Geomagnetism Program
Publications
Geomagnetism publications.
Magnetotelluric sampling and geoelectric hazard estimation: Are national-scale surveys sufficient?
At present, the most reliable information for inferring storm-time ground electric fields along electrical transmission lines comes from coarsely sampled, national-scale magnetotelluric (MT) data sets, such as that provided by the EarthScope USArray program. An underlying assumption in the use of such data is that they adequately sample the...
Murphy, Benjamin Scott; Lucas, Greg M.; Love, Jeffrey J.; Kelbert, Anna; Bedrosian, Paul A.; Rigler, E. Joshua
Geomagnetic monitoring in the mid-Atlantic United States
Near historic battlegrounds of the American Civil War, southeast of Fredericksburg, Virginia, on a secluded grassy glade surrounded by forest, a specially designed observatory records the Earth’s changing magnetic field. This facility, the Fredericksburg Magnetic Observatory, is 1 of 14 observatories the U.S. Geological Survey Geomagnetism Program...
Love, Jeffrey J.; Lewis, Kristen A. Electrical conductivity of the lithosphere-asthenosphere system
Electromagnetic geophysical methods image the electrical conductivity of the subsurface. Electrical conductivity is an intrinsic material property that is sensitive to temperature, composition, porosity, volatile and/or melt content, and other physical properties relevant to the solid Earth. Therefore, imaging the electrical structure of...
Naif, Samer; Selway, Kate; Murphy, Benjamin Scott; Egbert, Gary D.; Pommier, Anne Simultaneous observations of geoelectric and geomagnetic fields produced by magnetospheric ULF waves
Geomagnetic perturbations (BGEO) related to magnetospheric ultralow frequency (ULF) waves induce electric fields within the conductive Earth—geoelectric fields (EGEO)—that in turn drive geomagnetically induced currents. Though numerous past studies have examined ULF wave BGEO from a space weather perspective, few studies have linked ULF...
Hartinger, M. D.; Shih, X. R.; Lucas, G.; Murphy, Benjamin Scott; Kelbert, Anna; Baker, J.B.H.; Rigler, E. Joshua; Bedrosian, Paul A.
Geomagnetism Program research plan, 2020–2024
The Geomagnetism Program of the U.S. Geological Survey (USGS) monitors geomagnetic field variation through operation of a network of observatories across the United States and its territories, and it pursues scientific research needed to estimate and assess geomagnetic and geoelectric hazards. Over the next five years (2020–2024 inclusive) and in...
Love, Jeffrey J.; Kelbert, Anna; Murphy, Benjamin S.; Rigler, E. Joshua; Lewis, Kristen A.
Adjusted geomagnetic data—Theoretical basis and validation
Adjusted geomagnetic data are magnetometer measurements with provisional correction factors applied such that vector quantities are oriented in a local Cartesian frame in which the X axis points north, the Y axis points east, and the Z axis points down. These correction factors are determined from so-called absolute measurements, which are “ground...
Rigler, E. Joshua; Claycomb, Abram E. Recording the aurora borealis (northern lights) at seismometers across Alaska
We examine three continuously recording data sets related to the aurora: all‐sky camera images, three‐component magnetometer data, and vertical‐component, broadband seismic data as part of the EarthScope project (2014 to present). Across Alaska there are six all‐sky cameras, 13 magnetometers, and >200">>200>200 ...
Tape, C.; Ringler, Adam T.; Hampton, D.L. Magnetic field variations in Alaska: Recording space weather events on seismic stations in Alaska
Seismometers are highly sensitive instruments to not only ground motion but also many other nonseismic noise sources (e.g., temperature, pressure, and magnetic field variations). We show that the Alaska component of the Transportable Array is particularly susceptible to recording magnetic storms and other space weather events because the sensors...
Ringler, Adam T.; Anthony, Robert E.; Wilson, David C.; Claycomb, Abram E.; Spritzer, John Intensity and impact of the New York Railroad superstorm of May 1921
Analysis is made of low‐latitude ground‐based magnetometer data recording the magnetic superstorm of May 1921. By inference, the storm was driven by a series of interplanetary coronal mass ejections, one of which produced a maximum pressure on the magnetopause of ~64.5 nPa, sufficient to compress the subsolar magnetopause radius to ~5.3 Earth...
Love, Jeffrey J.; Hayakawa, Hisashi; Cliver, Edward W. Data sharing in magnetotellurics
Here, we introduce the first openly available comprehensive database of magnetotelluric (MT) and related electromagnetic data that we developed and matured over the past decade, explain how to access the data, and describe the challenges that had to be overcome to make MT data sharing possible. The database is a helpful tool for MT scientists, and...
Kelbert, Anna; Erofeeva, Svetlana; Trabant, Chad; Karstens, Rich; Van Fossen, Mickey C. The extreme space weather event in September 1909
We evaluate worldwide low-latitude auroral activity associated with the great magnetic storm of September 1909 for which a minimum Dst value of −595 nT has recently been determined. From auroral observations, we calculate that the equatorward boundary of the auroral oval in the 1909 event was in the range from 31°–35° invariant latitude (...
Hayakawa, Hisashi; Ebihara, Yusuke; Cliver, Edward W.; Hattori, Kentaro; Toriumi, Shin; Love, Jeffrey J.; Umemura, Norio; Namekata, Kosuke; Sakaue, Takahito; Takahashi, Takuya; Shibata, Kazunari Extreme‐value geoelectric amplitude and polarization across the northeast United States
Maps are presented of extreme‐value geoelectric field amplitude and horizontal polarization for the Northeast United States. These maps are derived from geoelectric time series calculated for sites across the Northeast by frequency‐domain multiplication (time‐domain convolution) of 172 magnetotelluric impedance tensors, acquired during a survey,...
Love, Jeffrey J.; Lucas, Greg M.; Bedrosian, Paul A.; Kelbert, Anna