MAGNETIC AND VLF-EM STUDIES OF THE GEYSER BASINS IN WESTERN YELLOWSTONE NATIONAL PARK, WYOMING

The Yellowstone volcanic complex (YVC) is one of the most famous geological features on Earth including its volcanic features and the geothermal features residing within the Yellowstone caldera. The YVC has long been studied using a variety of geophysical methods including seismic refraction, broadband seismic, earthquakes, magnetotellurics and regional gravity and magnetic data. These studies have mainly concentrated on the lithospheric structure of the YVC. Recently, detailed geophysical studies have been conducted in the geothermal regions of western Yellowstone including gravity within the Upper, Midway and Lower Geyser basins. However, the most detailed studies have been conducted surrounding the Old Faithful geyser in the Upper Geyser Basin and include gravity, seismic surface waves, magnetic and electromagnetics in order to understand the structures beneath the geyser and to predict when the geyser will erupt. In order to compliment the detailed gravity studies conducted within the Upper, Midway and Lower geyser basins, a detailed magnetic and VLF-electromagnetic survey was conducted in the summer of 2019. The data were collected using a GEM magnetic/VLF-EM system where magnetic data were collected every 1 second and the VLF-EM data were collected between 10 and 20 meters along all trails within the geyser basins. The magnetic data will help constrain the gravity data and aid in determining the location of hydrothermally altered regions. The VLF-EM data will aid in locating vertical conductors including faults and water conduits. The data will be analyzed using traditional map methods including wavelength filtering and derivative methods.