[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-657846-105":59,"doc-detail-657846-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","information-sheet-is-111-earthquake-location-single-station-location","Information Sheet IS 11.1 - Earthquake location - Single station location","","Earthquake location is presented as the determination of hypocenter coordinates (x0, y0, z0) together with origin time t0, and the conversion of this source information into epicenter estimates on Earth’s surface. The material contrasts practical location from arrival-time methods (often high-frequency P waves) with centroid locations from moment-tensor inversion of long-period waves. It then details single-station 3-component location using P-wave polarization, deriving backazimuth, incidence angle, and apparent parameters from component amplitudes and digital coherence approaches.",{"@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":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/information-sheet-is-111-earthquake-location-single-station-location/657846/",{"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/information-sheet-is-111-earthquake-location-single-station-location/657846.png","ImageObject",300,407,{"name":92,"@type":93},"Aria","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 does earthquake location determine in practical seismology?","Question",{"text":112,"@type":113},"It determines the hypocenter, given by x0, y0, z0 (longitude/latitude and depth), and the origin time t0, the start time of the rupture.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How is backazimuth obtained using a single 3-component station?",{"text":117,"@type":113},"Using P-wave motion polarization: vertical and radial/radial-amplitude relations give the arrival backazimuth, with a 180° ambiguity resolved by the vertical component first-motion polarity.",{"name":119,"@type":110,"acceptedAnswer":120},"Why do arrival-time locations differ from centroid locations?",{"text":121,"@type":113},"Arrival-time catalogs commonly use high-frequency P-wave times, while centroid locations represent average time and location of the full energy radiation derived from moment-tensor inversion of long-period waves.","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},657846,1793066067,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"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":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":145},2336464648322,"https://ap-avatar.wpscdn.com/avatar/2200025388227c56fec?_k=1778556882303663488","Information Sheet IS 11.1  \n\n| Topic | \u003Cbr>Earthquake location |\n| --- | --- |\n| compiled by | Jens Havskov, University of Bergen, Department of Earth Science, Allégaten 41, N-5007 Bergen, Norway, Fax: +47 55 583660,\u003Cbr>E-mail: [j](jens@geo.uib.no)[ens@geo.uib.no](jens@geo.uib.no)\u003Cbr>Peter Bormann, GeoForschungszentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany; Fax: +49 331 288 1204; [E-mail:](E-mail: pb65@gmx.net)[ ](E-mail: pb65@gmx.net)[pb65@gmx.net](E-mail: pb65@gmx.net)\u003Cbr>Johannes Schweitzer, NORSAR, P.O.Box 53, N-2027 Kjeller, Norway, Fax: +47 63818719,\u003Cbr>E-mail: johannes@norsar.no |\n| Version | October, 2002 |\n\n1 Introduction  \nThe exact location of a source, radiating seismic energy, is one of most important tasks in practical seismology and from time to time most seismologists have been involved in this task. The intention here is to describe the most common location methods without going into the mathematical details, which have been described in numerous textbooks and scientific papers but to give some practical advice on earthquake location.  \nThe earthquake location is defined by the earthquake hypocenter (x0, y0, z0) and the origin time t0. The hypocenter is the physical location, usually given in longitude (x0), latitude (y0), and depth below the surface (z0 [km]). For simplicity, the hypocenter will be labeled x0, y0, z0 with the understanding that it can be either measured in geographical or Cartesian coordinates, i.e., in [deg] or [km], respectively. The origin time is the start time of the earthquake rupture. The epicenter is the projection of the earthquake location on the Earth’s surface (x0, y0) . When the earthquake is large, the physical dimension can be several hundred kilometers and the hypocenter can in principle be located anywhere on the rupture surface. Since the hypocenter and origin time are determined by arrival times of seismic phases initiated by the first rupture, the computed location will correspond to the point where the rupture initiated and the origin time to the time of the initial rupture. This is also true using any P or S phases since the rupture velocity is smaller than the S-wave velocity so that P-or S-wave energy emitted from the end of a long rupture will always arrive later than energy radiated from the beginning of the rupture. Standard earthquake catalogs (such as from the International Seismological Center, ISC) report location based primarily on arrival times of high frequency P waves. This location can be quite different from the centroid time and location obtained by moment-tensor inversion of long-period waves. The centroid location represents the average time and location for the entire energy radiation of the event.  \nInformation Sheet IS 11.1  \n2 Single station location  \nIn general, epicenters are determined using many arrival times from different seismic stations and phases. However, it is also possible to locate an earthquake using a single 3-component station. Since the P waves are vertically and radially polarized, the vector of P-wave motion can be used to calculate the backazimuth to the epicenter (see Figure 1) . The radial component of P will be recorded on the 2 horizontal seismometers N(orth) and S(outh) and the ratio of the amplitudes AE/AN on the horizontal components can be used to calculate the backazimuth of arrival AZI (elsewhere in the Manual abbreviated as BAZ):  \nAZI = arctan AE/AN (1)  \nThere is then an ambiguity of 180° since the first polarity can be up or down so the polarity must also be used in order to get the correct backazimuth. If the first motion on vertical component of the P is upward, (which corresponds by definition to a compressional first motion (FM) arriving at the station related to an outward directed motion at the source then the radial component of P is directed away from the hypocenter. The opposite is true if the P polarity is negative (see also Figure 1 in Exercise EX 11.2) .  \nFigure 1 Example of P-wave first mo","cbCaiiLHpU4zperm","https://ap.wps.com/l/cbCaiiLHpU4zperm","pdf",659259,28,"English","# Introduction\n## Single station location","[{\"question\":\"What does earthquake location determine in practical seismology?\",\"answer\":\"It determines the hypocenter, given by x0, y0, z0 (longitude/latitude and depth), and the origin time t0, the start time of the rupture.\"},{\"question\":\"How is backazimuth obtained using a single 3-component station?\",\"answer\":\"Using P-wave motion polarization: vertical and radial/radial-amplitude relations give the arrival backazimuth, with a 180° ambiguity resolved by the vertical component first-motion polarity.\"},{\"question\":\"Why do arrival-time locations differ from centroid locations?\",\"answer\":\"Arrival-time catalogs commonly use high-frequency P-wave times, while centroid locations represent average time and location of the full energy radiation derived from moment-tensor inversion of long-period waves.\"}]","Information Sheet IS 11.1 - Earthquake location - Single station location | PDF",1792991996,71]