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.