Wasatch Fault
The Wasatch Fault is an
The Wasatch Fault is a
Geological history
During the past 10,000 years, major earthquakes (magnitude 7.0 or greater) occur about every 900–1,300 years along any one of the five central segments of the Wasatch Fault. However, the average time-span between earthquakes along the entirety of the central segments is about 300 years.[5] The segment that underlies Salt Lake City produced a major earthquake approximately 1,200–1,300 years ago, the Weber, Provo, and Nephi segments each produced one about 200–700 years ago and the Brigham City fault segment has not produced a major earthquake in about 2,200–2,800 years.[3]
Earthquake assessment
Statistically, the Wasatch Fault is overdue for another major earthquake. Experts have given a 57% probability of an earthquake magnitude 6.0 or greater occurring within the next 50 years. However, statistical frequency does not necessarily imply periodic behavior, though it can serve as a good indicator.[6] Liquefaction due to a strong earthquake is of particular concern because many highly populated areas along the Wasatch Front lie on soft lake sediments, remnants of Lake Bonneville.[7][8]
A strong earthquake on the Wasatch Fault could trigger landslides, cause mass liquefaction, and flooding of low-lying areas forming near lakes due to subsidence and tilting. The quake may also rupture the surface causing displacement of up to 20 feet (6.1 m), and severely damage gas, electric, water, communication, and transportation lifelines.[9] A report released by Bob Carey of Utah's Office of Emergency Services and published by the Deseret News in April 2006 predicts that a strong earthquake occurring in Salt Lake City could kill up to 6,200 people, injure 90,000, and cause US$40 billion in economic losses. Due to the earthquake danger not being well known when many structures were built in the area, at least 42% of the buildings along the Wasatch Front are at risk of moderate to severe damage in the event of a strong earthquake. Many buildings, such as hospitals and schools, are located directly atop the Wasatch Fault. Approximately 50% of hospital beds in Salt Lake City are at risk.[10] Currently, about 80% of Utah's population live along the Wasatch Fault, representing the largest earthquake threat in the interior Western U.S.[11][1]
On the west end of Salt Lake Valley is another fault zone called the West Valley fault zone that spans 9 miles (16 km) north-northwest. Recent trench studies have shown that the West Valley fault tends to rupture simultaneously with the Wasatch Fault, compounding issues such as liquefaction, landslides and flooding. The two faults likely converge into a single fault deep underneath Salt Lake Valley.[11][12] On March 18, 2020, a 5.7 magnitude earthquake occurred just north of Magna, causing moderate damage.[13] In March 2021, a new study based on evaluations of the 2020 earthquake and aftershocks determined that the Wasatch Fault undercuts the Salt Lake Valley at a shallower depth than previously thought. This means that a large earthquake on the Salt Lake section of the Wasatch Fault would likely cause more ground shaking and greater damage than previously expected.[14]
Public awareness
As awareness has increased since the 1980s, many key structures in the region have been undergoing extensive
References
- ^ a b "wasatch fault zone: Topics by Science.gov". www.science.gov. Retrieved 2019-02-28.
- ^ "Surficial geologic map of the Wasatch fault zone, eastern part of Utah Valley, Utah County and parts of Salt Lake and Juab counties, Utah" (PDF).
- ^ a b "How Big and How Frequent Are Earthquakes on the Wasatch Fault?". earthquake.usgs.gov. Retrieved 2020-03-19.
- .
- ^ "Large Earthquakes on the Wasatch Fault". utahdnr.maps.arcgis.com. Retrieved 2019-02-27.
- ^ "Reports | U of U Seismograph Stations". Retrieved 2019-02-26.
- ^ Schuske, Kim. "Explore Utah Science – Earthquake Risk in the Salt Lake Valley". www.exploreutahscience.org. Retrieved 2019-02-26.
- ^ "Liquefaction – Utah Geological Survey". Retrieved 2019-02-26.
- ^ "Earthquake Hazard & Safety in Utah" (PDF).
- ^ Deseret News article
- ^ a b "Salt Lake City Could See Bigger Earthquakes".
- ^ "Salt Lake City Earthquake Risk May Be Higher Due To Connected Fault Zones, Geologists Find".
- ^ "5.7 magnitude earthquake in Utah knocks out power to thousands and diverts flights". Retrieved 2020-03-22.
- ^ "'Curved' Wasatch fault may be even more destructive and deadly than previously thought". Retrieved 2021-03-22.
- ^ Utah Geological Survey
- ^ "Utah Earthquake Program". DPS – Emergency Management. Retrieved 2019-02-26.
- ^ "Utah Seismic Safety Commission". ussc.utah.gov. Retrieved 2019-02-26.
- ^ "Salt Lake City Emergency Management". www.slc.gov. Retrieved 2020-01-16.
External links
- Utah Geological Survey Public Information Series 40: The Wasatch Fault
- Utah Geological Survey presentation about the fault
- Utah Geological Survey Quaternary Fault and Fold Database
- Salt Lake City Emergency Management
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