A new scientific study reveals what happens at the surface of the earth can influence earthquakes originating deep underground.
Rain and snow do a lot in California—they deliver drinking water and mark the changing of seasons, but according to a new study published in the research journal Science, they can also trigger small earthquakes. UC Berkeley geophysicist Roland Burgmann and colleagues determined that the annual loading and unloading of snowpack actually raise and lower the state’s mountain ranges—by as much as a centimeter.
"We’re slightly flexing, bending, California’s crust by these fractions of an inch," Burgmann says, "but those bending stresses is enough to change stresses on the faults and make them respond to it in the form of having slightly more or slightly less small earthquakes."
Earthquake upticks vary seasonally by region, but near the Sierra Nevada, they occur in the wintertime as snowpack weighs the mountains down. Most of the quakes are too small to feel. Burgmann also emphasizes that researchers have not found a link between this seasonal motion and big, destructive quakes.
"People should not worry, 'oh my goodness, we had so much snow this year, there’ll be more earthquakes or even bigger earthquakes,'” he says. "That is not the case."