Benjamin S Murphy, PhD (Former Employee)
Science and Products
North American electricity power-grid and communication-network anomalies for several magnetic storms
Anomaly lists are presented documenting operational interference to electricity power grids and communication networks in the United States and Canada during magnetic storms. Four of the anomaly lists apply for magnetic storms that occurred in March 1989, August 1972, March 1940, and for various storms 1946-2000; yet another list consists of statistical values summarizing geomagnetically...
Geoelectric evidence for a wide spatial footprint of active extension in central Colorado
Three-dimensional magnetotelluric (MT) imaging in central Colorado reveals a set of north-striking high-conductivity tracks at lower-crustal (50–20 km) depths, with conductive finger-like structures rising off these tracks into the middle crust (20–5 km depth). We interpret these features to represent saline aqueous fluids and partial melt that are products of active extensional...
Authors
Benjamin S. Murphy, Jonathan Caine, Paul A. Bedrosian, Kayla (Jade) J Crosbie
Modeling geomagnetic induction in submarine cables
Submarine cables have become a vital component of modern infrastructure, but past submarine cable natural hazard studies have mostly focused on potential cable damage from landslides and tsunamis. A handful of studies examine the possibility of space weather effects in submarine cables. The main purpose of this study is to develop a computational model, using Python, of geomagnetic...
Authors
Shibaji Chakraborty, David H. Boteler, Xueling Shi, Benjamin Scott Murphy, Michael D. Hartinger, Xuan Wang, Greg M. Lucas, Joseph B. H. Baker
Geoelectric constraints on the Precambrian assembly and architecture of southern Laurentia
Using images from an updated and expanded three-dimensional electrical conductivity synthesis model for the contiguous United States (CONUS), we highlight the key continent-scale geoelectric structures that are associated with the Precambrian assembly of southern Laurentia. Conductivity anomalies are associated with the Trans-Hudson orogen, the Penokean suture, the ca. 1.8–1.7 Ga...
Authors
Benjamin Scott Murphy, Paul A. Bedrosian, Anna Kelbert
Graphite as an electrically conductive indicator of ancient crustal-scale fluid flow within mineral systems
Magnetotelluric (MT) imaging results from mineral provinces in Australia and in the United States show an apparent spatial relationship between crustal-scale electrical conductivity anomalies and major magmatic-hydrothermal iron oxide-apatite/iron oxide-copper-gold (IOA-IOCG) deposits. Although these observations have driven substantial interest in the use of MT data to image ancient...
Authors
Benjamin Scott Murphy, Jan Marten Huizenga, Paul A. Bedrosian
Mapping a magnetic superstorm: March 1989 geoelectric hazards and impacts on United States power systems
A study is made of the relationships between geomagnetic and geoelectric field variation, Earth-surface impedance, and operational interference (anomalies) experienced on electric-power systems across the contiguous United States during the March 13-14, 1989 magnetic storm. For this, a 1-minute-resolution sequence of geomagnetic field maps is constructed from magnetometer time series...
Authors
Jeffrey J. Love, Greg M. Lucas, E. Joshua Rigler, Benjamin Scott Murphy, Anna Kelbert, Paul A. Bedrosian
Characteristics and sources of intense geoelectric fields in the United States: Comparative analysis of multiple geomagnetic storms
Intense geoelectric fields during geomagnetic storms drive geomagnetically induced currents in power grids and other infrastructure, yet there are limited direct measurements of these storm-time geoelectric fields. Moreover, most previous studies examining storm-time geoelectric fields focused on single events or small geographic regions, making it difficult to determine the typical...
Authors
Xueling Shi, Michael D Hartinger, Joseph B. H. Baker, Benjamin Scott Murphy, Paul A. Bedrosian, Anna Kelbert, Erin (Josh) Rigler
Down to Earth with nuclear electromagnetic pulse: Realistic surface impedance affects mapping of the E3 geoelectric hazard
An analysis is made of Earth-surface geoelectric fields and voltages on electricity transmission power-grids induced by a late-phase E3 nuclear electromagnetic pulse (EMP). A hypothetical scenario is considered of an explosion of several hundred kilotons set several hundred kilometers above the eastern-midcontinental United States. Ground-level E3 geoelectric fields are estimated by...
Authors
Jeffrey J. Love, Greg M. Lucas, Benjamin Scott Murphy, Paul A. Bedrosian, E. Joshua Rigler, Anna Kelbert
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 spatial heterogeneity of the surface...
Authors
Benjamin Scott Murphy, Greg M. Lucas, Jeffrey J. Love, Anna Kelbert, Paul A. Bedrosian, E. Joshua Rigler
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 the crust and mantle yields valuable information...
Authors
Samer Naif, Kate Selway, Benjamin Scott Murphy, Gary D. Egbert, Anne Pommier
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 waves with EGEO. Using recently available...
Authors
M. D. Hartinger, X. R. Shih, G. Lucas, Benjamin Scott Murphy, Anna Kelbert, J.B.H. Baker, E. Joshua Rigler, Paul A. Bedrosian
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 support of national and agency priorities...
Authors
Jeffrey J. Love, Anna Kelbert, Benjamin S. Murphy, E. Joshua Rigler, Kristen A. Lewis
The first 3D conductivity model of the contiguous US: Reflections on geologic structure and application to induction hazards
Estimation of ground level geoelectric fields has been identified by the National Space Weather Action Plan as a key component of assessment and mitigation of space weather impacts on critical infrastructure. Estimates of spatially and temporally variable electric fields are used to generate statistically based hazard maps and show promise toward monitoring and responding to geomagnetic...
Authors
Anna Kelbert, Paul A. Bedrosian, Benjamin S. Murphy
Science and Products
North American electricity power-grid and communication-network anomalies for several magnetic storms
Anomaly lists are presented documenting operational interference to electricity power grids and communication networks in the United States and Canada during magnetic storms. Four of the anomaly lists apply for magnetic storms that occurred in March 1989, August 1972, March 1940, and for various storms 1946-2000; yet another list consists of statistical values summarizing geomagnetically...
Geoelectric evidence for a wide spatial footprint of active extension in central Colorado
Three-dimensional magnetotelluric (MT) imaging in central Colorado reveals a set of north-striking high-conductivity tracks at lower-crustal (50–20 km) depths, with conductive finger-like structures rising off these tracks into the middle crust (20–5 km depth). We interpret these features to represent saline aqueous fluids and partial melt that are products of active extensional...
Authors
Benjamin S. Murphy, Jonathan Caine, Paul A. Bedrosian, Kayla (Jade) J Crosbie
Modeling geomagnetic induction in submarine cables
Submarine cables have become a vital component of modern infrastructure, but past submarine cable natural hazard studies have mostly focused on potential cable damage from landslides and tsunamis. A handful of studies examine the possibility of space weather effects in submarine cables. The main purpose of this study is to develop a computational model, using Python, of geomagnetic...
Authors
Shibaji Chakraborty, David H. Boteler, Xueling Shi, Benjamin Scott Murphy, Michael D. Hartinger, Xuan Wang, Greg M. Lucas, Joseph B. H. Baker
Geoelectric constraints on the Precambrian assembly and architecture of southern Laurentia
Using images from an updated and expanded three-dimensional electrical conductivity synthesis model for the contiguous United States (CONUS), we highlight the key continent-scale geoelectric structures that are associated with the Precambrian assembly of southern Laurentia. Conductivity anomalies are associated with the Trans-Hudson orogen, the Penokean suture, the ca. 1.8–1.7 Ga...
Authors
Benjamin Scott Murphy, Paul A. Bedrosian, Anna Kelbert
Graphite as an electrically conductive indicator of ancient crustal-scale fluid flow within mineral systems
Magnetotelluric (MT) imaging results from mineral provinces in Australia and in the United States show an apparent spatial relationship between crustal-scale electrical conductivity anomalies and major magmatic-hydrothermal iron oxide-apatite/iron oxide-copper-gold (IOA-IOCG) deposits. Although these observations have driven substantial interest in the use of MT data to image ancient...
Authors
Benjamin Scott Murphy, Jan Marten Huizenga, Paul A. Bedrosian
Mapping a magnetic superstorm: March 1989 geoelectric hazards and impacts on United States power systems
A study is made of the relationships between geomagnetic and geoelectric field variation, Earth-surface impedance, and operational interference (anomalies) experienced on electric-power systems across the contiguous United States during the March 13-14, 1989 magnetic storm. For this, a 1-minute-resolution sequence of geomagnetic field maps is constructed from magnetometer time series...
Authors
Jeffrey J. Love, Greg M. Lucas, E. Joshua Rigler, Benjamin Scott Murphy, Anna Kelbert, Paul A. Bedrosian
Characteristics and sources of intense geoelectric fields in the United States: Comparative analysis of multiple geomagnetic storms
Intense geoelectric fields during geomagnetic storms drive geomagnetically induced currents in power grids and other infrastructure, yet there are limited direct measurements of these storm-time geoelectric fields. Moreover, most previous studies examining storm-time geoelectric fields focused on single events or small geographic regions, making it difficult to determine the typical...
Authors
Xueling Shi, Michael D Hartinger, Joseph B. H. Baker, Benjamin Scott Murphy, Paul A. Bedrosian, Anna Kelbert, Erin (Josh) Rigler
Down to Earth with nuclear electromagnetic pulse: Realistic surface impedance affects mapping of the E3 geoelectric hazard
An analysis is made of Earth-surface geoelectric fields and voltages on electricity transmission power-grids induced by a late-phase E3 nuclear electromagnetic pulse (EMP). A hypothetical scenario is considered of an explosion of several hundred kilotons set several hundred kilometers above the eastern-midcontinental United States. Ground-level E3 geoelectric fields are estimated by...
Authors
Jeffrey J. Love, Greg M. Lucas, Benjamin Scott Murphy, Paul A. Bedrosian, E. Joshua Rigler, Anna Kelbert
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 spatial heterogeneity of the surface...
Authors
Benjamin Scott Murphy, Greg M. Lucas, Jeffrey J. Love, Anna Kelbert, Paul A. Bedrosian, E. Joshua Rigler
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 the crust and mantle yields valuable information...
Authors
Samer Naif, Kate Selway, Benjamin Scott Murphy, Gary D. Egbert, Anne Pommier
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 waves with EGEO. Using recently available...
Authors
M. D. Hartinger, X. R. Shih, G. Lucas, Benjamin Scott Murphy, Anna Kelbert, J.B.H. Baker, E. Joshua Rigler, Paul A. Bedrosian
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 support of national and agency priorities...
Authors
Jeffrey J. Love, Anna Kelbert, Benjamin S. Murphy, E. Joshua Rigler, Kristen A. Lewis
The first 3D conductivity model of the contiguous US: Reflections on geologic structure and application to induction hazards
Estimation of ground level geoelectric fields has been identified by the National Space Weather Action Plan as a key component of assessment and mitigation of space weather impacts on critical infrastructure. Estimates of spatially and temporally variable electric fields are used to generate statistically based hazard maps and show promise toward monitoring and responding to geomagnetic...
Authors
Anna Kelbert, Paul A. Bedrosian, Benjamin S. Murphy