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airborne geophysical survey index map
Index map of 1,598 airborne geophysical surveys conducted or contracted by the USGS since the 1940s. The Project generated survey footprints and attributed each with survey specific information that helps users quickly assess available data sets on our geophysical data portal.

Why did USGS update their geophysical data sets?

Since the 1940s, the USGS has spent millions of dollars conducting airborne geophysical surveys. This trend continues as the USGS contracts commercial vendors to acquire new geophysical data sets that support research within the Mineral Resource Program and other USGS Programs. These government-funded data sets are valuable products that the USGS provides to both internal and external users.

What did USGS do to these data sets?

This Project helped to streamline the workflow from data acquisition to data distribution, and additionally provided user support for integration and interpretation of these complex data sets.

There were four main objectives:

  1. Contracting geophysical surveys
  2. Converting data from analog to digital format
  3. Archiving, retrieving, and integrating geophysical data
  4. Outreach

Contracting Geophysical Surveys

The collection of airborne geophysical data is mostly contracted to commercial vendors. As such, the Federal Government requires that the contracts are overseen by a Contracting Officer’s Representative. The Project supported this role and worked with USGS scientists and the Office of Acquisition and Grants to ensure that all legal obligations were met. The Contracting Officer’s Representative maintains a catalog describing each survey.

Converting Data from Analog to Digital Format

Many vintage USGS airborne survey data sets were only available as scanned contour maps. These data could be easily integrated within geographic information systems (GIS). However, the contour lines needed to be digitized and attributed allowing the data to be fully leveraged and manipulated within modern geophysical data processing software packages. This project performed the digitization task for known data gaps across the U.S. and for specified areas defined by other Mineral Resource Program projects.

Archiving, Retrieving, and Integrating Geoophysical Data

USGS spatial data delivery has been rapidly evolving over the last several years. Traditionally, airborne geophysical survey data were released through USGS publications; however, increased cost and time for generating these reports have made this form of data distribution less optimal. The Project developed alternative pathways for data distribution that aligns with USGS Data Management Policy.

The Project made the data archive publicly available through the Mineral Resources On-Line Spatial Data website. These data can now be found through map interfaces and by state/county, and there are also national-scale compilations that include magnetics, radiometrics, and gravity.

geophysical data flow chart
The Project cataloged contracted data into the data archive and generated FGDC-compliant metadata, map previews, and ASCII format representations of the data. This information synchronized to the USGS Mineral Resources On-Line Data portal where it became publicly available. The metadata files were then synchronized to additional USGS and Federal Government spatial data catalogs.


We addressed geophysical data questions from the public, as well as USGS scientists. The questions covered airborne and ground-based geophysical surveys with methods that include: magnetics, gravimetrics, radiometrics, and resistivity. The solutions sometimes involved data integration and manipulation that demonstrated the utility of these data sets when exploring for mineral deposits.


Geophysical Data

Airborne geophysical surveys web mapping application:

Magnetic anomaly maps for North America:

Gravity anomaly maps for conterminous U.S.:

Radiometric anomaly maps for North America:


Anderson, E.D., 2014, Book Review - Michael Dentith and Stephen T. Mudge: Geophysics for the Mineral Exploration Geoscientist: Mineralium Deposita, 50(1), p. 139-140, doi:10.1007/s00126-014-0557-9.

Anderson, E.D., Zhou, W., Li, Y., Hitzman, M.W., Monecke, T., Lang, J.R., and Kelley, K.D., 2014, Three-dimensional distribution of igneous rocks near the Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska: Constraints from regional-scale aeromagnetic data: Geophysic, 79(2), B63-B79, doi:10.1190/geo2013-0326.1.

Hill, P.L., Kucks, R.P., and Ravat, D., 2009, Aeromagnetic and aeroradiometric data for the conterminous United States and Alaska from the National Uranium Resources Evaluation (NURE) Program of the U.S. Department of Energy: U.S. Geological Survey Open-File Report 2009–1129.


Anderson, E.D., and McClung, C.T., 2015, Magnetic imaging for porphyry copper deposits in Alaska – Insights into mineral systems: Australian Society of Exploration Geophysicists 2015 Annual Meeting, 21-24 August 2015, Perth, Australia.

Anderson, E.D., Grauch, V.J.S., Powers, M.H., and Cannon, W., 2015, Seismic, gravimetric, and magnetic modeling over the Bayfield Peninsula, Wisconsin: Testing hypotheses on the source of a gravity low: Proceedings of the 61st ILSG Annual Meeting - Part1, p. 3-4. View ILSG 2015 Proceedings. [PDF file, 7.8 MB]

Anderson, E., Quigley, A., Quigley, P., and Monecke, T., 2015, Geophysical imaging of the bedrock geology of the Pembine-Wausau terrane, Wisconsin: Constraints on the setting of volcanogenic massive sulfide deposits: Proceedings of the 61st ILSG Annual Meeting - Part1, p. 5-6. View ILSG 2015 Proceedings. [PDF file, 7.8 MB]

Drenth, B., Ailes, C., and Anderson, E., 2015, Re-digitized public aeromagnetic data for the Baraga basin and surrounding region, Upper Peninsula, Michigan: Proceedings of the 61st ILSG Annual Meeting - Part1, p. 27-28. View ILSG 2015 Proceedings. [PDF file, 7.8 MB]

Grauch, V.J.S., Powers, M.H., Anderson, E.D., and Cannon, W.F., 2015, Preliminary 3D model of the Midcontinent Rift System in western Lake Superior region: Proceedings of the 61st ILSG Annual Meeting - Part1, p. 38-39. View ILSG 2015 Proceedings. [PDF file, 7.8 MB]

Project Contact

Eric Anderson
Phone: 303-236-5652
Crustal Geophysics and Geochemistry Science Center

Geophysical data support continues in the GIS and Information Management projects.

Mineral Resources Program Science Priority

The use of firm, trade, and brand names is for identification purposes only and does not constitute endorsement by the U.S. government.

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