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Airborne magnetic and radiometric survey, Charleston, South Carolina and surrounds, 2019

September 21, 2021

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over Charleston, South Carolina and the surrounding region. These data were collected to better understand earthquake hazards in the Charleston seismic zone by imaging structural features in the crystalline basement and to image heavy mineral sands containing titanium, zirconium, and rare earth elements using radiometric data (gamma spectrometry), which is sensitive to thorium in monazite. This survey represents a collaborative effort by the U.S. Geological Survey (USGS) Earthquake Hazards Program, Mineral Resources Program, National Cooperative Mapping Program, and Earth Mapping Resource Initiative (Earth MRI) effort. Data for this survey were collected by Terraquest, Ltd. under contract with the USGS using a fixed wing aircraft with magnetometers mounted in the tail stinger and each wing tip pod and a fully calibrated gamma ray spectrometer from May to July of 2019. The survey covers a 134-kilometer x 90-kilometer rectangular area parallel to the Atlantic Ocean shoreline along the long axis. Data were collected along northwest-southeast flight lines spaced 400 meters (m) apart with northeast-southwest tie lines flown every 4000 m. A mean terrain clearance of 127 m was maintained. Most of the survey data were collected at lower flying heights, except near and over the City of Charleston higher clearance was maintained due to safety considerations. A total of 32,447-line kilometers (km) of data were collected. Files that are available in this publication include flight line data for the magnetic survey in an ascii .csv file, flight line data for the radiometric survey in an ascii .csv file, geoTIFF images of the total magnetic intensity and radiometric total count, potassium, thorium, and uranium values, and a report describing the survey parameters, field operations, quality control and data reduction procedures. A zip file containing the contractor's deliverable products is also included. Binary files in this package are readable using the free software "Geosoft Viewer" or commercial software "Oasis Montaj."