A Model of Ambient Seismic Noise Recorded by the Utah Regional Network of Strong‐Motion Seismometers

Online Material: Tables of station and noise information, and figures of full year PDFs. The University of Utah Seismograph Stations (UUSS) has maintained a seismometer network in Utah and surrounding regions since 1966. The primary purpose of this network is to detect and locate regional earthquakes so that seismic hazard in the area can be better quantified. The seismic hazard and risk in Utah are severe with 80% of Utah’s 2.8 million people living and working along the Wasatch Front urban corridor, many in unreinforced masonry structures in close proximity to the Wasatch fault. Exploratory trenching and fault‐scarp morphology analyses indicate that moderate to large magnitude earthquakes ( M  6.5–7.5) occur repeatedly on the Wasatch fault (Swan, 1980; DuRoss, 2008), with a recurrence interval along one of the five central segments (Brigham City to Nephi) of 350 years and individual segment recurrence intervals in the range of 600–2300 years (McCalpin and Nishenko, 1996). In addition to direct ground shaking, the region is susceptible to other earthquake‐related hazards such as landslides, rock/snow avalanches, soil liquefaction, differential ground settlement, flooding, and disruption of vulnerable life‐support facilities that cross fault lines (Arabasz et al. , 1980; Utah Seismic Safety Commission, USSC, 2008). An important component of the Utah Regional Seismic Network (URSN) is the sub‐network of strong motion seismometers. These instruments are modern digital accelerometers that report data in near real time to the UUSS data center. The stations are located principally in the Wasatch Front urban corridor, southwestern Utah, and other population centers throughout the state (Fig. 1). The strong‐motion seismometers record ground motion at low gain, providing on‐scale recordings of moderate‐to‐large earthquakes that occur in the Utah region. This information is incorporated into ShakeMaps (Wald …