[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-657851-105":59,"doc-detail-657851-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","seismic-wave-propagation-and-earth-models-chapter-2-introduction","Seismic Wave Propagation and Earth models - Chapter 2 - Introduction","","Seismic wave propagation and Earth modeling are presented as the basis for interpreting observations from seismological stations and networks. The chapter contrasts theoretical depth with a more phenomenological approach, focusing on identifying seismic wave types, travel-time curves, and links to Earth velocity structure and observed amplitudes. It also explains how travel-time and amplitude-distance relationships support earthquake source location and magnitude estimation, and how accuracy depends on commonly used 1-D versus more realistic 2-D and 3-D Earth models, including considerations for synthetic seismogram assumptions.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/seismic-wave-propagation-and-earth-models-chapter-2-introduction/657851/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/seismic-wave-propagation-and-earth-models-chapter-2-introduction/657851.png","ImageObject",300,407,{"name":92,"@type":93},"Theodore","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-29","2026-10-26",true,{"@type":102,"interactionType":103,"userInteractionCount":14},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What data are recorded at seismological observatories that enable Earth structure studies?","Question",{"text":112,"@type":113},"Seismic sensors record seismic waves radiated by seismic sources. Their presence in seismic records allows analysis of travel times and amplitudes to infer Earth properties.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"Why can seismic noise complicate waveform interpretation?",{"text":117,"@type":113},"Weak signals may be masked or significantly distorted by seismic noise. The chapter notes that in some applications noise can become a useful signal, but generally it is considered unwanted.",{"name":119,"@type":110,"acceptedAnswer":120},"How do Earth model assumptions affect source parameter estimation?",{"text":121,"@type":113},"Source estimates depend on the precision and accuracy of commonly used 1-D Earth models. Using more realistic 2-D or 3-D models and accounting for secondary phase onsets can improve the estimates.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},657851,1792992008,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":14,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":21,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":129,"read_time":143},7971461740886,"https://ap-avatar.wpscdn.com/davatar_3d24733baf745e90a7e4bdd5f77d97b2","CHAPTER  \n2  \nSeismic Wave Propagation and Earth models  \nPeter Bormann, Bob Engdahl and Rainer Kind  \n2.1 Introduction  \nThe key data to be recorded by means of seismic sensors (Chapter 5) and recorders (Chapter 6) at seismological observatories (stations – Chapter 7, networks – Chapter 8, arrays – Chapter 9) are seismic waves, radiated by seismic sources (Chapter 3) . Weak signals may be masked or significantly distorted by seismic noise (Chapter 4), which is usually considered disturbing and unwanted. Only in some special engineering-seismological applications is seismic noise also appreciated as a useful signal, from which some information on the structure, velocity and fundamental resonance frequency of the uppermost sedimentary layers can be derived (e.g. Bard, 1999) . But most of what we know today of the structure and physical properties of our planet Earth, from its uppermost crust down to its center, results from the analysis of seismic waves generated by more or less localized natural or man-made sources such as earthquakes or explosions (Figs. 3.1 to 3.4) . Either (repeatedly) solving the so-called forward (direct) or the inverse problem of data analysis (Fig. 1.1) achieves this.  \nIt is not the task of the New Manual of Seismological Observatory Practice (NMSOP), to provide an in-depth understanding of the theoretical tools for this kind of analysis. There exist quite a number of good introductory (Lillie, 1999; Shearer, 1999) and more advanced textbooks (e.g., Aki and Richards, 1980 and 2002; Ben-Menahem and Singh,1981; Bullen and Bolt, 1985; Dahlen and Tromp, 1998; Lay and Wallace, 1995; Kennett, 2001), and a variety of special papers and monographs related to specific methods (e.g. Fuchs and Müller, 1971;Červený et al., 1977; Kennett, 1983; Müller, 1985; Červený, 2001), types of seismic waves (e.g., Malischewsky, 1987; Lapwood and Usami, 1981) or applications (e.g., Gilbert and Dziewonski, 1975; Sherif and Geldart, 1995) . Rather, we will take here a more phenomenological approach and refer to related fundamentals in physics and mathematical theory only as far as they are indispensable for understanding the most essential features of seismic waves and their appearance in seismic records and as far as they are required for:  \n• identifying and discriminating the various types of seismic waves;  \n• understanding how the onset-times of these phases, as observed at different distances from the source, form so-called travel-time curves;  \n• understanding how these curves and some of their characteristic features are related to the velocity-structure of the Earth and to the observed (relative) amplitudes of these phases in seismic records;  \n• using travel-time and amplitude-distance curves for seismic source location and magnitude estimation;  \n• understanding how much these source-parameter estimates depend on the precision and accuracy of the commonly used 1-D Earth models (see IS 11.1);  \n2. Seismic Wave Propagation and Earth models  \n• appreciating how these source parameter estimates can be improved by using more realistic (2-D, 3-D) Earth models as well as later (secondary) phase onsets in the processing routines; and  \n• being aware of the common assumptions and simplifications used in synthetic seismogram calculations that are increasingly used nowadays in seismological routine practice (see [2.5.4.4](2.5.4.4), 2.8, 3.5.3) .  \n2.2 Elastic moduli and body waves  \n2.2.1 Elastic moduli  \nSeismic waves are elastic waves. Earth material must behave elastically to transmit them. The degree of elasticity determines how well they are transmitted. By the pressure front expanding from an underground explosion, or by an earthquake shear rupture, the surrounding Earth material is subjected to stress (compression, tension and/or shearing) . As a consequence, it undergoes strain, i.e., it changes volume and/or distorts shape. In an inelastic (plastic, ductile) material this deformation remains while elastic behavior means","cbCaih0nw3z5nilM","https://ap.wps.com/l/cbCaih0nw3z5nilM","pdf",11824256,"English","# 2.1 Introduction\n## Key data recorded by seismic sensors and records\n## Phenomenological approach and essential features\n# 2.2 Elastic moduli and body waves\n## Elastic moduli\n## Hooke’s law and elastic-to-inelastic behavior","[{\"question\":\"What data are recorded at seismological observatories that enable Earth structure studies?\",\"answer\":\"Seismic sensors record seismic waves radiated by seismic sources. Their presence in seismic records allows analysis of travel times and amplitudes to infer Earth properties.\"},{\"question\":\"Why can seismic noise complicate waveform interpretation?\",\"answer\":\"Weak signals may be masked or significantly distorted by seismic noise. The chapter notes that in some applications noise can become a useful signal, but generally it is considered unwanted.\"},{\"question\":\"How do Earth model assumptions affect source parameter estimation?\",\"answer\":\"Source estimates depend on the precision and accuracy of commonly used 1-D Earth models. Using more realistic 2-D or 3-D models and accounting for secondary phase onsets can improve the estimates.\"}]","Seismic Wave Propagation and Earth models - Chapter 2 - Introduction | PDF",176]