Earthquake

Earthquake Columbia Electronic Encyclopedia - Cite This Source earthquake, trembling or shaking movement of the earth's surface. Most earthquakes are minor tremors. Larger earthquakes usually begin with slight tremors but rapidly take the form of one or more violent shocks, and end in vibrations of gradually diminishing force called aftershocks. The subterranean point of origin of an earthquake is called its focus; the point on the surface directly above the focus is the epicenter. The magnitude and intensity of an earthquake is determined by the use of scales, e.g., the Richter scale and the Mercalli scale.

Causes of Earthquakes Most earthquakes are causally related to compressional or tensional stresses built up at the margins of the huge moving lithospheric plates that make up the earth's surface (see lithosphere). The immediate cause of most shallow earthquakes is the sudden release of stress along a fault, or fracture in the earth's crust, resulting in movement of the opposing blocks of rock past one another. These movements cause vibrations to pass through and around the earth in wave form, just as ripples are generated when a pebble is dropped into water. Volcanic eruptions, rockfalls, landslides, and explosions can also cause a quake, but most of these are of only local extent. Shock waves from a powerful earthquake can trigger smaller earthquakes in a distant location hundreds of miles away if the geologic conditions are favorable. See also plate tectonics.

Seismic Waves There are several types of earthquake waves including P, or primary, waves, which are compressional and travel fastest; and S, or secondary, waves, which are transverse, i.e., they cause the earth to vibrate perpendicularly to the direction of their motion. Surface waves consist of several major types and are called L, or long, waves. Since the velocities of the P and S waves are affected by changes in the density and rigidity of the material through which they pass, the boundaries between the regions of the earth known as the crust, mantle, and core have been discerned by seismologists, scientists who deal with the analysis and interpretation of earthquake waves (see earth). Seismographs (see seismology) are used to record P, S, and L waves. The disappearance of S waves below depths of 1,800 mi (2,900 km) indicates that at least the outer part of the earth's core is liquid.

Damage Caused by Earthquakes

The effects of an earthquake are strongest in a broad zone surrounding the epicenter. Surface ground cracking associated with faults that reach the surface often occurs, with horizontal and vertical displacements of several yards common. Such movement does not have to occur during a major earthquake; slight periodic movements called fault creep can be accompanied by microearthquakes too small to be felt. The extent of earthquake vibration and subsequent damage to a region is partly dependent on characteristics of the ground. For example, earthquake vibrations last longer and are of greater wave amplitudes in unconsolidated surface material, such as poorly compacted fill or river deposits; bedrock areas receive fewer effects. The worst damage occurs in densely populated urban areas where structures are not built to withstand intense shaking. There, L waves can produce destructive vibrations in buildings and break water and gas lines, starting uncontrollable fires. Damage and loss of life sustained during an earthquake result from falling structures and flying glass and objects. Flexible structures built on bedrock are generally more resistant to earthquake damage than rigid structures built on loose soil. In certain areas, an earthquake can trigger mudslides, which slip down mountain slopes and can bury habitations below. A submarine earthquake can cause a tsunami, a series of damaging waves that ripple outward from the earthquake epicenter and inundate coastal cities.

Major Earthquakes On average about 1,000 earthquakes with intensities of 5.0 or greater are recorded each year. Great earthquakes (intensity 8.0 or higher) occur once a year, major earthquakes (intensity 7.0-7.9) occur 18 times a year, strong earthquakes (intensity 6.0-6.9) 10 times a month, and moderate earthquakes (intensity 5.0-5.9) more than twice a day. Because most of these occur under the ocean or in underpopulated areas, they pass unnoticed by all but seismologists. Notable earthquakes have occurred at Lisbon, Portugal (1755); New Madrid, Mo. (1811 and 1812); Charleston, S.C. (1886); Assam, India (1897 and 1950); San Francisco (1906); Messina, Italy (1908); Gansu, China (1920); Tokyo, Japan (1923); Chile (1960); Iran (1962); Managua, Nicaragua (1972); Guatemala (1976); Hebei, China (1976); Mexico (1985); Armenia (1988); Luzon, Philippines (1990); N Japan (1993); Kobe, Japan (1995); Izmit, Turkey (1999); central Taiwan (1999); Oaxaca state, Mexico (1999); Bam, Iran (2003); and NW Sumatra, Indonesia (2004). The Lisbon, Chilean, and Sumatran earthquakes were accompanied by tsunamis. On Good Friday 1964, one of the most severe North American earthquakes ever recorded struck Alaska, measuring 8.4 to 8.6 in intensity. Besides elevating some 70,000 sq mi (181,300 sq km) of land and devastating several cities, it generated a tsunami that caused damage as far south as California. Ten of the fifteen largest earthquakes in the United States have occurred in Alaska, and eight of the fifteen largest in the continental United States have occurred in California. Recent earthquakes that affected the United States include the Feb., 1971, movement of the San Fernando fault near Los Angeles. It rocked the area for 10 sec, thrust parts of mountains 8 ft (2.4 m) upward, killed 64 persons, and caused damage amounting to $500 million. In 1989, the Loma Prieta earthquake above Santa Cruz shook for 15 seconds at

an intensity of 7.1, killed 67 people, and toppled buildings and bridges. In Jan., 1994, an earthquake measuring 6.6 with its epicenter in N Los Angeles caused major damage to the city's infrastructure and left thousands homeless.

Bibliography See C. H. Scholz, The Mechanics of Earthquakes and Faulting (1991); C. Lomnitz, Fundamentals of Earthquake Prediction (1994); D. S. Brumbaugh, Earthquakes: Science and Society (1998); B. A. Bolt, Earthquakes (4th ed. 1999). See also bibliography under seismology.

The Columbia Electronic Encyclopedia Copyright © 2004, Columbia University Press. Licensed from Columbia University Press

Earthquake Crystal Reference Encyclopedia - Cite This Source

A series of shock waves generated at a point (focus) within the Earth, and caused by the movement of rocks on a fault plane releasing stored strain energy. The point on the surface of the Earth above the focus is the epicentre. Major earthquakes are associated with the edges of plates that make up the Earth's crust, and along mid-oceanic ridges where new crust is forming. The greatest concentration of earthquakes is in a belt around the Pacific Ocean (the ‘ring of fire’), and along a zone from the Mediterranean E to the Himalayas and China. The magnitude of an earthquake is measured on the Richter scale. Major earthquakes, such as in San Francisco in 1906 and Japan in 1923, can cause much damage to property and loss of life. Further dangers arise from associated effects, especially tsunamis. See also plate tectonics Richter scale seismology Major Earthquakes All magnitudes on the Richter Scalea Location Country Ica Peru Solomon Sea Solomon Is

Year 2007 2007

Magnitude 8·0 8·1

Deaths 500+ 39+

Java Muzaffarabad Indian Ocean Zarand Indian Ocean Niigata Yunnan Province Niigata Bam Xinjiang Bam Quazvin Gujarat El Salvador Taiwan Izmit Armenia Rostaq NW Afghanistan Khorasan Lijiang, Yunan Biak Is Neftegorsk Kobe Mascara Cauca Sumatra Los Angeles Maharashtra Hokkaido Cairo Erzincan Uttar Pradesh Ossetia Hindu Kush Mts Cabanatuan Caspian Sea Luzon Island San Francisco N Armenia Mexico City Naples

Indonesia N Pakistan Indonesia SE Iran Indonesia Japan SW China Japan SE Iran China SE Iran NW Iran India El Salvador Taiwan Turkey Colombia Afghanistan Afghanistan Iran China Indonesia Russia Japan Algeria Colombia Indonesia USA India Japan Egypt Turkey India Georgia Afghanistan/Pakistan Philippines Iran Philippines USA Armenia Mexico Italy

2006 2005 2005 2005 2004 2004 2004 2004 2003 2003 2003 2002 2001 2001 1999 1999 1999 1998 1998 1997 1996 1996 1995 1995 1994 1994 1994 1994 1993 1993 1992 1992 1991 1991 1991 1990 1990 1990 1989 1988 1985 1980

6·3 7·6 8·7 6·4 9·3 6·8 5.6 6·8 6·3 6·8 6·3 6·3 7·9 7·6 7·6 7·4 6·0 7·1 6·1 7·1 7.0 7.5 7.6 7.2 5.6 6.8 7.0 6.8 6.4 7.7 5.9 6.2 6.1 7.2 6.8 7.7 7.7 7.7 6.9 7.0 8.1 7.2

5000+ 87 000+ 1000+ 400+ 300 000+ 40 4 40 26 000+ 268 30 000 230 20 000/ 850 2000+ 15 000+ 2000+ 2000 4000+ 4000 250 100+ 1989 5477 171 269 215 57 9748 200 500 2000 1000 100 1300 1653 40 000 1600 100 25 000 7200 4500

El Asnam Algeria 1980 7.3 5000 Tabas Iran 1978 7.7 25 000 Tangshan China 1976 8.2 242 000 Guatemala City Guatemala 1976 7.5 22 778 Kashmir Pakistan 1974 6.3 5200 Managua Nicaragua 1972 6.2 5000 Tehran Iran 1972 6.9 5000 Chimbote Peru 1970 7.7 66 000 Anchorage USA 1964 8.5 131 Agadir Morocco 1960 5.8 12 000 Ashkhabad Turkmenistan 1948 7.3 19 800 Erzincan Turkey 1939 7.9 23 000 Chillan Chile 1939 7.8 30 000 Quetta India 1935 7.5 60 000 Gansu China 1932 7.6 70 000 Nan-Shan China 1927 8.3 200 000 Kanto Japan 1923 8.3 143 000 Gansu China 1920 8.6 180 000 Avezzano Italy 1915 7.5 30 000 Messina Italy 1908 7.5 120 000 Valparaiso Chile 1906 8.6 20 000 San Francisco USA 1906 8.3 500 Calabria Italy 1783 50 000 Lisbon Portugal 1755 70 000 Calcutta India 1737 300 000 Hokkaido Japan 1730 137 000 Catania Italy 1693 60 000 Shemaka Caucasia 1667 80 000 Shensi China 1556 830 000 Chihli China 1290 100 000 Cilicia Turkey 1268 60 000 Corinth Greece 856 45 000 Antioch Turkey 526 250 000 a The Richter scale is a logarithmic scale, devised in 1935 by geophysicist Charles Richter, for representing the energy released by earthquakes. A figure of 2 or less is barely perceptible, while an earthquake measuring over 5 may be destructive.

Crystal Reference Encyclopedia, © Crystal Reference Systems Limited 2006 2 More from Crystal Reference Encyclopedia »

Earthquake Wikipedia, the free encyclopedia - Cite This Source An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale. At the Earth's surface, earthquakes manifest themselves by a shaking and sometimes displacement of the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity. In its most generic sense, the word earthquake is used to describe any seismic event— whether a natural phenomenon or an event caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments. An earthquake's point of initial rupture is called its focus or hypocenter. The term epicenter means the point at ground level directly above this.

Naturally occurring earthquakes Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patchwork of plates in slow but constant motion caused by the release to space of the heat in the Earth's mantle and core. The heat causes the rock in the Earth to become flow on geological timescales, so that the plates move slowly but surely. Plate boundaries lock as the plates move past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the Elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convection flow of heat out from the Earth's deep interior.

The majority of tectonic earthquakes originate at depths not exceeding tens of kilometers. In subduction zones, where older and colder oceanic crust descends beneath another tectonic plate, Deep focus earthquakes may occur at much greater depths (up to seven hundred kilometers). These seismically active areas of subduction are known as WadatiBenioff zones. These are earthquakes that occur at a depth at which the subducted lithosphere should no longer be brittle, due to the high temperature and pressure. A possible mechanism for the generation of deep focus earthquakes is faulting caused by olivine undergoing a phase transition into a spinel structure. Earthquakes also often occur in volcanic regions and are caused there both by tectonic faults and by the movement of magma in volcanoes. Such earthquakes can serve as an early warning of volcanic eruptions. Some earthquakes occur in a sort of earthquake storm, where earthquake strike a fault in clusters, each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring on adjacent segments of fault, sometimes years later, 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, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.

Size and frequency of occurrence Small earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in Chile, Peru, Indonesia, Iran, the Azores in Portugal, New Zealand, Greece and Japan. Large 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. In the (low seismicity) United Kingdom, for example, it has been calculated that the average recurrences are: • • •

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

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 because of the vast improvement in instrumentation (not because the number of earthquakes has increased). The USGS estimates that, since 1900, there have been an average of 18 major earthquakes (magnitude 7.0-7.9) and one great earthquake (magnitude 8.0 or greater) per year, and that this average has been relatively stable. In fact, in recent years, the number of major earthquakes per year has actually decreased, although this is likely a statistical fluctuation. More detailed statistics on the size and frequency of earthquakes is available from the USGS.

Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate. Massive earthquakes tend to occur along other plate boundaries, too, such as along the Himalayan Mountains.

Effects/impacts of earthquakes There are many effects of earthquakes including, but 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 or other rigid structures. The severity of the local effects depends on the complex combination of the earthquake magnitude, the distance from epicenter, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation. The ground-shaking is measured by ground acceleration. Specific local geological, geomorphological, and geostructural features can induce high levels of shaking on the ground surface even from low-intensity earthquakes. This effect is called site or local amplification. It is principally due to the transfer of the seismic motion from hard deep soils to soft superficial soils and to effects of seismic energy focalization owing to typical geometrical setting of the deposits. Ground rupture is a visible breaking and displacement of the earth's surface along the trace of the fault, which may be of the order of few metres 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 likely to break the ground surface within the life of the structure.

Landslides and avalanches Earthquakes can cause landslides and avalanches, which may cause damage in hilly and mountainous areas.

Fires Following an earthquake, fires can be generated by break of the 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.

Soil liquefaction

Soil liquefaction occurs when, because of the shaking, water-saturated granular material temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, as buildings or bridges, to tilt or sink into the liquefied deposits.

Tsunamis Undersea earthquakes and earthquake-triggered landslides into the sea, can cause Tsunamis. See, for example, the 2004 Indian Ocean earthquake.

Human impacts Earthquakes may result in disease, lack of basic necessities, loss of life, higher insurance premiums, general property damage, road and bridge damage, and collapse of buildings or destabilization of the base of buildings which may lead to collapse in future earthquakes.

Preparation for earthquakes • • • • • • •

Earthquake preparedness Household seismic safety HurriQuake nail (for resisting hurricanes and earthquakes) Seismic retrofit Seismic hazard Mitigation of seismic motion Earthquake prediction

Specific fault articles • • • • • • • • • • • • •

Alpine Fault Calaveras Fault Cascadia subduction zone Geology of the Death Valley area Great Glen Fault Great Sumatran fault Hayward Fault Zone Highland Boundary Fault Hope Fault Liquiñe-Ofqui Fault North Anatolian Fault Zone New Madrid Fault Zone San Andreas Fault

Major earthquakes

Pre-20th century • • • •

• • • • • • •

• •

• • • • •

Pompeii (62). Aleppo Earthquake (1138). Basel earthquake (1356). Major earthquake that struck Central Europe in 1356. Carniola earthquake (1511). A major earthquake that shook a large portion of South-Central Europe. Its epicenter was around the town of Idrija, in today's Slovenia. It caused great damage to structures all over Carniola, including Ljubljana, and minor damage in Venice, among other cities. Shaanxi Earthquake (1556). Deadliest known earthquake in history, estimated to have killed 830,000 in China. Dover Straits earthquake of 1580 (1580). Dubrovnik earthquake (1667). Disastrous earthquake in Dubrovnik, Croatia killed about 3/5 of the population. The great Sicilian earthquake (1693). As many as 100,000 may have died. Cascadia Earthquake (1700). Kamchatka earthquakes (1737 and 1952). Lisbon earthquake (1755), one of the most destructive and deadly earthquakes in history, killing between 60,000 and 100,000 people and causing a major tsunami that affected parts of Europe, North Africa and the Caribbean. Calabria earthquake (1783). Series of 6 earthquakes in Calabria, Italy killed 50,000. New Madrid Earthquake (1811), and another tremor (1812) that also struck the small Missouri town, was reportedly the strongest ever in North America and made the Mississippi River temporarily change its direction and permanently altered its course in the region. Fort Tejon Earthquake (1857). Estimated Richter Scale above 8, said the strongest earthquake in Southern California history. 1872 Lone Pine earthquake (1872). Might been strongest ever measured in California with an estimated Richter Scale of 8.1 said seismologists. Charleston earthquake (1886). Largest earthquake in the southeastern United States, killed 100. Ljubljana earthquake (14. IV. 1895), a series of powerful quakes that ultimately had a vital impact on the city of Ljubljana, being a catalyst of its urban renewal. Assam earthquake of 1897 (1897). Large earthquake that destroyed all masonry structures, measuring more than 8 on the Richter scale.

20th century •

• • •

San Francisco Earthquake (1906). Between 7.7 and 8.3 magnitudes; killed approximately 3,000 people and caused around $400 million in damage; most devastating earthquake in California and U.S. history. Messina Earthquake (1908). Killed about 60,000 people. Gansu earthquake (1920). Killed 200,000 in Gansu province, China. Great Kantō earthquake (1923). On the Japanese island of Honshū, killing over 140,000 in Tokyo and environs.

• • • • • • • •

• • • • • • •

• • •

• •

• • • • •

1931 Hawke's Bay earthquake. Occurred in the Hawkes Bay in the North Island of New Zealand leaving 256 dead. 1933 Long Beach earthquake 1935 Balochistan earthquake at Quetta, Pakistan measuring 7.7 on the Richter scale. Anywhere from 30,000 to 60,000 people died 1939 Erzincan earthquake at Erzincan, Turkey measuring 7.9 on the Richter scale. Ashgabat earthquake (1948). Earthquake in Ashgabat, Soviet Union measuring 7.3 on the Richter scale killed over 110,000 (2/3 the population of the city). Assam earthquake of 1950 (1950). Earthquake in Assam, India measures 8.6M. Kamchatka earthquakes (1952 and 1737), measuring >9.0. Great Kern County earthquake (1952). This was second strongest tremor in Southern California history, epicentered 60 miles North of Los Angeles. Major damage in Bakersfield, California and Kern County, California, while it shook the Los Angeles area. Quake Lake (1959) Formed a lake in southern Montana, USA Great Chilean Earthquake (1960). Biggest earthquake ever recorded, 9.5 on Moment magnitude scale, and generated tsunamis throughout the Pacific ocean. 1960 Agadir earthquake, Morocco with around 15,000 casualties. 1963 Skopje earthquake, measuring 6.1 on the Richter scale kills 1,800 people, leaves another 120,000 homeless, and destroys 80% of the city. Good Friday Earthquake (1964) In Alaska, it was the second biggest earthquake recorded, measuring 9.2M. and generated tsunamis throughout the Pacific ocean. 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. Managua earthquake (1972), which killed more than 10,000 people and destroyed 90% of the city. The earthquake took place on December 23, 1972 at midnight. Friuli earthquake (1976), Which killed more than 2.000 people in Northeastern Italy on the 6th of May 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. Guatemala 1976 earthquake (1976). Causing 23,000 deaths, 77,000 injuries and the destruction of more than 250,000 homes. Coalinga, California earthquake (1983). 6.5 on the Richter scale on a section of the San Andreas Fault. Six people killed, downtown Coalinga, California devastated and oil field blazes. Great Mexican Earthquake (1985). Killed over 6,500 people (though it is believed as many as 30,000 may have died, due to missing people never reappearing.) Great San Salvador Earthquake (October 10, 1986). Killed over 1,500 people. Whittier Narrows earthquake (1987). Newcastle, NSW Australia earthquake 1989 {FLEMO} Armenian earthquake (1988). Killed over 25,000.

•

• • •

• • • • • • •

• • • • •

Loma Prieta earthquake (1989). Severely affecting Santa Cruz, San Francisco, San Jose and Oakland in California. This is also called the World Series Earthquake. It struck as Game 3 of the 1989 World Series was just getting underway at Candlestick Park in San Francisco. Revealed necessity of accelerated seismic retrofit of road and bridge structures. Iran Earthquake (1990). 7.7 on the Richter scale. Killed over 35,000 in Gilan Province, southwest of Caspian sea. Luzon Earthquake (1990). On 16 July 1990, an earthquake measuring 7.7 on the Richter scale struck the island of Luzon, Philippines. Landers, California earthquake (1992). Serious damage in the small town of Yucca Valley, California and was felt across 10 states in Western U.S. Another tremor measured 6.4 struck 3 hours later and felt across Southern California. August 1993 Guam Earthquake, measuring 8.2 on the Richter scale and lasting 60 seconds. Northridge, California earthquake (1994). Damage showed seismic resistance deficiencies in modern low-rise apartment construction. Sakhalin earthquake (1995). Measuring 7.6 on the Richter scale, killing over 2,000 people in Sakhalin, Russia. Great Hanshin earthquake (1995). Killed over 6,400 people in and around Kobe, Japan. Afghanistan earthquake (1998). 6.9 on the Richter scale. Some 125 villages were damaged and 4000 people killed. Athens earthquake (1999). 5.9 on the Richter scale, it hit Athens on September 7. Epicentered 10 miles north of the Greek capital, it claimed 143 lives. Chi-Chi earthquake (1999) Also called the 921 earthquake. Struck Taiwan on September 21, 1999. Over 2,000 people killed, destroyed or damaged over ten thousand buildings. Caused world computer prices to rise sharply. Armenia, Colombia (1999) 6.2 on the Richter scale, Killed over 2,000 in the Colombian Coffee Grown Zone. 1999 İzmit earthquake measuring 7.4 on the Richter scale and killed over 17,000 in northwestern Turkey. Hector Mine earthquake (1999). 7.1 on the Richter scale, epicentered 30 miles east of Barstow, California, widely felt in California and Nevada. 1999 Düzce earthquake at Düzce, Turkey measuring 7.2 on the Richter scale. Baku earthquake (2000).

21st century • • • • • •

Nisqually Earthquake (2001). El Salvador earthquakes (2001). 7.9 (13 January) and 6.6 (13 February) magnitudes, killed more than 1,100 people. Gujarat Earthquake (26 January 2001). Hindu Kush earthquakes (2002). Over 1.100 killed. Molise earthquake (2002) 26 killed. Bam Earthquake (2003). Over 40,000 people are reported dead.

•

• •

• • • • • • • • • • • • • • • • • • • • •

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. Chūetsu earthquake (2004). Sumatra-Andaman Earthquake (26 December 2004). By some estimates, the second largest earthquake in recorded history (estimates of magnitude vary between 9.1 and 9.3). Epicentered off the coast of the Indonesian island of Sumatra, this massive earthquake triggered a series of gigantic tsunamis that smashed onto the shores of a number of nations, causing more than 285,000 fatalities. Sumatran (Nias) Earthquake (2005). Fukuoka earthquake (2005). Northern Chile Earthquake (2005). 7.9 (13 June). Killed only 15 people, but left many poor families homeless. Kashmir earthquake (2005) (also known as the Great Pakistan earthquake). Killed over 79,000 people; and many more injured. Lake Tanganyika earthquake (2005). May 2006 Java earthquake (2006). July 2006 7.7 magnitude Java earthquake which triggered tsunamis (2006). September 2006 6.0 magnitude Gulf of Mexico earthquake (2006). October 2006 6.6 magnitude Kona, Hawaii earthquake (2006). November 2006 8.1 magnitude north of Japan (2006). December 26, 2006, 7.2 magnitude, southwest of Taiwan (2006). February 12, 2007, 6.0 magnitude, southwest of Cape St. Vincent, Portugal (2007). Sumatra Earthquakes March 06, 2007, 6.4 and 6.3 magnitude, Sumatra, Indonesia (2007). March 25, 2007, 6.9 magnitude, off the west coast of Honshū, Japan (2007). April 1, 2007, 8.1 magnitude, Solomon Islands (2007). 2007 Guatemala Earthquake 6.7 magnitude (2007) July 16, 2007, 6.6 magnitude, Niigata prefecture, Japan (2007) 2007 Peru earthquake 8.0 magnitude, August 15 (2007) September 2007 Sumatra earthquakes 8.0 magnitude September 12 (2007) September 30, 2007, 6.8 magnitude, south of Mariana Islands (2007). September 30, 2007, 7.3 magnitude, northwest of Auckland Island, New Zealand (2007).

Earthquakes in 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 would drip on Loki's face, forcing him to jerk his head away and thrash against his bonds, causing the earth to tremble.

In Greek mythology, Poseidon was the god of earthquakes. In Christian mythology, certain saints were invoked as patrons against earthquakes, including Saint Gregory Thaumaturgus, Saint Agatha, Saint Francis Borgia, and Saint Emygdius.

See also • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

Catastrophe modeling Cryoseism Earthquake insurance Earthquake lights Earthquake weather Earthquake (1974 disaster film) Elastic-rebound theory Geophysics Hypothetical future disasters Interplate earthquake Intraplate earthquake List of earthquakes List of all deadly earthquakes since 1973 List of earthquakes by death toll List of tectonic plates Megathrust earthquake Meizoseismal area Mercalli intensity scale Moonquake Plate tectonics Richter magnitude scale Seismic scale Seismic wave Seismogenic layer Seismograph Seismology Shock (mechanics) Submarine earthquake Tsunami The VAN method

References External links Educational

• • • • • • • • • • • • • • • •

How to survive an earthquake - Guide for children and youth Guide to earthquakes and plate tectonics Earthquakes — an educational booklet by Kaye M. Shedlock & Louis C. Pakiser The Severity of an Earthquake USGS Earthquake FAQs Latest Earthquakes in the World - Past 7 days - View in near-real time all of the recent earthquake events on the planet. Earthquake Information from the Deep Ocean Exploration Institute, Woods Hole Oceanographic Institution Geo.Mtu.Edu — How to locate an earthquake's epicenter Photos/images of historic earthquakes earthquakecountry.info Answers to FAQs about Earthquakes and Earthquake Preparedness Interactive guide: Earthquakes - an educational presentation by Guardian Unlimited Geowall — an educational 3D presentation system for looking at and understanding earthquake data Virtual Earthquake - educational site explaining how epicenters are located and magnitude is determined HowStuffWorks — How Earthquakes Work CBC Digital Archives — Canada's Earthquakes and Tsunamis Earthquakes Educational Resources - dmoz

Seismological data centers Europe • • • • • • •

European-Mediterranean Seismological Centre (EMSC) Global Seismic Monitor at GFZ Potsdam Global Earthquake Report – chart Earthquakes in Iceland during the last 48 hours Istituto Nazionale di Geofisica e Vulcanologia (INGV), Italy Database of Individual Seismogenic Sources (DISS), Central Mediterranean Portuguese Meteorological Institute (Seismic activity during the last month)

United States • • • • • • •

EQNET: Earthquake Information Network The U.S. National Earthquake Information Center Southern California Earthquake Data Center The Southern California Earthquake Center (SCEC) Putting Down Roots in Earthquake Country An Earthquake Science and Preparedness Handbook produced by SCEC Recent earthquakes in California and Nevada Seismograms for recent earthquakes via REV, the Rapid Earthquake Viewer

• • •

Incorporated Research Institutions for Seismology (IRIS), earthquake database and software IRIS Seismic Monitor - world map of recent earthquakes SeismoArchives - seismogram archives of significant earthquakes of the world

Seismic scales •

The European Macroseismic Scale

Scientific information • •

Earthquake Magnitudes and the Gutenberg-Richter Law. SimScience. Retrieved on 2006-08-14.. Hiroo Kanamori, Emily E. Brodsky (2001). "The Physics of Earthquakes". Physics Today 54 (6): 34.

Miscellaneous • • • • • • • • • • • • • •

• • •

Kashmir Relief & Development Foundation (KRDF) PBS NewsHour - Predicting Earthquakes USGS – Largest earthquakes in the world since 1900 The Destruction of Earthquakes - a list of the worst earthquakes ever recorded Los Angeles Earthquakes plotted on a Google map the EM-DAT International Disaster Database Earthquake Newspaper Articles Archive Earth-quake.org PetQuake.org- official PETSAAF system which relies on strange or atypical animal behavior to predict earthquakes. A series of earthquakes in southern Italy - November 23 1980, Gesualdo Recent Quakes WorldWide Real-time, worldwide earthquake list for the past 7 days Real-time earthquakes on Google Map, Australia and rest of the world Earthquake Information - Electricquakes.com Exploring possible links between solar activity and earthquakes with earthquake and solar data streaming sources shown side by side for visual correlation. Earthquake Information - detailed statistics and integrated with Google Maps and Google Earth Kharita - INGV portal for Digital Cartography - Last earthquakes recorded by INGV Italian Network (with Google Maps) Kharita - INGV portal for Digital Cartography - Italian Seismicity by region 1981-2006 (with Google Maps)

Wikipedia, the free encyclopedia © 2001-2006 Wikipedia contributors (Disclaimer) This article is licensed under the GNU Free Documentation License. Last updated on Saturday October 20, 2007 at 19:50:42 PDT (GMT -0700) View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation