State releases updated catalog of 1970s NPR-A seismic shothole samples

The Alaska Division of Geological & Geophysical Surveys has released an updated catalog of drill log cards, driller notes and sample photographs from about 26,000 U.S. Geological Survey seismic shothole sites in the National Petroleum Reserve-Alaska. The holes were drilled between 1974 and 1981.

The catalog was released to support identification of sand and gravel resources and planning for infrastructure development on the North Slope, according to the catalog metadata.

Shotholes are holes drilled to hold seismic charges. USGS geospatial data show about 99,850 of them, up to 175 feet deep, were drilled across the reserve. More than 12,000 line miles of seismic data were collected in the reserve from 1974 to 1982. The catalog holds transcribed drill-card data and driller notes, along with photographs of the geologic samples.

That work came during a second phase of exploration in the reserve, which began under the U.S. Navy in the 1970s and was later coordinated by the USGS. A 1976 federal law moved the reserve from the Navy to the Interior Department. The reserve covers about 23 million acres, from the north slope of the Brooks Range to the Arctic Coast.

The catalog covers 13 quadrangles, or map areas, including Barrow, Wainwright, Umiat, Teshekpuk and Howard Pass. Its records describe permafrost, gravel, sand, shale and coal.

N.E. Crawford, Simone Montayne, T.B. Stokes and T.D. Hubbard wrote the seven-page accompanying report. It replaces a 2025 version and is tied to the state's Arctic Strategic Transportation and Resources project.

The 2.1-megabyte database is free to download, and hard copies can be ordered from the division.