body waves and surface waves pdf

1 0 obj /Resources 49 0 R /ProcSet [ /PDF ] Earthquakes radiate seismic energy as both body and surface waves. As a longitudinal compressional waveform, P-waves move in the same way as sound waves. The first type of body wave is called the primary wave or pressure wave, and is commonly referred to as P-waves. /BBox [0 0 362.8347 272.1261] ��5�Z!YV�,U��;��d&�_�@�Azxx��33��o��{�� 篷��?��o�}��z��-��x�i|�>�[�c��~����_�ߎ/��*}��y�s��yh��^�p#��_�g��m��|ϓeW��b��7��R��vy/-}�r��7��VF��w�;�+(3��|��|�y\��^��Aw��뼑7�5u�=o��/��^��K��͏��J9�{;#��0�ϓ��8_��c��@[#O.f��v=/�3�\�z"��W��o��r�sȥ}�yM1��Q{�!c{z�V��g��7��>��c�F�>62�9�ӽ��8�Θü�*�'�N��o�9`s�w��1�\��C_b+7�/��`�@��8�yc��ہ1��y��|��G��lp�$��Zϴ�9�u��g�9ͳG��8[��2��v>�vB�ٽ=��8+L��Q�;6�5�n��@�?�l�cF��덽��s��g��U�ٲ)5̩Չ��c��Г+O0��u��C¢΋��3��\�s>y�ɜ�`?py.~�o؈��?��*@݁��t�ֵ��s��ɸ��,��J��(�4 �wO#��V��꿾��0J:K?��/�w��3��3�z�,�:�Y�. Body and surface waves Jascha Roedel, winter semester 2015/16 The term wave describes the spatial propagation of an oscillation or disturbance through a medium such as solid bodies, liquids or gases. t�=�}��`457�G�Q�D 4 0 obj /FormType 1 Body waves are of two types: Primary waves (also called P-waves, or pressure waves) and Secondary waves (S-waves, or shear waves). Body waves Introduction P- and S-waves are referred to as body waves because they are transmitted through the volume (or body) of the material, as apposed to travelling along the surface. 2001). /Subtype /Form When an earthquake occurs, some of the energy it releases is turned into heat within the earth. On the other hand, surface waves propagate only at the interface between two different media, like the interface between Earth and atmosphere (i.e. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 13 0 R] /MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 47 0 obj << persion characteristics of surface waves contained in strong motion data. Surface waves _____. /Filter /FlateDecode The rest of the energy, which is most of the energy, is radiated from the focus of the earthquake in the form of seismic waves. /Parent 46 0 R The first kind of body wave is the P wave or primary wave.This is the fastest kind of seismic wave, and, consequently, the first to 'arrive' at a seismic station. Two types of surface waves, known as Love waves … /Length 15 /Trans << /S /R >> Both types of body waves are non-dispersive (in purely elastic media). free surface waves we need to understand the boundary conditions on the free surface, any bodies under the waves, and on the sea floor: –Pressure is constant across the interface –Once a particle on the free surface, it remains there always. 14 0 obj << /ProcSet [ /PDF ] Body waves can propagate into the interior of the corresponding medium, whereas surface waves are concentrated along the surface of the medium. >>>> 11 0 obj /ProcSet [ /PDF ] endobj Surfaces wave energy (amplitudes) decay with distance as 1 / r Body wave energy decays as 1 / r2 So at a given distance, which will have more energy ? /PTEX.FileName (./figs/anulogo.pdf) P WAVES The … �&��Vc`�l)S��0@eT�,\L\YsE�ڼ�z��%��x�#��_;_iO��� endobj 19 0 obj << x��}In.Kvޜ�� forward and back-scattered surface waves; and (3) body-to-surface scattered waves (Figure 1). x��XYo7~ׯ��,�o � Ҥ�\E�A��N��~C�r�d iz ��%=3��"9��L�#� << /S /GoTo /D [12 0 R /Fit ] >> /R 22050 Types. /Resources 48 0 R Real-time analysis of earthquakes can be stream /Matrix [1 0 0 1 0 0] Thereby, waves do appear in various forms and differ in their characteristics. /Length 15 This type of seismic body wave travels at the greatest velocity through the ground. BY JOHN V. WEHAUSEN and EDMUND V. LAITONE l With 56 Figures. /Shading << /Sh << /ShadingType 3 /ColorSpace /DeviceRGB /Domain [0.0 7.99997] /Coords [7.99997 7.99997 0.0 7.99997 7.99997 7.99997] /Function << /FunctionType 3 /Domain [0.0 7.99997] /Functions [ << /FunctionType 2 /Domain [0.0 7.99997] /C0 [0.4375 0.375 0.3125] /C1 [0.4375 0.375 0.3125] /N 1 >> << /FunctionType 2 /Domain [0.0 7.99997] /C0 [0.4375 0.375 0.3125] /C1 [0.875 0.75 0.625] /N 1 >> ] /Bounds [ 3.99998] /Encode [0 1 0 1] >> /Extend [true false] >> >> As discussed all earthquakes are relatively shallow, with the deepest at about 700 km depth. Among the many types of seismic waves, one can make a broad distinction between body waves, which travel through the Earth, and surface waves, which travel at the Earth's surface. 9 0 obj << /Type /XObject >> endobj The solution was updated twice in three days. 17 0 obj << endobj In order to determine an exact equation for the problem of free surface gravity waves we will assume potential theory (ideal °ow) and ignore the eﬁects of viscosity. /Matrix [1 0 0 1 0 0] /Matrix [1 0 0 1 0 0] @QW�N�;:r��g�w��V��K#�i�Z��K,z��K쌗��Y�Vr��ܹ��%�$��آ��>�w�:L��fm�M�2��w��r�Gn��8a��jZ'N��&�m��1X��l��S��\��l�H��~��ZR?T� �Y�a 2 0 obj stream formulation used for body waves, except that the surface wave ‘‘ray’’ has a sensitivity that is very wide in depth (Figure 1). �~6��dVz�&�Z�Y�� d�3�݋�W��2��*�19˅��nU>�2-ޓ M:%��6P�x@��N��m@��e�\�y��ǫ'3��&�f��aZ�a~�|��뗯��2��ꦭώ2�*:Q��B�y� then constrained using both broadband body waves and long period seismic waves. <> These waves cause shaking that is felt, and cause damage in various ways. kinds of body waves, and two kinds of surface waves. /Length 8 P-waves are able to travel through both sol… Recent forays into the joint inversion of surface waves and body waves from portable arrays (e.g., Friederich, 2003; van der Lee et al., 2001b; West et al., 2004a), are mostly in an embryonic stage, but hold promise of major improvements in imaging with further development. Some of the energy is expended in breaking and permanently deforming the rocks and minerals along the fault. x��P(�� endstream –No flow through an impervious boundary or body. >> endobj Body waves are of two types: compressional or primary (P) waves and shear or secondary (S) waves. 48 0 obj << =��Q�d'�D��xy��d�RBr�Z0�IP��`e��:�mxXK��.��(*9��9��7�,��&M�� |�P4�2�a�i9�h�� ax�7�T7�N7۩QX�l�Q�8�U��&�i��~��h�E�$�`��.�#�,]l��-��t��U �`̬8b��;SIa�3o~�M��dC� �uu��/¢�.UУ��-=�:%��8�S�A�m�q=l)�$��#&�[��2�a�T3��ʬ /Type /XObject • Surface waves propagate at a speed lower than body waves and are recorded after the P and S waves. Seismic Waves is an on-line program which illustrates . <>>> endobj Unlike body waves, surface waves are strongly dispersed in the Earth, having phase and group velocities that depend on frequency. >> >> /Filter /FlateDecode t�5�O�n�(�Te��m!4「"]�Uͫ��)�e*�j��bW�Ձ��=��c/�]J��ħ]�T��/ݤ��G�*�U��J�R��!RQ�Ń�E�p��$xi�ZiP��$�'}2d^��XԀVW)�Q�n0芊�:��o��l��VnB�GZ�҇�KZ�N��.�1l0 Ҫ�� lC#��~�4[Nj�%.� h��#�+4�C��h�F�{:�%j�� ߡݞ��@#z�#�h��q#-h�S��`�H��ң1�іq��̶]]%�∲@�Y�m�%u��6-T�oj¡�ᒁ��uTt�5v6P9�rLWY�}9/��Ui�pԘ.��AҨ�F��"R�]��Q��G�?��OHuxD�N�qa�� na��ަ��īc��J�07�wG��t��}!6�Je��x�-#P=��"x��N��>>C�� ,a_��C. /ProcSet [ /PDF ] >> how waves propagate from an earthquake hypocenter to seismic stations across the globe. This generally causes the worst damage because the wave motion rocks the foundations of manmade structures. As you might imagine, only body waves can give us any information about the deep interior of the Earth. /Length 54 0 R Surface waves are typically generated when the source of the earthquake is close to the Earth’s surface. endobj waves together to the ﬁnite fault source study. /R7 53 0 R 12 0 obj << 3 0 obj Although they move even more slowly than S-waves, they can be much larger in amplitude and are often the most destructive type of seismic wave. stream /FormType 1 Because the volumes explored by surface and body waves are signi cantly di erent, the knowledge of stream x��P(�� endstream It pushes and pulls the rock it moves through just like sound waves push and pull the air. These waves are of a higher frequency than surface waves. A general endobj Surface waves are something like the waves in a body of water: They move the surface of the earth up and down & right and left. /PTEX.InfoDict 51 0 R These waves are similar in many important ways to the familiar waves in air generated by a hand-clap or in water generated by a stone thrown into water. /Resources 47 0 R <> ��٘�M��׎&M'Q�%ȵ�v8��.>��0��Z� iqH�ȕ�m�[>�Ѱ��j�t�֨��(�)�v��(H��k�&��a %PDF-1.5 Surface waves are the slowest moving of all waves, so the most intense shaking usually comes at the end of an earthquake. Other articles where Body wave is discussed: seismic wave: …elastic waves; two, known as body waves, travel within the Earth, whereas the other two, called surface waves, travel along its surface. P waves are also known as compression waves. Surface Waves. a. travel more rapidly than body waves b. produce most of the damage to buildings during earthquakes c. are the first waves initially produced in an earthquake d. are the first waves to arrive at a seismograph station after an earthquake ____ 65. >> endobj {:ľ?�v��XǸ��B�n_�Y�\��nl�5x��0͌�t��tH�+��p�.,�V�djC��[��]�O��W��CV�u� 50 0 obj << stream /Type /XObject /Type /XObject ��q��vm�x��oP�k�]�n\Ť�6��|ǯv��އ�Miќiٰ�(��`��5J'��~�J �فyn��^�?ص_ff;�� N�5��"#̾tZ�m�JØ�$�vd��YQ��V��nh�E��aaqc�s=��v S� �E�B�riA�yN�$�� ]��4��Ri5��sV��?�� j�ȟk�v&e��װ3:d8�'�ہ��LH2drLh��i�"w�=�ТL�&�E�;�(�ߤ��!Zjy�V�P�Ty�bI�AL�a��T �`҃�yg�%�O7�{��9�'�i ��v��F�Z��v��F��b0��D�B�(�u��W�� N��B �Z��ЁCg��+X`�$� o_�߁n��Gw�ĤÙ�PM�3�C��'l!6��+H�q^��-�g4�llxr�%�M�[캧B�V �A��Yoe��p.�ȥ�Gހ�m�TS4��l�o��4��-��|_��y�xG� �e��!�7��Tk��垩�֢ �3@|�3��>�"�{" /Resources 18 0 R /Resources << $��獶!��az�s�[?zbr�Ǧ��D�Xރ�A�P��\��Q�,��W ��ɶ;?��$*"b}�Rt�䢌�s��;��:$o,�HH ��?Gf��eb��E"��eL�6�($K�8k|��[.-n�(�Xn`�.^��ί��-pxs1e)��|��C�d�P�ȱP ��,*��%�1��+�%��뇼��#Y�c�� s&"Wd�0\��94B#�O��M63�c��6V �a��܁��=!��E�(�rZ��e�.��G�wd� ��Cbv�y@��cK��dh�#��g6��)�du��(�� `�C�dC�x�N�o �^B /FormType 1 /Filter /FlateDecode >> P- and S- waves are called \"body waves\" because they can travel through th… x��P(�� endstream /Resources 50 0 R �a�r�$�^��l��vVic�Owo?gʧ��1Sv��YJ�D��vT�n5��&�=�"]6�bO �s7�@�$ ��H��P�%9�j�$��I�|�[o�w��(�]�Ӿ�2��}��[׵��H^��h�\ �7W 2��~��/��d�~��m��ȬW�e��hq��L��L��n��u��vQ��]�,��F'��s��ǄZiqH�cH�{��N��q:)��{�?��Sendstream /Type /XObject Much of the motivation for joint inversion derives from two factors. >> /FormType 1 endobj As their name suggests, surface waves travel just below the surface of the ground. �;f e1�2�j�!P��b�m'dq)��k��RH��b�x�:A�G�s"8M3͓�Cg As they spread out, they alternately push (compress) and pull (expand) the ground as they move through it. /BBox [0 0 850.3937 8] stream These oscillations are generated by strong earthquakes. Our preferred model, which based on the MDC fault plane, local JMA hypocenter and calibrated alignments of body and surface waves, revealed a complex rupture process. moment-tensor inversion using regional surface waves. /PTEX.PageNumber 1 Body waves travel through the interior of the Earth. Surface waves usually have larger amplitudes and longer wavelengths than body waves, and they travel more slowly than body waves do. In view of its advantage during the study of the 2004 Sumatra-Andaman island earthquake (Ammon et al., 2005), we had developed a quick algorithm to routinely monitor global large earth-quakes by joint inverting body and surface waves. /Shading << /Sh << /ShadingType 2 /ColorSpace /DeviceRGB /Domain [0.0 7.99997] /Coords [0 0.0 0 7.99997] /Function << /FunctionType 3 /Domain [0.0 7.99997] /Functions [ << /FunctionType 2 /Domain [0.0 7.99997] /C0 [0.875 0.75 0.625] /C1 [0.4375 0.375 0.3125] /N 1 >> << /FunctionType 2 /Domain [0.0 7.99997] /C0 [0.4375 0.375 0.3125] /C1 [0.4375 0.375 0.3125] /N 1 >> ] /Bounds [ 3.99998] /Encode [0 1 0 1] >> /Extend [false false] >> >> The rupture initiated slowly at a depth of 23 km. x��ZYo�F~7��!�}� ��#�,6X��b��Lˊe�#ʞ��ߪ�"%e`�0�}TWW}�U5��w߽��/��"I��췫��w�'��sU&�w�g,)��%��E!�JTy%��G��U�,��"Y�Sm�~>?��~�owIV�?n�L��U��t�?.��}�:��\��#,�K��k�J��}N��o��Il��T��e��W�D�A��lV��0O��l&��_��'>�S2��2Uc��o��`q��]�DzOg�Hu�� A��@}�4j�U��'�v�f"}6��n�Q�7q�`]�B�n�� waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. /BBox [0.00000000 0.00000000 129.00000000 53.00000000] \g��K�$[n&��D�2U#T�I5�"OO|��F��v��N��! In our model, the scattering mean free path of body waves is depth dependent as a consequence of the body-to-surface coupling. At longer lapse-time, the surface waves couple with body waves and the coda eventually reaches an equipartition regime when all the propagative surface and body wave modes are excited to equal energy (Weaver 1982; Hennino et al. /Filter /FlateDecode The various problems of fluid motion treated in this article have in common the property that the fluid is subject to a gravitational force. endobj >> S��W��ut�R�y��"��buXEh�}�촴kF�숟C�F��pGNF��Y��`. /BBox [0 0 8 8] • There are two types of surface waves: Rayleigh and Love waves. stream A. /BBox [0 0 16 16] /Length 1396 Surface waves on the Seismogram Surface waves are the largest amplitude signal on the wave train Surfaces arrive after the P and S waves, because they travel along the surface layers of the Earth where velocities are lower. x��P(�� endstream Seismic waves can be classified into two basic types: body waves which travel through the Earth and surface waves, which travel along the Earth's surface. /Filter /FlateDecode Those waves that are the most destructive are the surface waves which generally have the strongest vibration. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. stream fRi6g��ߤ�!�j J�.O��ʈR�� : 48–50: 56–57 Other modes of wave propagation exist than those described in this article; though of comparatively minor importance for earth-borne waves, they are important in the case of asteroseismology. A body wave is a seismic wave that moves through the interior of the earth, as opposed to surface waves that travel near the earth's surface. Surface waves Introduction As a result of geometric spreading in 2-D, the energy carried by surface waves decays with distance r from the source as 1/r; this is in contrast to 1/r2 for body waves, which is why they are usually much less prominent on a seismogram. /FormType 1 Multiscale adjoint waveform tomography for surface and body waves Yanhua O. Yuan 1, Frederik J. Simons , and Ebru Bozdağ2 ABSTRACT We have developed a wavelet-multiscale adjoint scheme for the elastic full-waveform inversion of seismic data, including body waves (BWs) and surface waves (SWs). /Length 15 %PDF-1.4 /R8 52 0 R 16 0 obj << • Surface waves propagate along a boundary surface. the surface of the Earth). /Shading << /Sh << /ShadingType 2 /ColorSpace /DeviceRGB /Domain [0.0 272.12549] /Coords [0 0.0 0 272.12549] /Function << /FunctionType 3 /Domain [0.0 272.12549] /Functions [ << /FunctionType 2 /Domain [0.0 272.12549] /C0 [1 1 1] /C1 [0.75 0.5 0.25] /N 1 >> ] /Bounds [] /Encode [0 1 ] >> /Extend [false false] >> >> >> /Matrix [1 0 0 1 0 0] (2) Ground strains caused by body and surface waves have been analyzed for original data and its separated body and surface waves. /Subtype /Form Waves propagate out from the epicenter along the surface on a three-dimensional view of the earth. P and S waves are body waves. endobj /Subtype /Form /Type /Page speciﬁc energy density of surface and body waves in a medium containing a homogeneous distribution of point scatterers. /ProcSet [ /PDF ] /Annots [ 20 0 R 21 0 R 22 0 R 23 0 R 24 0 R 25 0 R 26 0 R 27 0 R 28 0 R 29 0 R 30 0 R 31 0 R 32 0 R 33 0 R 34 0 R 35 0 R 36 0 R 37 0 R 38 0 R 39 0 R ] /Subtype /Form endobj /Length 15 10 0 obj << Free surface water wave problem. 15 0 obj << x� endstream /MediaBox [0 0 362.8347 272.1261] %�� 49 0 obj << Seismographs record the amplitude and frequency of seismic waves and yield information about the Earth and its subsurface structure. BODY WAVES Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. LINEAR FREE SURFACE WAVES FALL 2003 °c A.H. TECHET 1. From the point of view of the spatial concentration of energy, waves can be divided into body waves and surface waves. Seismic waves fall into two general categories: body waves (P-waves and S-waves), which travel through the interior of the earth, and surface waves, which travel only at the earth’s … >> endobj Introduction. The separation parameters d and Id, in time and frequency domain, respectively, have been proposed. /Filter /FlateDecode At the same time viewer can watch waves propagating through a cross-sectional view of the earth. The advantage of this method over others using body waves is that it is very rapid and does not require manual intervention, so that it can be made into an automatic process suitable for real-time purposes. /Subtype /Form �1��_��w�[I;��e��\�v�`��^ /Contents 19 0 R Free Surface Water Waves z x y y=h(x,y,t) or F(x,y,z,t) = 0 B(x,y,z,t) = 0 Figure 1. /ExtGState << >> endobj Body Waves The body waves propagate within a body of rock. earthquake; these are body waves and surface waves. /Matrix [1.00000000 0.00000000 0.00000000 1.00000000 0.00000000 0.00000000] • Surface waves are larger in amplitude and longer in duration than body waves. /Filter /FlateDecode /Shading << /Sh << /ShadingType 3 /ColorSpace /DeviceRGB /Domain [0.0 3.99998] /Coords [3.99998 3.99998 0.0 3.99998 3.99998 3.99998] /Function << /FunctionType 3 /Domain [0.0 3.99998] /Functions [ << /FunctionType 2 /Domain [0.0 3.99998] /C0 [0.4375 0.375 0.3125] /C1 [0.875 0.75 0.625] /N 1 >> ] /Bounds [] /Encode [0 1 ] >> /Extend [true false] >> >>