Jared R. Peacock Jeffery D. Pepin 20240604 ACII and binary digital data, shapefile, image Denver, CO U.S. Geological Survey Additional information about Originators: Jared R. Peacock, https://orcid.org/0000-0002-0439-0224; Jeffery D. Pepin, https://orcid.org/0000-0002-7410-9979; Suggested citation: Peacock, J. R., and Pepin, J. D, 2021, Magnetotelluric and TEM Data from the Umatilla Indian Reservation Geothermal Resources Assessment: Phase 2, 2020: U.S. Geological Survey data release, https://doi.org/10.5066/P9DQJTL9 https://doi.org/10.5066/P9DQJTL9 This data set consists of 19 wideband magnetotelluric (MT) and 23 transient electromagnetic (TEM) soundings collected by the U.S. Geological Survey in June 2020 as part of the Umatilla Indian Reservation Geothermal Resources Assessment: Phase 2 project. Each MT station had 4 components, 2 orthogonal magnetic induction coils and 2 horizontal orthogonal electric dipoles. Data were collected for an average of 18 hours on a repeating schedule of alternating sampling rates of 256 samples/second for 5 hours and 50 minutes and 4096 samples/second for 10 minutes. The schedules were set such that each station was recording the same schedule to allow for remote reference processing. Data were processed with a bounded-influence robust remote reference processing scheme (BIRRP v5.2.1, Chave and Thomson, 2004). Data quality were generally poor due to episodic spikes in the electromagnetic fields likely caused by the power grid. TEM data were collected in 100 x 100 m loops or 40 x 40 m loops along 4 profiles in areas of interest for geothermal potential. Files included in this publication include measured electric- and magnetic-field time series for MT data, and TEM soundings and 1-D resistivity models. The purpose of this data release is provide MT and TEM station locations, time-series data, and processed MT transfer functions to the public. This data product contains magnetotelluric (MT) transfer functions (TFs), which define the frequency dependent linear relations between components of electromagnetic (EM) field variations measured at a single site. Two types of TF are provided for most sites, impedance data relating horizontal electric and magnetic fields and tipper data, relating vertical and horizontal magnetic fields. All of the TFs provide input data for subsequent MT inversion and interpretation. They are estimated from the raw EM time series by (a) Fourier transforming data in a series of short overlapping time windows, and (b) applying robust regression methods to calculate TFs from the resulting spectral field estimates. For remote reference processing, data from one or more synchronously recording sites are used for more effective signal/noise separation. The supplied TFs are calculated for a range of periods (which may vary, depending on instrumentation and deployment time), as well as estimation error variances. References relevant to this release include: Wight, D., 1991, MT/EMAP Data Interchange Standard, The Society of Exploration Geophysicists, accessed January 19, 2021, at https://www.seg.org/Portals/0/SEG/News%20and%20Resources/Technical%20Standards/seg_mt_emap_1987.pdf. This metadata documents the full suite of MT data for this site and includes the files below. Their contents are described in the PDF Guide_to_Magnetotelluric_Data_Types, available at https://doi.org/10.5066/F7610XTR. See the entity and attribute section of the metadata for more information. File List: um232.edi um232.png um232.h5 20200709 2049590000Z 20200710 1626539960Z ground condition Complete As needed -118.52085 -118.52085 45.68017 45.68017 ISO 19115 Topic Category geoscientificInformation None Geology Minerals Energy and Geophysics Science Center GMEGSC Energy Resources Program magnetotellurics MT time series impedance apparent resistivity phase tipper conductivity USGS Thesaurus magnetotelluric surveying magnetic field (earth) geophysics electromagnetic surveying geologic structure tectonics exploration USGS Metadata Identifier USGS:6195d5ead34eb622f690d501 Geographic Names Information System (GNIS) Umatilla Common Geographic Areas Umatilla County Nevada None Blue Mountains Geolex Mesozoic Cenozoic Miocene Quaternary None. Please see 'Distribution Info' for details. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Jared R. Peacock U.S. Geological Survey Research Geophysicist mailing address

PO Box 158

Moffett Field CA 94035 USA 650-439-2833 jpeacock@usgs.gov Energy Resource Program The data have been peer reviewed and compared with related ancillary data. Data were reviewed for consistency and analyses results were checked for validity. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Spatial locations were determined from hand-held global positioning system (GPS) devices. In general, the GPS units used by field scientists recorded sample locations to within 100 feet (30 meters) of the true location. The locations were verified using a geographic information system (GIS) and digital topographic maps. Elevations were determined from USGS, The National Map, Bulk Point Query Service based on the USGS 3DEP (3D elevation program) 1/3 arc-second layer (10-meter). Vertical accuracy was not assessed for this specific dataset. The overall absolute vertical accuracy of the seamless DEMs within the conterminous United States (2013), expressed as the root mean square error (RMSE) of 25,310 reference points, was 1.55 meters (USGS, 2014 - http://dx.doi.org/10.3133/ofr20141008). The vertical accuracy varies across the U.S. as a result of differences in source DEM quality, terrain relief, land cover, and other factors. Gesch, D.B., Oimoen, M.J., and Evans, G.A., 2014, Accuracy assessment of the U.S. Geological Survey National Elevation Dataset, and comparison with other large-area elevation datasets-SRTM and ASTER: U.S. Geological Survey Open-File Report 2014-1008, 10 p., https://doi.org/10.3133/ofr20141008. Time-series electric and magnetic field data were collected in a geomagnetic north and east coordinate system using wideband magnetotelluric instrumentation at each site location. These data are provided in HDf5 format (*.h5 files). More information about instrumentation and file formats can be found in the PDF Guide_to_MT_Data_types, available at https://doi.org/10.5066/F7610XTR and MTH5 available at https://mth5.readthedocs.io/en/latest/. 20200820 Fourier spectra were calculated from windowed time-series data and used to calculate cross- and auto-power spectra. Remote reference processing, in which synchronously recording stations are processed together to remove incoherent noise, was carried out using all possible station combinations. Impedance and tipper transfer functions were calculated at each station. System and sensor responses were accounted for during this process and transfer function estimates were made for particular frequency bandwidths for each data run. Processing software used can be found in the *.edi and file header information. These files are described in detail within the PDF Guide_to_MT_Data_Types, available at https://doi.org/10.5066/F7610XTR. 20201001 Transfer function estimates were constructed by selecting optimal transfer function estimates at each period from a series of processing runs using different reference combinations. High and low sampling rate wideband recordings provided transfer function estimates for 1000-1 Hz and 0.001-1 Hz, respectively. So-called optimal transfer functions were selected based on examination of phase slope, smooth curve assumptions, and operator discretion. Transfer function estimates provided in the *.edi files and displayed in the *.png files have been rotated to geographic coordinates (X = North). Additional metadata information can be found in the *.edi file headers as well as the provided *.h5 files. Descriptions of these metadata can be found in the PDF Guide_to_MT_Data_Types, available at https://doi.org/10.5066/F7610XTR and MTH5 available at https://mth5.readthedocs.io/en/latest/. 20201010 Point Entity point 1 0.0001 0.0001 Decimal degrees D_WGS_1984 WGS_1984 6378137.0 298.257223563 National Geodetic Vertical Datum of 1988 1.0 Meter Attribute values um232.edi Electrical Data Interchange (EDI) transfer function file for station um232. The *.edi file type is described in detail in the PDF document, Guide_to_Magnetotelluric_Data_Types, available at https://doi.org/10.5066/F7610XTR. um232.png Thumbnail image of the resistivity, phase, and tipper values for station um232, available at https://doi.org/10.5066/F7610XTR. um232.mth5 MTH5 format data file for station um232. The *.mth5 file type is described in detail in the PDF document, Guide_to_Magnetotelluric_Data_Types.pdf, available at https://doi.org/10.5066/F7610XTR. Science Base U.S. Geological Survey Mailing and physical

Building 810, Mail Stop 302, Denver Federal Center

Denver CO 80255 USA 1-888-275-8747 sciencebase@usgs.gov https://www.sciencebase.gov/catalog/item/6195d5ead34eb622f690d501 Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data Science Base DOI None 20240604 Jared R. Peacock U.S. Geological Survey Research Geophysicist mailing address

PO Box 158

Moffett Field CA 94035 USA 650-439-2833 jpeacock@usgs.gov gs_gggsc_dm_team@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998