Researchers have linked a 2010 earthquake near Prague to a magnitude-8.8 quake half a world away in Chile.
A new study led by researchers at Columbia University, published Friday in the journal Science, suggests a strong quake that strikes halfway around the globe can set off small to mid-size quakes near injection wells used in oil and gas development in the U.S. heartland.
“The seismic waves act as the straw that breaks the camel's back, pushing the faults that last little bit toward an earthquake,” lead researcher Nicholas van der Elst said in an email to The Associated Press.
There has been heightened scrutiny in recent years of quakes near industrial areas as drilling is ramped up to satisfy the country's energy hunger.
Research has shown that wastewater disposal — the process of pumping fluids deep into the ground at high pressures — can weaken nearby fault lines and even produce quakes big enough to be felt. Hydraulic fracturing, or fracking, which uses high-pressure mixtures of water, sand and chemicals to extract natural gas or oil, also can trigger quakes, but they're typically microquakes — smaller than magnitude-2.
The powerful earthquake that rocked Japan in 2011 set off tremors around a West Texas oil field, according to the Columbia team's research. It suggests oil and natural gas drilling operations may make fault zones sensitive to shock waves from distant big quakes.
Scientists long have known that large quakes can trigger minor jolts thousands of miles from the epicenter. Volcanically active spots like Yellowstone National Park often experience shaking after a large distant event.
Less is known about the influence of remote quakes on fault lines that have been weakened by man-made activity like the deep disposal of wastewater at the Texas oil field.
By poring through the quake archives, van der Elst and colleagues found evidence that faults near wastewater injection sites were loaded with stress when ripples from a faraway earthquake traveled around the planet.
The magnitude-9 Japan quake set off a swarm in the West Texas town of Snyder, where oil extraction has caused shaking in the past.