crust with a single straight fault. They tested rupture behaviors under varying lengths, starting points, and travel directions. Results showed that only earthquakes moving in one direction exhibited the reversal pattern. This distinct behavior was linked to friction along the fault that would fall, then rise, and then fall again.
The Mechanics of Reversal
The reversal pattern is explained by specific stress dynamics. When a segment of the fault ceases to slide, stress can reaccumulate behind the moving rupture.
This stored energy may then trigger a subsequent slip in the opposing direction.
Simulations imply that distance is a critical factor. Larger earthquakes potentially display behaviors not observed in smaller seismic events, suggesting that magnitude could play a significant role in this unique reversal phenomenon.