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Utah Fault Lines

The Wasatch Fault and Utah's Fault Lines

The Wasatch Fault runs about 220 miles along the foot of the Wasatch Range, right past Ogden, Salt Lake City and Provo.

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Last reviewed

Length
About 350 km (220 mi)
Runs From
Malad City, Idaho, to Fayette, Utah
Fault Type
Normal Fault
Segments
10, Each 30 to 60 km Long
Typical Large Earthquake
About M7.0
50-Year Odds, M6.75+
43% on the Wasatch Front

Wasatch Fault Line Map

Wasatch Fault Line Map: Where Is the Fault?

The Wasatch Fault follows the western base of the Wasatch Range for about 350 km (220 miles), from near Malad City, Idaho, to near Fayette in central Utah. It is the reason the mountains rise so sharply above the valleys: over many earthquakes, the valley side drops down and the range side rises.

The fault is made of 10 segments, each roughly 30 to 60 km (19 to 37 miles) long. The five central segments, from Brigham City to Nephi, are the most active and sit beside the state's largest cities. The USGS counts 22 surface-faulting earthquakes on this central part in the past 6,000 years.

The dashed line on the map is a simplified trace for orientation; the Utah Geological Survey maps the exact traces.

Salt Lake CityOgdenLoganProvoSt. GeorgeCedar CityMoabVernalPriceRichfieldDeltaWendoverKanabMonticelloWyomingWasatch Fault
Simplified Wasatch Fault trace (dashed) with major Utah cities.

Wasatch Fault Segments

Wasatch Fault Segments and Their Last Big Earthquakes

Each central segment produces earthquakes of about magnitude 7.0, roughly every 900 to 1,300 years. Here is how long ago each one last ruptured, according to the USGS.

Central Wasatch Fault Segments
SegmentLast Large EarthquakeNearby Cities
Brigham City2,200 to 2,800 years agoBrigham City, Perry, Willard
Weber200 to 700 years agoNorth Ogden, Ogden, Layton, Kaysville
Salt Lake City1,200 to 1,600 years agoSalt Lake City, Holladay, Sandy, Draper
Provo200 to 700 years agoAlpine, Orem, Provo, Springville
Nephi200 to 700 years agoPayson, Santaquin, Nephi

Source: USGS, "How Big and How Frequent Are Earthquakes on the Wasatch Fault?"

Utah Earthquake Forecast

Utah Earthquake Odds: The 50-Year Forecast

In 2016 the Working Group on Utah Earthquake Probabilities, including the USGS and the Utah Geological Survey, estimated the chances of large earthquakes in the Wasatch Front region over the next 50 years, counting the Wasatch Fault and the region's other faults.

43%At Least One M6.75 or Larger
57%At Least One M6.0 or Larger
93%At Least One M5.0 or Larger

Sources: USGS Fact Sheet 2016-3019 (M6.75 and M6.0) and the Utah Earthquake Program (M5.0).

Beyond the Wasatch

Other Utah Fault Lines

The Wasatch Fault gets the attention because of the cities beside it, but it is not Utah's only active fault. The largest earthquakes in the state's recorded history, two M6.6 events, struck elsewhere: near Marysvale in central Utah in 1901 and in Hansel Valley, north of the Great Salt Lake, in 1934.

On the west side of the Salt Lake Valley, the West Valley fault zone produced some of the shallower aftershocks of the 2020 Magna earthquake. Southwestern Utah has its own history too: the 1992 St. George area earthquake reached M5.9 in the USGS catalog.

Every one of these areas shows up on the live Utah earthquake map, which plots small earthquakes across the whole state every day.

Utah's Largest Recorded Earthquakes

From the 1901 Marysvale and 1934 Hansel Valley earthquakes to Magna in 2020, with dates and magnitudes.

Utah Earthquake History

Salt Lake City Earthquakes Today

Live earthquakes within 50 miles of downtown, along the central Wasatch Fault.

Salt Lake City Map

Earthquake Preparedness

Utah Earthquake Preparedness

A large Wasatch Fault earthquake cannot be predicted, but its damage can be reduced. The guidance from Utah emergency managers is practical:

  • Drop, cover and hold on when shaking starts, and stay put until it stops.
  • Secure heavy furniture and water heaters, and keep heavy objects off high shelves.
  • Store water, food and medications for several days, and plan how your family will reconnect.
  • Know your building: unreinforced masonry (older brick) buildings are among the most vulnerable in a strong earthquake.

Practice during the Great Utah ShakeOut each year, and follow official guidance from the Utah Division of Emergency Management.

Wasatch Fault Questions

Wasatch Fault FAQ

Where Is the Wasatch Fault Line?
Along the western base of the Wasatch Range, from near Malad City, Idaho, south to near Fayette in central Utah. Its central part passes right beside Brigham City, Ogden, Salt Lake City, Provo and Nephi, where the mountains meet the valley floor.
How Long Is the Wasatch Fault?
About 350 km (220 miles), according to the USGS. It is not one continuous break but 10 segments, each roughly 30 to 60 km (19 to 37 miles) long, that tend to rupture on their own.
When Was the Last Big Earthquake on the Wasatch Fault?
The most recent large, surface-rupturing earthquakes on the central segments happened 200 to 700 years ago, on the Weber, Provo and Nephi segments (USGS). In modern times, the M5.7 2020 Magna earthquake is linked by several studies to the Salt Lake City segment at depth, but it did not break the surface.
What Are the Chances of a Big Earthquake in Utah?
A 2016 forecast by the Working Group on Utah Earthquake Probabilities gives the Wasatch Front region a 43% chance of at least one M6.75 or larger earthquake, and a 57% chance of at least one M6.0 or larger, in the next 50 years (USGS Fact Sheet 2016-3019).
Is the Wasatch Fault Overdue?
Earthquakes don't run on a schedule, but the timing is worth knowing. The Salt Lake City segment last ruptured 1,200 to 1,600 years ago, at or beyond its typical gap of 900 to 1,300 years between large earthquakes (USGS).
How Big Can a Wasatch Fault Earthquake Be?
The central segments produce earthquakes of about magnitude 7.0, each segment roughly every 900 to 1,300 years, according to the USGS. Ruptures that join two segments may have produced earthquakes near magnitude 7.4, though that is less certain.
Is Salt Lake City on a Fault Line?
Yes. The Salt Lake City segment runs along the east side of the Salt Lake Valley, and the West Valley fault zone crosses the valley floor. Follow earthquakes there on the live Salt Lake City earthquake map.

Live Data

Watch the Wasatch Front in Real Time

Small earthquakes happen along Utah's faults every day. See each one on the live map within minutes.

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