GEOLOGIC HAZARDS

COSTS OF GEOLOGIC HAZARDS

Since 1847, approximately 6,075 fatalities from geologic hazards have been documented in Utah, as well as a significantly larger, but undetermined amount of injuries. Radon gas exposure (causing lung cancer) has been Utah’s most deadly geologic hazard, followed by landslide hazards, then flooding hazards.

Lung cancer fatalities caused by radon gas are Utah’s most deadly geologic hazard. Radon-related deaths account for 97 percent of all geologic hazard fatalities in Utah.

89.8 percent of landslide hazard fatalities resulted from snow avalanches and 10.2 percent from landslides, rockfalls, and debris flows.

80.1 percent of flooding hazard fatalities resulted from floods and flash floods, 14.9 percent from debris flows, and 5.0 percent from dam or water conveyance structure failures.

Using the economic value of a statistical life of $11.6 million (2016 data), the 6,075 fatalities are valued at $70.5 billion. The estimated economic value of human life is not considered in the hazard economic costs given in the tabbed area below.

In most all cases, it is more cost effective to perform a comprehensive engineering-geology investigation to identify and characterize geologic hazards and implement appropriate mitigation in project design and construction, rather than relying on additional maintenance over the life of the project or to incur costly change orders during construction.

  • Flooding along State Street, Salt Lake City, Utah, June 1983. Photo by S. Thiriot.
  • Parkway Drive Landslide

Earthquake Hazards

Although only two fatalities from earthquakes (ground shaking) have occurred in Utah since 1847, scenario modeling of a major (magnitude [M] 7.0) earthquake on the Salt Lake City segment of the Wasatch fault zone predicts 2,000 to 2,500 fatalities, 7,400 to 9,300 life-threatening injuries, 55,400 buildings completely damaged, 21 million tons of debris, and $33.2 billion in estimated short-term, direct economic losses. The short-term financial losses do not include the long-term economic costs that include closed businesses, lower productivity and economic output, and other costs. Sixty-one percent  of the total number of buildings in the 12-county area in northern Utah will be moderately damaged or totally destroyed. Such an event will likely take decades to recover from and will be the single most costly geologic hazard event to affect Utah.

Damage from the 2008 Wells, Nevada (population 1,657), earthquake (M 6.0) totaled approximately $10.5 million, with nearly half of the approximately 80 non-residential buildings damaged and 10 severely damaged. The Wells earthquake is an important analog for rural Utah towns and cities, which have similar unreinforced masonry (URM) building stock and fragile economic conditions.

More Data

Known Fatalities from Earthquakes in Utah Since 1850.

Date Location Fatalities Notes References1
3/12/1934 Hansel Valley fault zone (M6.6) 2 Trench collapse (1) and death of sick woman (1). UUSS
Total: 2

1 UUSS (University of Utah Seismograph Stations).


Earthquake Scenarios and Damage Estimates
Salt Lake City Segment, Wasatch Fault Zone Magnitude 7.0 Scenario
February 21, 2008 Mw 6.0 Wells, Nevada earthquake
Utah Earthquake Scenarios

Wasatch Front Region Earthquake Probabilities
There is a 57% (greater than 1 in 2 chance) probability of a M6.0 earthquake within the Wasatch Front region in the next 50 years.
Working Group

Geologic Hazards and Insurance – Are You Covered?

Damages caused by most geologic hazards are typically not covered by homeowners or other property insurance. However, damages to vehicles may be covered by automobile insurance. It is important to check your insurance policies and talk to your insurance agent about which losses and damages are covered.

Sediment deposited at the intersection of Lambert Avenue and Apple View Street in Santaquin. The debris flow moved cars and filled basements with sediment.

Personal auto policies generally cover all risks or perils (including geologic hazards such as earthquakes, flooding, falling objects, volcanic eruptions, etc.) if you have coverage for damage to your vehicle on the policy, such as collision and comprehensive coverage. There are exceptions and each policy should be reviewed for what damages are covered or excluded.

Commercial auto policies have more options available and coverage must be specified for each vehicle or type of vehicle. Damages from geologic hazards may or may not be covered, depending on the policy.

Homeowner’s property policies generally cover all risks or perils (property losses and damages), except for those specifically excluded. Common exclusions are damages from earth movements, earthquakes, mudflows, mine subsidence, sinkholes, flooding, and environmental factors. Special policies may be available to cover specific risks, such as a named perils insurance policy. Homeowners may be able to get coverage for generally excluded losses by adding them to an existing policy by endorsement or by the purchase of a separate policy. A difference in conditions policy provides coverage for some otherwise excluded perils and is also known as a catastrophe policy.

Multiple types of commercial property policies are available; however, flooding and earth movements (earthquakes, mudflows, mine subsidence, and sinkholes) are commonly excluded. Endorsements can typically be added to a policy to provide coverage for these perils, and for expanding coverage for other perils (such as volcanic eruptions).

Earthquake Insurance
Utah Insurance Department

Flooding Insurance
National Flood Insurance Program
Utah Insurance Department

Utah Insurance Department
Consumer
Commercial

Maps and Publications

Circular #122

Guidelines for Investigating Geologic Hazards and Preparing Engineering-Geology Reports, with a Suggested Approach to Geologic-Hazard Ordinances in Utah

Glad You Asked

What is an Earthquake Early Warning System, and does Utah have one?

Special Study #163

Surface Fault Rupture Map – Geologic Hazards of the Tickville Spring Quadrangle, Salt Lake and Utah Counties, Utah

Map #277

Utah Earthquakes (1850-2016) and Quaternary Faults


View All Hazard Publications

External Links