Accidental Findings of (Potentially) Seismic Proportions

Time magazine highlights the most recent findings regarding earthquake prediction—the subject of our blog post on seismic technology from earlier in the summer.  However, unlike the developments described in our June 6 post, these new discoveries were accidental, resulting from unrelated research analyzing underground changes caused by shifts in barometric pressure.  Using underground measuring devices and a high-tech version of a stereo speaker, researchers working near Parkfield, California, along the San Andreas Fault, found that seismic waves slowed significantly two hours before a magnitude-1 tremor and shockingly 10 hours before a magnitude-3 quake.
The researchers believe the cause of the transmission signal slowing to be the enormous amount of pressure that builds along the fault before a quake.  The pressure creates small cracks within the rock in the hours just before an earthquake, increasing rock density and thus slowing the waves.  If follow-up studies on future earthquakes expand these findings, the development of a much-improved earthquake early warning system might not be far behind.  However, there is still much to figure out:

“To use this for earthquake prediction, you need to know the precursor waves have a physical basis [that is, increased pressure and a pending quake] and that it’s repeatable [with a larger sample size of quakes],” says Fenglin Niu, the research team’s lead author and a seismologist at Rice University.

Click here for the abstract of the report on these findings, printed in the latest issue of Nature.