5-Mile Wide Buried Asteroid Crater Discovered in Canada

Elevation map and contour drawing of the buried impact crater found near Bow City, Alberta. Higher elevations are indicated by warmer colors, lower elevations by cooler colors. Credit: W. Xie and T. Brown

A 5-mile (8-kilometer) wide and 3,000-foot (900-meter) deep asteroid impact crater has been hidden near Bow City, Alberta, for millions of years. Bow City has been deserted for decades.

The findings were presented at the American Geophysical Union conference on December 3rd. People have suspected something odd in the region since the 1930s, because of the fragmented terrain.

So far, only a handful of these buried craters have been discovered. Wei Xie, a graduate student in geophysics at the University of Alberta, and her colleagues peered underneath the Earth’s surface using data from boreholes drilled into the area and seismic wave surveys, which bounce off the boundaries between layers of different types of rock. They helped scientists identify the structures underneath the surface.

The seismic data came from oil companies, and it helped reveal the subterranean crater. Many of the solar system’s most notable impact scars have a characteristic central peak, which is visible in the Bow City crater.

Scientists suspect that the asteroid impact occurred less than 70 million years ago, because of its placement near the surface. It’s mostly invisible to the naked eye. The confirmation of the crater’s presence hinges on the existence of telltale shocked minerals near the impact site. Xie and her colleagues will drill into the area in early 2013 to retrieve samples and confirm their findings.