Magnetotelluric Measurements at Geomagnetic Observatories

Jake Morris, Greg Lucas


USGS/Geologic Hazards Science Center, Denver,



Space weather interacts with the geomagnetic field to induce geoelectric fields within the Earth. These geoelectric fields have the potential to adversely affect electric power grids. The U.S. Geological Survey (USGS) is currently deploying magnetotelluric (MT) systems at ground-based USGS geomagnetic observatories, which simultaneously measure both the geoelectric and magnetic fields. The geoelectric field varies as a result of the regional geology and the magnitude of the magnetic field. MT measurements will provide geoelectric field data in a broad region around each magnetic observatory. Data from these measurements will be used to calculate realistic regional geoelectric fields using three-dimensional (3D) impedance functions to produce potential hazard maps useful for assessing risk to electric power grids.