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An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wit ...

Earth
's
lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion o ...
that creates
seismic wave Seismic waves are waves The United States Naval Reserve (Women's Reserve), better known as the WAVES (for Women Accepted for Volunteer Emergency Service), was the women's branch of the United States Naval Reserve The United States Navy ...
s. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the air, and wreak destruction across entire cities. The
seismicity Seismicity is a measure encompassing earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic wa ...
, or seismic activity, of an area is the frequency, type, and size of earthquakes experienced over a period of time. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter, hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage In most earthqua ...

epicenter
of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a
tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a . s, s and other s (including detonations, landslides, , and other dis ...

tsunami
. Earthquakes can also trigger
landslide Landslides, also known as landslips, are several forms of mass wasting Mass wasting, also known as mass movement, is a general term for the movement of rock (geology), rock or soil down slopes under the force of gravity. It differs from othe ...

landslide
s and, occasionally, volcanic activity. In its most general sense, the word ''earthquake'' is used to describe any seismic event—whether natural or caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults but also by other events such as volcanic activity, landslides, mine blasts, and
nuclear tests Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapon A nuclear weapon (also called an atom bomb, nuke, atomic bomb, nuclear warhead, A-bomb, or nuclear bomb) is a ...
. An earthquake's point of initial rupture is called its
hypocenter A hypocenter (or hypocentre; ) is the point of origin of an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosph ...
or focus. The
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter, hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage In most earthqua ...

epicenter
is the point at ground level directly above the hypocenter.


Naturally occurring earthquakes

Tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a
fault plane In geology, a fault is a Plane (geometry), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within the Earth's Crust (geolo ...
. The sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the fault surface that increase the frictional resistance. Most fault surfaces do have such asperities, which leads to a form of stick-slip behavior. Once the fault has locked, continued relative motion between the plates leads to increasing stress and, therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the
stored energy
stored energy
. This energy is released as a combination of radiated elastic strain
seismic waves Seismic waves are waves of energy In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its M ...
, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the
elastic-rebound theory __NOTOC__ In , the elastic-rebound theory is an explanation for how is released during an . As the Earth's deforms, the rocks which span the opposing sides of a are subjected to . Slowly they , until their internal rigidity is exceeded. Then ...
. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake
fracture Fracture is the separation of an object or material into two or more pieces under the action of stress (physics), stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the ...
growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available
elastic potential energy Elastic energy is the mechanical potential energy In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of p ...
and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.


Earthquake fault types

There are three main types of fault, all of which may cause an
interplate earthquake An interplate earthquake is an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth Earth is the third planet from the ...
: normal, reverse (thrust), and strike-slip. Normal and reverse faulting are examples of dip-slip, where the displacement along the fault is in the direction of
dip
dip
and where movement on them involves a vertical component. Normal faults occur mainly in areas where the crust is being extended such as a
divergent boundary In plate tectonics File:Earth cutaway schematic-en.svg, upright=1.35, Diagram of the internal layering of Earth showing the lithosphere above the asthenosphere (not to scale) Plate tectonics (from the la, label=Late Latin, tectonicus, from ...
. Reverse faults occur in areas where the crust is being shortened such as at a convergent boundary.
Strike-slip fault In geology Geology (from the γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is a branch of concerned with both the liquid and , the of which it is composed, and the processes by which they change over t ...

Strike-slip fault
s are steep structures where the two sides of the fault slip horizontally past each other; transform boundaries are a particular type of strike-slip fault. Many earthquakes are caused by movement on faults that have components of both dip-slip and strike-slip; this is known as oblique slip. Reverse faults, particularly those along convergent plate boundaries, are associated with the most powerful earthquakes,
megathrust earthquake Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolut ...
s, including almost all of those of magnitude 8 or more. Megathrust earthquakes are responsible for about 90% of the total seismic moment released worldwide. Strike-slip faults, particularly continental
transforms Transform may refer to: Arts and entertainment *Transform (Powerman 5000 album), ''Transform'' (Powerman 5000 album), 2003 *Transform (Rebecca St. James album), ''Transform'' (Rebecca St. James album), 2000 *Transform (scratch), a type of scratc ...

transforms
, can produce major earthquakes up to about magnitude 8. Earthquakes associated with normal faults are generally less than magnitude 7. For every unit increase in magnitude, there is a roughly thirtyfold increase in the energy released. For instance, an earthquake of magnitude 6.0 releases approximately 32 times more energy than a 5.0 magnitude earthquake and a 7.0 magnitude earthquake releases 1,000 times more energy than a 5.0 magnitude of earthquake. An 8.6 magnitude earthquake releases the same amount of energy as 10,000 atomic bombs like those used in
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
. This is so because the energy released in an earthquake, and thus its magnitude, is proportional to the area of the fault that ruptures and the stress drop. Therefore, the longer the length and the wider the width of the faulted area, the larger the resulting magnitude. The topmost, brittle part of the Earth's crust, and the cool slabs of the tectonic plates that are descending down into the hot mantle, are the only parts of our planet that can store elastic energy and release it in fault ruptures. Rocks hotter than about flow in response to stress; they do not rupture in earthquakes. The maximum observed lengths of ruptures and mapped faults (which may break in a single rupture) are approximately . Examples are the earthquakes in Alaska (1957),
Chile (1960)
Chile (1960)
, and Sumatra (2004), all in subduction zones. The longest earthquake ruptures on strike-slip faults, like the
San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is th ...
(
1857 Events January–March * January 1 – The biggest Estonian newspaper, ''Postimees'', is established by Johann Voldemar Jannsen. * January 7 – The partly French-owned London General Omnibus Company begins operating. * Januar ...
, 1906), the
North Anatolian Fault The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral Fault (geology)#Strike-slip faults, strike-slip fault in northern Anatolia, and is the Transform fault, transform boundary between the Eurasian Plate and t ...
in Turkey (
1939 This year also marks the start of the Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a that lasted from 1939 to 1945. It involved —including all of the great powers—forming two ...
), and the
Denali Fault
Denali Fault
in Alaska (
2002 2002 was designated as the International Year of Ecotourism and the International Year of Mountains. Events January * January 1 ** The Treaty on Open Skies, Open Skies mutual surveillance treaty, initially signed in 1992, officially enters ...

2002
), are about half to one third as long as the lengths along subducting plate margins, and those along normal faults are even shorter. The most important parameter controlling the maximum earthquake magnitude on a fault, however, is not the maximum available length, but the available width because the latter varies by a factor of 20. Along converging plate margins, the dip angle of the rupture plane is very shallow, typically about 10 degrees. Thus, the width of the plane within the top brittle crust of the Earth can become ( Japan, 2011; Alaska, 1964), making the most powerful earthquakes possible. Strike-slip faults tend to be oriented near vertically, resulting in an approximate width of within the brittle crust. Thus, earthquakes with magnitudes much larger than 8 are not possible. Maximum magnitudes along many normal faults are even more limited because many of them are located along spreading centers, as in Iceland, where the thickness of the brittle layer is only about . In addition, there exists a hierarchy of stress level in the three fault types. Thrust faults are generated by the highest, strike-slip by intermediate, and normal faults by the lowest stress levels. This can easily be understood by considering the direction of the greatest principal stress, the direction of the force that "pushes" the rock mass during the faulting. In the case of normal faults, the rock mass is pushed down in a vertical direction, thus the pushing force (''greatest'' principal stress) equals the weight of the rock mass itself. In the case of thrusting, the rock mass "escapes" in the direction of the least principal stress, namely upward, lifting the rock mass up, and thus, the overburden equals the ''least'' principal stress. Strike-slip faulting is intermediate between the other two types described above. This difference in stress regime in the three faulting environments can contribute to differences in stress drop during faulting, which contributes to differences in the radiated energy, regardless of fault dimensions.


Earthquakes away from plate boundaries

Where plate boundaries occur within the
continental lithosphere A lithosphere ( grc, wikt:λίθος#Ancient Greek, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. On Earth, it is composed of the crust (geol ...
, deformation is spread out over a much larger area than the plate boundary itself. In the case of the
San Andreas fault The San Andreas Fault is a continental transform fault that extends roughly through California California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is th ...
continental transform, many earthquakes occur away from the plate boundary and are related to strains developed within the broader zone of deformation caused by major irregularities in the fault trace (e.g., the "Big bend" region). The
Northridge earthquake The 1994 Northridge earthquake was a moment 6.7 (), blind thrust earthquake that occurred on the annual Martin Luther King, Jr. Day holiday, on Monday, January 17, 1994. It occurred at 4:30:55 a.m. (PST) and was located in the San Fe ...

Northridge earthquake
was associated with movement on a blind thrust within such a zone. Another example is the strongly oblique convergent plate boundary between the
Arabian The Arabian Peninsula (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs The Arabs (singular Arab ; singular ar, عَرَبِيٌّ, ISO 233: , Arabic pronunciati ...
and
Eurasian plate The Eurasian Plate is a tectonic plate This is a list of tectonic plates on Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around thick and consist ...
s where it runs through the northwestern part of the
Zagros Mountains The Zagros Mountains ( fa, کوه‌های زاگرس, ''Kuh hā-ye Zāgros;'' Luri language, Luri: کویل زاگروس‎, ''Koyal Zagros;'' Turkish language, Turkish: ''Zagros Dağları;'' ku, چیاکانی زاگرۆس, translit=Çiyakani ...
. The deformation associated with this plate boundary is partitioned into nearly pure thrust sense movements perpendicular to the boundary over a wide zone to the southwest and nearly pure strike-slip motion along the Main Recent Fault close to the actual plate boundary itself. This is demonstrated by earthquake
focal mechanism The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event it refers to the orien ...

focal mechanism
s. All tectonic plates have internal stress fields caused by their interactions with neighboring plates and sedimentary loading or unloading (e.g., deglaciation). These stresses may be sufficient to cause failure along existing fault planes, giving rise to intraplate earthquakes.


Shallow-focus and deep-focus earthquakes

The majority of tectonic earthquakes originate in the ring of fire at depths not exceeding tens of kilometers. Earthquakes occurring at a depth of less than are classified as "shallow-focus" earthquakes, while those with a focal-depth between are commonly termed "mid-focus" or "intermediate-depth" earthquakes. In
Subduction Subduction is a geological process in which the oceanic lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. O ...

Subduction
zones, where older and colder
oceanic crust The oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates This is a list of tectonic plates on Earth's surface. Tectonic plates are pieces of Earth's crust 350px, Plates in the crust of Earth Earth's crust i ...
descends beneath another tectonic plate,
deep-focus earthquakeA deep-focus earthquake in seismology Seismology (; from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roug ...
s may occur at much greater depths (ranging from ). These seismically active areas of subduction are known as
Wadati–Benioff zone Image:Kuril Benioff zone.JPG, 240px, Seismicity cross-section, Kuril Islands subduction zone, 2006 Kuril Islands earthquake, 15 November 2006, 8.3 Mw event marked as star A Wadati–Benioff zone (also Benioff–Wadati zone or Benioff zone or Beniof ...
s. Deep-focus earthquakes occur at a depth where the subducted
lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion o ...
should no longer be brittle, due to the high temperature and pressure. A possible mechanism for the generation of deep-focus earthquakes is faulting caused by
olivine The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. R ...

olivine
undergoing a
phase transition In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...
into a
spinel Spinel () is the magnesium Magnesium is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only o ...

spinel
structure.


Earthquakes and volcanic activity

Earthquakes often occur in volcanic regions and are caused there, both by
tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building A mountain is an elevated portion of the Earth's crust, gen ...

tectonic
faults and the movement of
magma Magma () is the molten or semi-molten natural material from which all igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others ...

magma
in
volcano A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet a ...

volcano
es. Such earthquakes can serve as an early warning of volcanic eruptions, as during the 1980 eruption of Mount St. Helens. Earthquake swarms can serve as markers for the location of the flowing magma throughout the volcanoes. These swarms can be recorded by
seismometers A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions, and explosions. Seismometers are usually combined with a timing device and a recording device to form a seismograph. The output of ...
and
tiltmeter A tiltmeter is a sensitive inclinometer designed to measure very small changes from the vertical level, either on the ground or in structures. Tiltmeters are used extensively for monitoring volcanoes, the response of dams to filling, the small mo ...
s (a device that measures ground slope) and used as sensors to predict imminent or upcoming eruptions.


Rupture dynamics

A tectonic earthquake begins by an initial rupture at a point on the fault surface, a process known as nucleation. The scale of the nucleation zone is uncertain, with some evidence, such as the rupture dimensions of the smallest earthquakes, suggesting that it is smaller than while other evidence, such as a slow component revealed by low-frequency spectra of some earthquakes, suggest that it is larger. The possibility that the nucleation involves some sort of preparation process is supported by the observation that about 40% of earthquakes are preceded by foreshocks. Once the rupture has initiated, it begins to propagate along the fault surface. The mechanics of this process are poorly understood, partly because it is difficult to recreate the high sliding velocities in a laboratory. Also the effects of strong ground motion make it very difficult to record information close to a nucleation zone. Rupture propagation is generally modeled using a
fracture mechanics Fracture mechanics is the field of mechanics Mechanics (Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Eur ...
approach, likening the rupture to a propagating mixed mode shear crack. The rupture velocity is a function of the fracture energy in the volume around the crack tip, increasing with decreasing fracture energy. The velocity of rupture propagation is orders of magnitude faster than the displacement velocity across the fault. Earthquake ruptures typically propagate at velocities that are in the range 70–90% of the S-wave velocity, which is independent of earthquake size. A small subset of earthquake ruptures appear to have propagated at speeds greater than the S-wave velocity. These
supershear earthquake A supershear earthquake is an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. E ...
s have all been observed during large strike-slip events. The unusually wide zone of coseismic damage caused by the 2001 Kunlun earthquake has been attributed to the effects of the
sonic boom A sonic boom is a sound associated with shock wave of an attached shock on a sharp-nosed supersonic F/A-18F Super Hornet in transonic flight Flight or flying is the process by which an object (physics), object motion (physics), m ...

sonic boom
developed in such earthquakes. Some earthquake ruptures travel at unusually low velocities and are referred to as
slow earthquake A slow earthquake is a discontinuous, earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic ...
s. A particularly dangerous form of slow earthquake is the tsunami earthquake, observed where the relatively low felt intensities, caused by the slow propagation speed of some great earthquakes, fail to alert the population of the neighboring coast, as in the
1896 Sanriku earthquake Events January–March * January 2 Events Pre-1600 *AD 69, 69 – The Roman legions in Germania Superior refuse to swear loyalty to Galba. They rebel and proclaim Vitellius as emperor. * 366 – The Alemanni cross the ...
.


Co-seismic overpressuring and effect of pore pressure

During an earthquake, high temperatures can develop at the fault plane so increasing pore pressure consequently to vaporization of the ground water already contained within rock. In the coseismic phase, such increase can significantly affect slip evolution and speed and, furthermore, in the post-seismic phase it can control the
Aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same Epicenter, area of the main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthquakes can h ...
sequence because, after the main event, pore pressure increase slowly propagates into the surrounding fracture network. From the point of view of the Mohr-Coulomb strength theory, an increase in fluid pressure reduces the normal stress acting on the fault plane that holds it in place, and fluids can exert a lubricating effect. As thermal overpressurization may provide a positive feedback between slip and strength fall at the fault plane, a common opinion is that it may enhance the faulting process instability. After the main shock, the pressure gradient between the fault plane and the neighboring rock causes a fluid flow which increases pore pressure in the surrounding fracture networks; such increase may trigger new faulting processes by reactivating adjacent faults, giving rise to aftershocks. Analogously, artificial pore pressure increase, by fluid injection in Earth’s crust, may induce seismicity.


Tidal forces

Tides Tides are the rise and fall of sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloquial, ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of t ...

Tides
may induce some
seismicity Seismicity is a measure encompassing earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic wa ...
.


Earthquake clusters

Most earthquakes form part of a sequence, related to each other in terms of location and time. Most earthquake clusters consist of small tremors that cause little to no damage, but there is a theory that earthquakes can recur in a regular pattern.


Aftershocks

An aftershock is an earthquake that occurs after a previous earthquake, the mainshock. Rapid changes of stress between rocks, and the stress from the original earthquake are the main causes of these aftershocks, along with the crust around the ruptured
fault plane In geology, a fault is a Plane (geometry), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within the Earth's Crust (geolo ...
as it adjusts to the effects of the main shock. An aftershock is in the same region of the main shock but always of a smaller magnitude, however they can still be powerful enough to cause even more damage to buildings that were already previously damaged from the original quake. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a
foreshock A foreshock is an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can ...
. Aftershocks are formed as the crust around the displaced
fault plane In geology, a fault is a Plane (geometry), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within the Earth's Crust (geolo ...
adjusts to the effects of the main shock.


Earthquake swarms

Earthquake swarms are sequences of earthquakes striking in a specific area within a short period of time. They are different from earthquakes followed by a series of
aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same Epicenter, area of the main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthquakes can h ...
s by the fact that no single earthquake in the sequence is obviously the main shock, so none has a notable higher magnitude than another. An example of an earthquake swarm is the 2004 activity at
Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the U.S. Congress and signed into law by ...

Yellowstone National Park
. In August 2012, a swarm of earthquakes shook
Southern California Southern California (sometimes known as SoCal; es, Sur de California) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California California is a in the . With over 39.3million resi ...

Southern California
's
Imperial Valley The Imperial Valley ( es, Valle de Imperial or ''Valle Imperial'') lies in the California counties of Imperial County, California, Imperial and Riverside County, California, Riverside in southeastern Southern California with an urban area centered ...
, showing the most recorded activity in the area since the 1970s. Sometimes a series of earthquakes occur in what has been called an ''earthquake storm'', where the earthquakes strike a fault in clusters, each triggered by the shaking or stress redistribution of the previous earthquakes. Similar to
aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same Epicenter, area of the main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthquakes can h ...
s but on adjacent segments of fault, these storms occur over the course of years, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the
North Anatolian Fault The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral Fault (geology)#Strike-slip faults, strike-slip fault in northern Anatolia, and is the Transform fault, transform boundary between the Eurasian Plate and t ...
in Turkey in the 20th century and has been inferred for older anomalous clusters of large earthquakes in the Middle East.


Intensity of earth quaking and magnitude of earthquakes

Quaking or shaking of the earth is a common phenomenon undoubtedly known to humans from earliest times. Prior to the development of that can measure peak ground speed and acceleration directly, the intensity of the earth-shaking was estimated on the basis of the observed effects, as categorized on various
seismic intensity scales Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the ...
. Only in the last century has the source of such shaking been identified as ruptures in the Earth's crust, with the intensity of shaking at any locality dependent not only on the local ground conditions but also on the strength or ''magnitude'' of the rupture, and on its distance. The was developed by
Charles F. Richter Charles Francis Richter (); April 26, 1900 – September 30, 1985) was an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United Stat ...
in 1935. Subsequent scales (see
seismic magnitude scales Seismic magnitude scales are used to describe the overall strength or "size" of an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in th ...
) have retained a key feature, where each unit represents a ten-fold difference in the amplitude of the ground shaking and a 32-fold difference in energy. Subsequent scales are also adjusted to have approximately the same numeric value within the limits of the scale. Although the mass media commonly reports earthquake magnitudes as "Richter magnitude" or "Richter scale", standard practice by most seismological authorities is to express an earthquake's strength on the
moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

moment magnitude
scale, which is based on the actual energy released by an earthquake.


Frequency of occurrence

It is estimated that around 500,000 earthquakes occur each year, detectable with current instrumentation. About 100,000 of these can be felt. Minor earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in El Salvador, Mexico, Guatemala, Chile, Peru, Indonesia, the Philippines, Iran, Pakistan, the
Azores The Azores ( , also ; pt, Açores ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal The two Autonomous Regions of Portugal ( pt, Regiões Autónomas de Portugal) are the Azores (''Região ...

Azores
in Portugal, Turkey, New Zealand, Greece, Italy, India, Nepal and Japan. Larger earthquakes occur less frequently, the relationship being
exponential Exponential may refer to any of several mathematical topics related to exponentiation Exponentiation is a mathematical operation, written as , involving two numbers, the '' base'' and the ''exponent'' or ''power'' , and pronounced as " raise ...
; for example, roughly ten times as many earthquakes larger than magnitude 4 occur in a particular time period than earthquakes larger than magnitude 5. In the (low seismicity) United Kingdom, for example, it has been calculated that the average recurrences are: an earthquake of 3.7–4.6 every year, an earthquake of 4.7–5.5 every 10 years, and an earthquake of 5.6 or larger every 100 years. This is an example of the
Gutenberg–Richter law In seismology, the Gutenberg–Richter law (GR law) expresses the relationship between the Richter magnitude scale, magnitude and total number of earthquakes in any given region and time period of ''at least'' that magnitude. : \!\,\log_ N = a - b ...
. The number of seismic stations has increased from about 350 in 1931 to many thousands today. As a result, many more earthquakes are reported than in the past, but this is because of the vast improvement in instrumentation, rather than an increase in the number of earthquakes. The
United States Geological Survey The United States Geological Survey, abbreviated USGS and formerly simply known as the Geological Survey, is a scientific government agency, agency of the Federal government of the United States, United States government. The scientists of the ...
estimates that, since 1900, there have been an average of 18 major earthquakes (magnitude 7.0–7.9) and one great earthquake (magnitude 8.0 or greater) per year, and that this average has been relatively stable. In recent years, the number of major earthquakes per year has decreased, though this is probably a statistical fluctuation rather than a systematic trend. More detailed statistics on the size and frequency of earthquakes is available from the
United States Geological Survey The United States Geological Survey, abbreviated USGS and formerly simply known as the Geological Survey, is a scientific government agency, agency of the Federal government of the United States, United States government. The scientists of the ...
(USGS). A recent increase in the number of major earthquakes has been noted, which could be explained by a cyclical pattern of periods of intense tectonic activity, interspersed with longer periods of low intensity. However, accurate recordings of earthquakes only began in the early 1900s, so it is too early to categorically state that this is the case. Most of the world's earthquakes (90%, and 81% of the largest) take place in the , horseshoe-shaped zone called the circum-Pacific seismic belt, known as the
Pacific Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth ...

Pacific Ring of Fire
, which for the most part bounds the
Pacific Plate The Pacific Plate is an oceanic tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant ...
. Massive earthquakes tend to occur along other plate boundaries too, such as along the
Himalayan Mountains The Himalayas, or Himalaya (); Sanskrit Sanskrit (, attributively , ''saṃskṛta-'', nominalization, nominally , ''saṃskṛtam'') is a classical language of South Asia belonging to the Indo-Aryan languages, Indo-Aryan branch of the In ...

Himalayan Mountains
. With the rapid growth of mega-cities such as Mexico City, Tokyo and Tehran in areas of high seismic risk, some seismologists are warning that a single quake may claim the lives of up to three million people.


Induced seismicity

While most earthquakes are caused by movement of the Earth's
tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibri ...
s, human activity can also produce earthquakes. Activities both above ground and below may change the stresses and strains on the crust, including building reservoirs, extracting resources such as coal or oil, and injecting fluids underground for waste disposal or fracking. Most of these earthquakes have small magnitudes. The 5.7 magnitude 2011 Oklahoma earthquake is thought to have been caused by disposing wastewater from oil production into injection wells, and studies point to the state's oil industry as the cause of other earthquakes in the past century. A
Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of ...

Columbia University
paper suggested that the 8.0 magnitude
2008 Sichuan earthquake The 2008 Sichuan earthquakeSome early Western reports used the term Chengdu quake; e.g., , , etc. This term never picked up widely in media reports, but was reportedly used by BBC America in a follow-up report on preparations for winter and ...
was induced by loading from the , though the link has not been conclusively proved.


Measuring and locating earthquakes

The instrumental scales used to describe the size of an earthquake began with the
Richter magnitude scale The Richter scale – also called the Richter magnitude scale and Richter's magnitude scale – is a measure of the strength of earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Ear ...
in the 1930s. It is a relatively simple measurement of an event's amplitude, and its use has become minimal in the 21st century.
Seismic waves Seismic waves are waves The United States Naval Reserve (Women's Reserve), better known as the WAVES (for Women Accepted for Volunteer Emergency Service), was the women's branch of the United States Naval Reserve The United States Navy ...
travel through the
Earth's interior The internal structure of Earth, structure of the solid Earth, or simply structure of Earth refers to concentric spherical layers subdividing the Solid earth, i.e., excluding Earth's atmosphere File:Atmosphere gas proportions.svg, Compositi ...
and can be recorded by
seismometer A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of ...

seismometer
s at great distances. The
surface wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology Seismology (; from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, an ...
was developed in the 1950s as a means to measure remote earthquakes and to improve the accuracy for larger events. The
moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surfa ...
not only measures the amplitude of the shock but also takes into account the
seismic moment Seismic moment is a quantity used by seismologist Seismology (; from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It ...

seismic moment
(total rupture area, average slip of the fault, and rigidity of the rock). The
Japan Meteorological Agency seismic intensity scale , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white rectangle , image_coat = Imperial Seal of Japan.svg , alt_coat = Golden circle subdiv ...
, the
Medvedev–Sponheuer–Karnik scale The Medvedev–Sponheuer–Karnik scale, also known as the MSK or MSK-64, is a macroseismic intensity scale used to evaluate the severity of ground shaking on the basis of observed effects in an area of the earthquake An earthquake (also know ...
, and the
Mercalli intensity scale The modified Mercalli intensity scale (MM or MMI), developed from Giuseppe Mercalli Giuseppe Mercalli (21 May 1850 – 19 March 1914) was an Italy, Italian volcanologist and Catholic Church, Catholic priest. He is known best for the Mercalli i ...
are based on the observed effects and are related to the intensity of shaking. Every tremor produces different types of seismic waves, which travel through rock with different velocities: * Longitudinal
P-waves A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves Seismic waves are waves The United States Naval Reserve (Women's Reserve), better known as the WAVES (for Women Acc ...
(shock- or pressure waves) * Transverse
S-waves __NOTOC__ In seismology Seismology (; from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divi ...
(both body waves) *
Surface wave In physics, a surface wave is a mechanical wave that propagates along the Interface (chemistry), interface between differing media. A common example is gravity waves along the surface of liquids, such as ocean waves. Gravity waves can also occu ...

Surface wave
s – ( and
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Love
waves) Propagation velocity of the seismic waves through solid rock ranges from approx. up to , depending on the
density The density (more precisely, the volumetric mass density; also known as specific mass), of a substance is its per unit . The symbol most often used for density is ''ρ'' (the lower case Greek letter ), although the Latin letter ''D'' can also ...

density
and
elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the clu ...
of the medium. In the Earth's interior, the shock- or P-waves travel much faster than the S-waves (approx. relation 1.7:1). The differences in travel time from the
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter, hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage In most earthqua ...
to the observatory are a measure of the distance and can be used to image both sources of quakes and structures within the Earth. Also, the depth of the
hypocenter A hypocenter (or hypocentre; ) is the point of origin of an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosph ...
can be computed roughly. In the upper crust, P-waves travel in the range per second (or lower) in soils and unconsolidated sediments, increasing to per second in solid rock. In the lower crust, they travel at about per second; the velocity increases within the deep mantle to about per second. The velocity of S-waves ranges from per second in light sediments and per second in the Earth's crust up to per second in the deep mantle. As a consequence, the first waves of a distant earthquake arrive at an observatory via the Earth's mantle. On average, the kilometer distance to the earthquake is the number of seconds between the P- and S-wave times 8. Slight deviations are caused by inhomogeneities of subsurface structure. By such analyzes of seismograms the Earth's core was located in 1913 by
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Beno Gutenberg
. S-waves and later arriving surface waves do most of the damage compared to P-waves. P-waves squeeze and expand material in the same direction they are traveling, whereas S-waves shake the ground up and down and back and forth. Earthquakes are not only categorized by their magnitude but also by the place where they occur. The world is divided into 754 Flinn–Engdahl regions (F-E regions), which are based on political and geographical boundaries as well as seismic activity. More active zones are divided into smaller F-E regions whereas less active zones belong to larger F-E regions. Standard reporting of earthquakes includes its Richter magnitude scale, magnitude, date and time of occurrence, geographic coordinates of its
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter, hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage In most earthqua ...

epicenter
, depth of the epicenter, geographical region, distances to population centers, location uncertainty, a number of parameters that are included in USGS earthquake reports (number of stations reporting, number of observations, etc.), and a unique event ID. Although relatively slow seismic waves have traditionally been used to detect earthquakes, scientists realized in 2016 that gravitational measurements could provide instantaneous detection of earthquakes, and confirmed this by analyzing gravitational records associated with the 2011 Tōhoku earthquake and tsunami, 2011 Tohoku-Oki ("Fukushima") earthquake.


Effects of earthquakes

The effects of earthquakes include, but are not limited to, the following:


Shaking and ground rupture

Shaking and surface rupture, ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings and other rigid structures. The severity of the local effects depends on the complex combination of the earthquake Richter magnitude scale, magnitude, the distance from the
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter, hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage In most earthqua ...

epicenter
, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation. The ground-shaking is measured by ground acceleration. Specific local geological, geomorphological, and geostructural features can induce high levels of shaking on the ground surface even from low-intensity earthquakes. This effect is called site or local amplification. It is principally due to the transfer of the seismic motion from hard deep soils to soft superficial soils and to effects of seismic energy focalization owing to typical geometrical setting of the deposits. Ground rupture is a visible breaking and displacement of the Earth's surface along the trace of the fault, which may be of the order of several meters in the case of major earthquakes. Ground rupture is a major risk for large engineering structures such as dams, bridges, and nuclear power stations and requires careful mapping of existing faults to identify any that are likely to break the ground surface within the life of the structure.


Soil liquefaction

Soil liquefaction occurs when, because of the shaking, water-saturated granular material (such as sand) temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits. For example, in the 1964 Alaska earthquake, soil liquefaction caused many buildings to sink into the ground, eventually collapsing upon themselves.


Human impacts

An earthquake may cause injury and loss of life, road and bridge damage, general property damage, and collapse or destabilization (potentially leading to future collapse) of buildings. The aftermath may bring disease, lack of basic necessities, mental consequences such as panic attacks, depression to survivors, and higher insurance premiums.


Landslides

Earthquakes can produce slope instability leading to landslides, a major geological hazard. Landslide danger may persist while emergency personnel are attempting rescue.


Fires

Earthquakes can cause fires by damaging electric power, electrical power or gas lines. In the event of water mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a fire once it has started. For example, more deaths in the 1906 San Francisco earthquake were caused by fire than by the earthquake itself.


Tsunami

Tsunamis are long-wavelength, long-period sea waves produced by the sudden or abrupt movement of large volumes of water—including when an earthquake Submarine earthquake, occurs at sea. In the open ocean the distance between wave crests can surpass , and the wave periods can vary from five minutes to one hour. Such tsunamis travel 600–800 kilometers per hour (373–497 miles per hour), depending on water depth. Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes. Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them. Ordinarily, subduction earthquakes under magnitude 7.5 do not cause tsunamis, although some instances of this have been recorded. Most destructive tsunamis are caused by earthquakes of magnitude 7.5 or more.


Floods

Floods may be secondary effects of earthquakes, if dams are damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods. The terrain below the Sarez Lake in Tajikistan is in danger of catastrophic flooding if the landslide dam formed by the earthquake, known as the Usoi Dam, were to fail during a future earthquake. Impact projections suggest the flood could affect roughly 5 million people.


Major earthquakes

One of the most devastating earthquakes in recorded history was the 1556 Shaanxi earthquake, which occurred on 23 January 1556 in Shaanxi, China. More than 830,000 people died. Most houses in the area were yaodongs—dwellings carved out of loess hillsides—and many victims were killed when these structures collapsed. The 1976 Tangshan earthquake, which killed between 240,000 and 655,000 people, was the deadliest of the 20th century. The 1960 Valdivia earthquake, 1960 Chilean earthquake is the largest earthquake that has been measured on a seismograph, reaching 9.5 magnitude on 22 May 1960. Its epicenter was near Cañete, Chile. The energy released was approximately twice that of the next most powerful earthquake, the Good Friday earthquake (27 March 1964), which was centered in Prince William Sound, Alaska. The ten largest recorded earthquakes have all been
megathrust earthquake Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolut ...
s; however, of these ten, only the 2004 Indian Ocean earthquake is simultaneously one of the deadliest earthquakes in history. Earthquakes that caused the greatest loss of life, while powerful, were deadly because of their proximity to either heavily populated areas or the ocean, where earthquakes often create tsunamis that can devastate communities thousands of kilometers away. Regions most at risk for great loss of life include those where earthquakes are relatively rare but powerful, and poor regions with lax, unenforced, or nonexistent seismic building codes.


Prediction

Earthquake prediction is a branch of the science of seismology concerned with the specification of the time, location, and seismic scale, magnitude of future earthquakes within stated limits. Many methods have been developed for predicting the time and place in which earthquakes will occur. Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific day or month.Earthquake Prediction
Ruth Ludwin, U.S. Geological Survey.


Forecasting

While forecasting is usually considered to be a type of prediction, earthquake forecasting is often differentiated from earthquake prediction. Earthquake forecasting is concerned with the probabilistic assessment of general earthquake hazard, including the frequency and magnitude of damaging earthquakes in a given area over years or decades. For well-understood faults the probability that a segment may rupture during the next few decades can be estimated. Earthquake warning systems have been developed that can provide regional notification of an earthquake in progress, but before the ground surface has begun to move, potentially allowing people within the system's range to seek shelter before the earthquake's impact is felt.


Preparedness

The objective of earthquake engineering is to foresee the impact of earthquakes on buildings and other structures and to design such structures to minimize the risk of damage. Existing structures can be modified by seismic retrofitting to improve their resistance to earthquakes. Earthquake insurance can provide building owners with financial protection against losses resulting from earthquakes. Emergency management strategies can be employed by a government or organization to mitigate risks and prepare for consequences. Artificial intelligence may help to assess buildings and plan precautionary operations: the Igor expert system is part of a mobile laboratory that supports the procedures leading to the seismic assessment of masonry buildings and the planning of retrofitting operations on them. It has been successfully applied to assess buildings in Lisbon, Rhodes, Naples. Individuals can also take preparedness steps like securing water heating, water heaters and heavy items that could injure someone, locating shutoffs for utilities, and being educated about what to do when shaking starts. For areas near large bodies of water, earthquake preparedness encompasses the possibility of a
tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a . s, s and other s (including detonations, landslides, , and other dis ...

tsunami
caused by a large quake.


Historical views

From the lifetime of the Greek philosopher Anaxagoras in the 5th century BCE to the 14th century CE, earthquakes were usually attributed to "air (vapors) in the cavities of the Earth." Thales of Miletus (625–547 BCE) was the only documented person who believed that earthquakes were caused by tension between the earth and water. Other theories existed, including the Greek philosopher Anaxamines' (585–526 BCE) beliefs that short incline episodes of dryness and wetness caused seismic activity. The Greek philosopher Democritus (460–371 BCE) blamed water in general for earthquakes. Pliny the Elder called earthquakes "underground thunderstorms".


Recent studies

In recent studies, geologists claim that global warming is one of the reasons for increased seismic activity. According to these studies, melting glaciers and rising sea levels disturb the balance of pressure on Earth's tectonic plates, thus causing an increase in the frequency and intensity of earthquakes.


In culture


Mythology and religion

In Norse mythology, earthquakes were explained as the violent struggling of the god Loki. When Loki, Aesir, god of mischief and strife, murdered Baldr, god of beauty and light, he was punished by being bound in a cave with a poisonous serpent placed above his head dripping venom. Loki's wife Sigyn stood by him with a bowl to catch the poison, but whenever she had to empty the bowl the poison dripped on Loki's face, forcing him to jerk his head away and thrash against his bonds, which caused the earth to tremble. In Greek mythology, Poseidon was the cause and god of earthquakes. When he was in a bad mood, he struck the ground with a trident, causing earthquakes and other calamities. He also used earthquakes to punish and inflict fear upon people as revenge. In Japanese mythology, Namazu (Japanese mythology), Namazu (鯰) is a giant catfish who causes earthquakes. Namazu lives in the mud beneath the earth, and is guarded by the god Kashima (god), Kashima who restrains the fish with a stone. When Kashima lets his guard fall, Namazu thrashes about, causing violent earthquakes.


In popular culture

In modern popular culture, the portrayal of earthquakes is shaped by the memory of great cities laid waste, such as Great Hanshin earthquake, Kobe in 1995 or 1906 San Francisco earthquake, San Francisco in 1906. Fictional earthquakes tend to strike suddenly and without warning. For this reason, stories about earthquakes generally begin with the disaster and focus on its immediate aftermath, as in ''Short Walk to Daylight'' (1972), ''A Wrinkle in the Skin, The Ragged Edge'' (1968) or ''Aftershock: Earthquake in New York'' (1999). A notable example is Heinrich von Kleist's classic novella, ''The Earthquake in Chile'', which describes the destruction of Santiago in 1647. Haruki Murakami's short fiction collection ''After the Quake'' depicts the consequences of the Kobe earthquake of 1995. The most popular single earthquake in fiction is the hypothetical "Big One" expected of California's
San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is th ...
someday, as depicted in the novels ''Richter 10'' (1996), ''Goodbye California (novel), Goodbye California'' (1977), ''2012 (film), 2012'' (2009) and ''San Andreas (film), San Andreas'' (2015) among other works. Jacob M. Appel's widely anthologized short story, ''A Comparative Seismology'', features a con artist who convinces an elderly woman that an apocalyptic earthquake is imminent. Contemporary depictions of earthquakes in film are variable in the manner in which they reflect human psychological reactions to the actual trauma that can be caused to directly afflicted families and their loved ones. Disaster mental health response research emphasizes the need to be aware of the different roles of loss of family and key community members, loss of home and familiar surroundings, loss of essential supplies and services to maintain survival. Particularly for children, the clear availability of caregiving adults who are able to protect, nourish, and clothe them in the aftermath of the earthquake, and to help them make sense of what has befallen them has been shown even more important to their emotional and physical health than the simple giving of provisions. As was observed after other disasters involving destruction and loss of life and their media depictions, recently observed in the 2010 Haiti earthquake, it is also important not to pathologize the reactions to loss and displacement or disruption of governmental administration and services, but rather to validate these reactions, to support constructive problem-solving and reflection as to how one might improve the conditions of those affected.


See also

* * * * * * * * Marsquake * * * * * * Vertical displacement, Vertical Displacement


References


Sources

* . * . * , NUREG/CR-1457. * Deborah R. Coen. ''The Earthquake Observers: Disaster Science From Lisbon to Richter'' (University of Chicago Press; 2012) 348 pages; explores both scientific and popular coverage * . * * . * . * .


External links


Earthquake Hazards Program
of the U.S. Geological Survey

– IRIS Consortium
Open Directory – Earthquakes

World earthquake map captures every rumble since 1898
– Mother Nature Network (MNN) (29 June 2012)
NIEHS Earthquake Response Training Tool: Protecting Yourself While Responding to Earthquakes



Icelandic Meteorological Office website
Shows current seismic and volcanic activity in Iceland. English available.
How Friction Evolves During an Earthquake
– Caltech {{Authority control Earthquakes, Geological hazards Seismology Natural disasters Lithosphere