UNDERSTANDING THE PLANET
SHAKE IT UP Researchers tested a six-story , lightweight steel-frame building to see how it would fare during an earthquake and subsequent fires .
FINDING FAULT
Revealing the cracks in the Earth and our structures .
BY ANNIE REISEWITZ AND IOANA PATRINGENARU
IF YOU ' VE SPENT time at UC San Diego , you know that when it comes to earthquakes , it ’ s not a matter of if , but when . For researchers , however , it ’ s also a matter of how — how it will happen and how it will impact the places where we live and work . A new study by scientists at Scripps Institution of Oceanography says that in addition to “ The Big One ,” subsequent aftershocks on separate faults following a large earthquake could cascade and lead to mega-earthquakes .
Scripps geophysicist Peter Shearer and graduate student Wenyuan Fan have discovered 48 previously unidentified large aftershocks that occurred on faults adjacent to the main shock rupture just after large-magnitude earthquakes . For instance , off the coast of Indonesia , a magnitude 7 quake triggered two large aftershocks over 200 kilometers ( 124 miles ) away .
These aftershocks , while miles away from the initial quake , reveal that stress can be transferred almost instantaneously by the passing of seismic waves from one fault to another .
“ By studying this type of triggering , we may be able to forecast hosting faults for large earthquakes ,” says Fan .
Scientists generally believe that most aftershocks are triggered by stress changes caused by permanent movement of the fault and mainly occur near the main rupture where these changes are largest . The new findings suggest that aftershocks can also be triggered by seismic wave transients , where the locations of the main quake and the aftershock may not be directly connected .
“ Multiple fault system interactions are not fully considered in seismic hazard analyses , and this study might motivate future modeling efforts to account for these effects ,” says Shearer .
12 TRITON | WINTER 2017