Utah FORGE: Phase 3 Magnetotelluric (MT) Data

Description

New high-quality tensor MT data at 122 sites, including the vertical magnetic field and utilizing ultra-remote referencing, have been acquired over the Utah FORGE project area. The results will be used to delineate the densities of faults and fractures in crystalline basement rocks, to define the heat sources, and to derive baseline 3D resistivity structure for later MT monitoring of temporal changes in resistivity structure following well stimulation in the EGS reservoir. There are three files here related to Utah FORGE magnetotelluric (MT) data acquisition and processing. The FORGE MT EDIs zip file contains the observed MT responses in industry-standard EDI format. For each site, there is an EDI response file that utilized a local independent reference for noise cancellation, and a file that utilized a distant reference cancelling noise associated with the DC transmission line of the Delta IPP passing down the west side of Milford Valley. These two site files could be merged as appropriate. The FORGE Model Cell Center file contains the model volume of the 3D Forge MT inversion for characterizing the resistivity structure in the project area. It was derived using finite element inversion methodology described in Wannamaker et al, in the attached FORGE Phase3 Geophysics paper, from the MT observation EDI files. It is ASCII format (.dat) and entries are defined at top of the file in a simple x-y-z-Rho listing in UTM coordinates. The element layers drape the topography so the Rho value layers are not purely horizontal slices. This greatly simplifies the listing.

Resources

Name Format Description Link
57 Contains the model volume of the 3D Forge MT inversion for characterizing the resistivity structure in the project area. It was derived using finite element inversion methodology. https://gdr.openei.org/files/1255/FRG200614_mdl17_cellcenter.zip
33 This document contains information about the 3D Forge MT inversion for characterizing the resistivity structure in the FORGE project area. It was derived using finite element inversion methodology. https://gdr.openei.org/files/1255/FORGE_Phase3_geophysics.pdf
57 Contains the observed magnetotelluric (MT) responses in industry-standard EDI format. For each site, there is an EDI response file that utilized a local independent reference for noise cancellation, and a file that utilized a distant reference cancelling noise (western Nevada, _bvv) associated with the DC transmission line of the Delta IPP passing down the west side of Milford Valley. These two site files could be merged as appropriate. https://gdr.openei.org/files/1255/FORGE_MT_190812_EDIs.zip
57 This updated MT model contains the resistivity values at the centers of the hexahedral finite elements computed by non-linear inversion of the posted MT responses over the FORGE property area and adjacent Mineral Mountains (Wannamaker et al., 2021, GRC Trans.). This inverse approach represents topography precisely by deforming the elements vertically. Hence, the elevations of all the resistivity values in principle are unique and not represented as horizontal planes of values as might result from a more common finite difference mesh inversion. This model should be considered preliminary. The dataset includes a .dat (text), a comma delimited text file, and a xyz shapefile. https://gdr.openei.org/files/1255/FORGE_MT_mdl17_cellcenter.zip
57 The FRG200614_mdl17_corners.zip file contains two folders with information about the MT model 17 corners. The FRG200614_mdl17_SurfaceTopo folder contains a file containing the UTM locations and elevations in m of the corners of the surface hexahedral elements for 3D FORGE MT resistivity inversion model FRG200614_mdl17. These elements are deformed vertically over the mesh to represent the topography. The FRG200614_Mdl17_Mesh folder contains a file containing the resistivity of each hexahedral element for 3D FORGE MT resistivity inversion model FRG200614_mdl17, plus the UTM locations and elevations in m of each of the eight corners of the elements. These elements are deformed vertically over the mesh to represent the topography. https://gdr.openei.org/files/1255/FRG200614_mdl17_MT_corners.zip

Tags

  • geophysics
  • forge
  • egs
  • utah-forge
  • magnetotellurics
  • geodesy
  • geophysical-data
  • gravity
  • milford
  • mt-data
  • magnetics
  • roosevelt-hot-springs
  • utah-geothermal
  • fea
  • site-characterization
  • finite-element
  • fem
  • seismic
  • utah-forge-mt
  • geothermal
  • magnetotelluric-data
  • energy

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