Big Quakes Beget More Shakes Worldwide

Massive earthquakes like this month's in China's Sichuan province can quite literally make waves on the other side of the Earth, a new seismology study finds. The surface tremors resulting from events like Indonesia's tsunami-triggering quake in 2004 lead to increased seismic activity around the globe—from two to five times the average, LiveScience reports.

Exactly why big quakes trigger remote shaking is still a mystery. Waves could add stress to existing faults, or it could be that the tremors re-rout water through faults, making them more prone to slip, one scientist theorizes. But ultimately, "we really need to better understand how stresses from these earthquakes are doing the triggering, the dynamics of what's happening." (More earthquake stories.)