Bob Odom - Academia.edu (original) (raw)
Papers by Bob Odom
GEOPHYSICS, 1984
Eisner has concocted a clever geometrical arrangement that appears to contradict the principle of... more Eisner has concocted a clever geometrical arrangement that appears to contradict the principle of acoustic reciprocity. In essence his example consists of a truncated opaque ellipsoidal reflector with the source and receiver situated at the foci as shown in Figure 1. In the limit of geometrical optics it is evident that only half the energy emitted by a source at 2 will contribute to the reflected arrival at 1 while a substantially larger fraction of the energy emitted by a source at 1 will appear at 2. Naively it seems as if the geometrical amplitude of the reflected arrival at 2 should exceed that at 1, in apparent violation of the reciprocity theorem.
Bulletin of the Seismological Society of America, Dec 1, 1987
READ INSTRUCTIONS BEFORE COMPLETING FORM I REPORT NUMB.RGOVT ACCESSION NO. 3. REC';7.NT'S !ATALOG... more READ INSTRUCTIONS BEFORE COMPLETING FORM I REPORT NUMB.RGOVT ACCESSION NO. 3. REC';7.NT'S !ATALOG HUMOSER 4 T T LE (nd Sbti ie)S. TYPE OF REPORT 4 PERIOD COVFPWIM Rapid generation of synthetic seismograms in layered media by vectorization of the algorit ________________ 41. PERFORMING O00. REPORT NUMSER 7 AuTmOR(e) 0. CONTRACT OR GRANT MUMNmER(s)
Agu Spring Meeting Abstracts, May 1, 2006
Guidance, Navigation and Control Conference, 1989
Reliable tracking in a high clutter, dense target environment requires the utilization of a flexi... more Reliable tracking in a high clutter, dense target environment requires the utilization of a flexible tracking system capable of solving difficult track associations with minimized computational burden. Through simulation, a joint probabilistic data association filter (JPDAF) with an ...
Noise Control Engineering Journal, 2011
This is an exciting new scientific publi cation. It is timely and welcome as there are few books ... more This is an exciting new scientific publi cation. It is timely and welcome as there are few books of this stature published in this discipline. Furthermore, it is up to date and readable. It is well researched, excellently presented and ranks with earlier books in this disci pline such as Horton (1 9 5 9), Urick (1967 and 1975), Clay and Medwin (1 977), and MacLennan and Simmonds (1 992). These books have been widely used and cited and this reviewer is con fident that An
IEEE Journal of Oceanic Engineering, 2011
ABSTRACT This communication corrects errors and supplies missing parameter values for a previous ... more ABSTRACT This communication corrects errors and supplies missing parameter values for a previous publication by the authors (ibid., vol. 35, no. 3, pp. 603-617, Jul. 2010) regarding the geoacoustic bottom interaction model (GABIM).
IEEE Journal of Oceanic Engineering, 2011
ABSTRACT This communication corrects errors and supplies missing parameter values for a previous ... more ABSTRACT This communication corrects errors and supplies missing parameter values for a previous publication by the authors (ibid., vol. 35, no. 3, pp. 603-617, Jul. 2010) regarding the geoacoustic bottom interaction model (GABIM).
Andrews University Seminary Studies, 1965
A very important testimony concerning the planetary week in the second century A.D. is that of Ve... more A very important testimony concerning the planetary week in the second century A.D. is that of Vettius Valens, a noted astrologer of Antioch, who was active during the reigns of Antoninus Pius (138-161) and Marcus Aurelius (161-180). His Anthology, an astrological treatise written in Greek, has been a valuable subject of study by scholars because of the astronomical and chronological data it contains. 0 t to Neugebauer, noted expert in the mathematics of ancient astronomy, has worked out, with the collaboration of Henry B. Van Hoesen, the horoscopes recorded by that astrologer. In their book presenting their findings they say :
Abstract : This report presents the results of an exploratory development study designed to inves... more Abstract : This report presents the results of an exploratory development study designed to investigate feasible alternatives for the simulation of indirect fire weapon systems. The study treats several alternative approaches and provides technical assessment costs and schedule for development. A Preliminary Systems Engineering Design, PSED, of the recommended approach is presented. (Author)
... The workshop participants made the following recommendations: Recommendation to IRIS to mak... more ... The workshop participants made the following recommendations: Recommendation to IRIS to make available in real time adequate waveform windows at a handful of island stations allowing T-phase evaluation and research in real time. ...
The Journal of the Acoustical Society of America, 2015
Experimental measurements of Scholte waves from underwater explosions collected off the coast of ... more Experimental measurements of Scholte waves from underwater explosions collected off the coast of Virginia Beach, VA in shallow water are presented. It is shown here that the dispersion of these explosion-generated Scholte waves traveling in the sandy seabed can be modeled using a power-law dependent shear wave speed profile and an empirical source model that determines the pressure time-series at 1 m from the source as a function of TNT-equivalent charge weight.
Broadband recordings from the GRF (Griifenberg) Array of the strongest earthquakes from Greece ar... more Broadband recordings from the GRF (Griifenberg) Array of the strongest earthquakes from Greece are examined. A P-wave seismogram section of a number of events in the range between 1,300 and 2,100 km epicentral distance is constructed. The dominant feature in this section is the second arrival, which is the reflection from the 400 km discontinuity. Characteristic amplitude changes of this phase across the array are observed. The apparent velocity across the array of the first arriving P phase is very slow, indicating a slower upper mantle in SE Europe than in other regions. There is also a very weak indication of a third phase. The resulting model of the upper mantle, which was derived with the aid of theoretical seismograms, shows a pronounced discontinuity at a depth of 400 km. The time difference between the observed first two phases can be used for a fast estimation of the epicentral distance.
The Journal of the Acoustical Society of America, 2009
Modeling acoustic propagation in the ocean requires a representation of the ocean sound speed. Fo... more Modeling acoustic propagation in the ocean requires a representation of the ocean sound speed. For a 1‐D, range independent ocean, probably the most common representation comprises constant sound speed layers and/or gradient layers. Gradients of the form 1/c2(z), admitting an exact solution for the acoustic pressure field in terms of Airy functions, are commonly employed. A disadvantage of using the Airy functions is that they are specific to that profile. For more general profiles, the best representation may be a stack of constant sound speed layers for which the pressure field is expressible in terms of simple exponentials. As an example, computing the backscattering strength from a stack of layers containing volume heterogeneities requires evaluation of an integral proportional to the 4th power of the pressure field. Integrating the simple exponential solutions for constant sound speed layers is trivial. Integrating a product of four Airy functions, either analytically or numerically, is not. If the m...
The Journal of the Acoustical Society of America, 2009
The resolution operator for a linear inverse problem indicates how much smearing exists in the ma... more The resolution operator for a linear inverse problem indicates how much smearing exists in the map between the true model and the estimated model. The trace of the resolution operator provides an estimate of the number of model parameters model that are resolved. In a series representation of the resolution operator for a nonlinear problem, the higher‐order terms indicates how much spurious nonlinear leakage there is from the true model to the estimated model. In previous work, the solution of a simple nonlinear ocean acoustic inverse problem as a perturbation series in the horizontal wavenumber was constructed, and the linear data kernels were presented. This linear problem permitted the quantification of the magnitude of the perturbation and indicated when nonlinear effects must be taken into consideration. In this extension of previous work, the second order resolution kernel is constructed, which describes how effectively nonlinear effects can be removed from the reconstructed model. [Work supported b...
The Journal of the Acoustical Society of America, 2006
The 4×4 linear system of differential equations describing the propagation of the displacements a... more The 4×4 linear system of differential equations describing the propagation of the displacements and tractions in an elastic layered medium becomes singular as the shear modulus of the elastic medium approaches zero. There are a number of approximate ways to handle this singularity in order to impart numerical stability to the computation of the elastic waves in a layered medium. For example, one can impose an irrotational constraint on the displacements or introduce a massive elastic interface (MEI). Both of these ways of handling the weak shear strength are approximate, but avoid the need for singular perturbation theory [Gilbert, 1998]. Scholte waves are interface waves that propagate along the interface between an elastic solid and a fluid. They have nodes near or on the interface and decay exponentially into the bounding media. Scholte waves do not occur at the boundary between fluids. As the shear speed in the bounding elastic medium approaches zero, the Scholte waves disappear from the spectrum. We ...
The Journal of the Acoustical Society of America, 2008
Inversion of ocean bottom geoacoustic properties from acoustic receptions in the water column is ... more Inversion of ocean bottom geoacoustic properties from acoustic receptions in the water column is a nonlinear inverse problem that is inherently unstable and nonunique. One common approach to stabilizing this problem is to assume that the ocean bottom is made up of a small number of layers. The solution from this approach does allow one to reproduce the scattered sound field if all the other experiment parameters such as frequency and geometry are also reproduced. However without extensive prior information about that ocean bottom, this approach yields only one of many equivalent nonunique solutions and may not accurately describe the actual ocean bottom itself. An alternate approach, which may allow one to reuse the results later with a different frequency or geometry, is to use the tools of geophysical continuum inversion to specify the degree of nonuniqueness by quantifying both the uncertainty and limited resolution of the continuum bottom solution. This work compares inversion uncertainty and resoluti...
The Journal of the Acoustical Society of America, 2000
The amplitudes of the propagating acoustic modes associated with T‐waves decay exponentially belo... more The amplitudes of the propagating acoustic modes associated with T‐waves decay exponentially below their ray equivalent turning points, and cannot be excited directly by an earthquake. The modal decomposition for a T‐wave producing earthquake that occurred near the western tip of the Blanco TFZ has been computed. The directly excited higher order modes are characterized by relatively large amplitudes in the ocean crust, significant water‐borne components, and often strong interface components at the ocean‐bottom boundary. Employing the modal scattering theory of Park and Odom (1999), it is found that energy has been transferred from higher order modes to the Stoneley fundamental and the lower order modes have significant amplitude at the water‐bottom interface. Scattering from irregular ocean bottom bathymetry is the mechanism for the energy transfer. The lowest order acoustic modes, modes 1 and 2, are only very weakly excited because they have very small amplitudes at the bottom. This is consistent with the interpretation of de Groot‐Hedlin and Orcutt (1999). [Work supported by the NOPP Program and ONR.]
The Journal of the Acoustical Society of America, 2011
The shallow water environment may be highly variable, with both range dependence and anisotropy a... more The shallow water environment may be highly variable, with both range dependence and anisotropy almost ubiquitous in the seafloor bottom/sub‐bottom regions. Some common causes of range dependence include marine‐sediment composition, non‐planar boundaries, rough surfaces, strong density, or velocity contrasts, and variation in water‐column depth and/or sediment‐cover thickness. Common causes of elastic anisotropy are compositional layering or vertically aligned cracks. There is an apparent trade‐off between anisotropy and range dependence, and difficult to separate the two effects in a propagating signal. If the symmetry axis of a compositionally layered sediment is not exactly normal to the seafloor, the seismo‐acoustic wave field has particle‐motion polarizations in all three coordinate directions. Even in a one‐dimensional medium, an explosion source excites sediment particle motion with all three polarizations. Assuming sediment isotropy when it is not justified can cause errors in layer‐thickness comp...
The Journal of the Acoustical Society of America, 2009
Elastic anisotropy is a nearly ubiquitous feature of marine sediments. The simplest type of sedim... more Elastic anisotropy is a nearly ubiquitous feature of marine sediments. The simplest type of sediment anisotropy is transverse isotropy, characterized by five elastic constants, and results from layered deposition. A modal scattering theory for volume perturbations of the sediment elastic moduli is presented. The scattering theory is based on the coupled mode formulation for propagation in range dependent fluid‐elastic media. The Born approximation is employed to derive a modal scattering matrix. Although the perturbations of the elastic moduli are random, they may not be arbitrary in the sense that certain symmetry and energy constraints among the moduli must be respected. Mode‐mode coupling matrices are computed for quasi‐P‐SV‐SH seismo‐acoustic modes, which show mode mixing and the importance of non‐nearest neighbor interactions. The effects of volume scattering can be combined with rough surface scattering and also incorporated into mode coupling caused by deterministic range dependence of the material...
The Journal of the Acoustical Society of America, 2013
ABSTRACT An important generating mechanism for received underwater acoustic and seismic signals a... more ABSTRACT An important generating mechanism for received underwater acoustic and seismic signals are buried or earth-bound sources. Most underwater acoustic studies involve purely compressional sources in the water column. The more complicated case of a coupled shear and compressional seismic source in the sediment has recently been implemented in an elastic parabolic equation solution [Frank et al., J. Acoust. Soc. Am. 133]. In this talk, generic seismic sources including those giving shear field contributions, are contrasted in normal mode and parabolic equation solutions. Scenarios considered are for an elastic-bottom Pekeris waveguide and a canonical Arctic propagation scenario with an elastic ice cover over the ocean and an elastic basement. For the Arctic case, the source is allowed in either the ice cover or in the elastic bottom. Solutions are benchmarked for purely compressional and shear seismic sources, and their relation to the seismic moment tensor is discussed. The ultimate goal of these solutions is to allow for seismic sources capable of representing generic geophysical events.
GEOPHYSICS, 1984
Eisner has concocted a clever geometrical arrangement that appears to contradict the principle of... more Eisner has concocted a clever geometrical arrangement that appears to contradict the principle of acoustic reciprocity. In essence his example consists of a truncated opaque ellipsoidal reflector with the source and receiver situated at the foci as shown in Figure 1. In the limit of geometrical optics it is evident that only half the energy emitted by a source at 2 will contribute to the reflected arrival at 1 while a substantially larger fraction of the energy emitted by a source at 1 will appear at 2. Naively it seems as if the geometrical amplitude of the reflected arrival at 2 should exceed that at 1, in apparent violation of the reciprocity theorem.
Bulletin of the Seismological Society of America, Dec 1, 1987
READ INSTRUCTIONS BEFORE COMPLETING FORM I REPORT NUMB.RGOVT ACCESSION NO. 3. REC';7.NT'S !ATALOG... more READ INSTRUCTIONS BEFORE COMPLETING FORM I REPORT NUMB.RGOVT ACCESSION NO. 3. REC';7.NT'S !ATALOG HUMOSER 4 T T LE (nd Sbti ie)S. TYPE OF REPORT 4 PERIOD COVFPWIM Rapid generation of synthetic seismograms in layered media by vectorization of the algorit ________________ 41. PERFORMING O00. REPORT NUMSER 7 AuTmOR(e) 0. CONTRACT OR GRANT MUMNmER(s)
Agu Spring Meeting Abstracts, May 1, 2006
Guidance, Navigation and Control Conference, 1989
Reliable tracking in a high clutter, dense target environment requires the utilization of a flexi... more Reliable tracking in a high clutter, dense target environment requires the utilization of a flexible tracking system capable of solving difficult track associations with minimized computational burden. Through simulation, a joint probabilistic data association filter (JPDAF) with an ...
Noise Control Engineering Journal, 2011
This is an exciting new scientific publi cation. It is timely and welcome as there are few books ... more This is an exciting new scientific publi cation. It is timely and welcome as there are few books of this stature published in this discipline. Furthermore, it is up to date and readable. It is well researched, excellently presented and ranks with earlier books in this disci pline such as Horton (1 9 5 9), Urick (1967 and 1975), Clay and Medwin (1 977), and MacLennan and Simmonds (1 992). These books have been widely used and cited and this reviewer is con fident that An
IEEE Journal of Oceanic Engineering, 2011
ABSTRACT This communication corrects errors and supplies missing parameter values for a previous ... more ABSTRACT This communication corrects errors and supplies missing parameter values for a previous publication by the authors (ibid., vol. 35, no. 3, pp. 603-617, Jul. 2010) regarding the geoacoustic bottom interaction model (GABIM).
IEEE Journal of Oceanic Engineering, 2011
ABSTRACT This communication corrects errors and supplies missing parameter values for a previous ... more ABSTRACT This communication corrects errors and supplies missing parameter values for a previous publication by the authors (ibid., vol. 35, no. 3, pp. 603-617, Jul. 2010) regarding the geoacoustic bottom interaction model (GABIM).
Andrews University Seminary Studies, 1965
A very important testimony concerning the planetary week in the second century A.D. is that of Ve... more A very important testimony concerning the planetary week in the second century A.D. is that of Vettius Valens, a noted astrologer of Antioch, who was active during the reigns of Antoninus Pius (138-161) and Marcus Aurelius (161-180). His Anthology, an astrological treatise written in Greek, has been a valuable subject of study by scholars because of the astronomical and chronological data it contains. 0 t to Neugebauer, noted expert in the mathematics of ancient astronomy, has worked out, with the collaboration of Henry B. Van Hoesen, the horoscopes recorded by that astrologer. In their book presenting their findings they say :
Abstract : This report presents the results of an exploratory development study designed to inves... more Abstract : This report presents the results of an exploratory development study designed to investigate feasible alternatives for the simulation of indirect fire weapon systems. The study treats several alternative approaches and provides technical assessment costs and schedule for development. A Preliminary Systems Engineering Design, PSED, of the recommended approach is presented. (Author)
... The workshop participants made the following recommendations: Recommendation to IRIS to mak... more ... The workshop participants made the following recommendations: Recommendation to IRIS to make available in real time adequate waveform windows at a handful of island stations allowing T-phase evaluation and research in real time. ...
The Journal of the Acoustical Society of America, 2015
Experimental measurements of Scholte waves from underwater explosions collected off the coast of ... more Experimental measurements of Scholte waves from underwater explosions collected off the coast of Virginia Beach, VA in shallow water are presented. It is shown here that the dispersion of these explosion-generated Scholte waves traveling in the sandy seabed can be modeled using a power-law dependent shear wave speed profile and an empirical source model that determines the pressure time-series at 1 m from the source as a function of TNT-equivalent charge weight.
Broadband recordings from the GRF (Griifenberg) Array of the strongest earthquakes from Greece ar... more Broadband recordings from the GRF (Griifenberg) Array of the strongest earthquakes from Greece are examined. A P-wave seismogram section of a number of events in the range between 1,300 and 2,100 km epicentral distance is constructed. The dominant feature in this section is the second arrival, which is the reflection from the 400 km discontinuity. Characteristic amplitude changes of this phase across the array are observed. The apparent velocity across the array of the first arriving P phase is very slow, indicating a slower upper mantle in SE Europe than in other regions. There is also a very weak indication of a third phase. The resulting model of the upper mantle, which was derived with the aid of theoretical seismograms, shows a pronounced discontinuity at a depth of 400 km. The time difference between the observed first two phases can be used for a fast estimation of the epicentral distance.
The Journal of the Acoustical Society of America, 2009
Modeling acoustic propagation in the ocean requires a representation of the ocean sound speed. Fo... more Modeling acoustic propagation in the ocean requires a representation of the ocean sound speed. For a 1‐D, range independent ocean, probably the most common representation comprises constant sound speed layers and/or gradient layers. Gradients of the form 1/c2(z), admitting an exact solution for the acoustic pressure field in terms of Airy functions, are commonly employed. A disadvantage of using the Airy functions is that they are specific to that profile. For more general profiles, the best representation may be a stack of constant sound speed layers for which the pressure field is expressible in terms of simple exponentials. As an example, computing the backscattering strength from a stack of layers containing volume heterogeneities requires evaluation of an integral proportional to the 4th power of the pressure field. Integrating the simple exponential solutions for constant sound speed layers is trivial. Integrating a product of four Airy functions, either analytically or numerically, is not. If the m...
The Journal of the Acoustical Society of America, 2009
The resolution operator for a linear inverse problem indicates how much smearing exists in the ma... more The resolution operator for a linear inverse problem indicates how much smearing exists in the map between the true model and the estimated model. The trace of the resolution operator provides an estimate of the number of model parameters model that are resolved. In a series representation of the resolution operator for a nonlinear problem, the higher‐order terms indicates how much spurious nonlinear leakage there is from the true model to the estimated model. In previous work, the solution of a simple nonlinear ocean acoustic inverse problem as a perturbation series in the horizontal wavenumber was constructed, and the linear data kernels were presented. This linear problem permitted the quantification of the magnitude of the perturbation and indicated when nonlinear effects must be taken into consideration. In this extension of previous work, the second order resolution kernel is constructed, which describes how effectively nonlinear effects can be removed from the reconstructed model. [Work supported b...
The Journal of the Acoustical Society of America, 2006
The 4×4 linear system of differential equations describing the propagation of the displacements a... more The 4×4 linear system of differential equations describing the propagation of the displacements and tractions in an elastic layered medium becomes singular as the shear modulus of the elastic medium approaches zero. There are a number of approximate ways to handle this singularity in order to impart numerical stability to the computation of the elastic waves in a layered medium. For example, one can impose an irrotational constraint on the displacements or introduce a massive elastic interface (MEI). Both of these ways of handling the weak shear strength are approximate, but avoid the need for singular perturbation theory [Gilbert, 1998]. Scholte waves are interface waves that propagate along the interface between an elastic solid and a fluid. They have nodes near or on the interface and decay exponentially into the bounding media. Scholte waves do not occur at the boundary between fluids. As the shear speed in the bounding elastic medium approaches zero, the Scholte waves disappear from the spectrum. We ...
The Journal of the Acoustical Society of America, 2008
Inversion of ocean bottom geoacoustic properties from acoustic receptions in the water column is ... more Inversion of ocean bottom geoacoustic properties from acoustic receptions in the water column is a nonlinear inverse problem that is inherently unstable and nonunique. One common approach to stabilizing this problem is to assume that the ocean bottom is made up of a small number of layers. The solution from this approach does allow one to reproduce the scattered sound field if all the other experiment parameters such as frequency and geometry are also reproduced. However without extensive prior information about that ocean bottom, this approach yields only one of many equivalent nonunique solutions and may not accurately describe the actual ocean bottom itself. An alternate approach, which may allow one to reuse the results later with a different frequency or geometry, is to use the tools of geophysical continuum inversion to specify the degree of nonuniqueness by quantifying both the uncertainty and limited resolution of the continuum bottom solution. This work compares inversion uncertainty and resoluti...
The Journal of the Acoustical Society of America, 2000
The amplitudes of the propagating acoustic modes associated with T‐waves decay exponentially belo... more The amplitudes of the propagating acoustic modes associated with T‐waves decay exponentially below their ray equivalent turning points, and cannot be excited directly by an earthquake. The modal decomposition for a T‐wave producing earthquake that occurred near the western tip of the Blanco TFZ has been computed. The directly excited higher order modes are characterized by relatively large amplitudes in the ocean crust, significant water‐borne components, and often strong interface components at the ocean‐bottom boundary. Employing the modal scattering theory of Park and Odom (1999), it is found that energy has been transferred from higher order modes to the Stoneley fundamental and the lower order modes have significant amplitude at the water‐bottom interface. Scattering from irregular ocean bottom bathymetry is the mechanism for the energy transfer. The lowest order acoustic modes, modes 1 and 2, are only very weakly excited because they have very small amplitudes at the bottom. This is consistent with the interpretation of de Groot‐Hedlin and Orcutt (1999). [Work supported by the NOPP Program and ONR.]
The Journal of the Acoustical Society of America, 2011
The shallow water environment may be highly variable, with both range dependence and anisotropy a... more The shallow water environment may be highly variable, with both range dependence and anisotropy almost ubiquitous in the seafloor bottom/sub‐bottom regions. Some common causes of range dependence include marine‐sediment composition, non‐planar boundaries, rough surfaces, strong density, or velocity contrasts, and variation in water‐column depth and/or sediment‐cover thickness. Common causes of elastic anisotropy are compositional layering or vertically aligned cracks. There is an apparent trade‐off between anisotropy and range dependence, and difficult to separate the two effects in a propagating signal. If the symmetry axis of a compositionally layered sediment is not exactly normal to the seafloor, the seismo‐acoustic wave field has particle‐motion polarizations in all three coordinate directions. Even in a one‐dimensional medium, an explosion source excites sediment particle motion with all three polarizations. Assuming sediment isotropy when it is not justified can cause errors in layer‐thickness comp...
The Journal of the Acoustical Society of America, 2009
Elastic anisotropy is a nearly ubiquitous feature of marine sediments. The simplest type of sedim... more Elastic anisotropy is a nearly ubiquitous feature of marine sediments. The simplest type of sediment anisotropy is transverse isotropy, characterized by five elastic constants, and results from layered deposition. A modal scattering theory for volume perturbations of the sediment elastic moduli is presented. The scattering theory is based on the coupled mode formulation for propagation in range dependent fluid‐elastic media. The Born approximation is employed to derive a modal scattering matrix. Although the perturbations of the elastic moduli are random, they may not be arbitrary in the sense that certain symmetry and energy constraints among the moduli must be respected. Mode‐mode coupling matrices are computed for quasi‐P‐SV‐SH seismo‐acoustic modes, which show mode mixing and the importance of non‐nearest neighbor interactions. The effects of volume scattering can be combined with rough surface scattering and also incorporated into mode coupling caused by deterministic range dependence of the material...
The Journal of the Acoustical Society of America, 2013
ABSTRACT An important generating mechanism for received underwater acoustic and seismic signals a... more ABSTRACT An important generating mechanism for received underwater acoustic and seismic signals are buried or earth-bound sources. Most underwater acoustic studies involve purely compressional sources in the water column. The more complicated case of a coupled shear and compressional seismic source in the sediment has recently been implemented in an elastic parabolic equation solution [Frank et al., J. Acoust. Soc. Am. 133]. In this talk, generic seismic sources including those giving shear field contributions, are contrasted in normal mode and parabolic equation solutions. Scenarios considered are for an elastic-bottom Pekeris waveguide and a canonical Arctic propagation scenario with an elastic ice cover over the ocean and an elastic basement. For the Arctic case, the source is allowed in either the ice cover or in the elastic bottom. Solutions are benchmarked for purely compressional and shear seismic sources, and their relation to the seismic moment tensor is discussed. The ultimate goal of these solutions is to allow for seismic sources capable of representing generic geophysical events.