Stunning natural wonder
Rainbow Bridge, a 300-foot-tall (91 meter) natural arch carved from sandstone in Utah, vibrates as a result of both natural and manmade movements, new research has found.
Rainbow Bridge is venerated by many tribal groups in the area, but University of Utah geophysicist Jeff Moore received permission to place seismic sensors on and around the arch to understand how it moved.
The seismic sensors revealed that the bridge usually hums at a low rate. But other factors can cause bigger vibrations.
For instance, waves on Lake Powell seem to cause movements at the same frequency in Rainbow Bridge.
Earthquakes can also cause movement in the natural arch. Here, another vibrational mode of the arch.
The researchers found that a manmade earthquake as far away as Oklahoma also caused motion in the natural bridge. However, it's not clear how this human-induced motion compares to the motion caused by the wind, researchers said.