Magnetics Data from the Escanaba Trough (Gorda Ridge)

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Frequently anticipated questions:

What does this data set describe?

Title: Magnetics Data from the Escanaba Trough (Gorda Ridge)
Abstract:
This data release provides access to magnetics data collected by the AUV Sentry during the TN403 cruise in the Escanaba Trough (USGS Field Activity 2022-621-FA).
Supplemental_Information:
Additional information about the field activity or activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2022-621-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Galley, Christopher, Sorenson, Daniel, Shapiro, Isabelle M., and Gartman, Amy, 20260401, Magnetics Data from the Escanaba Trough (Gorda Ridge): data release DOI:10.5066/P1DRPIQK, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: Galley, C., Sorenson, D., Shapiro, I.M., and Gartman, A., 2026, Magnetics Data from the Escanaba Trough (Gorda Ridge): U.S. Geological Survey data release, https://doi.org/10.5066/P1DRPIQK.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -127.5671
    East_Bounding_Coordinate: -127.4024
    North_Bounding_Coordinate: 41.1735
    South_Bounding_Coordinate: 40.6942
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Jul-2022
    Ending_Date: 23-Jan-2026
    Currentness_Reference:
    Magnetics data compiled and processed
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Vector data of the X, Y, and Z directions of the magnetic field were during each of AUV Sentry's dive while the magnetometer was attached.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is World Geodetic System 1984 (WGS 84).
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: mean sea level
      Altitude_Resolution: 0.1
      Altitude_Resolution: 0.1
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    escanaba_dXXX_mag.csv
    Comma Separated Value (CSV) file containing raw magnetics data. The XXX in the file name represents the dive number. For example, escanaba_d638_mag.csv contains data from dive 638. (Source: Producer Defined)
    Year
    The year component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:2022
    Maximum:2022
    Units:years
    Month
    The month component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:5
    Maximum:6
    Units:months
    Day
    The day component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:1
    Maximum:31
    Units:days
    Hour
    The hour component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:0
    Maximum:23
    Units:hours
    Minute
    The minute component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:0
    Maximum:59
    Units:minutes
    Second
    The second component of the data's timestamp (Source: Producer Defined)
    Range of values
    Minimum:0
    Maximum:60
    Units:seconds
    Longitude_DD
    Longitudinal data formatted in decimal degrees (Source: Producer Defined)
    Range of values
    Minimum:-127.5671398
    Maximum:-127.4023971
    Units:decimal degrees
    Latitude_DD
    Latitudinal data formatted in decimal degrees (Source: Producer Defined)
    Range of values
    Minimum:40.6942229
    Maximum:41.1735022
    Units:decimal degrees
    Elevation_m
    Elevation data of the observation points relative to sea-level, units in meters (m) (Source: Producer Defined)
    Range of values
    Minimum:-3273.01
    Maximum:-3086.87
    Units:meters
    Altitude_m
    Altitude data formatted in meters. This represents the relative height of the observation points above the seafloor (Source: Producer Defined)
    Range of values
    Minimum:49.34
    Maximum:127.37
    Units:meters
    Heading
    Heading data of the AUV (Source: Producer Defined)
    Range of values
    Minimum:0.0
    Maximum:360.0
    Units:degrees
    Pitch
    Pitch data of the AUV (Source: Producer Defined)
    Range of values
    Minimum:-11.85
    Maximum:11.301
    Units:degrees
    Roll
    Pitch data of the AUV (Source: Producer Defined)
    Range of values
    Minimum:-3.379
    Maximum:6.815
    Units:degrees
    Mag_x_raw_nT
    The x-component (North positive) of the raw magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:-29991.87
    Maximum:28199.46
    Units:nano tesla
    Mag_y_raw_nT
    The y-component (East positive) of the raw magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:-25141.69
    Maximum:24708.65
    Units:nano tesla
    Mag_z_raw_nT
    The x-component (North positive) of the raw magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:38935.41
    Maximum:49413.95
    Units:nano tesla
    TMI_raw_nT
    The total magnetic intensity raw data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:43661.5
    Maximum:51478.94
    Units:nano tesla
    Mag_x_veccorr_nT
    The x-component (North positive) of the vector-corrected magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:19060.95
    Maximum:23426.19
    Units:nano tesla
    Mag_y_veccorr_nT
    The y-component (East positive) of the vector-corrected magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:2767.21
    Maximum:8150.08
    Units:nano tesla
    Mag_z_veccorr_nT
    The z-component (vertical, down positive) of the vector-corrected magnetic field data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:37052.03
    Maximum:45919.48
    Units:nano tesla
    TMI_veccorr_nT
    The total magnetic intensity vector-corrected data. Units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:42218.74
    Maximum:51085.81
    Units:nano tesla
    dXXX_mag_lvled_50m_UTM9N.csv
    Comma Separated Value (CSV) file containing processed magnetics data. The XXX in the file name represents the dive number. For example, d638_mag_lvled_50m_UTM9N.csv contains data from dive 368. (Source: Producer Defined)
    Easting_m
    Easting positional data, in the WGS 1984 UTM Zone 9 projection. Units in meters (m) (Source: Producer Defined)
    Range of values
    Minimum:620722.4
    Maximum:633887.4
    Units:meters
    Northing_m
    Northing positional data, in the WGS 1984 UTM Zone 9 projection. Units in meters (m) (Source: Producer Defined)
    Range of values
    Minimum:4505892.6
    Maximum:4559228.9
    Units:meters
    Elevation_m
    Elevation data of the observation points relative to sea-level, units in meters (m) (Source: Producer Defined)
    Range of values
    Minimum:-3272.8
    Maximum:-3087.0
    Units:meters
    Altitude_m
    Altitude data formatted in meters. This represents the relative height of the observation points above the seafloor (Source: Producer Defined)
    Range of values
    Minimum:63.7
    Maximum:91.7
    Units:meters
    TMI_Anomaly_nT
    The total magnetic intensity anomaly data, units in nano tesla (nT) (Source: Producer Defined)
    Range of values
    Minimum:-415.9
    Maximum:2597.6
    Units:nano tesla
    Entity_and_Attribute_Overview:
    This dataset consists of data from eight marine magnetic field surveys collected down the length of the Escanaba Trough in the northeast Pacific Ocean. The data were measured with a three-component fluxgate magnetometer, mounted to Woods Hole Oceanographic Institute's autonomous underwater vehicle Sentry. Included in this dataset are the eight survey's calibrated vector (three-component) magnetic data, as well as the processed versions of the data presented as total magnetic intensity.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Christopher Galley
    • Daniel Sorenson
    • Isabelle M. Shapiro
    • Amy Gartman
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data serve to expand the knowledge and statistics for deep ocean marine mineral occurrences and composition within the global ocean.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 13-Jun-2022 (process 1 of 2)
    Magnetics data was collected by a three-component fluxgate magnetometer attached the autonomous underwater vehicle (AUV) Sentry during the TN403 expedition in the Escanaba Trough on the R/V Thomas G. Thompson. The expedition occurred between May 24, 2022, and June 13, 2022, and was led and staffed by USGS employees.
    Date: 23-Jan-2026 (process 2 of 2)
    Magnetics data were compiled and cleaned upon returning to land. To remove the magnetization effects from the AUV, a full-vector calibration was performed, which involved spinning the AUV in the water column to complete at least one 360-degree rotation. The attitude and vector magnetic field data from these rotations were used to calculate the induced and permanent magnetization of the AUV using a least-squares solution and subsequently removed from the raw data. The resulting files from this initial calibration are, which also include raw data columns: escanaba_d638_mag.csv; escanaba_d639_mag.csv; escanaba_d640_mag.csv; escanaba_d641_mag.csv; escanaba_d642_mag.csv; escanaba_d643_mag.csv; escanaba_d646_mag.csv; escanaba_d647_mag.csv. The calibration matrices used in the full-vector calibration are included in the file Calibration_Coefficient_Matrices.txt. To further prepare the vector magnetic data for the inversion modelling the data were: (1) low-pass filtered with a passband frequency of 0.01 Hz at a data frequency of 10 Hz; (2) projected to WGS 1984 UTM Zone 9N; (3) separated into single survey lines with the ends of the lines where the AUV turned around removed, each line was levelled to its survey's tie line(s); (4) further linear heading corrections were calculated and applied to each individual survey line, to remove artifacts left over from the full-vector calibration; (5) a 50 m moving mean was applied to the data along each survey line, and then the data was subsampled to a 50 m data point spacing; (6) the survey lines were combined into new survey groups, with dive 643's data being separated into two surveys, d643_1 and d643_23, and dive 638, 640, and 641 were combined into a single group; and (7) the Earth's field strength was calculated at each survey location using the WMM-2020 model (https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml#igrfwmm), and was subtracted from the data to produce a TMI anomaly. The resulting data files are: d638_mag_lvled_50m_UTM9N.csv; d639_mag_lvled_50m_UTM9N.csv; d640_mag_lvled_50m_UTM9N.csv; d641_mag_lvled_50m_UTM9N.csv; d642_mag_lvled_50m_UTM9N.csv; d646_mag_lvled_50m_UTM9N.csv; d647_mag_lvled_50m_UTM9N.csv.
  3. What similar or related data should the user be aware of?
    Galley, Christopher, Lelièvre, Peter G., Haroon, Amir, Graber, Sebastian, Jamieson, John, Szitkar, Florent, Yeo, Isobel, Farquharson, Colin G., Petersen, Sven, and Evans, Robert, 2021, Magnetic and Gravity Surface Geometry Inverse Modeling of the TAG Active Mound.

    Online Links:

    Other_Citation_Details:
    Galley, C., Lelievre, p., Haroon, A., Graber, S., Jamieson, J., Szitkar, F., Yeo, I., Farquharson, C., Petersen, S., and Evans,R. (2021). Magnetic and gravity surface geometry inverse modeling of the TAG active mound. Journal of Geophysical Research: Solid Earth, 126, e2021JB022228. https://doi.org/10.1029/2021JB022228. Citation added for users reference in metadata descriptions.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The noise levels for the final processed total magnetic intensity were determined to have a mean of 0.0 and a standard deviation of 8 percent (assuming Gaussian noise). This value was determined during the inversion modelling process, where multiple models were produced with varying data misfit targets (such as, the difference between the observed data and the final inversion model's calculated data), until a model was produced with minimal-to-no near-seafloor, small (single cell sized), high magnetic susceptibility artifacts interpreted to represent overfitting the data. This 8 percent standard deviation noise is likely so high because it incorporates positional inaccuracy of the survey platform (the AUV Sentry), see Galley and others (2021) in the Supplementary Material of the publication for details.
  2. How accurate are the geographic locations?
    Sentry’s internal navigation is dead reckoning based on the Inertial Navigation System (INS) and Doppler Velocity Log (DVL) sonar system. It has a typical accuracy of 0.1 percent of distance traveled. The Sentry dives at the Escanaba Trough were between 24-51 km in survey distance travelled, corresponding to positional accuracies of 24-51 m by the end of the surveys. However, post-processing can greatly increase the accuracy of the positional data. A better estimate of the horizontal accuracy of the Sentry AUV would be 6-8 m, as determined through testing in Galley and others (2021).
  3. How accurate are the heights or depths?
    Sentry's depth information is much more accurate than the horizontal positional data, as it is determined through pressure measurements (using a Parascientific 8B7000-1m Digiquartz depth sensor). The depth sensor boasts a 0.01 percent accuracy, so the average survey depth at the Escanaba Trough of approximately 3.2 km would correspond to a survey depth data accuracy of approximately 32 cm.
  4. Where are the gaps in the data? What is missing?
    Total magnetic intensity data is geographically dependent, such as, values can change greatly depending on where the survey took place. This data only represents total magnetic intensity data within the corresponding survey areas, in the spring of 2022.
  5. How consistent are the relationships among the observations, including topology?
    The data does match with details provided about it, and all data falls within expected ranges. No duplicates are present in the files.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints. Please see 'Distribution Information' for details.
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. These data are marked with a Creative Common CC0 1.0 Universal License. Please recognize and acknowledge the U.S. Geological Survey and the University of Ottawa as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: These data are available in comma-delimited text format accompanied by the associated CSDGM FGDC-compliant metadata. Files are provided in two zip folders as the final data (final_data_used_in_modeling) and the vector corrected data (vector_corrected). in format comma-delimited text (version 2025a) Size: 146.5
      Network links: https://doi.org/10.5066/P1DRPIQK
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    These data can be viewed with any text reader.

Who wrote the metadata?

Dates:
Last modified: 01-Apr-2026
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA
USA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/CMGDS_DR_tool/DR_P1DRPIQK/Magnetics_metadata.faq.html>
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