The Wasatch Fault is the dominant earthquake hazard of the Intermountain West. It runs about 350 km along the western base of the Wasatch Range, from central Utah north to near Malad City, Idaho — straight through the Salt Lake City–Provo–Ogden urban corridor. It is a normal fault: Basin-and-Range extension is pulling the region apart, dropping the valley floor and uplifting the Wasatch Range. Roughly 80% of Utah's population lives within 15 miles of the fault.
The USGS hazard model splits this fault into 16 sections, each with its own geometry and a geologic slip rate. Each rate says whether it rests on site slip-rate data in the USGS earthquake-geology database or only on the fault’s mapped slip-rate class.
| Section | Movement | Slip rate | Geometry |
|---|---|---|---|
| Wasatch (Brigham City) UT | Normal | 2.6 mm/yr (1.4–6.4)site data | dips 50° W · 0–15 km deep |
| Wasatch (Clarkston Mountain) UT | Normal | 0.13 mm/yr (0.01–0.13)site data | dips 50° SW · 0–15 km deep |
| Wasatch (Collinston) UT | Normal | 0.05 mm/yr (0.01–0.13)site data | dips 50° W · 0–15 km deep |
| Wasatch (East Bench) UT | Normal | 1.6 mm/yr (0.78–5.2)site data | dips 40° W · 0–15 km deep |
| Wasatch (Fayette) UT | Normal | 0.04 mm/yr (0.01–0.13)site data | dips 50° W · 0–15 km deep |
| Wasatch (Foothills) UT | Normal | 0.91 mm/yr (0.65–1.2)site data | dips 40° W · 0–15 km deep |
| Wasatch (Levan) UT | Normal | 0.65 mm/yr (0.13–0.78)site data | dips 50° NW · 0–15 km deep |
| Wasatch (Malad City) ID | Normal | 0.1 mm/yr (0.01–0.13)site data | dips 50° W · 0–15 km deep |
| Wasatch (Nephi, north) UT | Normal | 1 mm/yr (0.78–1.6)site data | dips 50° W · 0–15 km deep |
| Wasatch (Nephi, south) UT | Normal | 2.5 mm/yr (1–4.3)site data | dips 50° W · 0–15 km deep |
| Wasatch (Provo, north) UT | Normal | 1.2 mm/yr (0.91–1.6)site data | dips 50° W · 0–15 km deep |
| Wasatch (Provo, south) UT | Normal | 2.6 mm/yr (1.6–3.9)site data | dips 50° W · 0–15 km deep |
| Wasatch (Salt Lake City, north) UT | Normal | 1.7 mm/yr (0.78–2.7)rate class only | dips 40° W · 0–15 km deep |
| Wasatch (Salt Lake City, south) UT | Normal | 1.4 mm/yr (1–2.2)site data | dips 50° W · 0–15 km deep |
| Wasatch (Virginia Street) UT | Normal | 0.91 mm/yr (0.65–1.2)rate class only | dips 50° SW · 0–15 km deep |
| Wasatch (Weber) UT | Normal | 2 mm/yr (1.2–2.7)site data | dips 50° SW · 0–15 km deep |
Source: USGS NSHM23 fault sections database v3 and western US geologic deformation model v1.0 (on-plane slip rates, preferred with low–high range; site data = measured sites in the NSHM23 earthquake-geology database, rate class only = the fault’s mapped slip-rate category); central US and Cascadia sources from the model’s source files (code.usgs.gov/ghsc/nshmp/nshms/nshm-conus).
About 80% of Utah's population — including Salt Lake City, Provo, Ogden, and West Valley City — lives within 15 miles of the fault, along with roughly three-quarters of the state's economy. The Working Group on Utah Earthquake Probabilities estimates a 43% chance of one or more M6.75+ earthquakes somewhere on the Wasatch Front in the next 50 years (18% on the Wasatch fault zone alone). The Great Utah ShakeOut plans around a M7.0 rupture on the Salt Lake City segment.
No surface-rupturing earthquake has occurred on the Wasatch Fault in recorded (post-settlement) history. But paleoseismic trenching has identified at least 22 surface-faulting earthquakes in the past ~6,000 years. The most recent was on the Nephi segment about 500 years ago (a M~7.0 that left a 3–4 m scarp); the Salt Lake City segment last ruptured roughly 1,200–1,600 years ago. Large (M~7.0) earthquakes recur about every 900–1,300 years on individual segments, averaging ~300–350 years across the whole fault.
Utah's two notable modern earthquakes did not rupture the main Wasatch trace. The 1934 M6.6 Hansel Valley earthquake (Utah's largest historical quake, 2 killed) was on a related fault at the zone's northern end. The 2020 M5.7 Magna earthquake — Utah's most damaging, ~$629 million in losses — struck beneath Salt Lake Valley on the buried West Valley fault zone, a subsidiary structure, not the main Wasatch fault.
The USGS maps the fault in about 10 structural segments, each ~30–60 km long (including Brigham City, Weber, East Bench, Salt Lake City, Provo, and Nephi). Paleoearthquakes appear to cluster in time. A 2025 study in Geology suggests a deep, low-friction fault structure that steepens toward the surface, potentially producing stronger shaking than previously assumed. Slip rates, recurrence, and paleoearthquake dates are all estimates from trenching and radiocarbon dating — present them as ranges.
The Wasatch Fault is the reason the Wasatch Front takes earthquake preparedness seriously despite its quiet historical record. See the Utah page and our seismic risk lookup.