Magnitude 3.4 earthquake near Monroe, UT


University of Utah Seismograph Stations

Released: September 24, 2017 1:00 PM MDT

The University of Utah Seismograph Stations reports that a minor earthquake of magnitude 3.4 occurred at 10:38 PM on Saturday,
September 23, 2017 (MDT), in southern Utah. The shock was located beneath the Sevier Plateau, 6 km ( 4 mi) east-southeast of the town
of Monroe, UT, and 18 km (11 mi) south of the town of Richfield, UT. The earthquake was reported felt in the towns of Monroe, Richfield,
and Joseph, Utah. It was followed by two small aftershocks, one of M 1.7 at 10:46 pm on Saturday night and the other of M 1.6 at 09:43
on Sunday morning.

Yesterday evening’s earthquake occurred within a seismically active area of Utah A total of 23 earthquakes of magnitude 3.0 or greater
have occurred within 25 km (16 mi) of the epicenter of this event since 1962. The largest of these events was a magnitude 5.2 on
October 04, 1967, 10.1km ( 6.3 mi) ESE of Sevier, UT.

Anyone who felt the earthquake is encouraged to fill out a survey form either on the Seismograph Stations website: or the
US Geological Survey website:

Earthquake Summary:

Date (UTC): September 24, 2017 Time (UTC): 04:38

Date (local): September 23, 2017 Time (local): 10:38 PM MDT

Latitude: 38 36.39′ N

Longitude: 112 3.43′ W

Preferred magnitude: 3.4 Ml

Magnitude 3.3 near Park City, UT


University of Utah Seismograph Stations

Released: September 18, 2017 12:00 PM MDT

The University of Utah Seismograph Stations reports that a minor earthquake of magnitude 3.3 occurred at 11:21 AM on September 18, 2017 (MDT). The shock was located 14 km (8 miles) beneath the Wasatch Mountains, 5 km (3 miles) south of the town of Summit Park, Utah, and 11 km ( 7 mi) WNW of Park City, UT. This earthquake was reported felt in Park City and Salt Lake City, Utah, other locations in the Salt Lake Valley, and in northern Utah County. Four other earthquakes of magnitude 3.0 or greater have occurred within 25 km (16 miles) of the epicenter of this event since 1962. The largest of these events was a magnitude 3.6 on June 30, 1999, 6.9km ( 4.3 mi) W of Park City, UT.

Anyone who felt the earthquake is encouraged to fill out a survey form either on the Seismograph Stations website: or the US Geological Survey website:


Earthquake Summary:

Date (UTC): September 18, 2017 Time (UTC): 17:21

Date (local): September 18, 2017 Time (local): 11:21 AM MDT

Latitude: 40 42.05′ N

Longitude: 111 36.55′ W

Depth: 11.0 km below sea level
13.6 km below the surface

Preferred magnitude: 3.30 Ml

UUSS 2016 Annual Report

cover page of 2016 annual report2016 Annual Report

In April of 2016 the University of Utah Seismograph Stations (UUSS) celebrated the 50th anniversary of its creation as an organizational unit within the University of Utah. We celebrated this milestone with a party honoring the founding director, Dr. Ken Cook, and the unveiling of a new historical display just outside the Rio Tinto Earthquake Information Center. The ceremony was well attended by current and former UUSS employees, colleagues in the College of Mines and Earth Sciences, representatives of sister agencies in the Utah Earthquake Program, members of Dr. Cook’s family, and many other friends of UUSS. Here’s to another 50 years of reducing the risk from earthquakes in Utah through research, education, and public service.

2016 was also a year of transition for UUSS. Our administrative manager, Martha Knowlton, retired after 14 years of service. We will miss Martha’s attention to detail, professionalism, and strong work ethic. UUSS communications specialist Sheryl Peterson, who has worked in various capacities for UUSS since 1989, also left in the fall of 2016. Sheryl’s competence, cheerfulness, and organizational skills will serve her well as she pursues a new career as director of advancement operations at Southern Virginia University. We will also miss Katherine Whidden, a research scientist, student mentor, and the UUSS public information officer, who left in 2016 (ending a five-year stint with UUSS) to travel the country in an RV with her husband, John. In other news, Cindi Meier, who worked at UUSS during 1994-1999, agreed to return as our new full-time administrative officer. In 2016, we also welcomed Dr. Hao Zhang to UUSS as a post-doctoral research scientist focusing on the detection and location of sequences of very small earthquakes.

We look forward to an exciting new year in 2017. I encourage you to visit our revamped web page at to stay up- to-date on our new initiatives and products as well as to nd out about the latest seismic activity in Utah. You can also follow UUSS on Twitter with the handle @UUSS_Quake_Info.

UUSS 2015 Annual Report

UUSS Annual Report 2015

2015 Annual Report

2015 has been another vibrant and productive year for the University of Utah Seismograph Stations (UUSS). Our longstanding partnership with the United States Geological Survey (USGS) was extended with a new, 5-yr cooperative agreement from the USGS Earthquake Hazards Program. This award ensures that earthquake monitoring in Utah will continue to operate with state-of-the-art equipment and software at least through 2020. Congratulations to the UUSS staff for all their hard work on the USGS proposal, it was truly a team effort.

The legacy of UUSS in earthquake monitoring and research was recognized in 2015 as two former UUSS Directors received prestigious awards for career accomplishments. Research Professor Emeritus Dr. Walter J. Arabasz received the 2015 Alfred E. Alquist Special Recognition Medal from the Earthquake Engineering Research Institute, while Professor Emeritus Dr. Robert B. Smith received the 2015 Paul G. Silver Award from the American Geophysical Union. Congratulations to Walter and Bob for the leadership and service they have provided to the seismological community over the last several decades.

UUSS developed a new monitoring capability in 2015 with the acquisition of nearly 50 new wireless seismographs. The instruments were purchased in collaboration with Dr. Fan-Chi Lin and other University of Utah geoscientists, and will allow for the imaging of shallow Earth structure at a very small scale as well as the detection of small aftershocks that follow regional earthquakes. Please look inside to read about one of the first experiments carried out with the new instruments.

We expect great new things in 2016 as well. Keep an eye out for an updated UUSS web page and expanded social media presence. We also look forward to a celebration of the 50th anniversary of UUSS, in April 2016.

UUSS 2014 Annual report

uuss_ar2014 cover2014 Annual Report

Dear Friends,
It is a pleasure to present you with the 2014 Annual Report of the University of Utah seismograph Stations (UUSS). Reflecting on recent UUSS accomplishments, I was struck by the importance of partnerships in pursuing our dual mission of academic research in earthquake science, and communication to the residents of Utah of the latest information on earthquake risk.
As always, a key UUSS partner in 2014 was our home academic unit, the Department of Geology and Geophysics. A nice example of the support shown by our department is the recent hire of a new tenure-track faculty member in seismology, Dr. Fan-Chi Lin. Although Dr. Lin’s expertise is in seismic imaging, he has already expressed interest in collaborating with UUSS faculty on projects related to earthquake science in Utah and Yellowstone.
A second important UUSS partner is the Utah Division of Emergency Management (DEM). This agency administers Utah’s earthquake program and has the responsibility for mitigating and responding to earthquake hazards in the state. The DEM earthquake program funds the UUSS traveling earthquake exhibit, which visited 25 elementary and middle schools throughout Utah in 2014. The DEM also provides financial support for the Utah Seismic Safety Commission, the state’s official earthquake advisory board.
A third partner that is essential to the success of UUSS is the United States Geological Survey (USGS).  The USGS routinely and consistently supports UUSS by providing the latest seismic equipment—and the funding to operate and maintain this equipment. In 2014, USGS funding enabled over 115 seismic stations to be operated in the State of Utah. As with all of our
seismometers, these instruments operate 24 hours a day, 7 days a week, and transmit data to the UUSS earthquake information center within seconds of it being recorded.
Many people at the university, and within state and federal agencies, contribute to the success of UUSS. To learn more about all of our partners, and the achievements they have contributed to, please take a few moments to browse through this year’s Annual Report.

UUSS 2013 Annual Report

uuss_ar2013 cover
University of Utah Seismograph Stations (UUSS) had another busy year in 2013.

The professional highlight was hosting the annual meeting of the Seismological Society of America (SSA), April 17-19, at the Salt Palace Convention Center in downtown Salt Lake City. The SSA is the world’s premier scientific society dedicated to the study of earthquakes. UUSS personnel served on the organizing committee, led a Town Hall Meeting, moderated several of

the scientific sessions, and contributed to 12 scientific presentations. For some UUSS students, it was the first time attending a professional meeting and they were excited to meet scientists whom they had previously known by reputation only.
During 2013 UUSS detected and located about 6,000 earthquakes in the Intermountain West. This region includes all of Utah and Yellowstone National Park, as well as parts of Arizona, Colorado, Idaho, Montana, and Wyoming. Although none of the earthquakes were large enough to cause significant damage, careful documentation of these events allows us to better define
the locations of active faults and to estimate seismic hazard in the region more precisely. The geologic record clearly indicates that magnitude 6.5-7.5 earthquakes have repeatedly occurred along the Wasatch fault in areas of Utah that are now densely populated.
In addition to earthquakes, our seismic network often observes other “exotic” sources of seismic energy. Such a source occurred on the evening of April 10, 2013 when the northeastern wall of the Bingham Canyon, Utah open-pit copper mine collapsed in two distinct landslides separated by about 90 minutes. The combined episode was the largest non-volcanic landslide to occur in North America in modern times. Seismic waves were well recorded thousands of kilometers away from the mine, and at least 16 tiny earthquakes were triggered by stress changes associated
with the landslide. Owing to rigorous geotechnical monitoring, the mine operators were able to accurately predict the timing of the landslide and so avoid casualties.
A second exotic seismic source occurred on July 31 at 7:30 p.m. (local time) when the Steamboat Geyser in Yellowstone National Park erupted, sending water 200-300 feet in the air. Signals recorded at a nearby seismometer showed energy lasting for over two hours as steam poured out of vents following the initial eruption. Notably, acoustic energy from the eruption was recorded by one of the infrasound stations located in the park.
In 2014 the students, faculty, and staff of UUSS will continue to monitor earthquake activity in the Intermountain West and to raise awareness of the seismic hazard in the State of Utah. Academic research will focus on a range of topics including the rupture properties of large earthquakes, earthquake swarm and aftershock sequences, seismicity induced by mining and
other anthropogenic activities, as well as producing better images and models of the geological structure beneath Utah and Yellowstone.

UUSS 2012 Annual Report

uuss_ar2012 cover
UUSS Annual Report 2012

It is my pleasure to present the 2012 Annual Report of the University of Utah Seismograph Stations (UUSS).

Working with state and federal partners, we monitor seismicity in much of the Intermountain West, we carry out fundamental academic research on earthquakes, and we educate and inform the public about the risk from earthquakes. I hope that this inaugural annual report provides an informative update on our recent progress in these areas.

The operational highlight of 2012 was the installation of a state of-the-art software package developed by the Advanced National Seismic System (ANSS). ANSS Quake Monitoring System (AQMS) will provide UUSS new flexibility in detecting, locating, and publicizing earthquakes. A close second was the development of an in-house database containing all digital UUSS broadband and short-period seismic data recorded since 2001.

In 2012 UUSS scientists published academic papers on a diverse range of topics that included a new catalog of moment tensors for Utah earthquakes; modeling of infra sound recordings of the 2011 Circleville, Utah earthquake; simulations of ground motion in Utah expected for an M7 earthquake along the Wasatch fault; and the inference of short-period rupture properties of three recent great earthquakes in Peru, Chile, and the Indian Ocean.

On a rainy day in April 2012, UUSS also participated in the first ever Great Utah ShakeOut to help raise awareness of earthquake hazard in Utah. And the UUSS traveling earthquake exhibit visited over 50 schools throughout the state.  Although the next year looks to be a challenging environment in terms of funding, I am confident that the hardworking students, faculty, and staff of UUSS will maintain operational and academic excellence. A few of the exciting things to look forward to in 2013 include:

  • Starting February 1, 2013, UUSS will begin a new 3 year cooperative agreement with the U.S. Geological Survey (USGS) for monitoring and characterizing earthquakes in the Yellowstone region, one of the most geologically dynamic places in the world and a site of previous supervolcano eruptions.
    Professor Emeritus Robert B. Smith will be retiring from his role as the principal investigator of this project after three decades, but will continue to be involved with the UUSS Yellowstone work.
  • On April 17-19, 2013, UUSS will welcome the annual meeting of Seismological Society of America to Salt Lake City. This is the world’s most prestigious professional society dedicated to earthquake science.
  • Christine Gammans, first recipient of the UUSS graduate fellowship honoring Director Emeritus Walter J. Arabasz, will graduate with an master’s degree in geophysics and begin her career with Chevron in August.

As we approach the 50th anniversary of the founding of UUSS, we are mindful of many whose contributions have laid a solid foundation for the Seismograph Stations. We look forward to adding to that legacy in the year ahead.

Seismic characterization of coal-mining seismicity in Utah for CTBT monitoring

Arabasz, W. J. and J. C. Pechmann (2001). Seismic characterization of coal-mining seismicity in Utah for CTBT monitoring, Technical Report UCRL-CR-143772, Lawrence Livermore National Laboratory, Livermore, California, LLNL Research Agreement No. B344836, 122 pp., including tables and figures.