What happens when the crust is stretched?


     • Foam Fault Activity
Related Animations
     • Earthquake Faults
     • Divergent Plate Boundaries

Exploring the Basin and Range

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Over most of the last 30 million years, movement of hot mantle beneath the region caused the surface to dome up and then partially collapse under its own weight, as it pulled apart. Currently, there is very little actual stretching going on, and the small amount is concentrated on the Western and Eastern edges of the Basin and Range.

Quicktime Animation (3 MB)

Volcanic Processes

As the plates pull apart, the mantle rises and melts due to lower pressures near the surface. The style of eruption depends on how long the magma sits in the crust and undergoes processes such as crystallization and melting and assimilation of wall rock.

Quicktime Animation (2 MB)

GPS Measures Extension

Tension created by movements of Earth's tectonic plates have stretched the earth's surface to the breaking point. The entire region has been pulled apart, fracturing the tectonic plates and creating large faults.

Quicktime Animation (2 MB)

Deformation Sedimentation

As extension and uplift occur, erosion and sedimentation happen simultaneously but at slower rates. As extension slows down, erosion and sedimentation can overcome mountain building.

Quicktime Animation (1 MB)


Earthquakes are shallow in the Basin and Range (15 km deep or less). A shallow earthquake is more likely to create a break in the surface of the earth than a deeper one, particularly if it's large. The movement during Basin and Range earthquakes is a stretching apart motion, causing one of the fault to drop down past the other and create a scarp.

Quicktime Animation (2.73 MB)


Animations and videos are made in partnership with Earthscope, USGS, and Volcano Video & Graphics.

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