In DepthSeismology

Indonesian earthquake broke a geologic speed limit

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Science  08 Feb 2019:
Vol. 363, Issue 6427, pp. 570
DOI: 10.1126/science.363.6427.570

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Summary

The geological rupture responsible for the devastating magnitude-7.5 earthquake that struck Palu, Indonesia, in September 2018 ripped through Earth's crust at rare high speed, scientists report. This "supershear" behavior likely intensified the shaking in the quake, which triggered a tsunami and killed more than 2000 people. Typically, the ruptures that cause earthquakes travel at a speed slower than its damaging side-to-side waves, called shear waves. In the past 2 decades, however, seismologists have discovered a handful of high-speed ruptures on long, linear, and smooth strike-slip faults. The Palu rupture, however, occurred on a rougher strike-slip fault, with kinks in its path, raising fears that far more regions could be at risk of high-speed quakes than once thought.