Update on Utah’s Earthquake Early Warning Efforts
by Steve D. Bowman
Warning time scenario if a magnitude 7 (M7) earthquake occurred on the Brigham City segment of the Wasatch fault zone. The red circles show how much warning time would be provided at that location before shaking begins. The dashed red circle is the “no-alert zone” for an alert latency of eight seconds. Colors indicate the maximum intensity of expected shaking caused by “shear wave” energy created by the earthquake. OT = origin time. From Bowman et al., 2023, On the feasibility of implementing an earthquake early warning (EEW) system in Utah: Online at http://doi.org/10.34191/EEW-2023
Utah ranks 4th in the U.S. for having severe seismic risk. About 85% of Utah’s residents, infrastructure, and economy are concentrated within 15 miles of the state’s most active fault, the Wasatch fault, making the Wasatch Front the highest risk area in the state. A recent publication (Earthquake Probabilities for the Wasatch Front Region in Utah, Idaho, and Wyoming) reported that Utah has more than a 50% chance of a large magnitude 6.5 or greater earthquake occurring along the Wasatch Front within the next 50 years. This paper also reported that the Wasatch fault can generate an earthquake as large as a magnitude 7.6! A large earthquake (6.5 magnitude or greater) would be devastating to our homes, businesses, infrastructure, and livelihoods, with effects that would last for several decades. Although Utah does not currently have an earthquake early warning (EEW) system (see Survey Notes v. 47, no. 3), equipment and infrastructure are in place that make implementing a system a feasible reality with appropriate upgrades.
An EEW system uses a network of seismograph stations to detect earthquakes and provide residents with seconds to minutes of warning ahead of strong ground shaking, which could be enough time to act (such as temporarily shutdown machinery and critical infrastructure like trains, open fire station truck doors, “Drop, Cover, and Hold On,” etc.). The University of Utah Seismograph Stations (UUSS), in partnership with the U.S. Geological Survey (USGS), has over 200 seismograph stations deployed across Utah. Using this seismograph network system, the UUSS generates public alerts and information after an earthquake event. However, the current system is not intended or designed to work as an early warning system.
Illustration showing how an earthquake early warning system could work in Utah. From Bowman et al., 2023, On the feasibility of implementing an earthquake early warning (EEW) system in Utah: Online, doi.org/10.34191/EEW-2023.
1. When a fault ruptures and creates an earthquake, the fault sends out different types of seismic waves. The fast-moving, but less damaging, P-wave is the first to arrive. This wave is used to issue a warning before the slower but more damaging waves (S-wave and surface) arrive.
2. Sensors detect P-waves and immediately transmit data to an earthquake alert center.
3. The location, size, and estimated shaking of the earthquake are determined at the earthquake alert center.
4. A message is sent to partners, such as transportation agencies, emergency facilities, and hospitals, to alert people to Drop, Cover, and Hold On as well as trigger automated actions, such as shutting down a train or halting industrial processes.
Currently, an EEW system known as ShakeAlert is in operation along the West Coast of the U.S. This system was built and implemented by the USGS in partnership with the states of California, Oregon, and Washington and began operation in 2021. Due to the severe seismic risk in Utah, multiple agencies, researchers, businesses, and residents have asked if an EEW system could be built in Utah.
Locations of UUSS seismograph stations in the Utah region as of 23 March 2023. Stations that meet the requirements for use in EEW systems include broadband (black diamonds) and strong motion (red circles and yellow plus symbols). From Bowman et al., 2023, On the feasibility of implementing an earthquake early warning (EEW) system in Utah: Online, doi.org/10.34191/EEW-2023
The Utah Legislature, in the 2022 General Session, appropriated funding to the Utah Earthquake Program to study the feasibility of implementing an EEW system in Utah. The Utah Geological Survey (UGS) collaborated with the Utah Division of Emergency Management and the UUSS to generate a report detailing what is needed to build and implement such a system in our state. Research for the study consisted of
- reviewing the history and development of EEW systems within the U.S. and around the world,
- assessing the potential performance of an EEW system in Utah,
- determining what enhancements to the existing UUSS seismic network would be needed to implement an EEW system, and
- conducting an online survey of various Utah stakeholders to assess their knowledge of and potential interest in an EEW system.
The report was completed in November 2023 and found that an EEW system would be practical along the Wasatch Front and elsewhere in Utah.
Subsequently, the UGS requested $5 million in one-time (for construction) and $1 million in on-going (for operation) funding from the Governor’s Office to begin building and implementing a system in Utah. However, due to estimates of slower economic growth anticipated at that time, the funding was not included in the Governor’s 2024 budget proposal to the Utah Legislature, although the Legislature approved $40 million in funding for earthquake-related aqueduct improvements to protect vital infrastructure.
This year, the UGS’s request for $5 million in funding for an EEW system has been included in the 2026 Governor’s budget proposal, for consideration by the Legislature. If funding is approved, it will be used to upgrade the existing seismograph network in preparation for developing an EEW system in Utah that would provide a warning to Utahans immediately before a major earthquake is felt.
