Download or read book An Investigation of Seismic Wave Propagation in Eastern North America written by P. W. Pomeroy and published by . This book was released on 1978 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic waves propagated and recorded at regional distances in eastern North America are being studies for possible use in discriminating between explosion and earthquake sources. This report deals with (a) the propagation characteristics of the regional seismic wave designated L sub g and (b) an evaluation of the usefulness of a particular ocean bottom seismograph system as an aid in discrimination of seismic sources at regional distances. Results of the study of the propagation characteristics of L sub g, with predominant frequencies of 1-3 hertz, is consistently the largest amplitude portion of the short period signal from the Eastern North American events studied. Analysis of the group velocity for each event studied shows a clustering of measurements in the 3.47 km/sec range for the earthquakes studied and a significantly lower 3.24 km/sec mean for measurements from the SALMON explosion. This lower value is believed to be the result of propagation path or source effects. When group velocity information was divided into two regions, E (h)--high group velocity (4.0-3.4 km/sec) energy--and E(l)--low group velocity (3.4-2.8 km/sec) energy, the ratios of these areas showed a discrimination between SALMON ((E(h)/E(l) .5) and the earthquakes ((E(h)/E(l).5). Phase velocity measurements made using records from Cumberland Plateau Seismic Observatory have a mean of 4.18 km/sec. Analysis of a second event also yields measurements in the 4.0-4.4 km/sec range.
Download or read book An Investigation of Seismic Wave Propagation in the Eastern United States written by David E. Willis and published by . This book was released on 1968 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper describes the travel-time anomalies and attenuation losses of seismic compressional waves generated by a series of underwater explosions in the eastern United States. The efficient tamping of the shots fired in water provided a seismic source that could be detected at much larger ranges than could be accomplished by equivalent sized shots fired underground. A number of mobile field recording stations equipped with three-component matched short period seismometers and magnetic tape recorders were used to record 273 individual shots. A total of 1,295 recordings were obtained along a reversed profile extending from International Falls, Minnesota to the Atlantic Coast. The underwater shots were fired in Lake Superior and the Atlantic Ocean. Precise travel times were obtained by recording radio time signals at all of the recording stations. An analysis of the travel-times of the seismic waves disclosed that the earth's crust varies in thickness from 28.1 km near the Atlantic Coast in North Carolina to 50.4 km near the Keweenaw Peninsula in upper Michigan. The crust in North Carolina was found to be comprised of a single layer with a compressional wave velocity of 6.0 km/sec. A two-layer crust with compressional wave velocities of 6.2 and 7.7 km/sec was disclosed in upper Michigan. Travel time residuals across the Appalachian Mts. would indicate a mountain root system similar to that found under the Rocky Mts. The Lake Superior area was found to be more efficient in the coupling of energy into seismic waves by the underwater shots than in the Atlantic Ocean. (Author).
Download or read book Collection and Analysis of Seismic Wave Propagation Data written by David E. Willis and published by . This book was released on 1966 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report summarizes one year of theoretical and applied research on propagation of seismic waves and techniques for analyzing data. The main objectives were to determine the frequency and energy of seismic signatures, and investigate attenuation, patterns of azimuthal radiation from source regions, and methods of determining the type of motion at the source. Natural and artificial sources were studied to develop diagnostic aids for distinguishing between earthquakes and underground nuclear detonations. Equipment for selection, reformatting, and digital-to-analog conversion for digitally recorded LASA data was constructed and is being checked out. Several approaches for using the parallel computational capabilities of optics for LASA data were developed. A study of background noise and reciprocity for teleseismic events as recorded on the bottom of a large fresh water lake has commenced with the emplacement of three-component seismometers in Lake Superior. Array data have been used for crustal studies on the Eastern United States. Digital mode filtering was investigated. A perturbation theory for seismic sources was developed. (Author).
Download or read book Regional Seismic Wave Propagation written by Paul W. Pomeroy and published by . This book was released on 1979 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research reported here was carried out to enhance our understanding of seismic wave propagation at regional distances in the central portion of the USSR. Results in this region are contrasted with those from the Western USSR and with data from eastern North America.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global Investigation of Seismic Wave Propagation on a Regional Scale written by Jack E. Oliver and published by . This book was released on 1981 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Th Middle East study is focused on the Turkish and Iranian plateaus and the surrounding regions. Sn amplitude variations are very striking in these areas. Efficient Sn propagation is observed across a major part of the Turkish and Iranian plateaus. However, Sn is strongly attenuated in the northernmost part of the plateaus south of the Black and Caspian Seas, and in the area between these two areas. These regions are characterized, in general, by active tectonism, including volcanism, faulting, and folding. However, this active tectonism is not restricted to the areas of high Sn attenuation, but appears to extend, though with somewhat less apparent activity, beneath a major part of the Turkish and Iranian plateaus. Patterns of lateral variations in the propagation of Lg are not as consistent as those for Sn. Lg propagates efficiently across Turkey, Iran and adjacent regions, but the Lg waves that cross the Turkish and Iranian plateaus are, in general, weak and have relatively long predominant periods of about 2-5 seconds. The Lg phase is not observed when the path of propagation crosses the southern Caspian and the Black Seas, consistent with the available evidence of oceanic-type crustal structure beneath these seas. (Author).
Download or read book Report of Second Conference on Seismic Propagation Study written by and published by . This book was released on 1971 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Initial Investigation Into Seismic Wave Propagation Through a Fractured Medium written by Franklin David Lane and published by . This book was released on 1983 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ground motion Attenuation and Earthquake Source Scaling in Eastern North America written by and published by . This book was released on 1992 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Seismic Wave Propagation at Regional Distances in Five Areas of the World written by Z. A. Der and published by . This book was released on 1982 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propagation and excitation of regional phases in southern Africa, the southwestern United States, the Pakistan-India region, South America, and the Kamchatka-Kuriles region were studied. Comparison of the shield areas of South America, Pakistan and southern Africa reveals no appreciable differences in the excitation and attenuation of regional phases in these areas. On the other hand, excitation and attenuation rates for all regional phases are markedly different in the southwestern United States. The mountainous areas of South America are characterized by highly variable propagation characteristics, with Sn and Lg being absent from many seismograms studied. Attenuation of Sn and Lg is especially severe along the southern Andes mountains in Chile and Argentina. For these areas, the value of regional phases for detection and discrimination is highly questionable. The Andes region is also characterized by highly unusual seismograms with scattered, emergent phases resembling lunar seismograms. These problems are present, though to a much lesser degree, in the mountainous areas surrounding India and Pakistan. These areas are also characterized by highly variable propagation efficiency and by spatial attenuation that is higher than that of the shield.
Download or read book Investigation of Seismic Wave Propagation in Anisotropic and Inhomogeneous Media written by Charles R. Bentley and published by . This book was released on 1974 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this grant was to investigate some of the effects of anisotropy and inhomogeneity on the propagation of seismic waves by theoretical analysis and comparison with seismograms from the Antarctic ice sheet. Four specific topics were considered: (1) reflection coefficients at an isotropic-anisotropic boundary, (2) surface wave propagation in the presence of a strong velocity gradient, (3) conversion between body wave types upon total internal reflection, that is at the turning point of a refracted arrival, and (4) the continuous bodily conversion of P waves into shear waves in the course of propagation through a strong velocity gradient.
Download or read book A Study of Seismic Wave Propagation in Granular Media written by Frederick VanBuren Lawrence and published by . This book was released on 1962 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Investigation of Seismic Wave Propagation in Fracture Systems written by Weidong Yi and published by . This book was released on 1999 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Wave Propagation in Stratified Media written by Brian Kennett and published by ANU E Press. This book was released on 2009-05-01 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic Wave Propagation in Stratified Media presents a systematic treatment of the interaction of seismic waves with Earth structure. The theoretical development is physically based and is closely tied to the nature of the seismograms observed across a wide range of distance scales - from a few kilometres as in shallow reflection work for geophysical prospecting, to many thousands of kilometres for major earthquakes. A unified framework is presented for all classes of seismic phenomena, for both body waves and surface waves. Since its first publication in 1983 this book has been an important resource for understanding the way in which seismic waves can be understood in terms of reflection and transmission properties of Earth models, and how complete theoretical seismograms can be calculated. The methods allow the development of specific approximations that allow concentration on different seismic arrivals and hence provide a direct tie to seismic observations.
Download or read book An Investigation of the Seismic Wave Propagation Properties of a Thin Unsaturated Layer as a Wave Guide written by Raymond Charles Todd and published by . This book was released on 1971 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Seismic Wave Propagation in the Weathered Zone written by Dan Kosloff and published by . This book was released on 1993 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Wave Propagation and Scattering in the Heterogenous Earth written by Haruo Sato and published by Springer Science & Business Media. This book was released on 2008-12-17 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic waves – generated both by natural earthquakes and by man-made sources – have produced an enormous amount of information about the Earth's interior. In classical seismology, the Earth is modeled as a sequence of uniform horizontal layers (or sperical shells) having different elastic properties and one determines these properties from travel times and dispersion of seismic waves. The Earth, however, is not made of horizontally uniform layers, and classic seismic methods can take large-scale inhomogeneities into account. Smaller-scale irregularities, on the other hand, require other methods. Observations of continuous wave trains that follow classic direct S waves, known as coda waves, have shown that there are heterogeneities of random size scattered randomly throughout the layers of the classic seismic model. This book focuses on recent developments in the area of seismic wave propagation and scattering through the randomly heterogeneous structure of the Earth, with emphasis on the lithosphere. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and includes analyses of observations using the theoretical methods developed.
