| Many Task Computing for Real-Time Uncertainty Prediction and Data Assimilation in the Ocean |
Jan 2010 |
15 pages |
| Authors:
Constantinos Evangelinos; Pierre F Lermusiaux; Jinshan Xu; Haley; Patrick J Jr; Chris N Hill; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
 | Error Subspace Statistical Estimation (ESSE), the uncertainty prediction and data assimilation methodology employed for real-time ocean forecasts, is based on a characterization and prediction of the largest uncertainties. This is carried out by evolving an error subspace of variable size. We use an ensemble of stochastic model simulations, initialized based on an estimate of the dominant initial uncertainties, to predict the error subspace of the model fields. The dominant error ... |
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| P and S Wave Velocity Structure of the Crust and Upper Mantle Under China and Surrounding Areas From Body and Surface Wave Tomography |
31-Mar-2008 |
110 pages |
| Authors:
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We have used a combination of travel-time and surface wave tomography to obtain compressional and shear wave velocity distributions in the crust and upper mantle under China and surrounding areas. We first determined 3-D P- and S-wave velocity structures for the crust and uppermost mantle using local and regional arrival time data. Travel-time data from the Annual Bulletin of Chinese Earthquakes (ABCE) and the International Seismological Centre (ISC/EHB) were used. ... |
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| Error Analysis in the Joint Event Location/Seismic Calibration Inverse Problem |
15 FEB 2008 |
38 pages |
| Authors:
William L. Rodi; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The goal of this project was to develop new mathematical and computational techniques for quantifying the errors in seismic event locations, focusing on the effects of errors in travel-time predictions from a velocity model. Our approach associates these model errors with the uncertainty in path travel-time corrections inferred from a calibration analysis. The main accomplishment of the project was a general formulation of location uncertainty in terms of the joint ... |
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| U.S. GODAE: Sustained Global Ocean State Estimation for Scientific and Practical Application |
01-Jan-2007 |
9 pages |
| Authors:
Carl Wunsch; Ichiro Fukumori; Tong Lee; Dimitris Menemenlis; Michele Rienecker; Rui Ponte; David W Behringer; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This consortium project is attempting to use all existing ocean observations, including satellite data, for the purpose of understanding and ultimately predicting, the ocean on climate time-scales. To this end it is advancing ocean state estimation as a practical, quasi-operational tool, for studying the ocean circulation and its influence on societal problems such as climate change, sea level rise, and biological impacts. Observing the ocean is difficult owing to its ... |
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| Characterization of an Explosion Source in a Complex Medium by Modeling and Wavelet Domain Inversion |
01 JUN 2006 |
53 pages |
| Authors:
M. Nafi Toksoez; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Explosions are often conducted in complexes with chambers, tunnels, and shafts used for access and instrumentation. These structures and sharp topographic features can act as strong scatterers of seismic waves and complicate the radiation patterns from explosions. In extreme cases they could affect discrimination between earthquakes and explosions. The objectives of this research are (1) to study the effects of these near-source scatterers on seismic waves radiated from explosions, and ... |
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| U. S. GODAE: Sustained Global Ocean State Estimation for Scientific and Practical Application |
Jan-2006 |
9 pages |
| Authors:
Ichiro Fukumori; Tong Lee; Dimitris Menemenlis; Michele Rienecker; Rui Ponte; David W Behringer; Carl Wunsch-Pi; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This consortium project is attempting to use all existing ocean observations, including particularly, satellite data, for the purpose of understanding and ultimately predicting, the ocean on climate timescales. To this end it is advancing ocean state estimation as a practical, quasi-operational tool, for studying the ocean circulation and its influence on societal problems such as climate change, sea level rise, and biological impacts. Observing the ocean is difficult owing to ... |
|
| U.S. GODAE: Sustained Global Ocean State Estimation for Scientific and Practical Application |
01-Jan-2004 |
9 pages |
| Authors:
Carl Wunsch; Ichiro Fukumori; Tong Lee; Dimitris Menemenlis; Michele Rienecker; Rui Ponte; David W Behringer; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The project's central technical goal is to establish, and to continually improve, a complete global ocean state estimation over the 21-plus-year period from 1985 to present, combining all available large-scale data sets with state-of-the-art general circulation models. Two particular interests define the initial foci: (1) Understanding of processes underlying the seasonal-to-interannual changes of ocean circulation and their use with the estimates and models to predict climate variability. (2) Decadal timescale ... |
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| Frequency Dependent Electrokinetic Studies of Rocks and Soils |
15 JUL 97 |
37 pages |
| Authors:
Frank D. Morgan; Philip Reppert; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| An experimental apparatus and data acquisition system was constructed to acquire frequency dependent streaming potential coupling coefficient information. The purpose of the experiments was to validate the frequency dependent theories of Pride and Packard. Frequency dependent streaming potential experiments were conducted on one glass capillary and two porous filters. Results indicated that both Packard's and Pride's models can fit the data. Experimentation continued on rocks. The new database and/or models ... |
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| Source Functions of Nuclear Explosions from Spectral Synthesis and Inversion |
20 NOV 96 |
32 pages |
| Authors:
Peter Puster; Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We apply methods for the recovery of the frequency dependent moment rate tensor, M(w), to the study of Lop Nor nuclear explosions. This approach encompasses many source parameter diagnostics that have been traditionally used to discriminate nuclear explosions from chemical explosions and earthquakes and has the potential to provide new discrimination tools. We parameterize the source as M(w) = M1(a)) + MD(a)), where M1(co) and MD((O) are isotropic and deviatoric ... |
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| Effect of 3-D Heterogeneities and Topography on Seismic Wave Propagation and the Use of Empirical Green's Functions for Source Characterization and Discrimination |
01 SEP 96 |
174 pages |
| Authors:
Michel Bouchon; Ningya Cheng; Matthias G. Imhof; Yingping Li; William L. Rodi; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We investigate two topics related to seismic nuclear monitoring and discrimination. The first is elastic wave propagation in complex earth models containing lateral variations in elastic properties or irregular interfaces. We describe an improved boundary element technique based on the conjugate gradient method and apply it to study the effects of surface topography. We also investigate the usefulness of a hybrid modeling method that combines multiple multipole and finite element ... |
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| Development of Improved Geophysical Imaging Techniques for Environmental Site Characterization |
31 DEC 95 |
183 pages |
| Authors:
Robert J. Greaves; Matthijs W. Haartsen; Daria L. Kutrubes; Jung M. Lee; David P. Lesmes; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The objective of this research was to develop geophysical techniques for environmental site characterization: (1) a multi-offset ground penetrating radar profiling technique; (2) a nonlinear seismic refraction traveltime tomography; (3) a 3-D d.c. resistivity tomography; and (4) an electroseismic method. The goals of this project were accomplished successfully and a large amount of field data were collected and modeled for characterizing actual environmental sites. Specifically, we demonstrate that performing GPR ... |
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| Discrimination of Earthquakes, Explosions, and Mining Tremors Using the Empirical Green's Function Method, |
14 AUG 1995 |
10 pages |
| Authors:
Y. Li; W. Rodi; M. N. Toksoez; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Using the empirical Green's function (EGF) method, we have estimated source time functions for earthquakes, industrial blasts, nuclear explosions, and mining tremors covering the magnitude range 0.9 - 6.6. The results show that, for events with magnitudes less than 2.5 or greater than 4.5, the time duration of the source time function can discriminate earthquakes from explosions. For large magnitude events source duration is longer for earthquakes than explosions, but ... |
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| Seismic Sources and Wave Propagation in 3-D: Radiation from Cylindrical Cavities, |
14 AUG 1995 |
10 pages |
| Authors:
R. L. Gibson Jr.; M. N. Toksoez; W. Dong; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We apply the boundary element method (BEM) to study seismic wave radiation from explosions in cylindrical cavities. This approach simulates wave propagation by replacing the boundary between the cavity wall and the surrounding formation by a distribution of fictitious sources that produce the same composite wavefield as the original model. The cavity wall is discretized into elements in the numerical implementation, and the fictitious source amplitudes on each element are ... |
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| Stochastic Modeling of Small-Scale, Anisotropic Structures in the Continental Upper Mantle, |
14 AUG 1995 |
12 pages |
| Authors:
Thomas H. Jordan; James B. Gaherty; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| New methods for the analysis of three-component seismograms have been applied to data from both continental and oceanic regions. Polarization anisotropy, manifested as the splitting of surface, guided, and shear body waves, has been observed in all regions, but no significant azimuthal anisotropy has been detected. This is expected if the local orientation of olivine crystals in the upper mantle is incoherent on the scale of the path lengths used ... |
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| Elastic and Anelastic Structure Beneath Eurasia, |
14 AUG 1995 |
9 pages |
| Authors:
Goeran Ekstroem; Adam M. Dziewonski; Wei-jia Su; Gideon P. Smith; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We are collecting and analyzing large and diverse datasets of seismic waveforms, absolute and relative body wave traveltimes, and surface wave phase velocities and amplitudes. Our primary objective is to map the variations of elastic mantle properties beneath Eurasia over horizontal lengthscales of approximately 1000-1500 km and vertical lengthscales of 50-100 km. In comparison with recent Harvard global models, such as S12WM13, we have increased the horizontal resolution by expanding ... |
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| Fine Scale Structure of the Eurasian Crust and Upper Mantle from High- Frequency Waves |
10 APR 95 |
72 pages |
| Authors:
Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The purpose of this project is to provide a better understanding the effects of small-scale inhomogeneities on high-frequency waves excited by nuclear explosions, especially at regional distances. In this project, the PI and students developed and applied methods for extracting phase Uclays and amplitudes from three-component seismograms. These methods delivered new information about impedance discontinuities and velocity gradients in the upper mantle, and large data sets were inverted for radially ... |
|
| 'Q Tomography in Oceanic Crust' |
06 FEB 95 |
8 pages |
| Authors:
Sean C. Solomon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This project was aimed at an understanding of the Q structure of oceanic crust, the lateral variability of that structure, the relationship between Q and seismic velocity within oceanic crust, and the effect of both the mean structure and the superimposed variations on the mode and efficiency of seismic energy propagation. Specifically, we applied seismic tomographic techniques to determine quantitatively the three dimensional seismic attenuation structure of the oceanic crust, ... |
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| Theoretical Study 0f Gulf Stream Instabilities, Eddy Production and Interactions |
30 JAN 95 |
17 pages |
| Authors:
Glenn Flierl; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This project examined the dynamics of nonlinear, thin, baroclinic jets, with applications to Gulf Stream meandering and eddy formation. We also studied nonlinear eddies and their interactions in order to understand the better physics of mesoscale eddies and rings. (KAR) |
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| Crustal Deformation Measurements in the Vicinity of Vandenberg Air Force Base |
20 DEC 94 |
52 pages |
| Authors:
R. W. King; B. H. Hager; T. A. Herring; A. Cooray; S. McClusky; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Recent geological and geodetic studies have suggested that the region surrounding Vandenberg Air Force Base, CA, is undergoing active crustal deformation, with important implications for both the geodetic stability and the seismogenic potential of the Western Test Range. In 1989, funding was received (AFOSR 89-0400) for the purchase of several GPS receivers. Beginning in 1990, a series of measurements was funded (AFOSR 90-0339) to determine the magnitude and spatial distribution ... |
|
| Development of Improved Geophysical Imaging Techniques for Environmental Site Characterization |
08 OCT 94 |
43 pages |
| Authors:
Robert J. Greaves; Jung M. Lee; David P. Lesmes; M. N. Toksoef; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The common midpoint (CMP) processing technique has been shown to be effective in improving the results of ground penetrating radar profiling. When radar data are collected with the CMP multi-offset geometry, stacking increases the signal-to-noise ratio of subsurface radar reflections and the effective penetration depth. An important aspect of CMP processing is normal moveout velocity analysis. Most, if not all, GPR surveys, are very limited in spatial extent and the ... |
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| Crustal Deformation Measurements in the Vicinity of Vandenberg Air Force Base |
16 AUG 93 |
6 pages |
| Authors:
Robert W. King; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Recent geological and geodetic studies have suggested that the region surrounding Vandenberg AFB is undergoing active crustal deformation, with important implications for both the geodetic stability and the seismogenic potential of the Western Test Range (WTR) Feigl et al., 1990. Part of the evidence for significant deformation was obtained from GPS measurements which we carried out in cooperation with other university and government scientists beginning-in late 1986. These measurements were ... |
|
| Quantitative Modeling of Bottom Morphology and Subbottom Properties |
MAY 93 |
92 pages |
| Authors:
Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The objectives of this research were threefold: (1) To provide the methodology needed to quantify the two-dimensional variations in bottom topography and three-dimensional variations in subbottom properties observed within the ARSRP Central Atlantic study area: (2) To apply this methodology to geological data sets collected in the study area; and (3) To use the resulting geological models to understand the bottom reverberations observed at long ranges across the study area ... |
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| Research in Regional Seismology: The Effect of Anisotropy |
01 MAR 93 |
72 pages |
| Authors:
Batakrishna Mandal; M. N. Toksoz; William Rodi; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The objective of this study is to quantify the effects of fracturing and anisotropy in the vicinity of an underground explosion on the resulting seismic radiation patterns and in particular on the generation of shear waves. Theoretical finite difference calculations show that an explosive source embedded in either an anisotropic or randomly heterogeneous medium generates shear waves, with anisotropy at the source inducing larger shear waves than heterogeneity. We review ... |
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| GPS Measurements at Vandenberg, AFB |
22 FEB 93 |
15 pages |
| Authors:
Robert King; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Recent geological and geodetic studies have suggested that the region surrounding Vandenberg AFB is undergoing active crustal deformation, with important implications for both the geodetic stability and the seismogenic potential of the Western Test Range (WTR) (Feigl et al., 1990. Part of the evidence for significant deformation was obtained from GPS measurements over a broad area of central and southern California, which we carried out in cooperation with other university ... |
|
| Oceanic Distribution of Trace Metals |
05 OCT 92 |
2 pages |
| Authors:
John M. Edmond; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This is the final report on a series of ONR-funded projects that extended over 20 years at MIT. The general aim of the various projects was to elucidate the geochemical dynamics of dissolved trace elements in the oceanic water column. At the beginning of the project essentially nothing was known. Analytical methods and sampling protocols had to be developed to deal with concentration levels as low as 10-15 molar. Early ... |
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| Application of Ray-Born Scattering and Boundary Perturbation Methods to Acoustic Reverberation |
AUG 92 |
34 pages |
| Authors:
M. N. Toksoz; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This study utilizes ultrasonic water tank modeling to examine three- dimensional scattering trends from a random set of parallel grooves, and compares this with theoretical results obtained from two-dimensional finite- difference calculations. Ultrasonic laboratory modeling is carried out using computer-controlled source and receivers with an aluminum bock submerged in a water tank. The block's upper interface is plane for the reference model and grooved for the test model. The grooves ... |
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| GPS Measurements at Vandenberg AFB |
14 JAN 92 |
5 pages |
| Authors:
Robert W. King; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The objective was to measure directly the tectonic deformation in the Santa Maria Fold and Thrust Belt (SMFTB), northwest of Santa Barbara California. The principal measurement technique was space geodesy; using microwave signals transmitted by Blook II satellites of the Global Positioning System (GPS), from March to August 1990. Geodetic observations were analyzed to resolve tectonic deformation across the SMFTB. The geodetic network forms a braced quadrilateral with 40 km ... |
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| Modelling Studies in Support of Open-Ocean Convection Field Programs |
92 |
4 pages |
| Authors:
John C. Marshall; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We have begun an inquiry into the process of open-ocean deep convection guided by the field observations collected in the western Mediterranean during the past winter. Our goals are to understand the role of planetary rotation in the sinking and spreading of cold water and test our understanding against field observations and laboratory models. Objectives were to understand and parameterize the convective scale in general circulation models and to provide ... |
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| Manufacture of Additional External Sensor Packages for the New ONR OBS |
01 FEB 91 |
|
| Authors:
Sean C. Solomon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
 | The objective of this project was to construct four sensor packages for the ONR ocean bottom seismometer (OBS) system. These units augment 27 sensor packages designed and constructed under a separate ONR-supported subcontract from the Woods Hole Oceanographic Institution (WHOI). The sensor package is a semi-autonomous unit designed to be carried to the seafloor onboard the main ONR OBS frame. Upon landing the package is placed on the bottom by ... |
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| Crustal Deformation Measurements in the Vicinity of Vandenberg Air Force Base |
31 DEC 90 |
5 pages |
| Authors:
Robert W. King; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Recent geological and geodetic studies have suggested that the region surrounding Vandenberg AFB, CA is undergoing active crustal deformation. In 1989 funding under this grant was used to purchase five GPS receivers and to begin a series of measurements designed to determine the magnitude and spatial distribution of deformation in a region encompassing the major faults and folds within 50 km of Vandenberg. Four receivers were acquired in January 1990 ... |
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| Studies Toward Observing and Modelling Large Energetic Ocean Regions |
27 NOV 90 |
|
| Authors:
Carl Wunsch; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This grant is directed mainly at understanding the high energy region near the Gulf Stream system. The report consists essentially of a list of publications. Included topics are acoustic tomography, modelling, altimetry and scatterometry. Keywords: Bibliographies/oceanography; Ocean models; Measurement/ test methods; Acoustic scattering; Altimeters; Hydrography. (mm) |
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| Stochastic Modeling of Seafloor Morphology in Support of the Acoustic Reverberation SRP |
29 OCT 90 |
|
| Authors:
Thomas H. Jordan; John Goff; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This report describes two numerical models of small- scale seafloor topography, SM1-P, corresponding to a 100 km x 100 km area of the east central Pacific Ocean near the Cocos-Pacific spreading center of the East Pacific Rise and Sm1-A, corresponding to a 100 km x 100 km area of the North Atlantic Ocean west of the Mid-Atlantic Ridge. The models comprise both a deterministic component, taken from the DBDB5 digital ... |
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| ONR/NORDA Workshop on Terrain Analysis and Quantitative Geomorphology |
12 JUL 89 |
|
| Authors:
Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The purpose of the workshop on Terrain Analysis and Quantitative Geomorphology was to assess methods for the quantification and analysis of seafloor morphology, to examine their application to acoustic scattering problems, and to evaluate future research directions and needs. A broader goal was to foster cooperation among investigators and minimize the redundancy in Navy-sponsored research projects. This report summarizes the results of the workshop and makes recommendations regarding future research. ... |
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| Studies toward Observing and Modelling Large Energetic Ocean Regions |
22 NOV 88 |
|
| Authors:
Carl Wunsch; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| This report describes the third year of activity on a Secretary of the Navy Research Professor grant. Modelling work on the dynamics of energetic, near Gulf Stream features continues. Data-model combinations using altimetry and direct measurements are being made. A tomographic array was deployed near the Gulf Stream to test a new generation of operational instruments. Keywords: Physical oceanography, Acoustic tomography, Satellite altimetry, Gulf Stream. |
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| Studies Toward Observing and Modelling Large Energetic Ocean Regions |
02 NOV 87 |
|
| Authors:
Carl Wunsch; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Studies have been made directed at: modelling high energy, near Gulf Stream regions; optimally combining data with general models, including inverse and control methods; reducing satellite data (altimetry and scatterometry) for combination into the models; and developing a new generation of operational tomographic instruments. Keywords: Physical oceanography; Acoustic tomography; Satellite altimetry; Gulf stream. |
|
| Investigations of Eurasian Seismic Sources and Upper Mantle Structure |
06 MAR 87 |
|
| Authors:
Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The first section describes the observations of first-order mantle reverberations and develops techniques for using these data to constrain upper- mantle velocity and attenuation structure. The second section discusses our work on the waveform inversion of higher-mode surface waves, and the third analyzes the resolving power of the higher-mode data set. The fourth section reviews recent progress in seismic tomography and its implications for mantle dynamics. The fifth section applies ... |
|
| Investigation of Eurasian Seismic Sources and Upper Mantle Structure |
30 JUN 85 |
|
| Authors:
Thomas H. Jordon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Complex P-SV wavegroups are sucessfully fit on vertical component seismograms for paths crossing northern Eurasia with a model having a 39-km crust and no asthenospheric low-velocity zone. Between the Moho and the 400-km discontinuity, the shear velocities found from the P-SV waveform analysis are consistently lower than those inferred from the SH waveform modeling of Grand and Helmberger. We suggest that this discrepancy is diagnostic of a polarization anisotropy associated ... |
|
| Three-Dimensional Geodetic Control by Interferometry with GPS (Global Positioning System): Processing of GPS Phase Observables |
23 APR 85 |
|
| Authors:
Y. Bock; R. I. Abbot; C. C. Counselman III; R. W. King; S. A. Gourevitch; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Interferometry with the NAVSTAR Global Positioning System (GPS) is the most efficient method of establishing three-dimensional geodetic control on local and regional scales. This is already true, even though the constellation of satellites is incomplete. We consider some theoretical and practical aspects of using differenced carrier-phase observations of the GPS satellites to establish three-dimensional control networks. We present simple and efficient algorithms for processing multi-station, multi-satellite observations. These algorithms have ... |
|
| Interferometric Determination of GPS (Global Positioning System) Satellite Orbits |
23 APR 85 |
|
| Authors:
R. I. Abbot; Y. Bock; C. C. Counselman III; R. W. King; S. A. Gourevitch; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| One way phase observations of GPS satellites at three ground stations were differenced between stations to form interferometric observations. These single difference observations were differenced between satellites to form double difference observations. We analyzed the one way, single, and double difference observations by least-squares to determine the orbits of satellites. In most cases the formal standard errors of the estimated satellite positions were of the order of several meters---equivalent to ... |
|
| Inversion of Refraction Data from the Fram and Nansen Basins of the Arctic Ocean |
85 |
|
| Authors:
Gregory L. Duckworth; Arthur B. Baggeroer; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| As part of the Fram 2 experiment six refraction lines were shot in the Pole Abyssal Plain or Fram Basin of the eastern Arctic Ocean. During the Fram 4 experiment four refraction lines were also shot in the Nansen basin just northeast of the Yermak Plateau. The Fram 2 lines at 86 deg N, 24 deg W cover both the abyssal plain region and the northern flank of the Morris ... |
|
| Development of Ultrasonic Modeling Techniques for the Study of Crustal Inhomogeneities |
AUG 84 |
|
| Authors:
J. T. Bullitt; M. N. Toksoz; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| The effects of topographic features on Rayleigh wave propagation and scattering are investigated in the laboratory using three-dimensional ultrasonic models. The effects of different topographic features on Rayleigh wave transmission and scattering are examined as a function of wavelength and of angle of incidence. In general, backscattered or reflected Rayleigh waves are small compared to transmitted waves. A significant fraction of the Rayleigh wave energy is scattered into body waves. ... |
|
| Compressional and Shear Wave Structure of the East Pacific Rise at 11 deg 20 min N: Constraints from Three-Component Ocean Bottom Seismometer Data |
10 JUL 1984 |
|
| Authors:
S. R. Bratt; S. C. Solomon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
|
| Further Studies of Tidal-Current Sand Waves |
15 SEP 1981 |
|
| Authors:
John B. Southard; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Contents: Physiographic Setting (Vineyard Sound, Mass.); Navigation; Areal Surveys; Site Studies; Results -- Basic Features of the Shoal, Local Mean- Velocity Field, Sand-Wave Crest Patterns, Sand-Wave Migration Rates, Sediment Transport Rates. |
|
| Research in Seismology |
31 DEC 1978 |
|
| Authors:
M. N. Toksoz; K. Aki; S. C. Solomon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| Contents: Source and Propagation Effects of Rayleigh Waves from Central Asian Earthquakes; Three-Dimensional Crust and Upper Mantle Structure of the Northeastern United States; The Attenuation of Seismic Waves in Dry and Saturated Rocks; Thermal Cracking and Amplitude Dependent Attenuation; Ultrasonic P and S Wave Attenuation in Dry and Saturated Rocks under Pressure. |
|
| Thermal Expansion of Natural Spinel, Ferroan Gahnite, Magnesiochromite, and Synthetic Spinel. |
1975 |
|
| Authors:
H. P. Singh; Gene Simmons; P. F. McFarlin; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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| The lattice parameters of natural spinel, ferroan gahnite, magnesiochromite, and synthetic spinel at elevated temperatures have been determined. Expressions for thermal expansions are derived. The replacement of magnesium cations by zinc and iron and of Al2O3 by Cr2O3 in spinel decreases the mean thermal expansion in the range of temperatures covered, but increases the lattice parameters. |
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| Explosion Generated Seismic Waves |
DEC 1971 |
144 pages |
| Authors:
M. Nafi Toksoz; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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| The mechanisms of generation of SH and Love waves by underground nuclear explosions are investigated theoretically and experimentally. An explosion in pre-stressed medium is formulated as a composite source consisting of an isotropic explosion and a double-couple representing the tectonic strain release. From the radiation patterns of Rayleigh waves and Love-to-Rayleigh wave amplitude ratios relative strength of the strain release component is determined. It is found that relative amplitudes of ... |
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