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Rio Grande Rift Research Project >

Rio Grande Rift F.A.Q.
Measuring Rio Grande Rift Crustal Deformation

Map of Rio Grande Rift region (above) from USGS. Rift features, such as basins and faults, don't tell the whole story about the width and length of a rift.

What is the Rio Grande Rift? A rift is a thinning in the Earth's surface caused by stretching the surface through geological stress. It was initially formed between 35 and 29 million years ago when the crust began to spread apart, triggering volcanism in the region. The Rio Grande Rift runs south to north from the state of Chihuahua, Mexico to Leadville, Colorado and perhaps even further north.

Some rifts, such as the Basin and Range Province further west, are at higher elevation than their surroundings. Others, such as the Rio Grande, form basins (above) that, over thousands and millions of years, fill with sediments. At Albuquerque, NM, the basin sediments are three miles deep. The rift continues to widen today, although very slowly. The graphic to the right from the USGS shows the primary basins of the rift.

Where are there other rifts in the world? Most rifts are found along mid-ocean ridges. Only a few are located on land, such as the East African rift or Great Rift and Lake Baikal, a lake-filled rift in Russia. While ocean rifts are often caused by divergent plate boundaries, continental rifts such as the Rio Grande are referred to as "extentional tectonics" caused by the buoyancy of rocks deep below.

Is there a risk of earthquakes in or around the Rio Grande Rift? Seismic activity associated with earthquakes is considered to be low to moderate in New Mexico and Colorado, with a slightly higher risk in and around the rift region, but there are still many unknowns about the risks of the rift that require further study. There is geologic evidence that large earthquakes (7.0 to 7.3 magnitude) have occurred in south-central Colorado within the past 5,000 to 15,000 years. While statistically less likely to have large-scale seismic activity than regions such as the San Andreas Fault in California, a large earthquake (7.0 magnitude or larger) will occur at some point in the future.

Could there by volcanoes around the Rift? Intense volcanism (volcanic activity) has occurred in the region beginning at the onset of rifting millions of years ago. For example, Valles Caldera near modern day Los Alamos, NM, one of the world's largest and youngest calderas, was created 1.2 million years ago through the collapse of a magma chamber. Volcanism is considered by geologists to be dormant, not extinct, in the rift region.

Can I become involved? The scientists involved with the project are now in the process of identifying sites for the GPS systems. If you live or go to school near one of the green triangles on the map to the right, you may be able to help identify sites that have (1) bedrock exposed at the surface (the kind that rings when struck with a hammer), and (2) no sky obstructions due to vegetation or other barrier.

The Location Shown Can Change By Up To 10 Miles. If you or someone you know owns property near the target location and might be willing to host a GPS site, OR, If you know of a locality on public lands that might suit our purpose, please call 505-277-2580 for suggestions of sites in NM or email mroy@unm.edu. In Colorado, call 303-492-5141 or email arlowry@abdu.colorado.edu. For an education kit about rifts in general and the Rio Grande Rift in particular, contact mark.mccaffrey@colorado.edu.