An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities; the seismicity, or seismic activity, of an area is the frequency and size of earthquakes experienced over a period of time. The word tremor is used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground; when the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can trigger landslides, volcanic activity. In its most general sense, the word earthquake is used to describe any seismic event—whether natural or caused by humans—that generates seismic waves. Earthquakes are caused by rupture of geological faults, but by other events such as volcanic activity, mine blasts, nuclear tests.
An earthquake's point of initial rupture is called its hypocenter. The epicenter is the point at ground level directly above the hypocenter. Tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane; the sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the fault surface that increase the frictional resistance. Most fault surfaces do have such asperities and this leads to a form of stick-slip behavior. Once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface; this continues until the stress has risen sufficiently to break through the asperity allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, 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 convective flow of heat out from the Earth's deep interior. There are three main types of fault, all of which may cause an interplate earthquake: normal and strike-slip. Normal and reverse faulting are examples of dip-slip, where the displacement along the fault is in the direction of dip and movement on them involves a vertical component. Normal faults occur in areas where the crust is being extended such as a divergent boundary. Reverse faults occur in areas.
Strike-slip faults are steep structures where the two sides of the fault slip horizontally past each other. Many earthquakes are caused by movement on faults that have components of both dip-slip and strike-slip. Reverse faults those along convergent plate boundaries are associated with the most powerful earthquakes, megathrust earthquakes, including all of those of magnitude 8 or more. Strike-slip faults continental transforms, can produce major earthquakes up to about magnitude 8. Earthquakes associated with normal faults are less than magnitude 7. For every unit increase in magnitude, there is a thirtyfold increase in the energy released. For instance, an earthquake of magnitude 6.0 releases 30 times more energy than a 5.0 magnitude earthquake and a 7.0 magnitude earthquake releases 900 times more energy than a 5.0 magnitude of earthquake. An 8.6 magnitude earthquake releases the same amount of energy as 10,000 atomic bombs like those used in World War II. This is so because the energy released in an earthquake, thus its magnitude, is proportional to the area of the fault that ruptures and the stress drop.
Therefore, the longer the length and the wider the width of the faulted area, the larger the resulting magnitude. The topmost, brittle part of the Earth's crust, the cool slabs of the tectonic plates that are descending down into the hot mantle, are the only parts of our planet which can store elastic energy and release it in fault ruptures. Rocks hotter than about 300 °C flow in response to stress; the maximum observed lengths of ruptures and mapped faults are 1,000 km. Examples are the earthquakes in Chile, 1960; the longest earthquake ruptures on strike-slip faults, like the San Andreas Fault, the North Anatolian Fault in Turkey and the Denali Fault in Alaska, are about half to one third as long as the lengths along subducting plate margins, those along normal faults are shorter. The most important parameter controlling the maximum earthquake magnitude on a fault is however not the maximum available length, but the available width because the latter varies by a factor of 20. Along converging plate margins, the dip angle of the rupture plane is shallow about 10 de
2001 Nisqually earthquake
The 2001 Nisqually earthquake occurred at 10:54:32 local time on February 28, 2001. The intraslab earthquake had a moment magnitude of 6.8 and a maximum Mercalli intensity of VIII. The epicenter was in the southern Puget Sound, northeast of Olympia, but the shock was felt in Oregon, eastern Washington, Idaho; this was one of several large earthquakes that occurred in the Puget Sound region in the prior 52 years and caused property damage valued at between one and four billion dollars. One person died of a heart attack and several hundred were injured; the Puget Sound area is prone to deep earthquakes due to the Juan de Fuca tectonic plate's subduction under the North American Plate at 3.5 to 4.5 cm a year as part of the Cascadia subduction zone, which causes stress in the North American Plate as the Juan de Fuca Plate sinks into the mantle. Similar significant earthquakes occurred in the same general region on April 29, 1965, April 13, 1949. Although there were no directly-related deaths, local news outlets reported that there was one death from a heart attack.
About 400 people were injured. Most of the property damage occurred near the epicenter or in unreinforced concrete or masonry buildings, such as those in the First Hill, Pioneer Square and Sodo neighborhoods of Seattle; the Trinity Parish Church on First Hill was damaged. The air traffic control tower at Sea–Tac Airport was damaged; the quake splintered a buttress under the dome of the capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. Additionally, power outages affected downtown Seattle; the U. S. Military's Ft. Lewis and McChord Air Force Base received damage and there was slight damage in Victoria, British Columbia. Following the quake, many buildings and structures in the area were closed temporarily for inspection; this included several bridges, all state offices in Olympia, Boeing's factories in the Seattle area. Various schools in the state closed for the day; the Fourth Avenue Bridge in downtown Olympia was damaged and was torn down and re-built.
In Seattle, the Alaskan Way Viaduct and its seawall were damaged, forcing the viaduct to close for emergency repairs and factoring into the decision to replace the viaduct entirely. $305 million of insured losses and a total of $2 billion worth of damage was caused in the state of Washington. The area was declared a natural disaster area by president George W. Bush and was therefore able to receive federal recovery assistance; the number of businesses in the affected region was small. At least 20% of businesses surrounding the affected area took direct losses, while 2% had direct losses of over $10,000. None of these businesses received money for direct damage from federal insurance. Many businesses did not receive any aid at all; those that did receive aid had no help with indirect losses. Indirect losses varied from inventory or data corruption, disruption in the workplace, etc. Data and inventory losses were the most damaging for retail stores. Retail stores lost inventory as well as people's interest for a period of time after the quake.
One of the vital elements to prevent damage and injury were well structured buildings. This can prevent the loss of life as well as inventory. Businesses that did not sustain much damage gained a sense of security that may be unreliable as the moment magnitude was high but the hypocenter was deep under the earth; this earthquake was a 6.8 moment magnitude that caused $2 billion damage while the Northridge earthquake was a 6.7 moment magnitude, but caused more than $20 billion worth of damage as the hypocenter of the Northridge earthquake was much shallower and closer to the surface of the earth. Named after the Nisqually Delta, this earthquake hit the southern end of Puget Sound causing damage to the ports of Seattle and Tacoma. In the month following the earthquake, the National Oceanic and Atmospheric Administration and the USGS assembled a team to map the bathymetry of the deltas near the epicenter; this revealed multiple submarine failures on the Duwamish delta fronts. In other areas liquefaction, sand boils and soil slumping occurred.
Liquefaction was determined to be a main contributor to increased stream flows. With multiple stream gauges collecting data before and after the earthquake there was a regular pattern of higher increased stream flow around areas where liquefaction occurred. Soil liquefaction was observed at a wildlife refuge causing damage to the buildings within. A rapid response plan was developed a year later; the region realized how they avoided a potential damaging catastrophe. Many businesses, hospitals, etc. were asked to sign a regional disaster plan. This would allow disaster relief teams to aid places much faster than before, it would be able to direct limited resources to places with greatest immediate need. List of earthquakes in 2001 List of earthquakes in the United States List of earthquakes in Washington M 6.8 - Puget Sound region, Washington from the USGS 15 years after the Nisqually Earthquake, King County prepares for "the big one" – King County, Washington Special Coverage: Ash Wednesday Quake – Seattle Weekly The International Seismological Centre has a bibliography and/or authoritative data for this event
1811–12 New Madrid earthquakes
The 1811–12 New Madrid earthquakes were an intense intraplate earthquake series beginning with an initial earthquake of moment magnitude 7.5–7.9 on December 16, 1811, followed by a moment magnitude 7.4 aftershock on the same day. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. They, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid part of the Louisiana Territory, now within the US state of Missouri. There are estimates that these stable continental region earthquakes were felt over 130,000 square kilometers, moderately across nearly 3 million square kilometers; the 1906 San Francisco earthquake, by comparison, was felt moderately over 16,000 km2. The New Madrid earthquakes were interpreted variously by American Indian tribes, but one consensus was universally accepted: the powerful earthquake had to have meant something. For many tribes in Tecumseh's pan-Indian alliance, it meant that Tecumseh and his brother the Prophet must be supported.
December 16, 1811, 0815 UTC. It caused only slight damage to man-made structures because of the sparse population in the epicentral area; the future location of Memphis, experienced level IX shaking on the Mercalli intensity scale. A seismic seiche propagated upriver, Little Prairie was damaged by soil liquefaction. December 16, 1811, 1415 UTC; this shock was similar in intensity. January 23, 1812, 1500 UTC; the meizoseismal area was characterized by general ground warping, fissuring, severe landslides, caving of stream banks. Johnson and Schweig attributed this earthquake to a rupture on the New Madrid North Fault; this may have placed strain on the Reelfoot Fault. February 7, 1812, 0945 UTC. New Madrid was destroyed. In St. Louis, many houses were damaged, their chimneys were toppled; this shock was definitively attributed to the Reelfoot Fault by Schweig. Uplift along a segment of this reverse fault created temporary waterfalls on the Mississippi at Kentucky Bend, created waves that propagated upstream, caused the formation of Reelfoot Lake by obstructing streams in what is now Lake County, Tennessee.
Susan Hough, a seismologist of the United States Geological Survey, has estimated the earthquakes' magnitudes as around magnitude 7. There were many more aftershocks, including one magnitude 7 aftershock to the December 16, 1811 earthquake which occurred at 0600 UTC on December 17, 1811, one magnitude 7 aftershock to the February 7, 1812 earthquake which occurred on the same day at 0440 UTC. John Bradbury, a Fellow of the Linnean Society, was on the Mississippi on the night of December 15, 1811, describes the tremors in great detail in his Travels in the Interior of America in the Years 1809, 1810 and 1811, published in 1817. After supper, we went to sleep as usual: about ten o'clock, in the night I was awakened by the most tremendous noise, accompanied by an agitation of the boat so violent, that it appeared in danger of upsetting... I could distinctly see the river as. By the time we could get to our fire, on a large flag in the stern of the boat, the shock had ceased. At day-light we had counted twenty-seven shocks.
Eliza Bryan in New Madrid, Territory of Missouri, wrote the following eyewitness account in March 1812. On the 16th of December, 1811, about two o'clock, a.m. we were visited by a violent shock of an earthquake, accompanied by a awful noise resembling loud but distant thunder, but more hoarse and vibrating, followed in a few minutes by the complete saturation of the atmosphere, with sulphurious vapor, causing total darkness. The screams of the affrighted inhabitants running to and fro, not knowing where to go, or what to do—the cries of the fowls and beasts of every species—the cracking of trees falling, the roaring of the Mississippi— the current of, retrograde for a few minutes, owing as is supposed, to an irruption in its bed— formed a scene horrible. John Reynolds, the 4th governor of Illinois, among other political posts, mentions the earthquake in his biography My Own Times: Embracing Also the History of My Life: On the night of 16th November, 1811, an earthquake occurred, that produced great consternation amongst the people.
The centre of the violence was in New Madrid, but the whole valley of the Mississippi was violently agitated. Our family all were sleeping in a log cabin, my father leaped out of bed crying aloud "the Indians are on the house"... We laughed at the mistake of my father, but soon found out it was worse than the Indians. Not one in the family knew at the time; the next morning another shock made us acquainted with it, so we decided it was an earthquake. The cattle came running home bellowing with fear, all anim
1925 Santa Barbara earthquake
The 1925 Santa Barbara earthquake hit the area of Santa Barbara, California on June 29, with a moment magnitude between 6.5 and 6.8 and a maximum Mercalli Intensity of IX. It resulted in 13 casualties and destroyed the historic center of the city, with damage estimated at $8 million. Although no foreshocks were reported felt before the mainshock, a pressure gauge recording card at the local waterworks showed disturbances beginning at 3:27 a.m. which were caused by foreshocks. At 6:44 a.m. the mainshock occurred. The epicenter of the earthquake was located in the sea off the coast of Santa Barbara, in the Santa Barbara Channel; the fault on which it occurred appears to have been an extension of the Mesa fault or the Santa Ynez system. The earthquake was felt from Paso Robles to the north to Santa Ana to the south and to Mojave to the east. Major damage occurred in the city of Santa Barbara and along the coast, as well as north of Santa Ynez Mountains, including Santa Ynez and Santa Maria valleys.
Though thirteen people died, it may have been far worse without the actions of three heroes, who shut off the town gas and electricity preventing a catastrophic fire. Most homes survived the earthquake in good condition, although nearly every chimney in the city crumbled; the downtown of Santa Barbara was destroyed. Only a few buildings along State Street, the main commercial street, remained standing after the earthquake; the City Cab building and The Californian and Arlington garages, all large and occupied parking structures, collapsed full with cars. Many other vehicles were crushed in the downtown area. At least one death resulted when a driver near the San Marcos building was crushed as walls of buildings fell onto cars parked there. In the business district, an area of about 36 blocks, only a few structures were not damaged, many had to be demolished and rebuilt; the facade of the church of the Mission Santa Barbara was damaged and lost its statues. Many important buildings, including hotels and the Potter Theater, were lost.
The courthouse, library and churches were among the buildings sustaining serious damage. Concrete curbs buckled in every block in Santa Barbara. Pavement on the boulevard along the beach was displaced by about 20–36 centimeters, but the pavement in the downtown was not damaged; the earthen Sheffield Dam had been built near the city in 1917. It held 30 million US gallons of water; the soil under the dam liquefied during the earthquake and the dam collapsed. This was the only dam to fail during an earthquake in the US until the Lower San Fernando Dam failed in 1971; when it burst, a wall of water swept between Voluntario and Alisos Streets destroying trees, three houses and flooding the lower part of town to a depth of 2 feet. The Southern Pacific Company Railroad tracks were damaged in several places between Ventura and Gaviota. In particular, a portion between Naples and Santa Barbara was badly displaced. Seaside bluffs fell into the ocean, a slight tsunami was noted by offshore ships; the town was cut off from telephone and telegraph, news from the outside world arrived by shortwave radio.
The absence of post-earthquake fire permitted scientists to study earthquake damage to various types of construction. The American Legion and the Naval Reserves from the Naval Reserve Center Santa Barbara helped provide order amidst the chaos and manned posts and provided patrols throughout the town to inhibit looting of the damaged businesses and homes. Additional fire and police personnel arrived from as far as Los Angeles to assist the sailors and soldiers in maintaining order. Three strong aftershocks occurred in the next few hours, though none causing any additional damage, with events occurring at 8:08, 10:45, 10:57 am, many smaller shocks continued throughout the day. An aftershock on July 3 caused damaged chimneys. Since the downtown of Santa Barbara suffered irreparable damage, there was a large-scale construction effort in 1925 and 1926 aimed at removing or repairing damaged structures and constructing new buildings; this development altered the character of the city center. Before the earthquake, a considerable part of the center was built in the Moorish Revival style.
After the earthquake, the decision was made to rebuild it in the Spanish Colonial Revival style. This effort was undertaken by the Santa Barbara Community Arts Association, founded in the beginning of the 1920s and viewed the earthquake as the opportunity to rebuild the city center in the unified architectural style. Many architects were invited to design the building facades, among them James Osborne Craig, George Washington Smith, Carleton Winslow, Bertram Goodhue, Winsor Soule. Lionel Pries spent a year in Santa Barbara; as a result, many buildings listed on National Register of Historic Places were designed in the late 1920s, among them the Santa Barbara County Courthouse and the front of the Andalucia Building. Building codes in Santa Barbara were made more stringent after the earthquake demonstrated that traditional construction techniques of unreinforced concrete and masonry were unsafe and unlikely to survive strong temblors. List of earthquakes in 1925 List of earthquakes in California List of earthquakes in the United States Sources 1925 Santa Barbara Earthquake Survivor interview Views of Earthquake Damage in Santa Barbara, California 1925, finding aid and online photo collection, Bancroft Library, University of California, Berkeley M 6.8 - 14km SSE of Isla Vista, CA
Rocky Mountain Arsenal
The Rocky Mountain Arsenal was a United States chemical weapons manufacturing center located in the Denver Metropolitan Area in Commerce City, Colorado. The site was completed December 1942, operated by the United States Army throughout the 20th century and was controversial among local residents until its closure in 1992. Much of the site is now protected as the Rocky Mountain Arsenal National Wildlife Refuge. After the attack on Pearl Harbor and the United States entered World War II, the U. S. Army began looking for land to create a chemical manufacturing center. Located just north of Denver, in Commerce City and close to the Stapleton Airport, the U. S. Army purchased 20,000 acres; the location was ideal, not only because of the proximity to the airport, but because of the geographic features of the site, it was less to be attacked. The Rocky Mountain Arsenal manufactured chemical weapons including mustard gas, white phosphorus, chlorine gas, sarin gas. In the early 1960s, the U. S. Army began to lease out its facilities to private companies to manufacture pesticides.
In the early 1980s the site was selected as a superfund site and the cleanup process began. In the mid-1980s, including endangered species, moved into the space and the land became a protected park. Although comprising 17,056 acres in 1997 at the beginning of remediation, 5,976 acres of the RMA were determined to meet cleanup requirements, so were no longer part of the National Priorities List. Of that 4,927 acres were transferred to the USFWS in April 2004. In 2004 129 acres along the boundaries were transferred to local jurisdictions and to the U. S. Army Reserve Center for road-improvement projects. In October 2006, an additional 7,200 acres was transferred to the USFWS, making the Rocky Mountain Arsenal Wildlife Refuge one of the largest urban refuges in the United States at 12,500 acres; the environmental movement began in the United States in the 1960-1970s. The U. S. Congress responded to the movement in 1980 with the creation of the Comprehensive Environmental Response and Liability Act, most referred to as a Superfund.
CERCLA was a tax imposed on petroleum industries. CERCLA gave the Federal government the authority to respond to the release of life threatening hazardous materials. After 42 years of chemical manufacturing, in 1984, the United States Army began to inspect the level of contamination at Rocky Mountain Arsenal; the site was placed on the National Priorities List, a list of the most contaminated areas in the United States. Rocky Mountain Arsenal, among other post-military sites, was a top priority, establishing RMA as a superfund site; this was further exacerbated when the U. S. Army discovered the bald eagle. After the bald eagles were captured and found to be healthy, the National Wildlife Federation worked with policymakers to transition RMA to a wildlife refuge. In 1992, Congress Passed the Rocky Mountain Arsenal National Wildlife Refuge Act. Included in the RMANWR Act, areas within RMA that were still contaminated were still owned by the U. S. Army, the vast majority of the land, deemed clean would be managed by the Federal Fish and Wildlife Service.
Tensions arose between the United States Environmental Protection Agency, the State of Colorado, United States Army, the chemical industries as the partnered to clean up the site and create the RMANWR. This led to the State of Colorado to take legal action over who has legal authority over RMA remediation efforts, payment of natural resource damages, reimbursement of costs expended for cleanup activities; the Arsenal's location was selected due to its relative distance from the coasts, a sufficient labor force to work at the site, weather, conducive to outdoor work, the appropriate soil needed for the project. It was helpful that the location was close to Stapleton airfield, a major transportation hub. In 1942, the US Army acquired 19,915 acres of land on which to manufacture weapons in support of World War II military activities at a cost of $62,415,000. Additionally, some of this land was used for a prisoner of war camp and transferred to the city of Denver as Stapleton Airport expanded. A lateral was built off the High Line Canal to supply water to the Arsenal.
Weapons manufactured at RMA included both conventional and chemical munitions, including white phosphorus, mustard gas and chlorine gas. RMA is one of the few sites that had a stockpile of Sarin gas, an organophosphorus compound; the manufacture of these weapons continued until 1969. Rocket fuel to support Air Force operations was manufactured and stored at RMA. Subsequently, through the 1970s until 1985, RMA was used as a demilitarization site to destroy munitions and chemically related items. Coinciding with these activities, from 1946 to 1982, the Army leased RMA facilities to private industries for the production of pesticides. One of the major lessees, Shell Oil Company, along with Julius Hyman and Company and Colorado Fuel and Iron, had manufacturing and processing capabilities on RMA between 1952 and 1982; the military reserved the right to oust these companies and restart chemical weapon production in the event of a national emergency. RMA contained a deep injection well, constructed in 1961.
It was drilled to a depth of 12,045 feet. The well was cased and sealed to a depth of 1
1992 Big Bear earthquake
The 1992 Big Bear earthquake occurred at 08:05:33 PDT on June 28 in Big Bear Lake, with a moment magnitude of 6.5 and a maximum perceived intensity of VIII on the Mercalli intensity scale. The earthquake occurred at a shallow depth of 5 kilometers and caused landslides in the San Bernardino Mountains; the Big Bear earthquake happened just east of the "Big Bend" of the San Andreas Fault, where it takes an offset towards Los Angeles, 3 hours 26 minutes after the M 7.3 1992 Landers earthquake occurred 22 miles to the east. The Big Bear earthquake was first believed to be an aftershock of the Landers quake. However, the United States Geological Survey determined that this was a separate, but related, earthquake; these two earthquakes are considered a regional earthquake sequence, rather than a main shock and aftershock. They were part of a complex pattern of regional stress adjustment that led to the 1999 Hector Mine earthquake. On that day, proceeding the earthquake an experimental aircraft crashed at the Big Bear Airport.
Reenactment and some footage was taped and aired on the CBS TV series Rescue 911 List of earthquakes in California List of earthquakes in the United States M 6.3 - 7km SSE of Big Bear City, CA – United States Geological Survey The International Seismological Centre has a bibliography and/or authoritative data for this event
1946 Aleutian Islands earthquake
The 1946 Aleutian Islands earthquake occurred near the Aleutian Islands, Alaska on April 1. The shock had a moment magnitude of 8.6 and a maximum Mercalli intensity of VI. It resulted in 165 -- over $26 million in damage; the seafloor along the fault was elevated, triggering a Pacific-wide tsunami with multiple destructive waves at heights ranging from 45–130 ft. The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska among others, killed all five lighthouse keepers. Despite the destruction to the Aleutian Island Unimak, the tsunami had an imperceptible effect on the Alaskan mainland. Waves traveled across the ocean at 500 miles an hour and measured 55 feet high, crest to trough, according to the USGS; the wave reached Kauai, Hawaii 4.5 hours after the quake, Hilo, Hawaii 4.9 hours later. In Hilo, the death toll was high: 173 were killed, 163 injured, 488 buildings were demolished and 936 more were damaged. Witnesses told of waves inundating streets and storefronts. Many victims were swept out to sea by receding water.
The tsunami caused a lot of damage in Maui as well. Waves there demolished many other buildings; the residents of these islands were caught off-guard by the onset of the tsunami due to the inability to transmit any warnings from the destroyed posts at Scotch Cap, the tsunami is known as the April Fools Day Tsunami in Hawaii because it happened on April 1st and many people thought it to be an April Fool's Day prank. The effects of the tsunami reached the West Coast of the United States; the tsunami was unusually powerful for the size of the earthquake. The event was classified as a tsunami earthquake due to the discrepancy between the size of the tsunami and the low surface wave magnitude; the large-scale destruction prompted the creation of the Seismic Sea Wave Warning System, which became the Pacific Tsunami Warning Center in 1949. List of earthquakes in 1946 List of earthquakes in Alaska List of earthquakes in the United States Tsunami 1946 – Hilo on YouTube Tsunami Animation: Unimak Island, Aleutian Islands, 1946 – Pacific Tsunami Warning Center 1946 Aleutians Tsunami – Western States Seismic Policy Council Mystery of Deadly 1946 Tsunami Deepens – LiveScience The International Seismological Centre has a bibliography and/or authoritative data for this event