We will show that two types of solutions are possible, corresponding to compressional p and shear s waves, and we will derive the. The second type, or waves s, consists of wave propagation of shear, where the particles move in a direction perpendicular to the direction of propagation of the disturbance figure. In close connection with geophysical interior models, we analyze. Equations of motion and boundary conditions for the propagation of seismic waves in a nondispersive medium 30 4. Although considerable progress has been made in modelling and interpreting the complete seismic spectrum, much seismic interpretation still relies on ray theory and its extensions. I sh waves by rushan wu, shengwen jin, and xiaobi xie abstract the great advantages of oneway propagation methods, such as the generalized screen propagators gsp method, are the fast speed of computation, often. Propagation of seismic ground motion in the kanto basin. There are several types of seismic waves, often classified as body waves, which propagate through the volume of the earth, and surface waves, which travel along the surface of the earth. Propagation of seismic wave fields in layered media. For the numerical simulation of 2d earthquake dynamics, the spectral boundary integral equation code bimat is well suited for planar faults in homogeneous and bimaterial media, and the spectral element code sem2dpack is well suited for nonplanar faults in heterogeneous or nonlinear media.
Source and field experiments the nevada infrasound array nviar, located near the village of mina, nevada, is a fourchannel infrasound array with an aperture of approximately 1 km figure 2, embedded in the nevada seismic array nvar, a permanent international monitoring system array. In this work, an effective technique for the measurement of seismic wave propagation velocity in the real geological medium is presented. Modelling seismic wave propagation for geophysical imaging 3 in the entire domain or at the scale of an elementary element of a given mesh describing the medium structure. To understand the propagation of elastic waves we need to describe kinematically the deformation of our medium and the resulting forces stress. Every point on the wave front is a source of a new wave that travels out of it in the form of spherical shells. In a 2d environment, this sh motion is completely decoupled from the other types of seismic wave propagation. These are meant to be introductory and are abbreviated versions of topics in my book linear and nonlinear waves, which can be consulted for ampli. Kayniaa, zhao chengd anorwegian geotechnical institute, p. Surface waves, by contrast, may be highly dispersive. Propagation of seismic waves theoretical background. The wave energy can be recorded many kilometers from the source even if. Basic relations and notions of the theory are given for general cases of the anisotropy of a medium.
An example from northern taiwan by shiannjong lee, dimitri komatitsch, borshouh huang, and jeroen tromp abstract topography influences ground motion and, in general, increases the am plitude of shaking at mountain tops and ridges, whereas valleys have reduced ground. Seismic wave propagation in stratified media presents a systematic treatment of the interaction of seismic waves with earth structure. The key idea is to map each of the six sides of a cube to the surface of the sphere. The propagation of lg waves in complex media can be described either by means of a modal superposition scheme with numerical integration through the heterogeneity or by using ray diagrams. Wave motion is one of the wellknown scientific concepts. Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. Body waves transmit through media with continuously varying seismic properties. It is not the task of the new manual of seismological observatory practice nmsop. Types of seismic waves there are several different kinds of seismic waves, and they all move in different ways. Seismic wave propagation and scattering in heterogeneous. The records allow the visualization of the propagation of longperiod ground motion in the basin and show the refraction of surface waves at the basin edge.
Pdf seismic waves generated both by natural earthquakes and by manmade sources have produced an enormous amount of information. This page intentionally left blank iu jeofizik kulubu. On longitudinal waves in two contacting media 35 5. Information on teaching about seismic waves and demonstrations of seismic wave characteristics using a. An earthquake is started at the source x after which the signal spreads out. Mar 17, 2011 the world was shocked by the news of massive earthquakes and devastating tsunamis in japan. It is on water waves, with special emphasis on old and new results for waves on a sloping beach. Seismic wave propagation, volume waves onda p, s wave and surface waves love and rayleigh seismic wave propagation. To study the vertical propagation of the triggered stadsstids, measurements of seismic waves at tato, infrasonic waves at nk, magnetic. A teachers guide designed to introduce the concepts of waves and seismic waves that propagate within the earth, and to provide ideas and suggestions for how to teach about seismic waves. The seismic waves with the largest ground amplitude are the surface waves and especially the rayleigh waves.
Pressure waves pwave or shear waves sh or svwaves are phenomena that were first characterized within the field of classical seismology, and are now considered fundamental concepts in modern seismic tomography. In other words, the speed of propagation is independent of frequency or wavenumber. Seismic waves typically travel in the ground at 27 kms. The emphasis is on the propagation of seismic waves in realistic earth models, and the way in which this can be understood in terms of the re. For comparison, sound travels in air at approximately 0. Presented in two parts, this book takes an analytical approach on the subject and emphasizes new ideas and applications used today. Seismic wave propagation in icy ocean worlds arxiv. The second type, or waves s, consists of wave propagation of shear, where the particles move in a direction perpendicular to the direction of propagation of the disturbance figure b. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and. Seismic wave, vibration generated by an earthquake, explosion, or similar energetic source and propagated within the earth or along its surface.
Presenting a comprehensive introduction to the propagation of highfrequency, body waves in elastodynamics. Despite some similarities which water waves and seismic surface waves. It is based upon a weak formulation of the equations of motion and combines the. Seismic wave propagation and earth models gfzpublic. Behavior of the waves on the water surface, as well as propagation of acoustic or light waves are. Although considerable progress has been made in modelling and interpreting the complete seismic spectrum, much seismic. Similar waves, which are generated by earthquakes, artificial explosions and analogous sources, and prpagate along the earths surface, are referred to as seismic surface waves.
Information on teaching about seismic waves and demonstrations of seismic wave characteristics using a slinky are provided at. This is the velocity at which the energy moves, not the particles themselves. Pdf modelling seismic wave propagation for geophysical. The major topics in this book cover aspects on seismic wave propagation, characteristics of their velocities and attenuation, deformation process of the earths medium, seismic source process and tectonic dynamics with relating observations, as well as propagation modeling of seismic waves. Such a wave may have a length of hundreds of kilometres and a period on the order of a quarter of an hour. Propagation of seismic waves through liquefied soils. Codes for wave propagation and earthquake dynamics. The general theory of propagation of seismic wave fields of signal type is presented in a mathematically precise and physically descriptive form. Box 3930 ullevaal stadion, n0806 oslo, norway bdepartment of civil and environmental engineering, university of california, davis, ca 95616, usa cdepartment of mechanics, national technical university of athens. Modelling seismic wave propagation for geophysical imaging 10 willbesetbyintech from a maximum value. Seismic wave propagation and scattering in the heterogeneous. Finally, a series of theoretical seismograms for a layered halfspace showing the variation of the surface waves as a function of.
The world was shocked by the news of massive earthquakes and devastating tsunamis in japan. The celerity figure 4 was used to identify the nature of. Pekeris 1948 studied the excitation and propagation of guided waves in a. The refracted wave does not travel directly from the. A principal difference among p, sv, and sh wavefields is the manner in which they cause rock particles to oscillate. Due to this, it is necessary to evaluate the propagation of the seismic wave front between the different points in the ground. Psv motion, where the particles would move in the plane of the screen. Viscous seismic wave propagation simulation by using fractional order equation has attracted much recent attention. Seismic waves these are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. 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. We present a concise naming scheme for seismic waves and an overview of the features of the seismic wave eld on europa, titan, ganymede and enceladus. 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. Earthquakes generate four principal types of elastic waves.
They are the energy that travels through the earth and recorded on seismographs. The propagation of highfrequency, body waves or rays in elastic media is crucial to our understanding of the interior of the earth at all scales. However, conventional finitedifference fd methods of fractional partial difference equation adopt a global difference operator to. They are the energy that travels through the earth and is recorded on seismographs. Seismic wave propagation in stratified media anu press. Finally, a series of theoretical seismograms for a layered halfspace showing the variation of the surface waves as a function of depth and of the density in the lower medium is presented. This volume contains an extensive presentation of the theory, phenomenology and interpretation of seismic waves produced by natural and artificial sources. Seismic wave propagation in icy ocean worlds simon c. Seismic wave propagation in the earth sciencedirect. We will show that two types of solutions are possible, corresponding to compressional p and shear s waves, and we will derive the equations for their velocities that we presented in the last chapter.
Pdf the seismic records from significant earthquakes are profoundly affected by 3d variations in crustal structure both in the source zone itself and. Seismic waves and earthquake location earthquake science center. Seismic wave propagation is a ground motion phenomenon that relates to the passage of body waves, including compression waves and shear waves, radially from the source of earthquake energy release hypocenter into the surrounding rock and soil medium. Tables 1 and 2 gives the origin times, travel times, celerity, and phase velocity of the observed arrivals for 2006 and 2007, respectively. Interface waves are found when the physical parameters lie both inside and outside the region determined by the stoneley equation.
Further information on seismic waves, wave propagation in the earth, and visualizations of seismic waves can be found in bolt 1993, p. During the seismic waves propagation, the front of the waves. Seismic wave propagation and scattering in heterogeneous crustal waveguides using screen propagators. One of the most methodical treatments of electromagnetic wave propagation, radiation, and scatteringincluding new applications and ideas. Presenting a comprehensive introduction to the propagation of highfrequency, bodywaves in elastodynamics. Propagation of seismic waves caused by underwater infrasound. The seismic wave equation using the stress and strain theory developed in the previous chapter, we now construct and solve the seismic wave equation for elastic wave propagation in a uniform whole space. Kennett title page contents jj ii j i page 3 of 497 back full screen close quit rs s e anu 2 coupled equations for seismic waves 46. Propagation of elastic waves in layered media by finite.
Pdf propagation of seismic waves away from earthquakes. Lorenzx, martin van driel, tarje nissenmeyer, sharon kedar z november 20, 2017 seismology was developed on earth and shaped our model of the earths. These two types of waves can propagate through the interior of the earth and we will refer to them as waves of volume. We present a concise naming scheme for seismic waves and an overview of the features of the seismic wavefield on europa, titan, ganymede. The event could easily be one of the most tragic natural disasters in recent history. The method is implemented using mpi on a large pc cluster beowulf with 151 processors and 76 gb of ram. Pressure waves pwave or shear waves sh or sv waves are phenomena that were first characterized within the field of classical seismology, and are now considered fundamental concepts in modern seismic tomography. The earthquake depth is 600 km and the focal mechanism has a dip of 45 degrees, a slip of 0 degrees, and strike perpendicular to the direction of propagation. Each theoretical topic discussed in the book is presented in a selfcontained and mathematically rigorous form, yet without excessive demands on the readers mathematical background. Schmidts experiment and the theory of characteristics 25 3. The relation between deformation and stress is governed by elastic constants. Seismic wave propagation an overview sciencedirect topics.
In particular, the properties of plane and spherical waves at interfaces are described. Modeling of seismic wave propagation at the scale of the. Seismic waves can be generated by a sudden release of energy such as an earthquake, volcanic eruption, or chemical explosion. Seismic rays are used instead of the wave front to describe the wave propagation. Measurement of the seismic wave propagation velocity in the given geological area is of the fundamental importance for determination of the source location. Seismic waves waves in elastic continuum in isotropic media a model of the medium through which the waves propagate body waves in isotropic media. Introduction to the theory of seismic wave propagation indico. The vertical propagation of disturbances triggered by. Modelling seismic wave propagation for geophysical imaging. The analytical solution to this problem exists and is well known. Pdf propagation of seismic waves through liquefied soils. An increase in element size, to adapt it to the variations of wave speed with depth, can be obtained by.