View source for Earth:Seismology

{{Short description|Scientific study of earthquakes and propagation of elastic waves through a planet}}
[[File:2004 Indonesia Tsunami Complete.gif|thumb|Animation of [[Tsunami|tsunami]] triggered by the 2004 Indian Ocean earthquake]]
{{Earthquakes}}

'''Seismology''' ({{IPAc-en|s|aɪ|z|ˈ|m|ɒ|l|ə|dʒ|i|,_|s|aɪ|s|-}}; from [[Social:Ancient Greek|Ancient Greek]] σεισμός (''seismós'') meaning "[[Earth:Earthquake|earthquake]]" and -λογία (''-logía'') meaning "study of") is the scientific study of [[Earth:Earthquake|earthquake]]s (or generally, [[Astronomy:Quake (natural phenomenon)|quakes]]) and the generation and propagation of [[Physics:Linear elasticity#Elastic wave|elastic wave]]s through the [[Astronomy:Earth|Earth]] or other [[Astronomy:Planetary body|planetary bodies]]. It also includes studies of [[Earth:Earthquake environmental effects|earthquake environmental effects]] such as tsunamis as well as diverse [[Earth:Seismic source|seismic source]]s such as volcanic, tectonic, glacial, [[Earth:Fluvial seismology|fluvial]], oceanic [[Earth:Microseism|microseism]], atmospheric, and artificial processes such as explosions and [[Earth:Induced seismicity|human activities]]. A related field that uses [[Earth:Geology|geology]] to infer information regarding past earthquakes is [[Earth:Paleoseismology|paleoseismology]]. A recording of [[Astronomy:Earth|Earth]] motion as a function of time, created by a seismograph is called a [[Earth:Seismogram|seismogram]]. A '''seismologist''' is a scientist works in basic or applied seismology.

==History==
Scholarly interest in earthquakes can be traced back to antiquity. Early speculations on the natural causes of earthquakes were included in the writings of Thales of Miletus ({{circa|585 BCE}}), [[Biography:Anaximenes of Miletus|Anaximenes of Miletus]] ({{circa|550 BCE}}), [[Biography:Aristotle|Aristotle]] ({{circa|340 BCE}}), and [[Biography:Zhang Heng|Zhang Heng]] (132 CE).

In 132 CE, Zhang Heng of China's Han dynasty designed the first known seismoscope.<ref name=needham>{{cite book | last = Needham | first = Joseph | title = Science and Civilization in China, Volume 3: Mathematics and the Sciences of the Heavens and the Earth | place = Cambridge | publisher = Cambridge University Press | year = 1959 | pages = 626–635| bibcode = 1959scc3.book.....N }}</ref><ref name="DeweyByerly">{{cite journal|last1=Dewey|first1=James|last2=Byerly|first2=Perry|title=The early history of seismometry (to 1900)|journal=Bulletin of the Seismological Society of America|date=February 1969|volume=59|issue=1|pages=183&ndash;227|url=https://earthquake.usgs.gov/learn/topics/eqsci-history/early-seismometry.php}}</ref><ref>{{cite journal|last1=Agnew|first1=Duncan Carr|title=History of seismology|journal=International Handbook of Earthquake and Engineering Seismology|series=International Geophysics|volume=81A|pages=3&ndash;11|date=2002|doi=10.1016/S0074-6142(02)80203-0|isbn=9780124406520}}</ref>

In the 17th century, [[Biography:Athanasius Kircher|Athanasius Kircher]] argued that earthquakes were caused by the movement of fire within a system of channels inside the Earth. Martin Lister (1638–1712) and Nicolas Lemery (1645–1715) proposed that earthquakes were caused by chemical explosions within the Earth.<ref name=Lisbon>{{cite book|first1=Agustín|last1=Udías|last2=Arroyo|first2=Alfonso López|contribution=The Lisbon earthquake of 1755 in Spanish contemporary authors|editor-last1=Mendes-Victor|editor-first1=Luiz A.|editor-last2=Oliveira|editor-first2=Carlos Sousa|editor-last3=Azevedo|editor-first3=João|editor-last4=Ribeiro|editor-first4=Antonio|title=The 1755 Lisbon earthquake: revisited|page=14|date=2008|publisher=Springer|isbn=9781402086090}}</ref>

The Lisbon earthquake of 1755, coinciding with the general flowering of science in [[Earth:Europe|Europe]], set in motion intensified scientific attempts to understand the behaviour and causation of earthquakes.  The earliest responses include work by John Bevis (1757) and John Michell (1761). Michell determined that earthquakes originate within the Earth and were waves of movement caused by "shifting masses of rock miles below the surface".<ref>{{cite book|last1=Member of the Royal Academy of Berlin|title=The History and Philosophy of Earthquakes Accompanied by John Michell's 'conjectures Concerning the Cause, and Observations upon the Ph'nomena of Earthquakes'|date=2012|publisher=Cambridge Univ Pr|isbn=9781108059909}}</ref>

In response to a series of earthquakes near Comrie in Scotland in 1839, a committee was formed in the [[History:United Kingdom of Great Britain and Ireland|United Kingdom]] in order to produce better detection methods for earthquakes. The outcome of this was the production of one of the first modern [[Earth:Seismometer|seismometer]]s by James David Forbes, first presented in a report by David Milne-Home in 1842.<ref name=JamesForbes></ref> This seismometer was an inverted pendulum, which recorded the measurements of seismic activity through the use of a pencil placed on paper above the pendulum. The designs provided did not prove effective, according to Milne's reports.<ref name=JamesForbes>{{cite web |url=https://www.researchgate.net/publication/261697732 |title=The Study of Earthquakes in the Hundred Years Following Lisbon Earthquake of 1755 |last=Oldroyd |first=David |date=2007 |website=Researchgate |publisher=Earth sciences history: journal of the History of the Earth Sciences Society |access-date=4 October 2022}}</ref>

From 1857, Robert Mallet laid the foundation of modern instrumental seismology and carried out seismological experiments using explosives. He is also responsible for coining the word "seismology."<ref>{{Cite journal|last=Society|first=The Royal|date=2005-01-22|title=Robert Mallet and the 'Great Neapolitan earthquake' of 1857|journal=Notes and Records|language=en|volume=59|issue=1|pages=45–64|doi=10.1098/rsnr.2004.0076|s2cid=71003016|issn=0035-9149}}</ref>

In 1897, Emil Wiechert's theoretical calculations led him to conclude that the [[Earth:Structure of the Earth|Earth's interior]] consists of a mantle of silicates, surrounding a core of iron.<ref>{{cite journal|last1=Barckhausen|first1=Udo|last2=Rudloff|first2=Alexander|title=Earthquake on a stamp: Emil Wiechert honored|journal=Eos, Transactions American Geophysical Union|date=14 February 2012|volume=93|issue=7|pages=67|doi=10.1029/2012eo070002|bibcode=2012EOSTr..93...67B|doi-access=free}}</ref>

In 1906 Richard Dixon Oldham identified the separate arrival of [[P-wave]]s, S-waves and surface waves on seismograms and found the first clear evidence that the Earth has a central core.<ref>{{cite encyclopedia |title=Oldham, Richard Dixon |encyclopedia=Complete Dictionary of Scientific Biography |volume=10 |publisher=Charles Scribner's Sons |year=2008 |page=203}}</ref>

In 1909, Andrija Mohorovičić, one of the founders of modern seismology,<ref name="Penn state">{{cite web|url=https://www.e-education.psu.edu/earth520/node/1777|title=Andrya (Andrija) Mohorovicic|author=|publisher=[[Organization:Pennsylvania State University|Penn State]]|access-date=30 January 2021|archive-date=26 June 2013|archive-url=https://archive.today/20130626180816/https://www.e-education.psu.edu/earth520/node/1777|url-status=live}}</ref><ref name="Encyclopedia.com">{{cite web|url=https://www.encyclopedia.com/people/history/historians-miscellaneous-biographies/andrija-mohorovicic|title=Mohorovičić, Andrija|author=|publisher=[[Encyclopedia.com]]|access-date=30 January 2021|archive-date=1 February 2021|archive-url=https://archive.today/20210201205826/https://www.encyclopedia.com/people/history/historians-miscellaneous-biographies/andrija-mohorovicic|url-status=live}}</ref><ref name="ssn">{{cite web|url=http://www.seismosoc.org/Publications/SRL/SRL_78/srl_78-6_hs.html|title=Andrija Mohorovičić (1857–1936)—On the occasion of the 150th anniversary of his birth|author=|publisher=seismosoc.org|access-date=30 January 2021|archive-date=1 February 2021|archive-url=https://archive.today/20210201210211/http://www.seismosoc.org/Publications/SRL/SRL_78/srl_78-6_hs.html|url-status=live}}</ref> discovered and defined the [[Earth:Mohorovičić discontinuity|Mohorovičić discontinuity]].<ref name=McLeish>{{cite book |title=Geological science |author=Andrew McLeish |page=122 |url=https://books.google.com/books?id=rhkgwEvrVe8C&pg=PA122 |isbn=978-0-17-448221-5 |date=1992 |edition=2nd |publisher=Thomas Nelson & Sons}}</ref> Usually referred to as the "Moho discontinuity" or the "[[Earth:Mohorovičić discontinuity|Moho]]," it is the boundary between the [[Astronomy:Earth|Earth]]'s [[Earth:Crust (geology)|crust]] and the [[Earth:Mantle (geology)|mantle]]. It is defined by the distinct change in velocity of seismological waves as they pass through changing densities of rock.<ref>{{Citation|last1=Rudnick|first1=R. L.|title=3.01 – Composition of the Continental Crust|date=2003-01-01|url=http://www.sciencedirect.com/science/article/pii/B0080437516030164|journal=Treatise on Geochemistry|editor-last=Holland|editor-first=Heinrich D.|publisher=Pergamon|doi=10.1016/b0-08-043751-6/03016-4|isbn=978-0-08-043751-4|access-date=2019-11-21|last2=Gao|first2=S.|volume=3|page=659|bibcode=2003TrGeo...3....1R|editor2-last=Turekian|editor2-first=Karl K.}}</ref>

In 1910, after studying the April 1906 San Francisco earthquake, Harry Fielding Reid put forward the "[[Earth:Elastic-rebound theory|elastic rebound theory]]" which remains the foundation for modern tectonic studies.  The development of this theory depended on the considerable progress of earlier independent streams of work on the behavior of elastic materials and in mathematics.<ref>{{Cite web|url=https://earthquake.usgs.gov/regional/nca/1906/18april/reid.php|title=Reid's Elastic Rebound Theory|website=1906 Earthquake|publisher=United States Geological Survey|access-date=6 April 2018}}</ref>

An early scientific study of [[Earth:Aftershock|aftershock]]s from a destructive earthquake came after the January 1920 Xalapa earthquake. An {{cvt|80|kg}} Wiechert seismograph was brought to the Mexican city of Xalapa by rail after the earthquake. The instrument was deployed to record its aftershocks. Data from the seismograph would eventually determine that the mainshock was produced along a shallow crustal fault.<ref>{{cite journal |first1=G. |last1=Suárez |first2=D. A. |last2=Novelo‐Casanova |title=A Pioneering Aftershock Study of the Destructive 4 January 1920 Jalapa, Mexico, Earthquake |journal=Seismological Research Letters |date=2018 |volume=89 |issue=5 |pages=1894–1899 |doi=10.1785/0220180150 |s2cid=134449441 |url= https://www.researchgate.net/publication/326613511}}</ref>

In 1926, [[Biography:Harold Jeffreys|Harold Jeffreys]] was the first to claim, based on his study of earthquake waves, that below the mantle, the core of the Earth is liquid.<ref>{{Cite journal|last=Jeffreys|first=Harold|date=1926-06-01|title=On the Amplitudes of Bodily Seismic Waues.|journal=Geophysical Journal International|language=en|volume=1|pages=334–348|doi=10.1111/j.1365-246X.1926.tb05381.x|issn=1365-246X|bibcode=1926GeoJ....1..334J|doi-access=free}}</ref>

In 1937, Inge Lehmann determined that within Earth's liquid [[Physics:Outer core|outer core]] there is a solid [[Earth:Inner core|inner core]].<ref>{{Cite journal|last=Hjortenberg|first=Eric|date=December 2009|title=Inge Lehmann's work materials and seismological epistolary archive|url=http://www.annalsofgeophysics.eu/index.php/annals/article/viewFile/4625/4693|journal=Annals of Geophysics|volume=52|issue=6|doi=10.4401/ag-4625|doi-access=free}}</ref>

By the 1960s, Earth science had developed to the point where a comprehensive theory of the causation of seismic events and geodetic motions had come together in the now well-established theory of [[Earth:Plate tectonics|plate tectonics]].{{citation needed|date=October 2021}}

==Types of seismic wave==
{{Main|Earth:Seismic wave}}
[[Image:Seismogram.gif|thumb|320px|Seismogram records showing the three components of [[Earth:Ground motion|ground motion]]. The red line marks the first arrival of P-waves; the green line, the later arrival of S-waves. |alt=Three lines with frequent vertical excursions.]]
Seismic waves are elastic waves that propagate in solid or fluid materials. They can be divided into ''body waves'' that travel through the interior of the materials; ''surface waves'' that travel along surfaces or interfaces between materials; and ''normal modes'', a form of standing wave.

===Body waves===

There are two types of body waves, pressure waves or primary waves (P-waves) and [[Physics:Shearing|shear]] or secondary waves ([[S-wave]]s). P-waves are [[Physics:Longitudinal wave|longitudinal wave]]s that involve [[Earth:Compression (geology)|compression]] and [[Physics:Rarefaction|expansion]] in the direction that the wave is moving and are always the first waves to appear on a seismogram as they are the fastest moving waves through solids. S-waves are [[Physics:Transverse wave|transverse wave]]s that move perpendicular to the direction of propagation. S-waves are slower than P-waves. Therefore, they appear later than P-waves on a seismogram. Fluids cannot support transverse elastic waves because of their low shear strength, so S-waves only travel in solids.<ref name=Gubbins1990>{{harvnb|Gubbins|1990}}</ref>

===Surface waves===
Surface waves are the result of P- and S-waves interacting with the surface of the Earth. These waves are [[Physics:Dispersion (optics)|dispersive]], meaning that different frequencies have different velocities. The two main surface wave types are [[Physics:Rayleigh wave|Rayleigh wave]]s, which have both compressional and shear motions, and [[Love wave]]s, which are purely shear. Rayleigh waves result from the interaction of P-waves and vertically polarized S-waves with the surface and can exist in any solid medium. Love waves are formed by horizontally polarized S-waves interacting with the surface, and can only exist if there is a change in the elastic properties with depth in a solid medium, which is always the case in seismological applications. Surface waves travel more slowly than P-waves and S-waves because they are the result of these waves traveling along indirect paths to interact with Earth's surface. Because they travel along the surface of the Earth, their energy decays less rapidly than body waves (1/distance<sup>2</sup> vs. 1/distance<sup>3</sup>), and thus the shaking caused by surface waves is generally stronger than that of body waves, and the primary surface waves are often thus the largest signals on earthquake [[Earth:Seismogram|seismograms]]. Surface waves are strongly excited when their source is close to the surface, as in a shallow earthquake or a near-surface explosion, and are much weaker for deep earthquake sources.<ref name=Gubbins1990/>

===Normal modes===
Both body and surface waves are traveling waves; however, large earthquakes can also make the entire Earth "ring" like a resonant bell. This ringing is a mixture of normal modes with discrete frequencies and periods of approximately an hour or shorter.  Normal mode motion caused by a very large earthquake can be observed for up to a month after the event.<ref name=Gubbins1990/> The first observations of normal modes were made in the 1960s as the advent of higher fidelity instruments coincided with two of the largest earthquakes of the 20th century the 1960 Valdivia earthquake and the 1964 Alaska earthquake.  Since then, the normal modes of the Earth have given us some of the strongest constraints on the deep structure of the Earth.

==Earthquakes==
One of the first attempts at the scientific study of earthquakes followed the 1755 Lisbon earthquake.  Other notable earthquakes that spurred major advancements in the science of seismology include the 1857 Basilicata earthquake, the 1906 San Francisco earthquake, the 1964 Alaska earthquake, the 2004 Sumatra-Andaman earthquake, and the 2011 Great East Japan earthquake.

==Controlled seismic sources==
Seismic waves produced by explosions or vibrating controlled sources are one of the primary methods of [[Earth:Exploration geophysics|underground exploration in geophysics]] (in addition to many different [[Physics:Electromagnetic radiation|electromagnetic]] methods such as [[Earth:Induced polarization|induced polarization]] and [[Physics:Magnetotellurics|magnetotellurics]]).  Controlled-source seismology has been used to map [[Earth:Salt dome|salt dome]]s, anticlines and other geologic traps in [[Chemistry:Petroleum|petroleum]]-bearing [[Earth:Rock (geology)|rocks]], [[Earth:Fault (geology)|faults]], rock types, and long-buried giant meteor [[Astronomy:Impact crater|craters]]. For example, the Chicxulub Crater,  which was caused by an impact that has been [[Earth:Cretaceous–Paleogene extinction event|implicated in the extinction]] of the [[Biology:Dinosaur|dinosaur]]s, was localized to Central America by analyzing ejecta in the [[Earth:Cretaceous–Paleogene boundary|Cretaceous–Paleogene boundary]], and then physically proven to exist using seismic maps from oil exploration.<ref name=Schulte2010>{{harvnb|Schulte et al.|2010}}</ref>

==Detection of seismic waves==
[[File:Seismometer-iceland.JPG|thumb|Installation for a temporary seismic station, north Iceland highland.]]
[[Earth:Seismometer|Seismometer]]s are sensors that detect and record the motion of the Earth arising from elastic waves.  Seismometers may be deployed at the Earth's surface, in shallow vaults, in boreholes, or [[Earth:Ocean-bottom seismometer|underwater]].  A complete instrument package that records seismic signals is called a seismograph.  Networks of seismographs continuously record ground motions around the world to facilitate the monitoring and analysis of global earthquakes and other sources of seismic activity. Rapid location of earthquakes makes [[Tsunami|tsunami]] warnings possible because seismic waves travel considerably faster than tsunami waves. Seismometers also record signals from non-earthquake sources ranging from explosions (nuclear and chemical), to local noise from wind<ref>{{Cite journal | doi=10.1002/2015JB012478|title = Wind-induced ground motion| journal=Journal of Geophysical Research: Solid Earth| volume=121| issue=2| pages=917–930|year = 2016|last1 = Naderyan|first1 = Vahid| last2=Hickey| first2=Craig J.| last3=Raspet| first3=Richard|bibcode = 2016JGRB..121..917N| doi-access=free}}</ref> or anthropogenic activities, to incessant signals generated at the ocean floor and coasts induced by ocean waves (the global [[Earth:Microseism|microseism]]), to [[Physics:Cryosphere|cryospheric]] events associated with large [[Earth:Iceberg|icebergs]] and glaciers. Above-ocean meteor strikes with energies as high as 4.2 × 10<SUP>13</SUP> [[Joule|J]] (equivalent to that released by an explosion of ten kilotons of TNT) have been recorded by seismographs, as have a number of industrial accidents and terrorist bombs and events (a field of study referred to as [[Earth:Forensic seismology|forensic seismology]]).  A major long-term motivation for the global seismographic monitoring has been for the detection and study of nuclear testing.

==Mapping Earth's interior==
[[Image:Earthquake wave paths.svg|thumb|280px|Seismic velocities and boundaries in the interior of the Earth sampled by seismic waves |alt=Diagram with concentric shells and curved paths]]
Because seismic waves commonly propagate efficiently as they interact with the internal structure of the Earth, they provide high-resolution noninvasive methods for studying the planet's interior.  One of the earliest important discoveries (suggested by Richard Dixon Oldham in 1906 and definitively shown by Harold Jeffreys in 1926) was that the [[Physics:Outer core|outer core]] of the earth is liquid.  Since S-waves do not pass through liquids, the liquid core causes a "shadow" on the side of the planet opposite the earthquake where no direct S-waves are observed.  In addition, P-waves travel much slower through the outer core than the mantle.

Processing readings from many seismometers using [[Seismic tomography|seismic tomography]], seismologists have mapped the mantle of the earth to a resolution of several hundred kilometers.  This has enabled scientists to identify [[Physics:Convection cell|convection cell]]s and other large-scale features such as the [[Earth:Large low-shear-velocity provinces|large low-shear-velocity provinces]] near the [[Earth:Core–mantle boundary|core–mantle boundary]].<ref>{{harvnb|Wen|Helmberger|1998}}</ref>

==Seismology and society==

===Earthquake prediction===
{{main|Earthquake prediction}}
Forecasting a probable timing, location, magnitude and other important features of a forthcoming seismic event is called [[Earthquake prediction|earthquake prediction]]. Various attempts have been made by seismologists and others to create effective systems for precise earthquake predictions, including the [[Earth:VAN method|VAN method]].  Most seismologists do not believe that a system to provide timely warnings for individual earthquakes has yet been developed, and many believe that such a system would be unlikely to give useful warning of impending seismic events. However, more general forecasts routinely predict [[Earth:Seismic hazard|seismic hazard]]. Such forecasts estimate the probability of an earthquake of a particular size affecting a particular location within a particular time-span, and they are routinely used in [[Earth:Earthquake engineering|earthquake engineering]].

Public controversy over earthquake prediction erupted after Italian authorities indicted six seismologists and one government official for manslaughter in connection with a magnitude 6.3 earthquake in L'Aquila, Italy on April 5, 2009. The indictment has been widely perceived{{by whom|date=October 2011}} as an indictment for failing to predict the earthquake and has drawn condemnation from the American Association for the Advancement of Science and the [[Organization:American Geophysical Union|American Geophysical Union]]. The indictment claims that, at a special meeting in L'Aquila the week before the earthquake occurred, scientists and officials were more interested in pacifying the population than providing adequate information about earthquake risk and preparedness.<ref>{{harvnb|Hall|2011}}</ref>

=== Engineering seismology ===
Engineering seismology is the study and application of seismology for engineering purposes.<ref>{{Cite book|title = Encyclopaedia of Geology|publisher = Elsevier|date = 2005-01-01|location = Oxford|isbn = 978-0-12-369396-9|pages = 499–515|doi = 10.1016/b0-12-369396-9/90020-0|editor-first = Richard C. SelleyL. Robin M. CocksIan R.|editor-last = Plimer|chapter = Editors}}</ref> It generally applied to the branch of seismology that deals with the assessment of the seismic hazard of a site or region for the purposes of earthquake engineering. It is, therefore, a link between [[Earth:Earth science|earth science]] and [[Engineering:Civil engineering|civil engineering]].<ref name=":0">{{Cite journal|title = Engineering seismology: Part I|journal = Earthquake Engineering & Structural Dynamics|date = 1988-12-01|issn = 1096-9845|pages = 1–50|volume = 17|issue = 1|doi = 10.1002/eqe.4290170101|first = N. N.|last = Ambraseys}}</ref> There are two principal components of engineering seismology. Firstly, studying earthquake history (e.g. historical<ref name=":0" /> and instrumental catalogs<ref>{{Cite journal|title = A Software Package to Analyze Seismicity: ZMAP|journal = Seismological Research Letters|date = 2001-05-01|issn = 0895-0695|pages = 373–382|volume = 72|issue = 3|doi = 10.1785/gssrl.72.3.373|first = Stefan|last = Wiemer}}</ref> of seismicity) and [[Earth:Tectonics|tectonics]]<ref>{{Cite journal|title = Seismic Hazard Inferred from Tectonics: California|journal = Seismological Research Letters|date = 2007-01-01|issn = 0895-0695|pages = 37–48|volume = 78|issue = 1|doi = 10.1785/gssrl.78.1.37|first1 = Peter|last1 = Bird|first2 = Zhen|last2 = Liu}}</ref> to assess the earthquakes that could occur in a region and their characteristics and frequency of occurrence. Secondly, studying strong ground motions generated by earthquakes to assess the expected shaking from future earthquakes with similar characteristics. These strong ground motions could either be observations from [[Physics:Accelerometer|accelerometer]]s or seismometers or those simulated by computers using various techniques,<ref>{{Cite journal|last1=Douglas|first1=John|last2=Aochi|first2=Hideo|date=2008-10-10|title=A Survey of Techniques for Predicting Earthquake Ground Motions for Engineering Purposes|journal=Surveys in Geophysics|volume=29|issue=3|pages=187–220|doi=10.1007/s10712-008-9046-y|issn=0169-3298|bibcode=2008SGeo...29..187D|s2cid=53066367|url=https://hal-brgm.archives-ouvertes.fr/hal-00557625/file/simrev_revised_clean.pdf}}</ref> which are then often used to develop ground motion prediction equations<ref>{{Cite journal|last1=Douglas|first1=John|last2=Edwards|first2=Benjamin|date=2016-09-01|title=Recent and future developments in earthquake ground motion estimation|url= https://strathprints.strath.ac.uk/56975/1/Douglas_Edwards_ESR_2016_recent_and_future_developments_in_earthquake_ground_motion_estimation.pdf|journal=Earth-Science Reviews|volume=160|pages=203–219|doi=10.1016/j.earscirev.2016.07.005|bibcode=2016ESRv..160..203D}}</ref> (or ground-motion models)[http://www.gmpe.org.uk/].

== Tools ==
Seismological instruments can generate large amounts of data. Systems for processing such data include:

* CUSP (Caltech-USGS Seismic Processing)<ref>
{{cite conference
  | first = W. H. K.
  | last = Lee
  |author2=S. W. Stewart
   | title = Large-Scale Processing and Analysis of Digital Waveform Data from the USGS Central California Microearthquake Network
  | book-title = Observatory seismology: an anniversary symposium on the occasion of the centennial of the University of California at Berkeley seismographic stations
  | pages = 86
  | publisher = University of California Press
  | year = 1989
  | isbn = 9780520065826
 | url = https://books.google.com/books?id=yLJWcm0HXNIC
  | access-date = 2011-10-12
  | quote = The CUSP (Caltech-USGS Seismic Processing) System consists of on-line real-time earthquake waveform data acquisition routines, coupled with an off-line set of data reduction, timing, and archiving processes. It is a complete system for processing local earthquake data&nbsp;...
 }}
</ref>
* [[Earth:RadExPro seismic software|RadExPro seismic software]]
* SeisComP3<ref>
{{cite book
| editor1-last  = Akkar
| editor1-first = Sinan
| editor2-last  = Polat
| editor2-first = Gülkan
| editor3-last  = van Eck
| editor3-first = Torild 
| title         = Earthquake Data in Engineering Seismology: Predictive Models, Data Management and Networks
| url           = https://books.google.com/books?id=-VRFVONtHPsC
| access-date    = 2011-10-19
| series    = Geotechnical, Geological and Earthquake Engineering
| volume    = 14
| year      = 2010
| publisher = Springer
| isbn      = 978-94-007-0151-9
| page      = 194
}}
</ref>

==Notable seismologists==
<!--only add those who have articles on Wikipedia-->
{{div col|colwidth=15em}}
* Aki, Keiiti
* Ambraseys, Nicholas
* Anderson, Don L.
* Bolt, Bruce
* Claerbout, Jon
* Dziewonski, Adam Marian
* Ewing, Maurice
* Galitzine, Boris Borisovich
* Gamburtsev, Grigory A.
* Gutenberg, Beno
* Hough, Susan
* [[Biography:Harold Jeffreys|Jeffreys, Harold]]
* Jones, Lucy
* Kanamori, Hiroo
* Keilis-Borok, Vladimir
* Knopoff, Leon
* Lehmann, Inge
* Macelwane, James
* Mallet, Robert
* [[Biography:Giuseppe Mercalli|Mercalli, Giuseppe]]
* Milne, John
* Mohorovičić, Andrija
* Oldham, Richard Dixon
* Omori, Fusakichi
* Sebastião de Melo, Marquis of Pombal
* Press, Frank
* Richards, Paul G.
* Richter, Charles Francis
* Sekiya, Seikei
* Sieh, Kerry
* Paul G. Silver
* Stein, Ross
* Tucker, Brian
* Vidale, John
* Wen, Lianxing
* [[Biography:John Winthrop (educator)|Winthrop, John]]
* [[Biography:Zhang Heng|Zhang Heng]]
{{div col end}}

==See also==
{{clear}}
{{div col}}
*{{annotated link|Astronomy:Asteroseismology}} (starquakes)
*{{annotated link|Earth:Cryoseism}}
*{{annotated link|Earth:Earthquake swarm}}
*{{annotated link|Engineering:Engineering geology}}
*{{annotated link|Epicentral distance}}
*{{annotated link|Earth:Harmonic tremor}}
*{{annotated link|Astronomy:Helioseismology}}
*{{annotated link|Organization:IRIS Consortium}}
*{{annotated link|Earth:Isoseismal map}}
*{{annotated link|Linear seismic inversion}}
*{{annotated link|Astronomy:Lunar seismology}}
*{{annotated link|Astronomy:Marsquake}}
*{{annotated link|Astronomy:Quake (natural phenomenon)}}
*{{annotated link|Physics:Seismic interferometry}}
*{{annotated link|Earth:Seismic loading}}
*{{annotated link|Earth:Seismic migration}}
*{{annotated link|Earth:Seismic noise}}
*{{annotated link|Earth:Seismic velocity structure}}
*{{annotated link|Earth:Seismite}}
*{{annotated link|Physics:Seismo-electromagnetics}}
*{{annotated link|Earth:Seismotectonics}}
*{{annotated link|Earth:Stabilized inverse Q filtering}}
{{div col end}}

==Notes==
{{Reflist}}

==References==
{{Refbegin}}
*{{cite book |year=2003 |title= Oxford Dictionary of Earth Sciences|editor1-first=Ailsa |editor1-last=Allaby |editor2-first=Michael |editor2-last=Allaby |edition=Second |publisher=[[Organization:Oxford University Press|Oxford University Press]] }}
*{{citation|url=https://engineering.purdue.edu/~ce597m/Handouts/ConciseHistory_BenMenahem.pdf|title=A Concise History of Mainstream Seismology: Origins, Legacy, and Perspectives|first=Ari|last=Ben-Menahem|date=1995|journal=Bulletin of the Seismological Society of America|volume=85|number=4|pages=1202–1225}}
*{{cite book|last1=Bath|first1=M.|title=Introduction to Seismology|date=1979|publisher=Birkhäuser Basel|location=Basel|isbn=9783034852838|edition=Second, Revised}}
*{{cite book|last1=Davison|first1=Charles|title=The founders of seismology|date=2014|publisher=Cambridge University Press |isbn=9781107691490}}
*{{cite book |title=Elastic Waves in Layered Media |url=https://archive.org/details/elasticwavesinla0000ewin |url-access=registration |last1=Ewing |first1=W. M.|last2=Jardetzky |first2=W. S.|last3=Press |first3=F.| publisher=McGraw-Hill Book Company |year=1957 }}
*{{cite book |title=Seismology and Plate Tectonics |last1=Gubbins |first1=David | publisher={{wipe|Cambridge University Press}} |year=1990 |isbn=978-0-521-37141-4 }}
*{{cite journal |title=Scientists on trial: At fault? |first1=Stephen S. |last1=Hall |journal=Nature |volume=477 |pages=264–269  |year=2011 | doi=10.1038/477264a |issue=7364|bibcode = 2011Natur.477..264H |pmid=21921895|s2cid=205067216 |doi-access=free }}
*{{Cite book |url=http://www.gps.caltech.edu/uploads/File/People/kanamori/HKees03.pdf |last=Kanamori |first=Hiroo |title=Earthquake prediction: An overview |volume=81B |series=International Handbook of Earthquake and Engineering Seismology |year=2003 |publisher=International Association of Seismology & Physics of the Earth's Interior |pages=1205–1216 |url-status=dead |archive-url=https://web.archive.org/web/20131024140004/http://www.gps.caltech.edu/uploads/File/People/kanamori/HKees03.pdf |archive-date=2013-10-24 }}
*{{cite book |url=http://www.iris.edu/hq/lrsps/seis_plan_final.pdf |editor1-last=Lay |editor1-first=Thorne |year=2009 |title=Seismological Grand Challenges in Understanding Earth's Dynamic Systems  |series=Report to the National Science Foundation, IRIS consortium }}
*{{cite journal|last=Schulte|first=Peter |author2=Laia Alegret |author3=Ignacio Arenillas |author4=José A. Arz |author5=Penny J. Barton |author6=Paul R. Bown |author7=Timothy J. Bralower |author8=Gail L. Christeson |author9=Philippe Claeys |author10=Charles S. Cockell |author11=Gareth S. Collins |author12=Alexander Deutsch |author13=Tamara J. Goldin |author14=Kazuhisa Goto |author15=José M. Grajales-Nishimura |author16=Richard A. F. Grieve |author17=Sean P. S. Gulick |author18=Kirk R. Johnson |author19=Wolfgang Kiessling |author20=Christian Koeberl |author21=David A. Kring |author22=Kenneth G. MacLeod |author23=[[Biography:Takafumi Matsui|Takafumi Matsui]] |author24=Jay Melosh |author25=Alessandro Montanari |author26=Joanna V. Morgan|author26-link= Joanna Morgan |author27=Clive R. Neal |author28=Douglas J. Nichols |author29=Richard D. Norris |author30=Elisabetta Pierazzo |author31=Greg Ravizza |author32=Mario Rebolledo-Vieyra |author33=Wolf Uwe Reimold |author34=Eric Robin |author35=Tobias Salge |author36=Robert P. Speijer |author37=Arthur R. Sweet |author38=Jaime Urrutia-Fucugauchi |author39=Vivi Vajda |author40=Michael T. Whalen |author41=Pi S. Willumsen |date=5 March 2010|title=The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary|journal=Science|volume=327|issue=5970|pages=1214–1218|issn=1095-9203 |url=http://www.sciencemag.org/cgi/content/abstract/327/5970/1214|access-date=5 March 2010|doi=10.1126/science.1177265|pmid=20203042|bibcode=2010Sci...327.1214S|s2cid=2659741 |ref={{harvid|Schulte et al.|2010}} }}
*{{cite book |title=Introduction to Seismology |last1=Shearer |first1=Peter M. |publisher={{wipe|Cambridge University Press}} |year=2009 |edition=Second |isbn=978-0-521-70842-5 }}
*{{cite book |title=An Introduction to Seismology, Earthquakes and Earth Structure |last1=Stein |first1=Seth |last2=Wysession |first2=Michael | publisher=[[Company:Wiley-Blackwell|Wiley-Blackwell]] |year=2002 |isbn=978-0-86542-078-6 }}
*{{cite journal|first1=Lianxing |last1=Wen|first2=Donald V. |last2=Helmberger |title=Ultra-Low Velocity Zones Near the Core-Mantle Boundary from Broadband PKP Precursors |journal=Science |volume=279 |pages=1701–1703  |year=1998 |doi=10.1126/science.279.5357.1701 |pmid=9497284|url=http://geophysics.geo.sunysb.edu/wen/Reprints/WenHelmberger98Science.pdf |issue=5357|bibcode = 1998Sci...279.1701W }}
{{refend}}

==External links==
* [http://www.emsc-csem.org/ European-Mediterranean Seismological Center], real-time earthquake information website.
* [http://www.seismosoc.org/ Seismological Society of America].
* [http://www.iris.edu/ Incorporated Research Institutions for Seismology].
* [https://earthquake.usgs.gov/earthquakes/ USGS Earthquake Hazards Program].
* [https://projects.eri.ucsb.edu/understanding/history.html A brief history of seismology to 1910] (UCSB ERI)

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