Research Spotlight: Spooky action at a distance, for earthquakes

Abstract

On 27 February 2010 a magnitude 8.8 earthquake rocked millions of Chileans from their slumber, but the South American people weren't the only ones so affected. New research by Peng et al. suggests that the trembling off the Chilean coast could have triggered a swarm of shallow earthquakes nearly 10,000 kilometers away in central California. The team identified four earthquakes with magnitudes of 2 or higher, with the largest of the group being a M 3.5 quake that rattled the Coso geothermal field. The affected region is plagued by small earthquakes, but when the authors calculated the chance of a swarm so neatly following the Chilean earthquake, they inferred that the two seismic events were probably connected. The authors also saw a cluster of deep, low‐frequency earthquakes along the Parkfield‐Cholame section of the San Andreas Fault that also appeared to be influenced by the Chilean event. The researchers suggest that the timing of the California earthquakes was affected by the arrival of Love waves—horizontal surface movement that would have traveled out from the epicenter of the Chilean earthquake, pushing already stressed faults over the edge. (Geophysical Research Letters, doi:10.1029/2010GL045462, 2010)