Un terremoto (también conocido como un sismo , temblor o temblor ) es la agitación de la superficie de la Tierra como consecuencia de una liberación repentina de energía en la Tierra 's litosfera que crea ondas sísmicas . Los terremotos pueden variar en tamaño, desde aquellos que son tan débiles que no se pueden sentir hasta aquellos lo suficientemente violentos como para impulsar objetos y personas por el aire y causar destrucción en ciudades enteras. La sismicidad o actividad sísmica de un área es la frecuencia, el tipo y el tamaño de los terremotos experimentados durante un período de tiempo. La palabra temblor también se usa paraestruendo sísmico no sísmico .
En la superficie de la Tierra, los terremotos se manifiestan sacudiendo y desplazando o interrumpiendo el suelo. Cuando el epicentro de un gran terremoto se encuentra en alta mar, el lecho marino puede desplazarse lo suficiente como para provocar un tsunami . Los terremotos también pueden provocar deslizamientos de tierra y, ocasionalmente, actividad volcánica.
En su sentido más general, la palabra terremoto se usa para describir cualquier evento sísmico, ya sea natural o causado por humanos, que genera ondas sísmicas. Los terremotos son causados principalmente por la ruptura de fallas geológicas, pero también por otros eventos como actividad volcánica, deslizamientos de tierra, explosiones de minas y pruebas nucleares . El punto de ruptura inicial de un terremoto se llama hipocentro o foco. El epicentro es el punto a nivel del suelo directamente sobre el hipocentro.
Terremotos que ocurren naturalmente
Los terremotos tectónicos ocurren en cualquier lugar de la tierra donde haya suficiente energía de deformación elástica almacenada para impulsar la propagación de la fractura a lo largo de un plano de falla . Los lados de una falla se mueven uno al lado del otro de manera suave y asísmica solo si no hay irregularidades o asperezas a lo largo de la superficie de la falla que aumenten la resistencia por fricción. La mayoría de las superficies de falla tienen tales asperezas, lo que conduce a una forma de comportamiento de pegado-deslizamiento . Una vez que la falla se ha bloqueado, el movimiento relativo continuo entre las placas conduce a un aumento de la tensión y, por lo tanto, a la energía de deformación almacenada en el volumen alrededor de la superficie de la falla. Esto continúa hasta que la tensión ha aumentado lo suficiente como para romper la aspereza, permitiendo repentinamente deslizarse sobre la parte bloqueada de la falla, liberando la energía almacenada . [1] Esta energía se libera como una combinación de ondas sísmicas de deformación elástica radiadas , [2] calentamiento por fricción de la superficie de la falla y agrietamiento de la roca, lo que provoca un terremoto. Este proceso de acumulación gradual de deformaciones y tensiones puntuados por eventuales fallas repentinas por terremotos se conoce como teoría del rebote elástico . Se estima que solo el 10 por ciento o menos de la energía total de un terremoto se irradia como energía sísmica. La mayor parte de la energía del terremoto se utiliza para impulsar el crecimiento de la fractura del terremoto o se convierte en calor generado por la fricción. Por lo tanto, los terremotos reducen la energía potencial elástica disponible de la Tierra y aumentan su temperatura, aunque estos cambios son insignificantes en comparación con el flujo de calor conductivo y convectivo que sale del interior profundo de la Tierra. [3]
Tipos de fallas de terremotos
Hay tres tipos principales de fallas, todas las cuales pueden causar un terremoto entre placas : normal, inversa (empuje) y deslizamiento. Las fallas normales e inversas son ejemplos de buzamiento-deslizamiento, donde el desplazamiento a lo largo de la falla es en la dirección del buzamiento y donde el movimiento sobre ellas involucra un componente vertical. Las fallas normales ocurren principalmente en áreas donde la corteza se está extendiendo , como un límite divergente . Las fallas inversas ocurren en áreas donde la corteza se está acortando , como en un límite convergente. Las fallas de deslizamiento son estructuras empinadas donde los dos lados de la falla se deslizan horizontalmente uno al lado del otro; Los límites de transformación son un tipo particular de falla de deslizamiento. Muchos terremotos son causados por movimientos en fallas que tienen componentes tanto de deslizamiento como de deslizamiento; esto se conoce como deslizamiento oblicuo.
Las fallas inversas, particularmente aquellas a lo largo de los límites de las placas convergentes , están asociadas con los terremotos más poderosos, los mega-terremotos , incluidos casi todos los de magnitud 8 o más. Los terremotos megathrust son responsables de aproximadamente el 90% del momento sísmico total liberado en todo el mundo. [4] Las fallas por deslizamiento, en particular las transformadas continentales , pueden producir terremotos mayores de hasta una magnitud aproximada de 8. Los terremotos asociados con fallas normales son generalmente menores que la magnitud 7. Por cada unidad de aumento de magnitud, hay aproximadamente un aumento de treinta veces en la energía. liberado. Por ejemplo, un terremoto de magnitud 6.0 libera aproximadamente 32 veces más energía que un terremoto de magnitud 5.0 y un terremoto de magnitud 7.0 libera 1,000 veces más energía que un terremoto de magnitud 5.0. Un terremoto de magnitud 8,6 libera la misma cantidad de energía que 10.000 bombas atómicas como las que se utilizaron en la Segunda Guerra Mundial . [5]
Esto es así porque la energía liberada en un terremoto, y por lo tanto su magnitud, es proporcional al área de la falla que se rompe [6] y la caída de la tensión. Por lo tanto, cuanto mayor sea la longitud y el ancho del área con falla, mayor será la magnitud resultante. La parte más alta y frágil de la corteza terrestre, y las placas frías de las placas tectónicas que descienden hacia el manto caliente, son las únicas partes de nuestro planeta que pueden almacenar energía elástica y liberarla en rupturas de fallas. Las rocas a más de 300 ° C (572 ° F) fluyen en respuesta al estrés; no se rompen en terremotos. [7] [8] Las longitudes máximas observadas de rupturas y fallas mapeadas (que pueden romperse en una sola ruptura) son aproximadamente 1,000 km (620 millas). Algunos ejemplos son los terremotos de Alaska (1957) , Chile (1960) y Sumatra (2004) , todos en zonas de subducción. Las rupturas sísmicas más largas en fallas de deslizamiento, como la falla de San Andrés ( 1857 , 1906 ), la falla del norte de Anatolia en Turquía ( 1939 ) y la falla de Denali en Alaska ( 2002 ), son aproximadamente de la mitad a un tercio del largo de las longitudes a lo largo de los márgenes de las placas en subducción y las de las fallas normales son incluso más cortas.
Sin embargo, el parámetro más importante que controla la magnitud máxima del terremoto en una falla no es la longitud máxima disponible, sino el ancho disponible porque este último varía en un factor de 20. A lo largo de los márgenes de las placas convergentes, el ángulo de inclinación del plano de ruptura es muy grande. poco profundo, típicamente alrededor de 10 grados. [9] Por lo tanto, el ancho del plano dentro de la corteza frágil superior de la Tierra puede llegar a ser de 50 a 100 km (31 a 62 millas) ( Japón, 2011 ; Alaska, 1964 ), lo que hace posible los terremotos más poderosos.
Las fallas de deslizamiento tienden a estar orientadas casi verticalmente, lo que da como resultado un ancho aproximado de 10 km (6.2 millas) dentro de la corteza quebradiza. [10] Por lo tanto, los terremotos con magnitudes mucho mayores que 8 no son posibles. Las magnitudes máximas a lo largo de muchas fallas normales son aún más limitadas porque muchas de ellas están ubicadas a lo largo de centros de expansión, como en Islandia, donde el grosor de la capa frágil es de solo unos seis kilómetros (3.7 millas). [11] [12]
Además, existe una jerarquía de niveles de tensión en los tres tipos de fallas. Las fallas de empuje son generadas por las más altas, el deslizamiento por las intermedias y las fallas normales por los niveles de tensión más bajos. [13] Esto se puede entender fácilmente considerando la dirección del esfuerzo principal más grande, la dirección de la fuerza que "empuja" el macizo rocoso durante la falla. En el caso de fallas normales, el macizo rocoso se empuja hacia abajo en dirección vertical, por lo que la fuerza de empuje ( mayor esfuerzo principal) es igual al peso del propio macizo rocoso. En el caso de empuje, el macizo rocoso "escapa" en la dirección del menor esfuerzo principal, es decir, hacia arriba, levantando el macizo rocoso y, por lo tanto, la sobrecarga es igual al menor esfuerzo principal. Las fallas por deslizamiento son intermedias entre los otros dos tipos descritos anteriormente. Esta diferencia en el régimen de esfuerzos en los tres entornos de fallas puede contribuir a diferencias en la caída de esfuerzos durante la falla, lo que contribuye a diferencias en la energía radiada, independientemente de las dimensiones de la falla.
Terremotos lejos de los límites de las placas
Donde los límites de las placas ocurren dentro de la litosfera continental , la deformación se extiende sobre un área mucho más grande que el límite de las placas en sí. En el caso de la transformada continental de la falla de San Andrés , muchos terremotos ocurren lejos del límite de la placa y están relacionados con deformaciones desarrolladas dentro de la zona más amplia de deformación causada por irregularidades importantes en la traza de la falla (por ejemplo, la región de "Big bend"). El terremoto de Northridge se asoció con un movimiento de empuje ciego dentro de dicha zona. Otro ejemplo es el límite de placa convergente fuertemente oblicuo entre las placas árabe y euroasiática donde atraviesa la parte noroeste de las montañas Zagros . La deformación asociada con este límite de placa se divide en movimientos de sentido de empuje casi puros perpendiculares al límite sobre una zona amplia hacia el suroeste y un movimiento de deslizamiento casi puro a lo largo de la falla reciente principal cerca del límite de placa real en sí. Esto se demuestra por los mecanismos focales de los terremotos . [14]
Todas las placas tectónicas tienen campos de tensión internos causados por sus interacciones con las placas vecinas y la carga o descarga sedimentaria (p. Ej., Desglaciación). [15] Estas tensiones pueden ser suficientes para causar fallas a lo largo de los planos de falla existentes, dando lugar a terremotos dentro de la placa. [dieciséis]
Terremotos de enfoque superficial y profundo
La mayoría de los terremotos tectónicos se originan en el anillo de fuego a profundidades que no superan las decenas de kilómetros. Los terremotos que ocurren a una profundidad de menos de 70 km (43 millas) se clasifican como terremotos de "foco superficial", mientras que aquellos con una profundidad focal entre 70 y 300 km (43 y 186 millas) se denominan comúnmente "de foco medio". o terremotos de "profundidad intermedia". En las zonas de subducción , donde la corteza oceánica más vieja y fría desciende debajo de otra placa tectónica, pueden ocurrir terremotos de enfoque profundo a profundidades mucho mayores (que van de 300 a 700 km (190 a 430 millas)). [17] Estas áreas de subducción sísmicamente activas se conocen como zonas de Wadati-Benioff . Los terremotos de foco profundo ocurren a una profundidad donde la litosfera subducida ya no debería ser frágil, debido a la alta temperatura y presión. Un posible mecanismo para la generación de terremotos de enfoque profundo es la falla causada por el olivino que experimenta una transición de fase a una estructura de espinela . [18]
Earthquakes and volcanic activity
Earthquakes often occur in volcanic regions and are caused there, both by tectonic faults and the movement of magma in volcanoes. Such earthquakes can serve as an early warning of volcanic eruptions, as during the 1980 eruption of Mount St. Helens.[19] Earthquake swarms can serve as markers for the location of the flowing magma throughout the volcanoes. These swarms can be recorded by seismometers and tiltmeters (a device that measures ground slope) and used as sensors to predict imminent or upcoming eruptions.[20]
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 100 m (330 ft) 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.[21]
Rupture propagation is generally modeled using a fracture mechanics 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 earthquakes 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 developed in such earthquakes. Some earthquake ruptures travel at unusually low velocities and are referred to as slow earthquakes. 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.[21]
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.[22][23][24] 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 sequence because, after the main event, pore pressure increase slowly propagates into the surrounding fracture network.[25][24] 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 overpressurisation 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 neighbouring 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.[25][24] Analogously, artificial pore pressure increase, by fluid injection in Earth’s crust, may induce seismicity.
Tidal forces
Tides may induce some seismicity.
Earthquake clusters
Most earthquakes form part of a sequence, related to each other in terms of location and time.[26] 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.[27]
Aftershocks
An aftershock is an earthquake that occurs after a previous earthquake, the mainshock. An aftershock is in the same region of the main shock but always of a smaller magnitude. 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. Aftershocks are formed as the crust around the displaced fault plane adjusts to the effects of the main shock.[26]
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 aftershocks 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.[28] In August 2012, a swarm of earthquakes shook Southern California's Imperial Valley, showing the most recorded activity in the area since the 1970s.[29]
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 aftershocks 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 in Turkey in the 20th century and has been inferred for older anomalous clusters of large earthquakes in the Middle East.[30][31]
Intensidad del temblor de la tierra y magnitud de los terremotos
Quaking or shaking of the earth is a common phenomenon undoubtedly known to humans from earliest times. Prior to the development of strong-motion accelerometers 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. 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.[32]
The first scale for measuring earthquake magnitudes was developed by Charles F. Richter in 1935. Subsequent scales (see seismic magnitude scales) 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.[33]
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 scale, which is based on the actual energy released by an earthquake.[34]
Frecuencia de ocurrencia
It is estimated that around 500,000 earthquakes occur each year, detectable with current instrumentation. About 100,000 of these can be felt.[35][36] 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 in Portugal, Turkey, New Zealand, Greece, Italy, India, Nepal and Japan.[37] Larger earthquakes occur less frequently, the relationship being exponential; for example, roughly ten times as many earthquakes larger than magnitude 4 occur in a particular time period than earthquakes larger than magnitude 5.[38] 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.[39] This is an example of the Gutenberg–Richter law.
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 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.[41] In recent years, the number of major earthquakes per year has decreased, though this is probably a statistical fluctuation rather than a systematic trend.[42] More detailed statistics on the size and frequency of earthquakes is available from the United States Geological Survey (USGS).[43] 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.[44]
Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000-kilometre-long (25,000 mi), horseshoe-shaped zone called the circum-Pacific seismic belt, known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate.[45][46] Massive earthquakes tend to occur along other plate boundaries too, such as along the Himalayan Mountains.[47]
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.[48]
Sismicidad inducida
While most earthquakes are caused by movement of the Earth's tectonic plates, 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.[49] 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,[50] and studies point to the state's oil industry as the cause of other earthquakes in the past century.[51] A Columbia University paper suggested that the 8.0 magnitude 2008 Sichuan earthquake was induced by loading from the Zipingpu Dam,[52] though the link has not been conclusively proved.[53]
Medición y localización de terremotos
The instrumental scales used to describe the size of an earthquake began with the Richter magnitude scale 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 travel through the Earth's interior and can be recorded by seismometers at great distances. The surface wave magnitude was developed in the 1950s as a means to measure remote earthquakes and to improve the accuracy for larger events. The moment magnitude scale not only measures the amplitude of the shock but also takes into account the seismic moment (total rupture area, average slip of the fault, and rigidity of the rock). The Japan Meteorological Agency seismic intensity scale, the Medvedev–Sponheuer–Karnik scale, and the Mercalli intensity scale 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 (shock- or pressure waves)
- Transverse S-waves (both body waves)
- Surface waves – (Rayleigh and Love waves)
Propagation velocity of the seismic waves through solid rock ranges from approx. 3 km/s (1.9 mi/s) up to 13 km/s (8.1 mi/s), depending on the density and elasticity 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 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 can be computed roughly.
In the upper crust, P-waves travel in the range 2–3 km (1.2–1.9 mi) per second (or lower) in soils and unconsolidated sediments, increasing to 3–6 km (1.9–3.7 mi) per second in solid rock. In the lower crust, they travel at about 6–7 km (3.7–4.3 mi) per second; the velocity increases within the deep mantle to about 13 km (8.1 mi) per second. The velocity of S-waves ranges from 2–3 km (1.2–1.9 mi) per second in light sediments and 4–5 km (2.5–3.1 mi) per second in the Earth's crust up to 7 km (4.3 mi) 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.[54] Slight deviations are caused by inhomogeneities of subsurface structure. By such analyses of seismograms the Earth's core was located in 1913 by 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.[55]
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 magnitude, date and time of occurrence, geographic coordinates of its 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.[56]
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 Tohoku-Oki ("Fukushima") earthquake.[57][58]
Efectos de los terremotos
The effects of earthquakes include, but are not limited to, the following:
Shaking and ground rupture
Shaking and 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 magnitude, the distance from the epicenter, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation.[59] 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.[60]
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.[61]
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,[62] 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.[63]
Fires
Earthquakes can cause fires by damaging 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.[64]
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 occurs at sea. In the open ocean the distance between wave crests can surpass 100 kilometers (62 mi), 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.[65]
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.[65]
Floods
Floods may be secondary effects of earthquakes, if dams are damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods.[66]
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.[67]
Grandes terremotos
One of the most devastating earthquakes in recorded history was the 1556 Shaanxi earthquake, which occurred on 23 January 1556 in Shaanxi province, China. More than 830,000 people died.[69] 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.[70]
The 1960 Chilean earthquake is the largest earthquake that has been measured on a seismograph, reaching 9.5 magnitude on 22 May 1960.[35][36] 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.[71][72] The ten largest recorded earthquakes have all been megathrust earthquakes; 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.
Predicción
Earthquake prediction is a branch of the science of seismology concerned with the specification of the time, location, and magnitude of future earthquakes within stated limits.[73] 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.[74]
Previsión
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.[75] For well-understood faults the probability that a segment may rupture during the next few decades can be estimated.[76][77]
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.
Preparación
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.[78]
Individuals can also take preparedness steps like securing 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 caused by a large quake.
Vistas históricas
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."[79] Thales of Miletus (625–547 BCE) was the only documented person who believed that earthquakes were caused by tension between the earth and water.[79] 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.[79] Pliny the Elder called earthquakes "underground thunderstorms".[79]
Estudios recientes
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.[80][better source needed]
En cultura
Mythology and religion
In Norse mythology, earthquakes were explained as the violent struggling of the god Loki. When Loki, 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.[81]
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.[82]
In 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 who restrains the fish with a stone. When Kashima lets his guard fall, Namazu thrashes about, causing violent earthquakes.[83]
In popular culture
In modern popular culture, the portrayal of earthquakes is shaped by the memory of great cities laid waste, such as Kobe in 1995 or San Francisco in 1906.[84] Fictional earthquakes tend to strike suddenly and without warning.[84] For this reason, stories about earthquakes generally begin with the disaster and focus on its immediate aftermath, as in Short Walk to Daylight (1972), The Ragged Edge (1968) or Aftershock: Earthquake in New York (1999).[84] 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 someday, as depicted in the novels Richter 10 (1996), Goodbye California (1977), 2012 (2009) and San Andreas (2015) among other works.[84] 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.[85]
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.[86] 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.[87][88] 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.[89] 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.[90]
Ver también
- Earth sciences portal
- Asteroseismology – Study of oscillations in stars
- Helioseismology
- European-Mediterranean Seismological Centre
- Injection-induced earthquakes
- IRIS Consortium
- Lists of earthquakes – Lists of earthquakes
- Marsquake
- Quake (natural phenomenon) – Surface shaking on interstellar bodies in general
- Seismite – Sediment/structure shaken seismically
- Seismological Society of America
- Seismotectonics
- Types of earthquake – Wikipedia list article
- Vertical Displacement
Referencias
- ^ Ohnaka, M. (2013). The Physics of Rock Failure and Earthquakes. Cambridge University Press. p. 148. ISBN 978-1-107-35533-0.
- ^ Vassiliou, Marius; Kanamori, Hiroo (1982). "The Energy Release in Earthquakes". Bull. Seismol. Soc. Am. 72: 371–387.
- ^ Spence, William; S.A. Sipkin; G.L. Choy (1989). "Measuring the Size of an Earthquake". United States Geological Survey. Archived from the original on 2009-09-01. Retrieved 2006-11-03.
- ^ Stern, Robert J. (2002), "Subduction zones", Reviews of Geophysics, 40 (4): 17, Bibcode:2002RvGeo..40.1012S, doi:10.1029/2001RG000108
- ^ Geoscience Australia
- ^ Wyss, M. (1979). "Estimating expectable maximum magnitude of earthquakes from fault dimensions". Geology. 7 (7): 336–340. Bibcode:1979Geo.....7..336W. doi:10.1130/0091-7613(1979)7<336:EMEMOE>2.0.CO;2.
- ^ Sibson, R.H. (1982). "Fault Zone Models, Heat Flow, and the Depth Distribution of Earthquakes in the Continental Crust of the United States". Bulletin of the Seismological Society of America. 72 (1): 151–163.
- ^ Sibson, R.H. (2002) "Geology of the crustal earthquake source" International handbook of earthquake and engineering seismology, Volume 1, Part 1, p. 455, eds. W H K Lee, H Kanamori, P C Jennings, and C. Kisslinger, Academic Press, ISBN 978-0-12-440652-0
- ^ "Global Centroid Moment Tensor Catalog". Globalcmt.org. Retrieved 2011-07-24.
- ^ "Instrumental California Earthquake Catalog". WGCEP. Archived from the original on 2011-07-25. Retrieved 2011-07-24.
- ^ Hjaltadóttir S., 2010, "Use of relatively located microearthquakes to map fault patterns and estimate the thickness of the brittle crust in Southwest Iceland"
- ^ "Reports and publications | Seismicity | Icelandic Meteorological office". En.vedur.is. Retrieved 2011-07-24.
- ^ Schorlemmer, D.; Wiemer, S.; Wyss, M. (2005). "Variations in earthquake-size distribution across different stress regimes". Nature. 437 (7058): 539–542. Bibcode:2005Natur.437..539S. doi:10.1038/nature04094. PMID 16177788. S2CID 4327471.
- ^ Talebian, M; Jackson, J (2004). "A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran". Geophysical Journal International. 156 (3): 506–526. Bibcode:2004GeoJI.156..506T. doi:10.1111/j.1365-246X.2004.02092.x.
- ^ Nettles, M.; Ekström, G. (May 2010). "Glacial Earthquakes in Greenland and Antarctica". Annual Review of Earth and Planetary Sciences. 38 (1): 467–491. Bibcode:2010AREPS..38..467N. doi:10.1146/annurev-earth-040809-152414.
- ^ Noson, Qamar, and Thorsen (1988). Washington State Earthquake Hazards: Washington State Department of Natural Resources. Washington Division of Geology and Earth Resources Information Circular 85.CS1 maint: multiple names: authors list (link)
- ^ "M7.5 Northern Peru Earthquake of 26 September 2005" (PDF). National Earthquake Information Center. 17 October 2005. Retrieved 2008-08-01.
- ^ Greene II, H.W.; Burnley, P.C. (October 26, 1989). "A new self-organizing mechanism for deep-focus earthquakes". Nature. 341 (6244): 733–737. Bibcode:1989Natur.341..733G. doi:10.1038/341733a0. S2CID 4287597.
- ^ Foxworthy and Hill (1982). Volcanic Eruptions of 1980 at Mount St. Helens, The First 100 Days: USGS Professional Paper 1249.
- ^ Watson, John; Watson, Kathie (January 7, 1998). "Volcanoes and Earthquakes". United States Geological Survey. Retrieved May 9, 2009.
- ^ a b National Research Council (U.S.). Committee on the Science of Earthquakes (2003). "5. Earthquake Physics and Fault-System Science". Living on an Active Earth: Perspectives on Earthquake Science. Washington, D.C.: National Academies Press. p. 418. ISBN 978-0-309-06562-7. Retrieved 8 July 2010.
- ^ Sibson, R.H. (1973). "Interactions between Temperature and Pore-Fluid Pressure during Earthquake Faulting and a Mechanism for Partial or Total Stress Relief". Nat. Phys. Sci. 243 (126): 66–68. doi:10.1038/physci243066a0.
- ^ Rudnicki, J.W.; Rice, J.R. (2006). "Effective normal stress alteration due to pore pressure changes induced by dynamic slip propagation on a plane between dissimilar materials". J. Geophys. Res. 111, B10308. doi:10.1029/2006JB004396.
- ^ a b c Guerriero, V; Mazzoli, S. (2021). "Theory of Effective Stress in Soil and Rock and Implications for Fracturing Processes: A Review". Geosciences. 11 (3): 119. doi:10.3390/geosciences11030119.
- ^ a b Nur, A; Booker, J.R. (1972). "Aftershocks Caused by Pore Fluid Flow?". Science. 175 (4024): 885–887. doi:10.1126/science.175.4024.885. PMID 17781062. S2CID 19354081.
- ^ a b "What are Aftershocks, Foreshocks, and Earthquake Clusters?". Archived from the original on 2009-05-11.
- ^ "Repeating Earthquakes". United States Geological Survey. January 29, 2009. Retrieved May 11, 2009.
- ^ "Earthquake Swarms at Yellowstone". United States Geological Survey. Retrieved 2008-09-15.
- ^ Duke, Alan. "Quake 'swarm' shakes Southern California". CNN. Retrieved 27 August 2012.
- ^ Amos Nur; Cline, Eric H. (2000). "Poseidon's Horses: Plate Tectonics and Earthquake Storms in the Late Bronze Age Aegean and Eastern Mediterranean" (PDF). Journal of Archaeological Science. 27 (1): 43–63. doi:10.1006/jasc.1999.0431. ISSN 0305-4403. Archived from the original (PDF) on 2009-03-25.
- ^ "Earthquake Storms". Horizon. 1 April 2003. Retrieved 2007-05-02.
- ^ Bolt 1993.
- ^ Chung & Bernreuter 1980, p. 1.
- ^ The USGS policy for reporting magnitudes to the press was posted at USGS policy Archived 2016-05-04 at the Wayback Machine, but has been removed. A copy can be found at http://dapgeol.tripod.com/usgsearthquakemagnitudepolicy.htm.
- ^ a b "Cool Earthquake Facts". United States Geological Survey. Retrieved 2021-04-21.
- ^ a b Pressler, Margaret Webb (14 April 2010). "More earthquakes than usual? Not really". KidsPost. Washington Post: Washington Post. pp. C10.
- ^ "Earthquake Hazards Program". United States Geological Survey. Retrieved 2006-08-14.
- ^ USGS Earthquake statistics table based on data since 1900 Archived 2010-05-24 at the Wayback Machine
- ^ "Seismicity and earthquake hazard in the UK". Quakes.bgs.ac.uk. Retrieved 2010-08-23.
- ^ "Italy's earthquake history." BBC News. October 31, 2002.
- ^ "Common Myths about Earthquakes". United States Geological Survey. Archived from the original on 2006-09-25. Retrieved 2006-08-14.
- ^ Are Earthquakes Really on the Increase? Archived 2014-06-30 at the Wayback Machine, USGS Science of Changing World. Retrieved 30 May 2014.
- ^ "Earthquake Facts and Statistics: Are earthquakes increasing?". United States Geological Survey. Archived from the original on 2006-08-12. Retrieved 2006-08-14.
- ^ The 10 biggest earthquakes in history Archived 2013-09-30 at the Wayback Machine, Australian Geographic, March 14, 2011.
- ^ "Historic Earthquakes and Earthquake Statistics: Where do earthquakes occur?". United States Geological Survey. Archived from the original on 2006-09-25. Retrieved 2006-08-14.
- ^ "Visual Glossary – Ring of Fire". United States Geological Survey. Archived from the original on 2006-08-28. Retrieved 2006-08-14.
- ^ Jackson, James (2006). "Fatal attraction: living with earthquakes, the growth of villages into megacities, and earthquake vulnerability in the modern world". Philosophical Transactions of the Royal Society. 364 (1845): 1911–1925. Bibcode:2006RSPTA.364.1911J. doi:10.1098/rsta.2006.1805. PMID 16844641. S2CID 40712253.
- ^ "Global urban seismic risk." Cooperative Institute for Research in Environmental Science.
- ^ Fougler, Gillian R.; Wilson, Miles; Gluyas, Jon G.; Julian, Bruce R.; Davies, Richard J. (2018). "Global review of human-induced earthquakes". Earth-Science Reviews. 178: 438–514. Bibcode:2018ESRv..178..438F. doi:10.1016/j.earscirev.2017.07.008. Retrieved July 23, 2020.
- ^ Fountain, Henry (March 28, 2013). "Study Links 2011 Quake to Technique at Oil Wells". The New York Times. Retrieved July 23, 2020.
- ^ Hough, Susan E.; Page, Morgan (2015). "A Century of Induced Earthquakes in Oklahoma?". Bulletin of the Seismological Society of America. 105 (6): 2863–2870. Bibcode:2015BuSSA.105.2863H. doi:10.1785/0120150109. Retrieved July 23, 2020.
- ^ Klose, Christian D. (July 2012). "Evidence for anthropogenic surface loading as trigger mechanism of the 2008 Wenchuan earthquake". Environmental Earth Sciences. 66 (5): 1439–1447. arXiv:1007.2155. doi:10.1007/s12665-011-1355-7. S2CID 118367859.
- ^ LaFraniere, Sharon (February 5, 2009). "Possible Link Between Dam and China Quake". The New York Times. Retrieved July 23, 2020.
- ^ "Speed of Sound through the Earth". Hypertextbook.com. Retrieved 2010-08-23.
- ^ "Newsela | The science of earthquakes". newsela.com. Retrieved 2017-02-28.
- ^ Geographic.org. "Magnitude 8.0 - SANTA CRUZ ISLANDS Earthquake Details". Global Earthquake Epicenters with Maps. Retrieved 2013-03-13.
- ^ "Earth's gravity offers earlier earthquake warnings". Retrieved 2016-11-22.
- ^ "Gravity shifts could sound early earthquake alarm". Retrieved 2016-11-23.
- ^ "On Shaky Ground, Association of Bay Area Governments, San Francisco, reports 1995,1998 (updated 2003)". Abag.ca.gov. Archived from the original on 2009-09-21. Retrieved 2010-08-23.
- ^ "Guidelines for evaluating the hazard of surface fault rupture, California Geological Survey" (PDF). California Department of Conservation. 2002. Archived from the original (PDF) on 2009-10-09.
- ^ "Historic Earthquakes – 1964 Anchorage Earthquake". United States Geological Survey. Archived from the original on 2011-06-23. Retrieved 2008-09-15.
- ^ "Earthquake Resources". Nctsn.org. Retrieved 2018-06-05.
- ^ "Natural Hazards – Landslides". United States Geological Survey. Retrieved 2008-09-15.
- ^ "The Great 1906 San Francisco earthquake of 1906". United States Geological Survey. Retrieved 2008-09-15.
- ^ a b Noson, Qamar, and Thorsen (1988). Washington Division of Geology and Earth Resources Information Circular 85 (PDF). Washington State Earthquake Hazards.CS1 maint: multiple names: authors list (link)
- ^ "Notes on Historical Earthquakes". British Geological Survey. Archived from the original on 2011-05-16. Retrieved 2008-09-15.
- ^ "Fresh alert over Tajik flood threat". BBC News. 2003-08-03. Retrieved 2008-09-15.
- ^ USGS: Magnitude 8 and Greater Earthquakes Since 1900 Archived 2016-04-14 at the Wayback Machine
- ^ "Earthquakes with 50,000 or More Deaths Archived November 1, 2009, at the Wayback Machine". U.S. Geological Survey
- ^ Spignesi, Stephen J. (2005). Catastrophe!: The 100 Greatest Disasters of All Time. ISBN 0-8065-2558-4
- ^ Kanamori Hiroo. "The Energy Release in Great Earthquakes" (PDF). Journal of Geophysical Research. Archived from the original (PDF) on 2010-07-23. Retrieved 2010-10-10.
- ^ USGS. "How Much Bigger?". United States Geological Survey. Retrieved 2010-10-10.
- ^ Geller et al. 1997, p. 1616, following Allen (1976, p. 2070), who in turn followed Wood & Gutenberg (1935)
- ^ Earthquake Prediction. Ruth Ludwin, U.S. Geological Survey.
- ^ Kanamori 2003, p. 1205. See also International Commission on Earthquake Forecasting for Civil Protection 2011, p. 327.
- ^ Working Group on California Earthquake Probabilities in the San Francisco Bay Region, 2003 to 2032, 2003, "Archived copy". Archived from the original on 2017-02-18. Retrieved 2017-08-28.CS1 maint: archived copy as title (link)
- ^ Pailoplee, Santi (2017-03-13). "Probabilities of Earthquake Occurrences along the Sumatra-Andaman Subduction Zone". Open Geosciences. 9 (1): 4. Bibcode:2017OGeo....9....4P. doi:10.1515/geo-2017-0004. ISSN 2391-5447. S2CID 132545870.
- ^ Salvaneschi, P.; Cadei, M.; Lazzari, M. (1996). "Applying AI to Structural Safety Monitoring and Evaluation". IEEE Expert. 11 (4): 24–34. doi:10.1109/64.511774.
- ^ a b c d "Earthquakes". Encyclopedia of World Environmental History. 1: A–G. Routledge. 2003. pp. 358–364.
- ^ "Fire and Ice: Melting Glaciers Trigger Earthquakes, Tsunamis and Volcanos". about News. Retrieved October 27, 2015.
- ^ Sturluson, Snorri (1220). Prose Edda. ISBN 978-1-156-78621-5.
- ^ George E. Dimock (1990). The Unity of the Odyssey. Univ of Massachusetts Press. pp. 179–. ISBN 978-0-87023-721-8.
- ^ "Namazu". World History Encyclopedia. Retrieved 2017-07-23.
- ^ a b c d Van Riper, A. Bowdoin (2002). Science in popular culture: a reference guide. Westport: Greenwood Press. p. 60. ISBN 978-0-313-31822-1.
- ^ JM Appel. A Comparative Seismology. Weber Studies (first publication), Volume 18, Number 2.
- ^ Goenjian, Najarian; Pynoos, Steinberg; Manoukian, Tavosian; Fairbanks, AM; Manoukian, G; Tavosian, A; Fairbanks, LA (1994). "Posttraumatic stress disorder in elderly and younger adults after the 1988 earthquake in Armenia". Am J Psychiatry. 151 (6): 895–901. doi:10.1176/ajp.151.6.895. PMID 8185000.
- ^ Wang, Gao; Shinfuku, Zhang; Zhao, Shen; Zhang, H; Zhao, C; Shen, Y (2000). "Longitudinal Study of Earthquake-Related PTSD in a Randomly Selected Community Sample in North China". Am J Psychiatry. 157 (8): 1260–1266. doi:10.1176/appi.ajp.157.8.1260. PMID 10910788.
- ^ Goenjian, Steinberg; Najarian, Fairbanks; Tashjian, Pynoos (2000). "Prospective Study of Posttraumatic Stress, Anxiety, and Depressive Reactions After Earthquake and Political Violence" (PDF). Am J Psychiatry. 157 (6): 911–916. doi:10.1176/appi.ajp.157.6.911. PMID 10831470. Archived from the original (PDF) on 2017-08-10.
- ^ Coates, SW; Schechter, D (2004). "Preschoolers' traumatic stress post-9/11: relational and developmental perspectives. Disaster Psychiatry Issue". Psychiatric Clinics of North America. 27 (3): 473–489. doi:10.1016/j.psc.2004.03.006. PMID 15325488.
- ^ Schechter, DS; Coates, SW; First, E (2002). "Observations of acute reactions of young children and their families to the World Trade Center attacks". Journal of ZERO-TO-THREE: National Center for Infants, Toddlers, and Families. 22 (3): 9–13.
Fuentes
- Allen, Clarence R. (December 1976), "Responsibilities in earthquake prediction", Bulletin of the Seismological Society of America, 66 (6): 2069–2074.
- Bolt, Bruce A. (1993), Earthquakes and geological discovery, Scientific American Library, ISBN 978-0-7167-5040-6.
- Chung, D.H.; Bernreuter, D.L. (1980), Regional Relationships Among Earthquake Magnitude Scales., 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
- Geller, Robert J.; Jackson, David D.; Kagan, Yan Y.; Mulargia, Francesco (14 March 1997), "Earthquakes Cannot Be Predicted" (PDF), Science, 275 (5306): 1616, doi:10.1126/science.275.5306.1616, S2CID 123516228.
- Donald Hyndman; David Hyndman (2009). "Chapter 3: Earthquakes and their causes". Natural Hazards and Disasters (2nd ed.). Brooks/Cole: Cengage Learning. ISBN 978-0-495-31667-1.
- International Commission on Earthquake Forecasting for Civil Protection (30 May 2011), "Operational Earthquake Forecasting: State of Knowledge and Guidelines for Utilization", Annals of Geophysics, 54 (4): 315–391, doi:10.4401/ag-5350.
- Kanamori, Hiroo (2003), "Earthquake Prediction: An Overview", International Handbook of Earthquake and Engineering Seismology, International Geophysics, 616: 1205–1216, doi:10.1016/s0074-6142(03)80186-9, ISBN 978-0-12-440658-2.
- Wood, H.O.; Gutenberg, B. (6 September 1935), "Earthquake prediction", Science, 82 (2123): 219–320, Bibcode:1935Sci....82..219W, doi:10.1126/science.82.2123.219, PMID 17818812.
enlaces externos
- Earthquake Hazards Program of the U.S. Geological Survey
- IRIS Seismic Monitor – 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
- CDC – NIOSH Earthquake Cleanup and Response Resources
- Icelandic Meteorological Office website Shows current seismic and volcanic activity in Iceland. English available.
- How Friction Evolves During an Earthquake – Caltech