Investigation of the History of Earthquakes at the North Creek site, Juab County, Utah

View to the east of Google Earth image showing location of the North Creek site (red triangle, NC) at the base of the steep range front.  Yellow lines along the range front are mapped traces of recently active fault strands of the Wasatch fault zone. Detailed view to the east of the North Creek site (red triangle, NC) and the trace of the Wasatch fault zone (yellow line).  The image uses LiDAR (Light Detection and Ranging) data in Google Earth to reveal details of the topography near the site. The 2012 trench was located at the position of the triangle.

In June 2012, geologists from the Utah Geological Survey and U.S. Geological Survey collaborated in a field investigation of the Wasatch fault zone at the North Creek site, which is located about 6 km (4 mi) northeast of the town of Mona, and 16 km (10 mi) north-northeast of the town of Nephi, in Juab County, Utah. The North Creek site was one of the first sites studied along the entire Wasatch fault zone in 1980 with the goal of documenting the record of large prehistoric earthquakes that had displaced the ground surface (Hansen and others, 1981, 1982). The purpose of the 2012 study was to refine the ages of the prehistoric earthquakes and to extend the record of farther back in time.

Repeated displacements on the Wasatch fault zone have vertically offset young stream sediments about 8 m (26 ft) at the mouth of North Creek Canyon (fig. 2). The field team excavated a 40-m-long trench across the large fault scarp to map the sediments adjacent to the fault (fig. 3) and to collect samples that will be used to date the sediments (fig. 4).

During the field work, the Utah Geological Survey documented the progress of the investigation and compiled 10 days of field work into a short video. View the field work video.

The results of this investigation will be published by the Utah Geological Survey when completed.

View of the 2012 trench at the North Creek site showing the field team discussing interpretations of faults and sediments exposed in the trench. Geologists analyzing and collecting sediment samples in the 2012 trench at the North Creek site.

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