| 3D Modeling of Iran and Surrounding Areas from Simultaneous Inversion of Multiple Geophysical Datasets |
30-Sep-2009 |
10 pages |
| Authors:
Charles J Ammon; Monica Maceira; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
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 | The objective of this work is to help improve seismic monitoring technology through the development and application of advanced multivariate inversion techniques to generate realistic, comprehensive, and high-resolution 3D models of the seismic structure of the crust and upper mantle that satisfy independent geophysical datasets. Our focus is on the region surrounding Iran from the east coast of the Mediterranean in the west, to Pakistan in the east, an area ... |
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| Crustal Structure from In-Country and Ground-Truth Data |
30-Sep-2009 |
11 pages |
| Authors:
Eric A Bergman; Michael H Ritzwoller; Stephen C Myers; E R Engdahl; COLORADO UNIV AT BOULDER
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| We are investigating the crustal and upper mantle structure of the region in central Asia bounded approximately by longitude 41-67 deg E and latitude 20-44 deg N by using in-country datasets of seismic phase arrival times, supplemented by ground truth datasets developed from our previous research efforts. We present the results of Pn tomography using a dataset consisting entirely of GT5 events in the region. From 27 calibrated earthquake clusters ... |
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| Estimating the Uncertainty and Predictive Capabilities of Three-Dimensional Earth Models |
30-Sep-2009 |
11 pages |
| Authors:
Stephen C Myers; Delaine T Reiter; William L Rodi; WESTON GEOPHYSICAL LEXINGTON MA
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| Many three-dimensional models of seismic velocity structure in Eurasia have been developed in recent years by the seismic nuclear monitoring community. Most of these models are not accompanied by quantitative estimates of uncertainty, either in the model velocities themselves or in geophysical observables predicted by the models (e.g., body-wave travel times). Moreover, the various 3D models produced by these studies have not been compared to one another for their predictive ... |
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| High-Resolution Seismic Velocity and Attenuation Models of the Caucasus-Caspian Region |
30-Sep-2008 |
10 pages |
| Authors:
Robert Mellors; Rengin Gok; Michael Pasyanos; Gleb Skobeltsyn; Ugur Teoman; Tea Godoladze; Eric Sandvol; SAN DIEGO STATE UNIV CA
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| The southwest edge of Eurasia is a tectonically and structurally complex region that includes the Caspian and Black Sea basins, the Caucasus Mountains, and the high plateaus south of the Caucasus. Using data from 25 broadband stations located in the region, new estimates of crustal and upper mantle thickness, velocity structure, and attenuation are being developed. Receiver functions have been determined for all stations. Depth to Moho is estimated using ... |
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| Seismic Tomography of the Arabian-Eurasian Collision Zone and Surrounding Areas |
30-Sep-2008 |
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| Authors:
M N Van der Toksoz; Robert D Hilst; Youshun Sun; Levent Gulen; Dogan Kalafat; Huseyin S Kuleli; Chang Li; Haijiang Zhang; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | The objectives of this study are to determine P- and S-wave velocity structures in the crust and upper mantle and to characterize seismic wave propagation in the Arabian-Eurasian collision zone and surrounding areas, including Iran, Arabia, Eastern Turkey, and the Caucasus. The Arabian-Eurasian plate boundary is a complex tectonic zone shaped by continent-continent collision processes. In recent years the number of seismic stations has increased greatly in the region because ... |
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| Shear Velocity Structure in NE China and Characterization of Infrasound Wave Propagation in the 1-210 Kilometer Range |
30-Sep-2008 |
11 pages |
| Authors:
Brian W Stump; Rong-Mao Zhou; Tae-Sung Kim; Yun-Tai Chen; Zhi-Xian Yang; Robert B Herrmann; Relu Burlacu; Chris Hayward; Kristine Pankow; SOUTHERN METHODIST UNIV DALLAS TX
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| We continued the operation of the Southern Methodist University-Institute of Geophysics, China Earthquake Administration (SMU-IGPCEA) broadband seismic network through May 2008 using Program for the Array Seismic Studies of the Continental Lithosphere (PASSCAL) instrumentation. The operating network included three stations northwest of Beijing and 10 stations in Xiuyan. Lisoning Province, NE China. At the end of May, the PASSCAL instrumentation was returned to the U.S. During the 5.5-year operation, we ... |
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| Estimating Local and Near-Regional Velocity and Attenuation Structure from Seismic Noise |
30-Sep-2008 |
11 pages |
| Authors:
Peter Gerstoft; Jian Zhang; William A Kuperman; Nick Harmon; Karim G Sabra; Michael C Fehler; Steven R Taylor; CALIFORNIA UNIV SAN DIEGO LA JOLLA
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| This paper investigates the utility of computing Time-Domain Green's Functions (TDGF) to be used for estimating velocity and attenuations structure for the purposes of nuclear explosion monitoring over local and near-regional distances. Our objective is to extend and apply the methodology of deriving TDGF for propagation between two receivers by cross correlation of seismic noise and/or coda of earthquakes observed at the receivers and concentrates on the following four tasks: ... |
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| Refined Local and Regional Seismic Velocity and Attenuation Models from Finite-Frequency Waveforms |
30-Sep-2008 |
11 pages |
| Authors:
Wei Zhang; Yang Shen; Li Zhao; Xiaoping Yang; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
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| In seismic tomography, the reference or starting models are commonly one-dimensional (1D) and the structural sensitivity kernels of seismic data are calculated without considering the finiteness of seismic waves in both time and frequency domains. These simplifications result in a theoretical limit, in addition to that from the data coverage, on the structural resolution in tomography inversions. In small-scale (such as the crustal) structural imaging, however, a higher resolution is ... |
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| Obtaining Unique, Comprehensive Deep Seismic Sounding Data Sets for CTBT Monitoring and Broad Seismological Studies |
02 JUL 2007 |
62 pages |
| Authors:
Igor B. Morozov; Elena A. Morozova; Scott B. Smithson; WYOMING UNIV LARAMIE DEPT OF GEOLOGY AND GEOPHYSICS
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| In cooperation with the Center for Geophysical and Geoecological Studies (GEON, Moscow, Russia), the University of Wyoming and now also with the University of Saskatchewan digitized, edited, transferred into standard digital formats, and delivered to public domain seismic records from 12 major Deep Seismic Sounding (DSS) projects acquired in 1970-1980's in the former Soviet Union. The data include 3-component records from 22 Peaceful Nuclear Explosions (PNEs) and over 500 chemical ... |
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| Seismicity Characterization and Velocity Structure of Northeast Russia |
MAY 2005 |
182 pages |
| Authors:
MICHIGAN STATE UNIV EAST LANSING DEPT OF GEOLOGY
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| Improved Surface Wave Dispersion Models and Amplitude Measurements |
24 OCT 2003 |
37 pages |
| Authors:
J. L. Stevens; D. A. Adams; M. G. Eneva; G. B. Baker; SCIENCE APPLICATIONS INTERNATIONAL CORPSAN DIEGO CA
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| The report describes the status and results to reduce the magnitude threshold for which surface waves can be identified and measured reliably, and to improve the accuracy of surface wave measurements, using phase-matched filtering, development of global regionalized earth and dispersion models, and other techniques. We have focused on improvements to global earth models and dispersion maps, and improved techniques for measuring surface wave amplitudes. Completed work on implementation and ... |
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| Analysis of Soviet DSS Records of Propagation and Modeling of Lg Blockage across Major Crustal Features |
20 MAR 2000 |
45 pages |
| Authors:
Scott B. Smithson; James C. Schatzman; WYOMING UNIV LARAMIE
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| Analysis of Quartz data resulted in two main conclusions directly relevant to the problem of nuclear test discrimination: (1) the uppermost mantle velocity and attenuation structure is significantly heterogeneous, and (2) the propagation of regional phases, including Lg is highly sensitive to this heterogeneity, and to the variation in crustal structure. The uppermost mantle is significantly heterogeneous, with vertical and horizontal velocity contrasts, high-and low-velocity zones, ... |
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| Seismic Characterization Using the Belbasi Array |
JUN 1998 |
32 pages |
| Authors:
Sadi Kuleli; KANDILLI OBSERVATORY AND EARTHQUAKE RESEARCH INST ISTANBUL (TURKEY)
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| This report results from a contract tasking Kandilli Observatory and Earthquake Research Institute as follows: The contractor will characterize the seismic structure and behavior of the Anatolian region using data from the Belbasi and Keskin arrays near Ankara, Turkey. The research will include studies to understand the amplitude and phase behavior of seismic signals received at Belbasi and other regional stations operated by KOERI. It will ... |
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| Numerical Modeling of Linear and Nonlinear Seismic Wave Attenuation |
APR 1998 |
81 pages |
| Authors:
Steven M. Day; J. B. Minster; Heming Xu; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
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| CTBT verification requires an understanding of the propagation of seismic phases over complex regional paths which cut across major structural boundaries. The computation of synthetic seismograms by finite difference methods plays an important role in developing such understanding. In order for synthetic seismograms to be realistic, the models must account not only for regional elastic structure of the path, but also for an elastic losses. ... |
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| Seismic Velocity, Stratigraphy and Acoustic Study of the South China Sea |
1998 |
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| Authors:
Peter D. Clift; Jian Lin; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| A study was performed of the seismic velocity structure of the South China Shelf from the westernmost parts of the Beibu Gulf, adjacent to the Gulf of Tonkin, south of Hainan Island and offshore southern mainland China, as far east as 118 deg east. Stacking velocities from petroleum industry multichannel seismic surveys were compiled into a database from which the depth or two way travel ... |
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| Seismic P-Velocities in Outcrops of the Troodos Ophiolite Complex, Cyprus |
15 SEP 1997 |
41 pages |
| Authors:
Susan E. Dittus; J. R. Pelton; BOISE STATE UNIV ID
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| Estimates of seismic P-wave velocity for the rocks comprising the outcrops at the Troodos sites were obtained using three different procedures applied to the first arrival-time data: (1) Straight-Ray Procedure: computation of the reciprocal of the slope of a best-fit least-squares straight line through first arrival times plotted as a function of the distance along the straight ray from source to receiver; (2) Hawkins' Procedure: computation of the reciprocal of ... |
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| Analysis of Analog Airgun/Sonobuoy Records: A New Appraisal of the Variation of Upper Crustal Seismic Velocity with Age |
FEB 97 |
32 pages |
| Authors:
Richard L. Carlson; Brian P. Cerney; TEXAS A AND M UNIV COLLEGE STATION DEPT OF GEOLOGY
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| Analog sonobuoy records shot over 0 - 10 m.y. old crust along the East Pacific Rise have been digitally scanned, scaled, and analyzed for upper crustal velocity structure. Previous analyses of the original analog records E. G., Houtz and Ewing, 1976 suggested that the average velocity of layer 2A at the EPR is 3.4 km/s and increases with age to about 4.5 km/s in 40-m.y.-old crust. Later work Diebold and ... |
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| Evolution of Porosity and Seismic Properties of Shallow Oceanic Crust |
NOV 96 |
5 pages |
| Authors:
Gerard J. Fryer; Jill L. Karsten; Roy H. Wilkens; HAWAII UNIV HONOLULU SCHOOL OF OCEAN AND EARTH SCIENCE AND TECHNOLOGY
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| The uppermost oceanic crust undergoes substantial changes in physical properties as it is transported away from a mid-ocean ridge. Porosity must play a central role in dictating such changes. This study sought to use seismic measurements to infer porosities and so to gain an understanding of crustal aging. Techniques used were development of the theory linking porosity to seismic velocity, microscope investigation of seafloor lavas, measurement of ultrasonic velocities in ... |
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| Two-Dimensional Crustal and Upper-Mantle Velocity Models from Profile 'Quartz', Russia, |
14 AUG 1995 |
10 pages |
| Authors:
Igor Morozov; Werner Schueller; Elena Morozova; Scott Smithson; WYOMING UNIV LARAMIE DEPT OF GEOLOGY
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| We develop two-dimensional (2-D) P-wave velocity models for the crust and for the upper mantle along the ultra-long Deep Seismic Sounding profile (DSS) 'Quartz'. Two-dimensional effects play a principal role in Lg propagation and are directly related to the problem of quantitative modeling of Lg and its use as a seismic discriminant. The use of DSS profiles provides us with unique opportunities to study large-scale propagation effects of various seismic ... |
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| The LANL Source Geometry Experiment, |
14 AUG 1995 |
10 pages |
| Authors:
B. W. Stump; D. C. Pearson; C. L. Edwards; D. F. Baker; LOS ALAMOS NATIONAL LAB NM
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| The Source Geometry Experiment was successfully conducted over the time period 17 April to 7 May 95. Recording in the mine was conducted 24 April to 4 May 95. Five single sources were instrumented that included four cylindrical charges at different burdens (distance from the free face) and a pseudo-spherical charge. Nine production shots conducted during the two week visit to the mine were also recorded. Included in these production ... |
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| Practical Issues in the Location of Small Events Under a CTBT: Poor Station Coverage and Poorly Known Velocity Structure, |
14 AUG 1995 |
10 pages |
| Authors:
Katharine Kadinsky-Cade; Rong-Song Jih; Anton Dainty; John Cipar; PHILLIPS LAB HANSCOM AFB MA
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| In regions that do not contain good station coverage, a reasonably well known velocity structure and moderate or large magnitude events (the latter needed for calibration using teleseismic constraints on the location of a master event), it is very difficult to obtain accurate regional event locations. In this situation standard error ellipses generated during event locations may give the impression that an event location is better deterinined than it really ... |
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| Seismic Studies of the Caspian Basin and Surrounding Regions |
14 MAY 94 |
34 pages |
| Authors:
Stephen Mangino; Keith Priestley; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF EARTH SCIENCES
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| In order to investigate the anomalous crust and upper mantle structure of the south Caspian Basin, we installed a network of six three- component seismograph stations within the former Soviet republics of Turkmenistan and Azerbaijan. Our objective is to determine the velocity structure and surface wave modeling techniques. This first year report documents the seismographs network installation and data processing methods, discusses the crustal velocity structure for one network station ... |
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| Tomographic Analysis of the Three-Dimensional Variation of the Seismic Velocity Structure of the Shallow Crust Underlying Southern New England |
30 SEP 93 |
156 pages |
| Authors:
A. K. Bowers; A. L. Kafka; WESTON OBSERVATORY MA
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| This report describes a study in which tomographic inversion was used to investigate the three-dimensional variation of the seismic velocity structure of the shallow crust underlying southern New England (SNE). Group velocity dispersion curves for Rg waves with periods between 0.5 and 2.0 sec have been published for SNE. Dispersion curves from these studies and from our own analyses were converted to travel time data. Two dimensional tomography was then ... |
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| Investigation of Lateral Variation in the Seismic Velocity Structure of the Shallow Crust Beneath Eastern Massachusetts and Southern New Hampshire |
30 SEP 93 |
99 pages |
| Authors:
S. E. D'Annolfo; A. L. Kafka; BOSTON COLL CHESTNUT HILL MA
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| This is one of five scientific reports describing specific research projects conducted at Weston Observatory under Contract No. F19628-90-K-0035. The research conducted under this contract covers a range of topics related to seismology in general and to nuclear test monitoring in particular. This report describes a study in which group velocity dispersion was determined for short- period Rayleigh waves recorded from blasts detonated at the San-Vel quarry in Littleton, MA. ... |
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| Mapping Crust and Upper Mantle Structure Beneath Southern Eurasia |
31 AUG 93 |
46 pages |
| Authors:
Donald V. Helmberger; CALIFORNIA INST OF TECH PASADENA
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| In this study of lateral variations in compressional velocity in the uppermost mantle underneath the Tibetan plateau, 353 Pn travel times were collected for 44 Tibetan earthquakes at 46 seismic stations. The inverse method and procedures in this study differ from previous Pn tomography studies in that corrections were applied to the biases caused by (1) event mislocation by ISC, (2) mantle velocity gradient, and (3) large-scale variations in crustal ... |
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| Effects of a Descending Lithospheric Slab on Yield Estimates of Aleutian Nuclear Tests. Incorporation of Velocity Gradients in the Synthesis of Complete Seismograms by the Locked Mode Method |
10 AUG 90 |
63 pages |
| Authors:
Vernon F. Cormier; CONNECTICUT UNIV STORRS DEPT OF GEOLOGY AND GEOPHYSICS
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| The locked mode method of synthesizing complete regional seismograms (Harvey, 1981) was modified to include the Langer uniform asymptotic approximation to vertical wave-functions within layers having linear vertical velocity gradients. Good agreement is obtained in gradient models between synthetics computed using the Langer-locked mode method, the colocation method, and the conventional locked mode method in models parameterized by thin homogeneous layers. Errors in calculated displacement introduced by the use of ... |
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| Project Sedan: Seismic Velocity Study |
DEC 1962 |
51 pages |
| Authors:
S. E. Warner; CALIFORNIA UNIV LIVERMORE RADIATION LAB
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| This series of experiments evaluates the performance of pressure-pulse transducers in determining distances of installed gages from small H.E. detonations by measuring seismic wave travel times. Because of the superiority of the system time resolution as compared with conventional geophysical exploration equipment, improved accuracy was anticipated as well as an opportunity to dry-run the installed system in the operational environment. Also, a requirement for seismic velocity measurements in situ was ... |
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Reports by Keyword(s)
*SEISMIC VELOCITY
