Seismology

Seismology

Overview
Seismology is the scientific study of earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s and the propagation of elastic waves through the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic source
Seismic source
A seismic source is a device that generates controlled seismic energy used to perform both reflection and refraction seismic surveys. A seismic source can be simple, such as dynamite, or it can use more sophisticated technology, such as a specialized air gun. Seismic sources can provide single...

s such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions). A related field that uses geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 to infer information regarding past earthquakes is paleoseismology
Paleoseismology
Paleoseismology looks at geologic sediments and rocks, for signs of ancient earthquakes. It is used to supplement seismic monitoring, for the calculation of seismic hazard...

.
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Encyclopedia
Seismology is the scientific study of earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s and the propagation of elastic waves through the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic source
Seismic source
A seismic source is a device that generates controlled seismic energy used to perform both reflection and refraction seismic surveys. A seismic source can be simple, such as dynamite, or it can use more sophisticated technology, such as a specialized air gun. Seismic sources can provide single...

s such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions). A related field that uses geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 to infer information regarding past earthquakes is paleoseismology
Paleoseismology
Paleoseismology looks at geologic sediments and rocks, for signs of ancient earthquakes. It is used to supplement seismic monitoring, for the calculation of seismic hazard...

. A recording of earth motion as a function of time is called a seismogram
Seismogram
A seismogram is a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. Seismograms typically record motions in three cartesian axes , with the z axis perpendicular to the Earth's surface and the x- and y- axes parallel to the surface...

.

Types of seismic wave




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 wave, P-wave
P-wave
P-waves are a type of elastic wave, also called seismic waves, that can travel through gases , solids and liquids, including the Earth. P-waves are produced by earthquakes and recorded by seismographs...

s and S-wave
S-wave
A type of seismic wave, the S-wave, secondary wave, or shear wave is one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves....

s (both body waves). Pressure waves or Primary waves (P-wave
P-wave
P-waves are a type of elastic wave, also called seismic waves, that can travel through gases , solids and liquids, including the Earth. P-waves are produced by earthquakes and recorded by seismographs...

s), are longitudinal wave
Longitudinal wave
Longitudinal waves, as known as "l-waves", are waves that have the same direction of vibration as their direction of travel, which means that the movement of the medium is in the same direction as or the opposite direction to the motion of the wave. Mechanical longitudinal waves have been also...

s that involve compression
Compression (geology)
In geology the term compression refers to a set of stresses directed toward the center of a rock mass. Compressive strength refers to the maximum compressive stress that can be applied to a material before failure occurs. When the maximum compressive stress is in a horizontal orientation, thrust...

 and rarefaction
Rarefaction
Rarefaction is the reduction of a medium's density, or the opposite of compression.A natural example of this is as a phase in a sound wave or phonon. Half of a sound wave is made up of the compression of the medium, and the other half is the decompression or rarefaction of the medium.Another...

 (expansion) in the direction that the wave is traveling. P-waves are the fastest waves in solids and are therefore the first waves to appear on a seismogram
Seismogram
A seismogram is a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. Seismograms typically record motions in three cartesian axes , with the z axis perpendicular to the Earth's surface and the x- and y- axes parallel to the surface...

. S-waves, also called shear or secondary waves, are transverse wave
Transverse wave
A transverse wave is a moving wave that consists of oscillations occurring perpendicular to the direction of energy transfer...

s that involve motion perpendicular to the direction of propagation. S-waves appear later than P-waves on a seismogram. Fluids cannot support this perpendicular motion, or shear
Shearing (physics)
Shearing in continuum mechanics refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. It is induced by a shear stress in the material...

, so S-waves only travel in solids. P-waves travel in both solids and fluids.

Surface waves


The two main kinds of surface wave are the Rayleigh wave
Rayleigh wave
Rayleigh waves are a type of surface acoustic wave that travels on solids. They are produced on the Earth by earthquakes, in which case they are also known as "ground roll", or by other sources of seismic energy such as ocean waves an explosion or even a sledgehammer impact...

, which has some compressional motion, and the Love wave
Love wave
In elastodynamics, Love waves are horizontally polarized shear waves guided by an elastic layer, which is "welded" to an elastic half space on one side while bordering a vacuum on the other side...

, which does not. Such waves can be theoretically explained in terms of interacting P- and/or S-waves. Surface waves travel more slowly than P-waves and S-waves, but because they are guided by the surface of the Earth (and their energy is thus trapped near the Earth's surface) they can be much larger in amplitude than body waves, and can be the largest signals seen in earthquake seismograms. They are particularly strongly excited when their source is close to the surface of the Earth, as in a shallow earthquake or explosion.

Normal modes


The above waves are traveling waves. Large earthquakes can also make the Earth "ring" like a bell. This ringing is a mixture of normal modes with discrete frequencies and periods of an hour or longer. Motion caused by a large earthquake can be observed for up to a month after the event. 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 Great Chilean Earthquake
Great Chilean Earthquake
The 1960 Valdivia earthquake or Great Chilean Earthquake of Sunday, 22 May 1960 is to date the most powerful earthquake ever recorded on Earth, rating 9.5 on the moment magnitude scale...

 and the 1964 Great Alaskan Earthquake
Good Friday Earthquake
The 1964 Alaska earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964...

. 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
1755 Lisbon earthquake
The 1755 Lisbon earthquake, also known as the Great Lisbon Earthquake, was a megathrust earthquake that took place on Saturday 1 November 1755, at around 9:40 in the morning. The earthquake was followed by fires and a tsunami, which almost totally destroyed Lisbon in the Kingdom of Portugal, and...

. Other especially notable earthquakes that spurred major developments in the science of seismology include the 1857 Basilicata earthquake, 1906 San Francisco earthquake
1906 San Francisco earthquake
The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...

, the 1964 Alaska earthquake and the 2004 Sumatra-Andaman earthquake. An extensive list of famous earthquakes can be found on the List of earthquakes page.

Controlled seismic sources



Seismic waves produced by explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

s or vibrating controlled sources are one of the primary methods of underground exploration in geophysics
Exploration geophysics
Exploration geophysics is the applied branch of geophysics which uses surface methods to measure the physical properties of the subsurface Earth, in order to detect or infer the presence and position of ore minerals, hydrocarbons, geothermal reservoirs, groundwater reservoirs, and other geological...

 (in addition to many different electromagnetic
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

 methods such as induced polarization
Induced polarization
Induced polarization is a geophysical imaging technique used to identify subsurface materials, such as ore. The method is similar to electrical resistivity tomography, in that an electric current is induced into the subsurface through two electrodes, and voltage is monitored through two other...

 and magnetotellurics
Magnetotellurics
Magnetotellurics is an electromagnetic geophysical method of imaging the earth's subsurface by measuring natural variations of electrical and magnetic fields at the Earth's surface. Investigation depth ranges from 300m below ground by recording higher frequencies down to 10,000m or deeper with...

). Controlled-source seismology has been used to map salt dome
Salt dome
A salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....

s, faults, anticlines and other geologic traps in petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

-bearing rocks
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

, geological faults, rock types, and long-buried giant meteor
METEOR
METEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...

 craters
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

. For example, the Chicxulub Crater
Chicxulub Crater
The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named...

, which was caused by an impact that has been implicated in the extinction of the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s, was localized to Central America by analyzing ejecta in the Cretaceous-Tertiary boundary
K–T boundary
The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...

, and then physically proven to exist using seismic maps from oil exploration
Oil exploration
Hydrocarbon exploration is the search by petroleum geologists and geophysicists for hydrocarbon deposits beneath the Earth's surface, such as oil and natural gas...

.

Detection of seismic waves


Seismometer
Seismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...

s are sensors that sense and record the motion of the Earth arising from elastic waves. Seismometers may be deployed at Earth's surface, in shallow vaults, or in boreholes. 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 seismic sources. Rapid location of earthquakes makes tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 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 or anthropogenic activities, to incessant signals generated at the ocean floor and coasts induced by ocean waves (the global microseism
Microseism
In seismology, a microseism is defined as a faint earth tremor caused by natural phenomena. The term is most commonly used to refer to the dominant background seismic noise signal on Earth, which are mostly composed of Rayleigh waves and caused by water waves in the oceans and lakes...

), to cryospheric
Cryosphere
The cryosphere is the term which collectively describes the portions of the Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground . Thus there is a wide overlap with the hydrosphere...

 events associated with large icebergs and glaciers. Above-ocean meteor strikes with energies as high as 4.2 × 1013 J
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...

 (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 forensic seismology
Forensic seismology
Forensic seismology is the forensic use of the techniques of seismology to detect and study distant phenomena, particularly explosions, including those of nuclear weapons....

). A major long-term motivation for the global seismographic monitoring has been for the detection and study of nuclear testing
Nuclear testing
Nuclear weapons tests are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them...

.

Mapping the Earth's interior


Because seismic waves commonly propagate efficiently and interact with internal structure, they provide high-resolution noninvasive methods for studying Earth's interior. One of the earliest important discoveries (suggested by Richard Dixon Oldham
Richard Dixon Oldham
Richard Dixon Oldham FRS was a British geologist who made the first clear identification of the separate arrivals of P-waves, S-waves and surface waves on seismograms and the first clear evidence that the Earth has a central core.-Life:Born on 31 July 1858 to Thomas Oldham, a Fellow of the Royal...

 in 1906 and definitively shown by Harold Jeffreys
Harold Jeffreys
Sir Harold Jeffreys, FRS was a mathematician, statistician, geophysicist, and astronomer. His seminal book Theory of Probability, which first appeared in 1939, played an important role in the revival of the Bayesian view of probability.-Biography:Jeffreys was born in Fatfield, Washington, County...

 in 1926) was that the outer core
Outer core
The outer core of the Earth is a liquid layer about 2,266 kilometers thick composed of iron and nickel which lies above the Earth's solid inner core and below its mantle. Its outer boundary lies beneath the Earth's surface...

 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 of 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
Seismic tomography is a methodology for estimating the Earth's properties. In the seismology community, seismic tomography is just a part of seismic imaging, and usually has a more specific purpose to estimate properties such as propagating velocities of compressional waves and shear waves . It...

 , seismologists have mapped the mantle of the Earth to a resolution of several hundred kilometers. This has enabled scientists to identify convection cell
Convection cell
A convection cell is a phenomenon of fluid dynamics that occurs in situations where there are density differences within a body of liquid or gas. The convection usually requires a gravitational field but in microgravity experiments, thermal convection has been observed without gravitational effects...

s and other large-scale features such as Ultra Low Velocity Zones near the core–mantle boundary
Core–mantle boundary
The core–mantle boundary lies between the Earth's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2900 km of depth beneath the Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth...

.

Earthquake prediction



Forecasting a probable timing, location, magnitude and other important features of a forthcoming seismic event is called earthquake prediction
Earthquake prediction
An earthquake prediction is a prediction that an earthquake of a specific magnitude will occur in a particular place at a particular time . Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific day or month...

. Various attempts have been made by seismologists and others to create effective systems for precise earthquake predictions, including the VAN method
VAN method
The VAN method is a controversial method for earthquake prediction based on the assumption that minerals under mechanical stress emit characteristic electrical signals. The name of the method derives from the surname initials of each of its inventors, Greek physicists Panayotis Varotsos, Caesar...

. 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 significant warning of impending seismic events. However, more general forecasts routinely predict seismic hazard
Seismic hazard
Seismic hazard refers to the study of expected earthquake ground motions at the earth's surface, and its likely effects on existing natural conditions and man-made structures for public safety considerations; the results of such studies are published as seismic hazard maps, which identify the...

. 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
Earthquake engineering
Earthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels...

.

Public controversy over earthquake prediction erupted after Italian authorities indicted six seismologists and one government official for manslaughter
Manslaughter
Manslaughter is a legal term for the killing of a human being, in a manner considered by law as less culpable than murder. The distinction between murder and manslaughter is said to have first been made by the Ancient Athenian lawmaker Dracon in the 7th century BC.The law generally differentiates...

 in connection with a magnitude 6.3 earthquake in L'Aquila, Italy on April 5, 2009
2009 L'Aquila earthquake
The 2009 L'Aquila earthquake occurred in the region of Abruzzo, in central Italy. The main shock occurred at 3:32 local time on 6 April 2009, and was rated 5.8 on the Richter scale and 6.3 on the moment magnitude scale; its epicentre was near L'Aquila, the capital of Abruzzo, which together...

. The indictment has been widely perceived as an indictment for failing to predict the earthquake and has drawn condemnation from the American Association for the Advancement of Science
American Association for the Advancement of Science
The American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...

 and the American Geophysical Union
American Geophysical Union
The American Geophysical Union is a nonprofit organization of geophysicists, consisting of over 50,000 members from over 135 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international field of geophysics...

. 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.

Tools


Seismological instruments can generate large amounts of data. Systems for processing such data include:
  • CUSP (Caltech-USGS Seismic Processing)
  • RadExPro seismic software
    RadExPro seismic software
    RadExPro is a Windows-based seismic processing software system produced by DECO Geophysical Software Company. It is suitable for processing of near-surface seismics, including seismic reflection, refraction, and MASW...

  • SeisComP3

Notable seismologists


  • Aki, Keiiti
    Keiiti Aki
    was a professor of Geophysics at the Massachusetts Institute of Technology , seismologist, author and mentor. He co-authored with Paul G. Richards, "Quantitative Seismology: theory and methods".Aki was born in Yokohama, Japan...

  • Don L. Anderson
    Don L. Anderson
    Don Lynn Anderson is an American geophysicist who has made important contributions to the determination of the large-scale structure of the Earth's interior, especially using seismological methods. He is Eleanor and John R. McMillan Professor emeritus of geophysics at the California Institute of...

  • Bolt, Bruce
    Bruce Bolt
    Bruce Bolt was a Professor of Earth and Planetary Science at the University of California, Berkeley. Professor Bolt was a seismologist known as pioneer of engineering seismology...

  • Claerbout, Jon
  • Dziewonski, Adam Marian
    Adam Dziewonski
    Adam Marian Dziewoński is a Polish-American geophysicist who has made seminal contributions to the determination of the large-scale structure of the Earth's interior and the nature of earthquakes using seismological methods. He is the Frank B. Baird, Jr...

  • Ewing, Maurice
    Maurice Ewing
    William Maurice "Doc" Ewing was an American geophysicist and oceanographer.Ewing has been described as a pioneering geophysicist who worked on the research of seismic reflection and refraction in ocean basins, ocean bottom photography, submarine sound transmission , deep sea coring of the ocean...

  • Galitzine, Boris Borisovich
    Boris Borisovich Galitzine
    Prince Boris Borisovich Galitzine was a prominent Russian physicist who invented the first electromagnetic seismograph in 1906. He was one of the founders of modern Seismology. In 1911 he was chosen to be the president of the International Sesmiology Association...

  • Gamburtsev, Grigory A.
    Grigoriy A. Gamburtsev
    Grigoriy Aleksandrovich Gamburtsev was a Soviet seismologist and academician from Saint Petersburg, Russia who worked in the area of seismometry and earthquake prediction.-Life:...

  • Gutenberg, Beno
    Beno Gutenberg
    Beno Gutenberg was a German-American seismologist who made several important contributions to the science...

  • Hough, Susan
    Susan Hough
    Susan Elizabeth Hough is a seismologist at the United States Geological Survey in Pasadena, California, and scientist in charge of the office. She has served as an editor and contributor for many journals and is a contributing editor to Geotimes Magazine...

  • Jeffreys, Harold
    Harold Jeffreys
    Sir Harold Jeffreys, FRS was a mathematician, statistician, geophysicist, and astronomer. His seminal book Theory of Probability, which first appeared in 1939, played an important role in the revival of the Bayesian view of probability.-Biography:Jeffreys was born in Fatfield, Washington, County...

  • Jones, Lucy
    Lucy Jones
    Lucile M. Jones is a seismologist and public voice for earthquake science and earthquake safety in California. She has been with the US Geological Survey and a Visiting Research Associate at the Seismological Laboratory of Caltech since 1983...

  • Kanamori, Hiroo
    Hiroo Kanamori
    is a Japanese American seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them....

  • Keilis-Borok, Vladimir
    Vladimir Keilis-Borok
    Vladimir Keilis-Borok was born in Moscow, Russia on July 31, 1921. He is a mathematical geophysicist.- Biography :In 1948, he received a Ph.D. in mathematical geophysics from the Academy of Sciences in Moscow. He was the founder, and is the Director Emeritus, of the International Institute of...

  • Knopoff, Leon
    Leon Knopoff
    Leon Knopoff was a geophysicist and musicologist. He received his education at Caltech, graduating in 1949 with a PhD in physics, and after holding several academic positions, moved to UCLA...

  • Lehmann, Inge
    Inge Lehmann
    Inge Lehmann FRS , was a Danish seismologist who, in 1936, argued that the Earth's core is not one single molten sphere, but that an inner core exists which has physical properties that are different from those of the outer core.-Life:Inge Lehmann was born and grew up in Østerbro, a part of...

  • Mallet, Robert
    Robert Mallet
    Robert Mallet FRS , Irish geophysicist, civil engineer, and inventor who distinguished himself in research on earthquakes and is sometimes called the father of seismology.-Early life:...

  • Mercalli, Giuseppe
    Giuseppe Mercalli
    Giuseppe Mercalli was an Italian volcanologist. He is best remembered today for his Mercalli scale for measuring earthquakes which is still used today.-Biography:...

  • Milne, John
    John Milne
    For other uses, see John Milne .John Milne was the British geologist and mining engineer who worked on a horizontal seismograph.-Biography:...

  • Mohorovičić, Andrija
    Andrija Mohorovicic
    Andrija Mohorovičić was a Croatian meteorologist and seismologist. He is best known for the eponymous Mohorovičić discontinuity and is considered a founder of modern seismology.-Early years:...

  • Oldham, Richard Dixon
    Richard Dixon Oldham
    Richard Dixon Oldham FRS was a British geologist who made the first clear identification of the separate arrivals of P-waves, S-waves and surface waves on seismograms and the first clear evidence that the Earth has a central core.-Life:Born on 31 July 1858 to Thomas Oldham, a Fellow of the Royal...

  • Sebastião de Melo, Marquis of Pombal
  • Press, Frank
    Frank Press
    Frank Press is an American geophysicist.Born in Brooklyn, New York, Press was science advisor to President Jimmy Carter from1976 to 1980,and president of the U.S. NationalAcademy of Sciences from 1981 to 1993...

  • Richards, Paul G.
    Paul G. Richards
    Paul G. Richards is an English-born, American seismologist who has made fundamental contributions to the theory of seismic wave link propagation and in methods to understand how the recorded shapes of seismic waves are affected by processes of diffraction, attenuation and scattering...

  • Richter, Charles Francis
    Charles Francis Richter
    Charles Francis Richter , was an American seismologist and physicist. Richter is most famous as the creator of the Richter magnitude scale which, until the development of the moment magnitude scale in 1979, quantified the size of earthquakes...

  • Sekiya, Seikei
  • Sieh, Kerry
    Kerry Sieh
    Kerry E. Sieh is an American geologist and seismologist.Sieh's principal research interest is earthquake geology, which uses geological layers and landforms to understand the geometries of active faults, the earthquakes they generate, and the crustal structure their movements produce...

  • Paul G. Silver
    Paul Silver
    Paul Gordon Silver was an American seismologist.A member of the research staff at the of the Carnegie Institution of Washington since 1982, Paul Silver made a series of important contributions to the investigation of seismic anisotropy and to earthquake research by observing the slow...

  • Tucker, Brian
    Brian Tucker
    Brian E. Tucker is a seismologist specialising in disaster prevention.He holds a Ph.D. in Earth Sciences from the Scripps Institution of Oceanography at the University of California, San Diego, an M.A. in Public Policy from the John F. Kennedy School of Government at Harvard University, and a B.A....

  • Vidale, John
    John Vidale
    John Emilio Vidale is an American-born seismologist who specializes in examining seismograms to explore features within the Earth. He received the American Geophysical Union's James B. Macelwane Medal in 1994....

  • Wen, Lianxing
    Lianxing Wen
    Lianxing Wen is a Chinese seismologist, geodynamicist and planetary scientist, who has made fundamental contributions to many discoveries in the Earth's interior. His ability to formulate new theoretical methods and apply to new seismological observations have led to some of the most fundamental...

  • Winthrop, John
  • Zhang Heng
    Zhang Heng
    Zhang Heng was a Chinese astronomer, mathematician, inventor, geographer, cartographer, artist, poet, statesman, and literary scholar from Nanyang, Henan. He lived during the Eastern Han Dynasty of China. He was educated in the capital cities of Luoyang and Chang'an, and began his career as a...



See also


  • Ambient Vibrations
    Ambient Vibrations
    Various types of vibration sources are always producing so called Ambient Vibrations on the Earth ground . These vibrations are mostly surface waves propagating on the surface. Low frequency waves are generally called microseisms and high frequency waves are called microtremors...

  • Asteroseismology
    Asteroseismology
    Asteroseismology also known as stellar seismology is the science that studies the internal structure of pulsating stars by the interpretation of their frequency spectra. Different oscillation modes penetrate to different depths inside the star...

  • Cryoseism
    Cryoseism
    A cryoseism, also known as a frost quake, may be caused by a sudden cracking action in frozen soil or rock saturated with water or ice. As water seeps down into the rock, it freezes and expands, putting stress on surrounding rock...

  • Engineering geology
    Engineering geology
    Engineering geology is the application of the geologic sciences to engineering practice for the purpose of assuring that the geologic factors affecting the location, design, construction, operation and maintenance of engineering works are recognized and adequately provided for...

  • Forensic seismology
    Forensic seismology
    Forensic seismology is the forensic use of the techniques of seismology to detect and study distant phenomena, particularly explosions, including those of nuclear weapons....

  • Geophysical migration
    Geophysical migration
    Geophysical migration is the process by which geophysical events are geometrically re-located in either space or time to the location the event occurred in the subsurface rather than the location that it was recorded at the surface, thereby creating an accurate image of the subsurface...

  • Helioseismology
    Helioseismology
    Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...

  • The IRIS Consortium
  • Isoseismal map
    Isoseismal map
    In seismology an isoseismal map is used to show lines of equal felt seismic intensity, generally measured on the Modified Mercalli scale. Such maps help to identify earthquake epicenters, particularly where no instrumental records exist, such as for historical earthquakes...

  • Seismic loading
    Seismic loading
    Seismic loading is one of the basic concepts of earthquake engineering which means application of an earthquake-generated agitation to a structure...

  • Seismic performance analysis
  • Seismite
    Seismite
    Seismites are sedimentary beds disturbed by seismic shaking. The German paleontologist Adolf Seilacher first used the term in 1969 to describe a variety of post-depositional effects of seismic shocks on unconsolidated sediments...

  • Seismo-electromagnetics
    Seismo-electromagnetics
    Seismo-electromagnetics is the study of electromagnetic phenomena associated with seismic activity such as earthquakes and volcanos, and also the use of electromagnetic methods in seismology such as magnetotellurics. Links between the electromagnetic fields in the lithosphere and those in the...

  • Seismotectonics
    Seismotectonics
    Seismotectonics is the study of the relationship between the earthquakes, active tectonics and individual faults of a region. It seeks to understand which faults are responsible for seismic activity in an area by analysing a combination of regional tectonics, recent instrumentally recorded events,...



External links


European-Mediterranean Sismological Center, real-time earthquake information website.