Even remote rocky landforms feel the effects of human activities. In southern Utah, waves and earthquakes caused by people set the enormous Rainbow Bridge vibrating, indicates a study published September 21 in Geophysical Research Letters.
Rainbow Bridge is a sandstone arch that is nearly 300 feet tall, making it one of the world’s largest natural bridges. When researchers stuck seismic sensors on and near it, they measured eight different types of vibrations. Most of these small movements were natural. But energy carried through the ground from distant, manmade events also made the bridge resonate. These included waves from Lake Powell, an artificial reservoir, and an induced earthquake in Oklahoma (these are usually caused when people get rid of wastewater from oil and gas drilling by injecting it into the earth).
“Many things we do are actually felt by Rainbow Bridge,” coauthor Jeff Moore, of the University of Utah in Salt Lake City, said in a statement. “It’s worth trying to understand what forces play a role in accelerating the demise of such sensitive and exceptional natural features.”
For now, however, the impact of these vibrations on Rainbow Bridge is unknown.