Earthquake

Global earthquake epicenters, 1963–1998

An earthquake is a sudden and sometimes catastrophic movement of a part of the Earth's surface. Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. Earthquakes typically result from the movement of faults, planar zones of deformation within the Earth's upper crust. The word earthquake is also widely used to indicate the source region itself. The Earth's lithosphere is a patch work of plates in slow but constant motion (see plate tectonics). Earthquakes occur where the stress resulting from the differential motion of these plates exceeds the strength of the crust. The highest stress (and possible weakest zones) are most often found at the boundaries of the tectonic plates and hence these locations are where the majority of earthquakes occur. Events located at plate boundaries are called interplate earthquakes; the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes (see, for example, New Madrid Seismic Zone). Earthquakes related to plate tectonics are called tectonic earthquakes. Most earthquakes are tectonic, but they also occur in volcanic regions and as the result of a number of anthropogenic sources, such as reservoir induced seismicity, mining and the removal or injection of fluids into the crust. Seismic waves including some strong enough to be felt by humans can also be caused by explosions (chemical or nuclear), landslides, and collapse of old mine shafts, though these sources are not strictly earthquakes.

Characteristics

Large numbers of earthquakes occur on a daily basis on Earth, but the majority of them are detected only by seismometers and cause no damage .

Most earthquakes occur in narrow regions around plate boundaries down to depths of a few tens of kilometres where the crust is rigid enough to support the elastic strain. Where the crust is thicker and colder they will occur at greater depths and the opposite in areas that are hot. At subduction zones where plates descend into the mantle, earthquakes have been recorded to a depth of 600 km, although these deep earthquakes are caused by different mechanisms than the more common shallow events. Some deep earthquakes may be due to the transition of olivine to spinel, which is more stable in the deep mantle.

Large earthquakes can cause serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion (i.e., shaking), inundation (e.g., tsunami, seiche, dam failure), various kinds of permanent ground failure (e.g. liquefaction, landslide), and fire or a release of hazardous materials. In a particular earthquake, any of these agents of damage can dominate, and historically each has caused major damage and great loss of life, but for most of the earthquakes shaking is the dominant and most widespread cause of damage. There are four types of seismic waves that are all generated simultaneously and can be felt on the ground. S-waves (secondary or shear waves) and the two types of surfaces waves (Love waves and Rayleigh waves) are responsible for the shaking hazard.

Damage from the 1906 San Francisco earthquake. Section of collapsed freeway after the 1989 Loma Prieta earthquake.

Most large earthquakes are accompanied by other, smaller ones, that can occur either before or after the principal quake — these are known as foreshocks or aftershocks, respectively. While almost all earthquakes have aftershocks, foreshocks are far less common occurring in only about 10% of events. The power of an earthquake is distributed over a significant area, but in the case of large earthquakes, it can spread over the entire planet. Ground motions caused by very distant earthquakes are called teleseisms. The Rayleigh waves from the Sumatra-Andaman Earthquake of 2004 caused ground motion of over 1 cm even at the seismometers that were located far from it, although this displacement was abnormally large. Using such ground motion records from around the world it is possible to identify a point from which the earthquake's seismic waves appear to originate. That point is called its "focus" or "hypocenter" and usually proves to be the point at which the fault slip was initiated. The location on the surface directly above the hypocenter is known as the "epicenter". The total size of the fault that slips, the rupture zone, can be as large as 1000 km, for the biggest earthquakes. Just as a large loudspeaker can produce a greater volume of sound than a smaller one, large faults are capable of higher magnitude earthquakes than smaller faults are.

Earthquakes that occur below sea level and have large vertical displacements can give rise to tsunamis, either as a direct result of the deformation of the sea bed due to the earthquake or as a result of submarine landslips or "slides" directly or indirectly triggered by it.

Earthquake Size

The first method of quantifying earthquakes was intensity scales. In the United States the Mercalli (or Modified Mercalli, MM) scale is commonly used, while Japan (shindo) and the EU (European Macroseismic Scale) each have their own scales. These assign a numeric value (different for each scale) to a location based on the size of the shaking experienced there. The value 6 (normally denoted "VI") in the MM scale for example is:

Everyone feels movement. People have trouble walking. Objects fall from shelves. Pictures fall off walls. Furniture moves. Plaster in walls might crack. Trees and bushes shake. Damage is slight in poorly built buildings. No structural damage.

A Shakemap recorded by the Pacific Northwest Seismograph Network that shows the instrument recorded intensity of the shaking of the Nisqually earthquake on February 28, 2001. A Community Internet Intensity Map generated by the USGS that shows the intensity felt by humans by ZIP Code of the shaking of the Nisqually earthquake on February 28, 2001.

The problem with these scales is the measurement is subjective, often based on the worst damage in an area and influenced by local effects like site conditions that make it a poor measure for the relative size of different events in different places. For some tasks related to engineering and local planning it is still useful for the very same reasons and thus still collected. If you feel an earthquake in the US you can report the effects to the USGS.

The first attempt to qualitatively define one value to describe the size of earthquakes was the magnitude scale (the name being taking from similar formed scales used on the brightness of stars). In the 1930s, a California seismologist named Charles F. Richter devised a simple numerical scale (which he called the magnitude) to describe the relative sizes of earthquakes in Southern California. This is known as the “Richter scale”, “Richter Magnitude” or “Local Magnitude” (ML). It is obtained by measuring the maximum amplitude of a recording on a Wood-Anderson torsion seismometer (or one calibrated to it) at a distance of 600km from the earthquake. Other more recent Magnitude measurements include: body wave magnitude (mb), surface wave magnitude (Ms) and duration magnitude (MD). Each of these is scaled to gives values similar to the values given by the Richter scale. However as each is also based on the measurement of one part of the seismogram they do not measure the overall power of the source and can suffer from saturation at higher magnitude values (larger events fail to produce higher magnitude values).These scales are also empirical and as such there is no physical meaning to the values. They are still useful however as they can be rapidly calculated, there are catalogues of them dating back many years and are they are familiar to the public. Seismologists now favor a measure called the seismic moment, related to the concept of moment in physics, to measure the size of a seismic source. The seismic moment is calculated from seismograms but can also by obtained from geologic estimates of the size of the fault rupture and the displacement. The values of moments for different earthquakes ranges over several order of magnitude. As a result the moment magnitude (MW) scale was introduced by Hiroo Kanamori, which is comparable to the other magnitude scales but will not saturate at higher values.

Larger earthquakes occur less frequently than smaller earthquakes, the relationship being exponential, ie roughly ten times as many earthquakes larger than 4 occur in a particular time period than earthquakes larger than magnitude 5. For example it has been calculated that the average recurrence for the United Kingdom can be described as follows:

  • an earthquake of 3.7 or larger every 1 year
  • an earthquake of 4.7 or larger every 10 years
  • an earthquake of 5.6 or larger every 100 years.

Causes

Most earthquakes are powered by the release of the elastic strain that accumulate over time, typically, at the boundaries of the plates that make up the Earth's lithosphere via a process called Elastic-rebound theory. The Earth is made up of tectonic plates driven by the heat in the Earth's mantle and core. Where these plates meet stress accumulates. Eventually when enough stress accumulates, the plates move, causing an earthquake. Deep focus earthquakes, at depths of 100's km, are possibly generated as subducted lithospheric material catastrophically undergoes a phase transition since at the pressures and temperatures present at such depth elastic strain cannot be supported. Some earthquakes are also caused by the movement of magma in volcanoes, and such quakes can be an early warning of volcanic eruptions. A rare few earthquakes have been associated with the build-up of large masses of water behind dams, such as the Kariba Dam in Zambia, Africa, and with the injection or extraction of fluids into the Earth's crust (e.g. at certain geothermal power plants and at the Rocky Mountain Arsenal). Such earthquakes occur because the strength of the Earth's crust can be modified by fluid pressure. Earthquakes have also been known to be caused by the removal of natural gas from subsurface deposits, for instance in the northern Netherlands. Finally, ground shaking can also result from the detonation of explosives. Thus scientists have been able to monitor, using the tools of seismology, nuclear weapons tests performed by governments that were not disclosing information about these tests along normal channels. Earthquakes such as these, that are caused by human activity, are referred to by the term induced seismicity.

Another type of movement of the Earth is observed by terrestrial spectroscopy. These oscillations of the earth are either due to the deformation of the Earth by tide caused by the Moon or the Sun, or other phenomena.

A recently proposed theory suggests that some earthquakes may occur in a sort of earthquake storm, where one earthquake will trigger a series of earthquakes each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring years later.

Preparation for earthquakes

  • Emergency preparedness
  • Household seismic safety
  • Seismic retrofit
  • Earthquake prediction

Specific fault articles

  • Alpine Fault
  • Calaveras Fault
  • Hayward Fault Zone
  • North Anatolian Fault Zone
  • New Madrid Fault Zone
  • San Andreas Fault

Specific earthquake articles

  • Shaanxi Earthquake (1556). Deadliest known earthquake in history, estimated to have killed 830,000 in China.
  • Cascadia Earthquake (1700).
  • Kamchatka earthquakes (1737 and 1952).
  • Lisbon earthquake (1755).
  • New Madrid Earthquake (1811).
  • Fort Tejon Earthquake (1857).
  • Charleston earthquake (1886). Largest earthquake in the Southeast and killed 100.
  • San Francisco Earthquake (1906).
  • Great Kanto earthquake (1923). On the Japanese island of Honshu, killing over 140,000 in Tokyo and environs.
  • Kamchatka earthquakes (1952 and 1737).
  • Great Chilean Earthquake (1960). Biggest earthquake ever recorded, 9.5 on Moment magnitude scale.
  • Good Friday Earthquake (1964) Alaskan earthquake.
  • Ancash earthquake (1970). Caused a landslide that buried the town of Yungay, Peru; killed over 40,000 people.
  • Sylmar earthquake (1971). Caused great and unexpected destruction of freeway bridges and flyways in the San Fernando Valley, leading to the first major seismic retrofits of these types of structures, but not at a sufficient pace to avoid the next California freeway collapse in 1989.
  • Tangshan earthquake (1976). The most destructive earthquake of modern times. The official death toll was 255,000, but many experts believe that two or three times that number died.
  • Great Mexican Earthquake (1985). 8.1 on the Richter Scale, killed over 6,500 people (though it is believed as many as 30,000 may have died, due to missing people never reappearing.)
  • Whittier Narrows earthquake (1987).
  • Armenian earthquake (1988). Killed over 25,000.
  • Loma Prieta earthquake (1989). Severely affecting Santa Cruz, San Francisco and Oakland in California. Revealed necessity of accelerated seismic retrofit of road and bridge structures.
  • Northridge, California earthquake (1994). Damage showed seismic resistance deficiencies in modern low-rise apartment construction.
  • Great Hanshin earthquake (1995). Killed over 6,400 people in and around Kobe, Japan.
  • İzmit earthquake (1999) Killed over 17,000 in northwestern Turkey.
  • Düzce earthquake (1999)
  • Chi-Chi earthquake (1999).
  • Nisqually Earthquake (2001).
  • Gujarat Earthquake (2001).
  • Dudley Earthquake (2002).
  • Bam Earthquake (2003).
  • Parkfield, California earthquake (2004). Not large (6.0), but the most anticipated and intensely instrumented earthquake ever recorded and likely to offer insights into predicting future earthquakes elsewhere on similar slip-strike fault structures.
  • Chuetsu Earthquake (2004).
  • Indian Ocean Earthquake (2004). One of the largest earthquakes ever recorded at 9.0. Epicenter off the coast of the Indonesian island Sumatra. Triggered a tsunami which caused nearly 300,000 deaths spanning several countries.
  • Sumatran Earthquake (2005).
  • Fukuoka earthquake (2005).
  • Kashmir earthquake (2005). Killed over 79,000 people. Many more at risk from the Kashmiri winter.
  • Lake Tanganyika earthquake (2005).

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A recently proposed theory suggests that some earthquakes may occur in a sort of earthquake storm, where one earthquake will trigger a series of earthquakes each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring years later. Some other eras were in official use in modern times or are still in use in several countries alongside the current international Anno Domini era. These oscillations of the earth are either due to the deformation of the Earth by tide caused by the Moon or the Sun, or other phenomena. Even though Anno Domini was in widespread use by the ninth century, Before Christ (or its equivalent) did not become widespread until the late fifteenth century. Another type of movement of the Earth is observed by terrestrial spectroscopy. Another system was to date from the crucifixion of Jesus Christ, which as early as Hippolytus and Tertullian was believed to have occurred in the consulate of the Gemini (AD 29), which appears in the occasional medieval manuscript. Earthquakes such as these, that are caused by human activity, are referred to by the term induced seismicity. The Era of Martyrs, which numbered years from the accession of Diocletian in 284, who launched the last yet most severe persecution of Christians, prevailed in the East and is still used officially by the Coptic and used to be used by the Ethiopian church.

Thus scientists have been able to monitor, using the tools of seismology, nuclear weapons tests performed by governments that were not disclosing information about these tests along normal channels. Outside the Carolingian Empire, Spain continued to date by the Era of the Caesars, or Spanish Era, well into the Middle Ages, which counted beginning with 38 BC. Finally, ground shaking can also result from the detonation of explosives. This endorsement by Charlemagne and his successors popularizing the usage of the epoch and spreading it throughout the Carolingian Empire ultimately lies at the core of the system's prevalence until present times. Earthquakes have also been known to be caused by the removal of natural gas from subsurface deposits, for instance in the northern Netherlands. On the continent of Europe, Anno Domini was introduced as the era of choice of the Carolingian Renaissance by Alcuin. Such earthquakes occur because the strength of the Earth's crust can be modified by fluid pressure. Both Dionysius and Bede regarded Anno Domini as beginning at the incarnation, or conception, of Jesus, not his birth approximately nine months later (Annunciation style).

at certain geothermal power plants and at the Rocky Mountain Arsenal). In this same history, he was the first to use the Latin equivalent of before Christ and established the standard for historians of no year zero, even though he used zero in his computus. A rare few earthquakes have been associated with the build-up of large masses of water behind dams, such as the Kariba Dam in Zambia, Africa, and with the injection or extraction of fluids into the Earth's crust (e.g. A few generations later, the Anglo-Saxon historian Bede, who was familiar with the work of Dionysius, also used Anno Domini dating in his Ecclesiastical History of the English People, finished in 731. Some earthquakes are also caused by the movement of magma in volcanoes, and such quakes can be an early warning of volcanic eruptions. The first historian or chronicler to use Anno Domini as his primary dating mechanism was Victor of Tonnenna, an African chronicler of the seventh century. Deep focus earthquakes, at depths of 100's km, are possibly generated as subducted lithospheric material catastrophically undergoes a phase transition since at the pressures and temperatures present at such depth elastic strain cannot be supported. The latest bound for the birth of Christ is the death of Herod the Great which occurred in 4 BC according to Kepler.

Eventually when enough stress accumulates, the plates move, causing an earthquake. Almost all Biblical scholars believe that Dionysius was incorrect in his calculation, and that the date claimed for Jesus' birth was between 8 BC and 4 BC. Where these plates meet stress accumulates. Another formulation, dominant in the East during the early centuries of the Byzantine Empire, was developed by the Alexandrian monk Anninus. The Earth is made up of tectonic plates driven by the heat in the Earth's mantle and core. The Latin translator Jerome helped popularize Eusebius's AM count in the West. Most earthquakes are powered by the release of the elastic strain that accumulate over time, typically, at the boundaries of the plates that make up the Earth's lithosphere via a process called Elastic-rebound theory. One popular formulation was that established by Eusebius of Caesarea, a historian at the time of Constantine I.

For example it has been calculated that the average recurrence for the United Kingdom can be described as follows:. No single Anno Mundi epoch was dominant. Larger earthquakes occur less frequently than smaller earthquakes, the relationship being exponential, ie roughly ten times as many earthquakes larger than 4 occur in a particular time period than earthquakes larger than magnitude 5. These eras, sometimes called Anno Mundi, "year of the world" (abbreviated AM), by modern scholars, had their own disagreements. As a result the moment magnitude (MW) scale was introduced by Hiroo Kanamori, which is comparable to the other magnitude scales but will not saturate at higher values. Byzantine chroniclers like Theophanes continued to date each year in their world chronicles on a different Judaeo-Christian basis — from the notional creation of the World as calculated by Christian scholars in the first five centuries of the Christian era. The values of moments for different earthquakes ranges over several order of magnitude. The Anno Domini system was developed by a Scythian monk named Dionysius Exiguus in Rome in 525, as an outcome of his work on calculating the date of Easter.

The seismic moment is calculated from seismograms but can also by obtained from geologic estimates of the size of the fault rupture and the displacement. The papacy was in regular contact throughout the Middle Ages with envoys of the Byzantine world, and had a clear idea — sudden deaths and deposals notwithstanding — of who was the Byzantine emperor at any one time. Seismologists now favor a measure called the seismic moment, related to the concept of moment in physics, to measure the size of a seismic source. The last consul nominated was Anicius Faustus Albinus Basilius in 541. They are still useful however as they can be rapidly calculated, there are catalogues of them dating back many years and are they are familiar to the public. Use of consular dating ended when the emperor Justinian I discontinued appointing consuls in the mid sixth century, shortly after he required that the use of imperial regnal dating. However as each is also based on the measurement of one part of the seismogram they do not measure the overall power of the source and can suffer from saturation at higher magnitude values (larger events fail to produce higher magnitude values).These scales are also empirical and as such there is no physical meaning to the values. Early Christians designated the year via a combination of consular dating, imperial regnal year dating, and Creation dating.

Each of these is scaled to gives values similar to the values given by the Richter scale. In 1422, Portugal became the last country of western Europe to adopt the Anno Domini era). Other more recent Magnitude measurements include: body wave magnitude (mb), surface wave magnitude (Ms) and duration magnitude (MD). The most important of these include the Seleucid era (in use until the eighth century), and the Spanish era (in use in official documents in Aragon, Valencia, and in Castile, into the fourteenth century. It is obtained by measuring the maximum amplitude of a recording on a Wood-Anderson torsion seismometer (or one calibrated to it) at a distance of 600km from the earthquake. The beginning of the numbered year also varied from place to place, and was not largely standardized in Europe (except England) as January 1 until the sixteenth century. This is known as the “Richter scale”, “Richter Magnitude” or “Local Magnitude” (ML). A great many local systems or eras were also important, for example the year from the foundation of one particular city, the regnal year of the neighboring Persian emperor, and eventually even the year of the reigning Caliph.

Richter devised a simple numerical scale (which he called the magnitude) to describe the relative sizes of earthquakes in Southern California. This system was used in Gaul, in Egypt until the Islamic conquest, and in the Eastern Roman Empire until its conquest in 1453. In the 1930s, a California seismologist named Charles F. Documents and events began to be dated by the year of the cycle (e.g., "fifth indiction", "tenth indiction") in the fourth century, and was used long after the tax was no longer collected. The first attempt to qualitatively define one value to describe the size of earthquakes was the magnitude scale (the name being taking from similar formed scales used on the brightness of stars). Another common system was to use the indiction cycle (15 indictions made up an agricultural tax cycle, an indiction being a year in duration). If you feel an earthquake in the US you can report the effects to the USGS. His successors followed his practice until the memory of the Roman Republic faded (late in the second century or early in the third century), when they openly began to use their regnal year.

For some tasks related to engineering and local planning it is still useful for the very same reasons and thus still collected. At first, Augustus would indicate the year of his rule by counting how many times he had held the office of consul, and how many times the Roman Senate had granted him Tribunican powers, carefully observing the fiction that his powers came from these offices granted to him, rather than from his own person or the many legions under his control. The problem with these scales is the measurement is subjective, often based on the worst damage in an area and influenced by local effects like site conditions that make it a poor measure for the relative size of different events in different places. Another system that is less commonly found than thought was to use the regnal year of the Roman emperor. No structural damage. Pope Boniface IV (about AD 600) may have been the first to use both the ab urbe condita era and the Anno Domini era (he put AD 607 = AUC 1360). Damage is slight in poorly built buildings. About AD 400 the Iberian historian Orosius used the ab urbe condita era.

Trees and bushes shake. Modern historians usually adopt the epoch of Varro, which we place in 753 BC. Plaster in walls might crack. Several epochs were in use by Roman historians. Furniture moves. Another method of dating, rarely used, was to indicate the year ab urbe condita, or "from the foundation of the City" (abbreviated AUC), where "the City" meant Rome. Pictures fall off walls. Sometimes one or both consuls might not be appointed until November or December of the previous year, and news of the appointment may not have reached parts of the Roman empire for several months into the current year; thus we find the occasional inscription where the year is defined as "after the consulate" of a pair of consuls.

Objects fall from shelves. This involved naming both consulares ordinares who had been appointed to this office on January 1 of the civil year. People have trouble walking. The earliest and most common practice was Roman 'consular' dating. Everyone feels movement. This redundancy allows historians to construct parallel regnal lists for many kingdoms and polities by comparing chronicles from different regions, which include the same rulers. The value 6 (normally denoted "VI") in the MM scale for example is:. Like the other inhabitants of the Roman Empire, early Christians used one of several methods to indicate a specific year — and it was not uncommon for more than one to be used in the same document.

These assign a numeric value (different for each scale) to a location based on the size of the shaking experienced there. Anno Domini dating was not adopted in Western Europe until the eighth century. In the United States the Mercalli (or Modified Mercalli, MM) scale is commonly used, while Japan (shindo) and the EU (European Macroseismic Scale) each have their own scales. This article, however, is about the civil usage without a year zero. The first method of quantifying earthquakes was intensity scales. This results in a one-year shift between the two systems (eg −1 equals 2 BC). Earthquakes that occur below sea level and have large vertical displacements can give rise to tsunamis, either as a direct result of the deformation of the sea bed due to the earthquake or as a result of submarine landslips or "slides" directly or indirectly triggered by it. In keeping with 'standard decimal numbering', a negative sign '−' is added for earlier years, so counting down from year 2 would give 2, 1, 0, −1, −2, and so on.

Just as a large loudspeaker can produce a greater volume of sound than a smaller one, large faults are capable of higher magnitude earthquakes than smaller faults are. This is a problem with some calculations; so in astronomical year numbering a zero is added, and the 'AD' and 'BC' are dropped. The total size of the fault that slips, the rupture zone, can be as large as 1000 km, for the biggest earthquakes. Historians do not use a year zero — AD 1 is the first year or epoch of the Anno Domini era, and 1 BC immediately precedes it as the first year before the epoch. The location on the surface directly above the hypocenter is known as the "epicenter". It is often used in a more elaborate form such as Anno Nostrae Salutis (in the year of our salvation), Anno Salutis Humanae (in the year of human well-being), Anno Reparatae Salutis (in the year of accomplished salvation). That point is called its "focus" or "hypocenter" and usually proves to be the point at which the fault slip was initiated. It can be explained in the context of Christian belief, where the birth of Jesus saved mankind from eternal damnation.

Using such ground motion records from around the world it is possible to identify a point from which the earthquake's seismic waves appear to originate. Anno Salutis (often translated from Latin as in the year of salvation) is a dating style used up until the eighteenth century, which like Anno Domini dates years from the birth of Christ. The Rayleigh waves from the Sumatra-Andaman Earthquake of 2004 caused ground motion of over 1 cm even at the seismometers that were located far from it, although this displacement was abnormally large. do not presuppose faith in Christ and hence are more appropriate for interfaith dialog than the conventional B.C./A.D." When the People's Republic of China abolished the Republic of China era in 1949, it adopted Western years, calling that era gōngyuán, 公元, which literally means Common Era. Ground motions caused by very distant earthquakes are called teleseisms. .. The power of an earthquake is distributed over a significant area, but in the case of large earthquakes, it can spread over the entire planet. For example, Cunningham and Starr (1998) write that "B.C.E./C.E.

While almost all earthquakes have aftershocks, foreshocks are far less common occurring in only about 10% of events. This term is often preferred by those who want to avoid the association with the Christian era. Most large earthquakes are accompanied by other, smaller ones, that can occur either before or after the principal quake — these are known as foreshocks or aftershocks, respectively. Anno Domini is sometimes referred to as the Common Era (CE) instead. S-waves (secondary or shear waves) and the two types of surfaces waves (Love waves and Rayleigh waves) are responsible for the shaking hazard. . There are four types of seismic waves that are all generated simultaneously and can be felt on the ground. The English usage adheres to the traditional practice of placing the abbreviation before the year, as in Latin (e.g., 64 BC, but AD 2001).

In a particular earthquake, any of these agents of damage can dominate, and historically each has caused major damage and great loss of life, but for most of the earthquakes shaking is the dominant and most widespread cause of damage. This Christian era is currently dominant all around the world in both commercial and scientific use.
Presently, it is the common, international standard, recognised by international institutions such as the United Nations and the Universal Postal Union.
This is due both to the tradition and to the fact that the solar Gregorian calendar has long time been considered to be astronomically correct.[1]. liquefaction, landslide), and fire or a release of hazardous materials. This is the designation used to number years in the Christian Era, conventionally used with the Julian and Gregorian calendars.
"Before Christ", abbreviated as BC or B.C. is now usually used to denote years before Anno Domini years in English language.
More extensive, the years may be also designed by Anno Domini Nostri Iesu Christi, in English translation from Latin: "In the Year of Our Lord Jesus Christ". Large earthquakes can cause serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion (i.e., shaking), inundation (e.g., tsunami, seiche, dam failure), various kinds of permanent ground failure (e.g. Anno Domini ("In the Year of the Lord"), abbreviated as AD or A.D. defines an epoch based on the traditionally-reckoned year of the birth (or actually Incarnation) of Jesus of Nazareth. Some deep earthquakes may be due to the transition of olivine to spinel, which is more stable in the deep mantle. In the Islamic world, traditional Islamic dating according to the Anno Hegiræ (in the year of the hijra) era remains in use to a varying extent, especially for religious purposes.

At subduction zones where plates descend into the mantle, earthquakes have been recorded to a depth of 600 km, although these deep earthquakes are caused by different mechanisms than the more common shallow events. In Israel, the traditional Hebrew calendar, using an era dating from Creation, is in official use. Where the crust is thicker and colder they will occur at greater depths and the opposite in areas that are hot. This is one of the versions of the Buddhist calendar. Most earthquakes occur in narrow regions around plate boundaries down to depths of a few tens of kilometres where the crust is rigid enough to support the elastic strain. This is the so-called Thai solar calendar or Thailand Buddhist Era clearly relied on the western solar calendar. Large numbers of earthquakes occur on a daily basis on Earth, but the majority of them are detected only by seismometers and cause no damage . 543.

. In 1941, the Prime Ministre Phibunsongkhram decided to count the years since B.C. Seismic waves including some strong enough to be felt by humans can also be caused by explosions (chemical or nuclear), landslides, and collapse of old mine shafts, though these sources are not strictly earthquakes. In 1912 the New Year's Day was shifted to April 1. Most earthquakes are tectonic, but they also occur in volcanic regions and as the result of a number of anthropogenic sources, such as reservoir induced seismicity, mining and the removal or injection of fluids into the crust. In Thailand in 1888 King Chulalongkorn decreed a National Thai Era since founding of Bangkok on 1782, April 6. Earthquakes related to plate tectonics are called tectonic earthquakes. Juche means "autarchy, self-reliance".

Events located at plate boundaries are called interplate earthquakes; the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes (see, for example, New Madrid Seismic Zone). The year 2004 was "Juche 93". The highest stress (and possible weakest zones) are most often found at the boundaries of the tectonic plates and hence these locations are where the majority of earthquakes occur. North Korea uses a system that starts in 1912 (= Juche 1), the year of the birth of their founder Kim Il-Sung. Earthquakes occur where the stress resulting from the differential motion of these plates exceeds the strength of the crust. It is still very common in Taiwan to date events via the Republic of China era, whose first year is 1912. The Earth's lithosphere is a patch work of plates in slow but constant motion (see plate tectonics). The official Japanese system numbers years from the accession of the current emperor, regarding the calendar year during which the accession occurred as the first year.

The word earthquake is also widely used to indicate the source region itself. This era was abolished with the fall of fascism in Italy on July 25, 1943.
Both attempts ultimately failed to replace the standard calendar.. Earthquakes typically result from the movement of faults, planar zones of deformation within the Earth's upper crust. Therefore, 1934, for example, was Year XII. Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. The Italian Fascists used the standard system along with Roman numerals to denote the number of years since the establishment of the Fascist government in 1922. An earthquake is a sudden and sometimes catastrophic movement of a part of the Earth's surface. Napoléon finally abolished the calendar effective 1 January 1806, the day after 10 nivôse an XIV.

Lake Tanganyika earthquake (2005). (see French Revolutionary Calendar). Many more at risk from the Kashmiri winter. The French Revolution seriously attempted to displace the Anno Domini system by instead dating from 22 September 1792 = 1 vendémiaire an I (an means year in French) of the First French Republic. Killed over 79,000 people. Kashmir earthquake (2005).

Fukuoka earthquake (2005). Sumatran Earthquake (2005). Triggered a tsunami which caused nearly 300,000 deaths spanning several countries. Epicenter off the coast of the Indonesian island Sumatra.

One of the largest earthquakes ever recorded at 9.0. Indian Ocean Earthquake (2004). Chuetsu Earthquake (2004). Not large (6.0), but the most anticipated and intensely instrumented earthquake ever recorded and likely to offer insights into predicting future earthquakes elsewhere on similar slip-strike fault structures.

Parkfield, California earthquake (2004). Bam Earthquake (2003). Dudley Earthquake (2002). Gujarat Earthquake (2001).

Nisqually Earthquake (2001). Chi-Chi earthquake (1999). Düzce earthquake (1999). İzmit earthquake (1999) Killed over 17,000 in northwestern Turkey.

Killed over 6,400 people in and around Kobe, Japan. Great Hanshin earthquake (1995). Damage showed seismic resistance deficiencies in modern low-rise apartment construction. Northridge, California earthquake (1994).

Revealed necessity of accelerated seismic retrofit of road and bridge structures. Severely affecting Santa Cruz, San Francisco and Oakland in California. Loma Prieta earthquake (1989). Killed over 25,000.

Armenian earthquake (1988). Whittier Narrows earthquake (1987). 8.1 on the Richter Scale, killed over 6,500 people (though it is believed as many as 30,000 may have died, due to missing people never reappearing.). Great Mexican Earthquake (1985).

The official death toll was 255,000, but many experts believe that two or three times that number died. The most destructive earthquake of modern times. Tangshan earthquake (1976). Caused great and unexpected destruction of freeway bridges and flyways in the San Fernando Valley, leading to the first major seismic retrofits of these types of structures, but not at a sufficient pace to avoid the next California freeway collapse in 1989.

Sylmar earthquake (1971). Caused a landslide that buried the town of Yungay, Peru; killed over 40,000 people. Ancash earthquake (1970). Good Friday Earthquake (1964) Alaskan earthquake.

Biggest earthquake ever recorded, 9.5 on Moment magnitude scale. Great Chilean Earthquake (1960). Kamchatka earthquakes (1952 and 1737). On the Japanese island of Honshu, killing over 140,000 in Tokyo and environs.

Great Kanto earthquake (1923). San Francisco Earthquake (1906). Largest earthquake in the Southeast and killed 100. Charleston earthquake (1886).

Fort Tejon Earthquake (1857). New Madrid Earthquake (1811). Lisbon earthquake (1755). Kamchatka earthquakes (1737 and 1952).

Cascadia Earthquake (1700). Deadliest known earthquake in history, estimated to have killed 830,000 in China. Shaanxi Earthquake (1556). San Andreas Fault.

New Madrid Fault Zone. North Anatolian Fault Zone. Hayward Fault Zone. Calaveras Fault.

Alpine Fault. Earthquake prediction. Seismic retrofit. Household seismic safety.

Emergency preparedness. an earthquake of 5.6 or larger every 100 years. an earthquake of 4.7 or larger every 10 years. an earthquake of 3.7 or larger every 1 year.

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