A5065260177- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Geophysical and Geoelectrical Methods
- Ionosphere and magnetosphere dynamics
- Seismic Waves and Analysis
- Geophysics and Gravity Measurements
- earthquake and tectonic studies
- Geology and Paleoclimatology Research
- Seismology and Earthquake Studies
- Innovations in Medical Education
- Astro and Planetary Science
- Geological and Geochemical Analysis
- Inertial Sensor and Navigation
- Clinical Reasoning and Diagnostic Skills
- Geochemistry and Geologic Mapping
- Radiology practices and education
- Lightning and Electromagnetic Phenomena
- Meteorological Phenomena and Simulations
- Planetary Science and Exploration
- COVID-19 Pandemic Impacts
- Geophysical Methods and Applications
- Health and Medical Research Impacts
- Power Quality and Harmonics
- Health Sciences Research and Education
United States Geological Survey
2015-2024
Geologic Hazards Science Center
2018-2024
Ideas Engineering & Technology (United States)
2023
Georgetown University
2012-2020
Brown University
2018-2020
George Washington University
2019-2020
Harbor–UCLA Medical Center
2019-2020
Virginia Commonwealth University
2020
UCLA Medical Center
2020
AARP
2017-2020
Abstract This paper is the primary deliverable of very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Group. The provides broad overview current status and future challenges pertaining to science, engineering, applications GIC problem. Science understood here as basic space Earth sciences research that allows improved understanding physics‐based modeling physical processes behind GIC. Engineering, in turn, “impact” aspect Applications are...
Since its formation in the late 1980s, International Real‐Time Magnetic Observatory Network (INTERMAGNET), a voluntary consortium of geophysical institutes from around world, has promoted operation magnetic observatories according to modern standards [e.g., Rasson , 2007]. INTERMAGNET have cooperatively developed infrastructure for data exchange and management as well methods processing checking. also helped expand global geomagnetic monitoring capacity, most notably by assisting observatory...
Abstract Extreme space weather events are low‐frequency, high‐risk phenomena. Estimating their rates of occurrence, as well associated uncertainties, is difficult. In this study, we derive statistical estimates and uncertainties for the occurrence rate an extreme geomagnetic storm on scale Carrington event (or worse) occurring within next decade. We model distribution either a power law or lognormal use (1) Kolmogorov‐Smirnov statistic to estimate goodness fit, (2) bootstrapping quantify...
Abstract Empirical impedance tensors obtained from EarthScope magnetotelluric data at sites distributed across the midwestern United States are used to examine feasibility of mapping magnetic storm induction geoelectric fields. With these tensors, in order isolate effects Earth conductivity structure, we perform a synthetic analysis—calculating field variations induced by geomagnetic that is geographically uniform but varying sinusoidally with chosen set oscillation frequencies...
With data provided by magnetic observatories, geophysicists can gain insights into our planet’s interior and nearby space environment without even leaving the ground.
Abstract An examination is made of the hypothesis that statistics magnetic storm maximum intensities are realization a lognormal stochastic process. Weighted least squares and likelihood methods used to fit functions − D s t time maxima for years 1957–2012; bootstrap analysis established confidence limits on forecasts. Both provide fits reasonably consistent with data; both also superior those can be power‐law function. In general, method provides forecasts having tighter intervals than...
Abstract Analysis is made of low‐latitude ground‐based magnetometer data recording the magnetic superstorm May 1921. By inference, storm was driven by a series interplanetary coronal mass ejections, one which produced maximum pressure on magnetopause ~64.5 nPa, sufficient to compress subsolar radius ~5.3 Earth radii. Over course storm, geomagnetic disturbance exhibited extreme local time (longitude) asymmetry that can be attributed substorm extending low latitudes. The attained an estimated...
Abstract Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to operation of electric power grids and related infrastructure. The ability estimate these geoelectric in close real time provide local predictions would better equip industry mitigate negative impacts on their operations. Here we report progress toward this goal: development robust algorithms that convolve storm series with frequency domain impedance for realistic three‐dimensional (3‐D) Earth,...
In its 18-year lifetime, the United States Magnetotelluric Array (USMTArray) has acquired more than 1,700 long-period magnetotelluric (MT) stations covering entirety of contiguous States. Funding from multiple federal agencies sustained this effort to completion in 2024. Important components project included active guidance and participation scientific community, open timely availability all data, application consistent instrumentation robust data processing. Together with parallel...
Abstract. A revised version of the storm-time disturbance index Dst is calculated using hourly-mean magnetic-observatory data from four standard observatories and collected over years 1958–2007. The calculation algorithm a revision that established by Sugiura et al., which now used Kyoto World Data Center for routine production Dst. most important new development removal solar-quiet variation. This done through time frequency-domain band-stop filtering – selectively removing specific Fourier...
Statistical analysis is made of rare, extreme geophysical events recorded in historical data – counting the number k with sizes that exceed chosen thresholds during specific durations time τ. Under transformations stabilize and model‐parameter variances, most likely Poisson‐event occurrence rate, / τ , applies for frequentist inference and, also, Bayesian a Jeffreys prior ensures posterior invariance under changes variables. Frequentist confidence intervals (Jeffreys) credibility are...
Abstract We examine the claim that solar‐terrestrial interaction, as measured by sunspots, solar wind velocity, and geomagnetic activity, might play a role in triggering earthquakes. count number of earthquakes having magnitudes exceed chosen thresholds calendar years, months, days, we order these counts corresponding rank annual, monthly, daily averages variables. measure statistical significance difference between earthquake‐number distributions below above median χ 2 Student's t tests....
Abstract Maps of extreme value geoelectric field amplitude are constructed for the Mid‐Atlantic United States, a region with high population density and critically important power grid infrastructure. Geoelectric time series years 1983–2014 estimated by convolving Earth surface impedances obtained from 61 magnetotelluric survey sites across historical 1 min (2 Nyquist) measurements geomagnetic variation nearby observatory. Statistical models fitted to maximum amplitudes occurring during...
Abstract Commonly, one‐dimensional (1‐D) Earth impedances have been used to calculate the voltages induced across electric power transmission lines during geomagnetic storms under assumption that much of three‐dimensional structure gets smoothed when integrating along lines. We voltage in mid‐Atlantic region with both regional 1‐D and 64 empirical 3‐D obtained from a magnetotelluric survey. The use produces substantially more spatial variance calculated voltages, being than an order...
Using 1‐second magnetometer data recorded 67 km from the epicenter of 1993 M w 7.7 Guam earthquake, Hayakawa et al. (1996) and Miyahara (1999) identify anomalous precursory changes in ultra‐low frequency magnetic polarization (the ratio vertical to horizontal field components). In a check their results, we compare (GAM) with Kakioka observatory (KAK) Japan global activity index Kp . We also examine log books kept by USGS staff working on observatory. find (1) analysis problems both al., (2)...
Magnetic storms result from the dynamic interaction of solar wind with coupled magnetosphericionospheric system. Large represent a potential hazard for activities and infrastructure modern, technologically based society [Baker et al., 2008]; they can cause loss radio communications, reduce accuracy global positioning systems, damage satellite electronics affect operations, increase pipeline corrosion, induce voltage surges in electric power grids, causing blackouts. So while space weather...
Using Global Positioning System (GPS) data from sites near the 16 Oct. 1999 Hector Mine, California earthquake, Pulinets et al. (2007) identified anomalous changes in ionospheric total electron content (TEC) starting one week prior to earthquake. suggested that precursory phenomena of this type could be useful for predicting earthquakes. On other hand, and a separate analysis, Afraimovich (2004) concluded TEC variations epicenter were controlled by solar geomagnetic activity unrelated In an...
Abstract In support of a multiagency project for assessing induction hazards, we present maps extreme‐value geoelectric amplitudes over about half the continental United States. These are constructed using parameterization induction: estimates Earth surface impedance, obtained at discrete geographic sites from magnetotelluric survey data, convolved with latitude‐dependent statistical geomagnetic activity, decades magnetic observatory data. Geoelectric estimated waveforms having 240 s...
We evaluate worldwide low-latitude auroral activity associated with the great magnetic storm of September 1909 for which a minimum Dst value −595 nT has recently been determined. From observations, we calculate that equatorward boundary oval in event was range from 31°–35° invariant latitude (assuming height 400 km) to 37°–38° (800 km). These locations compare satellite-based observations precipitating electrons down 40° March 1989 its comparable −589 nT. According Japanese records, bluish...
Abstract A once‐per‐century geoelectric hazard map is created for the U.S. high‐voltage power grid. statistical extrapolation from 31 years of magnetic field measurements made by identifying 84 geomagnetic storms with Kp and Dst indices. Data 24 observatories, 1,079 magnetotelluric survey sites, 17,258 transmission lines are utilized to perform a analysis most comprehensive data publicly available. With these data, we estimate fields at sites calculate theoretical voltages within in...
Abstract The 774 AD solar proton event (SPE) detected in cosmogenic nuclides had an inferred >1 GV (>430 MeV) fluence estimated to have been ∼30–70 times larger than that of the 1956 February 23 ground level (GLE). GLE was itself ∼2.5 at >430 MeV episode strong activity from 1989 August–October. We use soft X-ray (SXR) class X20 ± 10 for eruptive flare as a bridge source SPE. A correlation >200 fluences hard-spectra post-1975 GLEs with SXR peak fluxes their associated flares...
Abstract Past studies found that large‐amplitude geomagnetically induced current (GIC) related to magnetospheric Ultra Low Frequency (ULF) waves tend be associated with periods >120 s at magnetic latitudes >60°, comparatively (a) smaller GIC amplitudes lower and shorter wave (b) fewer reports of latitudes. ULF generally decrease decreasing latitude; thus, we examine whether these trends might due, in part, the undersampling fields commonly available measurements 60 sampling intervals....
Mostly on the basis of paleomagnetic sedimentary data, it has been suggested that maps virtual geomagnetic poles (VGPs), corresponding to directions magnetic field at each site, tend fall along American and Asian longitudes during reversals excursions. Such geometric regularity in transitional fields may indicate core mantle are dynamically coupled. However, studies lava data have thus far failed show any pattern fields. In this paper we examine a database covering excursions which occurred...
Received 12 January 2011; revised 14 February accepted 18 published 24 March 2011. [1] We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993–2008. The number substorms substorm mean duration depict an annual with maxima Winter Summer, respectively, reflecting change local ionosphere. In contradiction, amplitude, total efficiency global show a dominant variation, equinoctial alternating between Spring cycle 22 Fall 23....