Seismology
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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
In 132 CE, Zhang Heng of China's
In the 17th century, 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.[4]
The Lisbon earthquake of 1755, coinciding with the general flowering of science in 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".[5]
In response to a series of earthquakes near Comrie in Scotland in 1839, a committee was formed in the United Kingdom in order to produce better detection methods for earthquakes. The outcome of this was the production of one of the first modern seismometers by James David Forbes, first presented in a report by David Milne-Home in 1842.[6] 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.[6]
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."[7]
In 1897,
In 1906
In 1909, Andrija Mohorovičić, one of the founders of modern seismology,[10][11][12] discovered and defined the Mohorovičić discontinuity.[13] Usually referred to as the "Moho discontinuity" or the "Moho," it is the boundary between the Earth's crust and the mantle. It is defined by the distinct change in velocity of seismological waves as they pass through changing densities of rock.[14]
In 1910, after studying the April 1906 San Francisco earthquake, Harry Fielding Reid put forward the "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.[15]
An early scientific study of aftershocks from a destructive earthquake came after the January 1920 Xalapa earthquake. An 80 kg (180 lb) 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.[16]
In 1926, 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.[17]
In 1937,
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 plate tectonics.[19]
Types of seismic wave
Seismic waves are
Body waves
There are two types of body waves, pressure waves or primary waves (P-waves) and
Surface waves
Surface waves are the result of P- and S-waves interacting with the surface of the Earth. These waves are dispersive, meaning that different frequencies have different velocities. The two main surface wave types are Rayleigh waves, which have both compressional and shear motions, and Love waves, 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/distance2 vs. 1/distance3), 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 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.[20]
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
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
Controlled seismic sources
Seismic waves produced by
Detection of seismic waves
Mapping Earth's interior
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
Processing readings from many seismometers using seismic tomography, seismologists have mapped the mantle of the earth to a resolution of several hundred kilometers. This has enabled scientists to identify convection cells and other large-scale features such as the large low-shear-velocity provinces near the core–mantle boundary.[23]
Seismology and society
Earthquake prediction
Forecasting a probable timing, location, magnitude and other important features of a forthcoming seismic event is called earthquake prediction. Various attempts have been made by seismologists and others to create effective systems for precise earthquake predictions, including the 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 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 earthquake engineering.
Public controversy over earthquake prediction erupted after Italian authorities
In locations where a historical record exists it may be used to estimate the timing, location and magnitude of future seismic events. There are several interpretative factors to consider. The epicentres or foci and magnitudes of historical earthquakes are subject to interpretation meaning it is possible that 5-6mw earthquakes described in the historical record could be larger events occurring elsewhere that were felt moderately in the populated areas that produced written records. Documentation in the historic period may be sparse or incomplete, and not give a full picture of the geographic scope of an earthquake, or the historical record may only have earthquake records spanning a few centuries, a very short time frame in a
Engineering seismology
Engineering seismology is the study and application of seismology for engineering purposes.[27] 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 science and civil engineering.[28] There are two principal components of engineering seismology. Firstly, studying earthquake history (e.g. historical[28] and instrumental catalogs[29] of seismicity) and tectonics[30] 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 accelerometers or seismometers or those simulated by computers using various techniques,[31] which are then often used to develop ground motion prediction equations[32] (or ground-motion models)[1].
Tools
Seismological instruments can generate large amounts of data. Systems for processing such data include:
- CUSP (Caltech-USGS Seismic Processing)[33]
- RadExPro seismic software
- SeisComP3[34]
Notable seismologists
- 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
- Jeffreys, Harold
- Jones, Lucy
- Kanamori, Hiroo
- Keilis-Borok, Vladimir
- Knopoff, Leon
- Lehmann, Inge
- Macelwane, James
- Mallet, Robert
- 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
- Winthrop, John
- Zhang Heng
See also
- Asteroseismology – Study of oscillations in stars (starquakes)
- Cryoseism – Non-tectonic seismic event
- Earthquake swarm – Series of localized seismic events within a short time period
- Engineering geology – Application of geology to engineering practice
- Epicentral distance
- Harmonic tremor – Sustained ground vibration associated with underground movement of magma or volcanic gas
- Helioseismology – Sunquake
- IRIS Consortium – university research consortium dedicated to exploring the Earth's interior through the collection and distribution of seismographic data
- Isoseismal map – Type of map used in seismology
- Linear seismic inversion – Interpretation of seismic data using linear model
- Lunar seismology – Study of ground motions of the Moon
- Marsquake – Seismic event occurring on Mars
- Quake (natural phenomenon) – Surface shaking on interstellar bodies in general
- Seismic interferometry
- Seismic loading – basic concept in earthquake engineering
- Seismic migration – Measurement process
- Seismic noise – generic name for a relatively persistent vibration of the ground
- Seismic performance analysis– Study of the response of buildings and structures to earthquakes
- Seismic velocity structure – Seismic wave velocity variation
- Seismite – Sediment/structure shaken seismically
- Seismo-electromagnetics – Electro-magnetic phenomena
- Seismotectonics – study of how tectonic faults influence earthquakes
- Stabilized inverse Q filtering – Data processing technology
Notes
- Bibcode:1959scc3.book.....N.
- ^ Dewey, James; Byerly, Perry (February 1969). "The early history of seismometry (to 1900)". Bulletin of the Seismological Society of America. 59 (1): 183–227.
- ISBN 9780124406520.
- ISBN 9781402086090.
- ISBN 9781108059909.
- ^ a b Oldroyd, David (2007). "The Study of Earthquakes in the Hundred Years Following Lisbon Earthquake of 1755". Researchgate. Earth sciences history: journal of the History of the Earth Sciences Society. Retrieved 4 October 2022.
- S2CID 71003016.
- .
- ^ "Oldham, Richard Dixon". Complete Dictionary of Scientific Biography. Vol. 10. Charles Scribner's Sons. 2008. p. 203.
- ^ "Andrya (Andrija) Mohorovicic". Penn State. Archived from the original on 26 June 2013. Retrieved 30 January 2021.
- ^ "Mohorovičić, Andrija". Encyclopedia.com. Archived from the original on 1 February 2021. Retrieved 30 January 2021.
- ^ "Andrija Mohorovičić (1857–1936)—On the occasion of the 150th anniversary of his birth". seismosoc.org. Archived from the original on 1 February 2021. Retrieved 30 January 2021.
- ISBN 978-0-17-448221-5.
- ISBN 978-0-08-043751-4, retrieved 2019-11-21
- ^ "Reid's Elastic Rebound Theory". 1906 Earthquake. United States Geological Survey. Retrieved 6 April 2018.
- S2CID 134449441.
- ISSN 1365-246X.
- doi:10.4401/ag-4625.
- ^ "History of plate tectonics". scecinfo.usc.edu. Retrieved 2024-02-20.
- ^ a b c Gubbins 1990
- ^ Schulte et al. 2010
- .
- ^ Wen & Helmberger 1998
- ^ Hall 2011
- ^ Historical Seismology: Interdisciplinary Studies of Past and Recent Earthquakes(2008) Springer Netherlands
- hdl:2027.42/170290.
- ISBN 978-0-12-369396-9.
- ^ ISSN 1096-9845.
- ISSN 0895-0695.
- ISSN 0895-0695.
- S2CID 53066367.
- .
- ^
Lee, W. H. K.; S. W. Stewart (1989). "Large-Scale Processing and Analysis of Digital Waveform Data from the USGS Central California Microearthquake Network". Observatory seismology: an anniversary symposium on the occasion of the centennial of the University of California at Berkeley seismographic stations. University of California Press. p. 86. ISBN 9780520065826. Retrieved 2011-10-12.
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 ...
- ^
Akkar, Sinan; Polat, Gülkan; van Eck, Torild, eds. (2010). Earthquake Data in Engineering Seismology: Predictive Models, Data Management and Networks. Geotechnical, Geological and Earthquake Engineering. Vol. 14. Springer. p. 194. ISBN 978-94-007-0151-9. Retrieved 2011-10-19.
References
- Allaby, Ailsa; Allaby, Michael, eds. (2003). Oxford Dictionary of Earth Sciences (Second ed.). Oxford University Press.
- Ben-Menahem, Ari (1995), "A Concise History of Mainstream Seismology: Origins, Legacy, and Perspectives" (PDF), Bulletin of the Seismological Society of America, 85 (4): 1202–1225
- Bath, M. (1979). Introduction to Seismology (Second, Revised ed.). Basel: Birkhäuser Basel. ISBN 9783034852838.
- Davison, Charles (2014). The founders of seismology. Cambridge University Press. ISBN 9781107691490.
- Ewing, W. M.; Jardetzky, W. S.; Press, F. (1957). Elastic Waves in Layered Media. McGraw-Hill Book Company.
- Gubbins, David (1990). Seismology and Plate Tectonics. ISBN 978-0-521-37141-4.
- Hall, Stephen S. (2011). "Scientists on trial: At fault?". S2CID 205067216.
- Kanamori, Hiroo (2003). Earthquake prediction: An overview (PDF). International Handbook of Earthquake and Engineering Seismology. Vol. 81B. International Association of Seismology & Physics of the Earth's Interior. pp. 1205–1216. Archived from the original (PDF) on 2013-10-24.
- Lay, Thorne, ed. (2009). Seismological Grand Challenges in Understanding Earth's Dynamic Systems (PDF). Report to the National Science Foundation, IRIS consortium.
- Schulte, Peter; Laia Alegret; Ignacio Arenillas; José A. Arz; Penny J. Barton; Paul R. Bown; Timothy J. Bralower; Gail L. Christeson; Philippe Claeys; Charles S. Cockell; Gareth S. Collins; Alexander Deutsch; Tamara J. Goldin; Kazuhisa Goto; José M. Grajales-Nishimura; Richard A. F. Grieve; Sean P. S. Gulick; Kirk R. Johnson; Wolfgang Kiessling; Christian Koeberl; David A. Kring; Kenneth G. MacLeod; S2CID 2659741. Retrieved 5 March 2010.
- Shearer, Peter M. (2009). Introduction to Seismology (Second ed.). ISBN 978-0-521-70842-5.
- Stein, Seth; Wysession, Michael (2002). An Introduction to Seismology, Earthquakes and Earth Structure. ISBN 978-0-86542-078-6.
- Wen, Lianxing; Helmberger, Donald V. (1998). "Ultra-Low Velocity Zones Near the Core-Mantle Boundary from Broadband PKP Precursors" (PDF). PMID 9497284.
External links
- European-Mediterranean Seismological Center, real-time earthquake information website.
- Seismological Society of America.
- Incorporated Research Institutions for Seismology.
- USGS Earthquake Hazards Program.
- A brief history of seismology to 1910 (UCSB ERI)