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Every year students in Prof. John Louie’s Applied Geophysics class happily abandon plans for Spring Break fun.  Instead, they spend the week eagerly conducting a variety of geophysical surveys at a geologically interesting field location. With the support of the Desert Research Institute, the University of ÁùºÏ±¦µä, Reno Dept. of Geological Sciences and Engineering; the ÁùºÏ±¦µä Seismological Lab; and the IRIS-PASSCAL Instrument Center, this year’s action took place at Fly Ranch located near Gerlach, ÁùºÏ±¦µä. 

Students gained boots-on-the-ground practical experience while employing several geophysical methods that included: DC resistivity; seismic reflection/refraction; refraction microtremor at large and small scales; ground magnetics; and gravity.  In the video students can be seen working on a seismic line getting ready to take “shots” with a sledge hammer, thus putting seismic energy into the ground.

Students discovered that Fly Ranch is an ideal location for geophysical education and training. For seismic reflection, the travertine deposits at the surface allowed recording reflections from 60 m depth at unprecedented high frequencies of 1500 Hz. All surveys at the hot springs and further out across Hualapai Flat were consistently successful. With only a one week investment of effort, students produced a wide set of complementary research results, that they can integrate into reports that will likely be published in the peer-reviewed scientific literature.

With support from the Center for Transformative Environmental Monitoring Programs (CTEMPs) students were also introduced to more recently developed geoscience instrumentation and techniques.  Distributed Temperature Sensing (DTS) is a technology enables the measurement of temperature at half-meter intervals along a fiber optic cable in time intervals as frequently as every two seconds – truly transformative!  DTS is used in geoscience for groundwater-surface water studies, well-bore temperature profiling, and contaminant tracking. 

At Fly Ranch students recorded temperature on a fiber optic cable deployed across the bottom of a 30 m wide warm spring pool.  Students also got exposure to a programmed Unmanned Arial System (UAS) Structure from Motion (SfM) mission.  These types of surveys are becoming more commonly used to generate high-resolution (1 cm/pixel) orthorectification and digital surface models with one-centimeter vertical accuracy.  The method relies on flying a programmed mission, or “mowing the lawn”, while the camera takes hundreds of overlapping photos.  SfM software then “stitches” the photos together by identifying common tie points across multiple images and calculates the true horizontal and vertical position of each pixel based on the different viewing geometry.  A preliminary example is shown in the video above.