A5079521299- earthquake and tectonic studies
- Seismic Waves and Analysis
- High-pressure geophysics and materials
- Seismic Imaging and Inversion Techniques
- Seismology and Earthquake Studies
- Geological and Geochemical Analysis
- Geological and Geophysical Studies Worldwide
- Earthquake Detection and Analysis
- Geophysics and Sensor Technology
- Geological Modeling and Analysis
- Geological Studies and Exploration
- Geology and Paleoclimatology Research
- Geotechnical and Geomechanical Engineering
- Landslides and related hazards
- Hydrocarbon exploration and reservoir analysis
- Geological formations and processes
- Teacher Education and Leadership Studies
- Reservoir Engineering and Simulation Methods
- Collaborative Teaching and Inclusion
- Hydraulic Fracturing and Reservoir Analysis
- Marine and environmental studies
- Geological and Geophysical Studies
- Geochemistry and Geologic Mapping
- Seismic Performance and Analysis
- Disability Education and Employment
University of Memphis
2014-2023
Virginia Commonwealth University
2023
Washington State University
2022
University of Washington
2010
University of Tennessee at Knoxville
2009
The University of Western Australia
2001
Pacific Island Ecosystems Research Center
2000
United States Geological Survey
2000
University of North Carolina at Chapel Hill
1984-1998
Macquarie University
1979
About 1500 readings of teleseismic P-time residuals obtained from the US Geological Survey seismograph network in central California have been used to obtain a three-dimensional image seismic velocity anomalies for this area by method Aki, Christoffersson & Husebye We found that is less suitable than LASA and NORSAR arrays kind studies because its greater proportion peripheral blocks which resolution very poor stochastic inverse solution random error effect severe generalized solution....
Abstract Detailed, upper mantle P and S wave velocity ( V p s ) models are developed for the northern Mississippi Embayment (ME), a major physiographic feature in Central United States (U.S.) location of active New Madrid Seismic Zone (NMSZ). This study incorporates local earthquake teleseismic data from Network, Earthscope Transportable Array, FlexArray Northern Lithospheric Experiment stations. The solutions contain anomalies with similar magnitudes spatial distributions. High velocities...
Abstract The cause of intraplate seismic zones persists as an important scientific and societal question. Most earthquakes are concentrated in specific along or adjacent to large‐scale basement structures (e.g., rifts sutures at ancient plate boundaries) within continental crust. major limited segments not distributed the lengths structures. We present a new hypothesis that restricted places where crustal deformation (CCD) is overprinted on Examples CCD affects stability parts response...
Ten years of monitoring microearthquakes with a regional seismic network has revealed the presence well-defined, linear zone activity in eastern Tennessee. This produced second highest release strain energy United States east Rocky Mountains during last decade, when normalized by crustal area. The data indicate that seismicity regional, intraplate stresses is now concentrating near boundary between relatively strong and weak basement blocks.
Abstract Three‐dimensional P and S wave velocity ( V ) models high‐resolution earthquake relocations are determined for the New Madrid Seismic Zone using double‐difference local tomography. The data set consists of arrival times differential recorded by Cooperative Network (CNMSN) from 2000 to 2007 1989–1992 Portable Array Data Acquisition deployment. Waveform cross correlation–derived CNMSN also incorporated. solutions compatible with previous centered on active arms seismicity cover a...
Abstract The location and orientation of possible seismogenic basement faults in the eastern Tennessee seismic zone is studied using information provided by focal mechanisms earthquake epicenters. Twenty-six well-constrained mechanism solutions are derived a new velocity model relocated hypocenters. results suggest that strike-slip motion on steeply dipping planes dominant mode faulting throughout 300-km-long zone. Most can be grouped into two populations. larger population characterized...
Detailed P wave velocity (V p ) and S s models V /V ratios were determined for a major portion of the New Madrid seismic zone using arrival times recorded by network Portable Array Numerical Data Acquisition (PANDA) stations. We performed simultaneous inversion velocities hypocentral locations, yielding most detailed tomographic image upper crust to date. Low high anomalies resulted in low that correspond arms seismicity north intersection Cottonwood Grove–Blytheville Arch (CG‐BA) fault with...
Abstract We present three‐dimensional P and S wave velocity models for the active eastern Tennessee seismic zone (ETSZ) using arrival time data from more than 1000 local earthquakes. A nonlinear tomography method is used that involves sequential inversion model hypocenter parameters. image several anomalies persist through most of volume. Some support presence known features such as an ancient rift in northern Tennessee. Other reveal basement can be correlated with regional gravity magnetic...
Research Article| January 01, 2016 Grenville basement structure associated with the Eastern Tennessee seismic zone, southeastern USA Christine A. Powell; Powell 1Center for Earthquake and Information, The University of Memphis, 38152, Search other works by this author on: GSW Google Scholar William Thomas 2Geological Survey Alabama, Tuscaloosa, Alabama 35486, Author Article Information Publisher: Geological Society America Received: 17 Aug 2015 Revision 23 Oct Accepted: 29 First Online: 09...
Other| March 01, 2010 High-resolution Earthquake Relocation in the New Madrid Seismic Zone Meredith Dunn; Dunn Center for Research and Information University of Memphis 3890 Central Avenue Memphis, Tennessee 38152 U.S.A. capowell@memphis.edu (C. A. P.) *Now at Hess Corporation, Houston, Texas. Search other works by this author on: GSW Google Scholar Steve Horton; Horton Heather DeShon; DeShon Christine Powell Seismological Letters (2010) 81 (2): 406–413....
We develop a tomographic inversion method that uses teleseismic P wave polarization data to obtain velocity structure. Polarization has some intrinsic advantages over travel time inversion: It is not influenced by source location and origin errors; it sensitive deep mantle structure can be used iteratively improve the result. more near‐station gradient complementary in this sense. The applied California Institute of Technology‐U.S. Geological Servey southern array data. result generally...
Previous studies have indicated that the crust and upper mantle beneath Caltech‐USGS large seismic array, SCARLET, is extremely heterogeneous. In this study, Chernov theory has been applied to characterize as a random medium. The data consist of travel‐time residuals from plane waves fit teleseismic arrival times. Amplitude were not available. Consistent results obtained for events arriving NW, SW SE indicate correlation distance inhomogeneities 25 km maximum velocity perturbation 3.26%....
We have estimated P-wave andS-wave anelastic attenuation coefficients for the thick, unconsolidated sediments of Mississippi embayment, central United States, using spectral distance decay explosion P and Rayleigh waves. The sediment-trapped wave, Psed, is observed to ranges 80 km at 10 Hz, 1-Hz waves are out 130 from a 5000-lb borehole in northern part embayment. 4 Hz seen distances 3 smaller 50-lb explosion. Analysis group velocity amplitude- both yields an average Qs 100 Qp 200 embay-...
Other| May 01, 2010 The Enola, Arkansas, Intraplate Swarm of 2001 Ivan Rabak; Rabak University Washington Department Earth and Space Sciences Box 351310 Seattle, 98195-1310 U.S.A. bodin@uw.edu (P. B.) 1Center for Earthquake Research Information (CERI), Memphis, Tennessee 2Now at Geodesy Laboratory PANGA Data Analysis Facility, Geological Sciences, Central Washington, University, Ellensburg, USA Search other works by this author on: GSW Google Scholar Charles Langston; Langston Paul Bodin;...
The central enigma of the mid‐continent region in United States known as New Madrid seismic zone (NMSZ; Figure 1) involves mechanisms that give rise to recurrent great earthquakes far from plate boundaries. Given lack significant topographic relief is hallmark tectonic activity most actively deforming regions, us feel a need “pinch ourselves see if we're dreaming” when confronted with evidence that, at some probability levels, earthquake hazard throughout NMSZ comparable estimated for San...
Two strong-motion arrays were deployed for the October 2002 Embay- ment Seismic Excitation Experiment to study spatial variation of strong ground motions in deep, unconsolidated sediments Mississippi embayment because there are no comparable data from natural earthquakes area. Each linear array consisted eight three-component K2 accelerographs spaced 15 m apart situated 1.2 and 2.5 km 2268-kg 1134-kg borehole explosion sources, respectively. The show distinct body-wave surface-wave arrivals...
The California Institute of Technology (CIT) operates a dense network short‐period vertical seismometers which we have used as large seismic array to measure the azimuth approach ζ and ray parameter dT / d Δ teleseismic P waves. Analysis over 145 globally distributed events indicates that values measured by are in close agreement with predicted U.S. Geological Survey event locations. Most anomalies (measured minus values) do not exceed 1°. small magnitude suggests can be construct radial...
A three‐dimensional P wave velocity model for the New Madrid seismic zone (NMSZ) has been developed using a nonlinear travel time tomography method. The inversion involved 709 earthquakes recorded by digital, three‐component Portable Array Numerical Data Acquisition stations deployed in NMSZ over period 1989 through 1992. Analysis of ray coverage and synthetic data set showed that high resolution to depth 11 km. Low‐velocity anomalies correlate with prominent northwest northeast trending...
A three‐dimensional S wave velocity model for the New Madrid Seismic Zone (NMSZ) has been developed using nonlinear travel time tomography. The inversion utilized 5544 arrival times from 720 earthquakes recorded by digital, three‐component stations deployed in NMSZ over period 1989 through 1992. We imaged anomalies ranging −5% to +8% relative starting one‐dimensional model. Lowest velocities are found south of Ridgley, Tennessee, an area characterized a high earthquake swarm rate and...
Abstract Teleseismic transfer function analysis is used to investigate crust and upper mantle velocity structure in the vicinity of active eastern Tennessee seismic zone (ETSZ). The ETSZ associated with New York‐Alabama (NY‐AL) magnetic lineament, a prominent aeromagnetic anomaly indicative Grenville‐age, basement structure. Radial component, P wave functions for 10 short‐period stations operated by Center Earthquake Research Information are inverted Velocity profiles also determined three...
Abstract Detailed P wave velocity and anisotropy structure of the uppermost mantle below central United States is presented based on a tomographic inversion Pn traveltimes for earthquakes in range 2 to 14°. Dense raypath coverage throughout northern Mississippi Embayment obtained using Northern Lithosphere Experiment U.S. Transportable Array data sets. A detailed analysis trade‐off between variations demonstrates that both are well resolved over most study area. Anomalously fast velocities...
Abstract Shear wave splitting associated with the Mississippi Embayment (ME) is determined using teleseismic SKS phases recorded by Northern Lithosphere Experiment (NELE), USArray Transportable Array (TA), and New Madrid seismic network for period 2005–2016. Our data set consists of ~5900 individual measurements from 257 earthquakes at 151 stations within outside ME. Stations ME exhibit significant shear splitting, average delay times between ~ 0.4 s ~1.8 s. To northeast east ME, nearly all...
A joint hypocenter‐velocity inversion for the eastern Tennessee seismic zone (ETSZ) has resolved velocity features in basement rock below detached Appalachian thrust sheets. P and S wave arrival times from 492 earthquakes have been inverted one‐(1‐D) three‐dimensional (3‐D) models to midcrustal depths. The 3‐D solutions are computed independly very similar. In relation 1‐D model, anomalies range −8% +16% first layer (upper 5 km) between ±7% deeper layers. Prominent parallel consistent layer....