Nevada is a seismically dynamic state, ranking as the third most earthquake-prone state in the United States, following only Alaska and California. The state experiences thousands of minor tremors each year, with the vast majority too small to be felt by residents. Historical records and geological evidence confirm that the potential for a major, damaging earthquake is a constant, long-term hazard across much of the region.
The Basin and Range Province: Why Nevada is Active
The fundamental reason for Nevada’s seismicity is its location within the Basin and Range Province, a vast geological feature where continental crust is actively being pulled apart (crustal extension). The North American Plate is stretching in an east-to-west direction, causing the Earth’s crust to thin and fracture. (49 words)
This fracturing is accommodated by a large network of predominantly normal faults, where one block of land moves downward relative to the other. This action creates the distinctive topography of alternating, linear mountain ranges and flat valleys. (45 words)
Geologists estimate that this stretching has effectively doubled the original width of the central Basin and Range Province over millions of years. The mountain ranges are the uplifted blocks (horsts), while the valleys are the down-dropped blocks (grabens). Earthquakes occur when the stress from continuous stretching exceeds the friction holding these normal fault blocks in place, causing a sudden slip. The crust in this area is relatively thin, which contributes to the shallow focus of many Nevada earthquakes, often resulting in strong shaking at the surface. (85 words)
Defining Nevada’s Major Seismic Zones
Nevada’s seismic hazard is concentrated in the western and central parts of the state. Western Nevada, particularly the corridor encompassing Reno, Carson City, and the Lake Tahoe area, falls within the complex Walker Lane Belt. This belt is a major shear zone that accommodates between 15 and 25 percent of the relative movement between the Pacific and North American tectonic plates.
The Walker Lane Belt is characterized by a mix of strike-slip and normal faults. The high concentration of active faults near urban centers, such as the Mount Rose fault system, results in a seismic hazard level comparable to many areas in California. Geologic deformation rates in this zone are significant, with a slip rate of 6 to 9 millimeters per year relative to central Nevada.
Activity also runs through the Central Nevada Seismic Belt, a north-south trending zone that has been the epicenter of several of the state’s largest historical earthquakes. In contrast, the seismic risk in Southern Nevada, including the Las Vegas metropolitan area, is generally considered lower than the western and central regions.
The risk in Southern Nevada is not absent, as the region is subject to motion along faults like the Stateline Fault. This fault, located about 25 miles from Las Vegas, is part of the Walker Lane system and is estimated to be capable of producing an earthquake of magnitude 7.8 or greater. While these fault systems are less numerous and slower-moving than those in the north, they still represent a significant hazard.
Record of Significant Historical Earthquakes
Nevada has a history of major earthquakes, demonstrating the capacity of the Basin and Range faults to generate events above magnitude 7.0. The state’s largest recorded event was the 1915 Pleasant Valley earthquake, which registered magnitude 7.3. This powerful event caused ground ruptures nearly 40 miles long south of Winnemucca and resulted in significant damage to structures across most of Nevada.
Another major event was the 1932 Cedar Mountain earthquake, which struck on December 20 with an estimated magnitude of 7.2. This complex strike-slip earthquake occurred in a remote area of western Nevada, limiting overall damage and casualties. The rupture zone was extensive, spanning approximately 40 miles and causing surface offsets of up to 8.9 feet.
The state experienced a notable cluster of large quakes in 1954. This sequence began with the Fairview Peak earthquake (magnitude 7.1) followed just four minutes later by the Dixie Valley earthquake (magnitude 6.9). These two events occurred in the Central Nevada Seismic Belt and created dramatic surface ruptures, with fault scarps up to 20 feet high stretching for over 60 miles. The remoteness of the epicenters meant that property damage was minor.