At least 1,567 dead, 2,300 injured, and around 50,000 homeless[1][2]
The Qayen earthquake, also known as the Ardekul or Qaen earthquake, struck northern Iran's Khorasan Province in the vicinity of Qaen on May 10, 1997 at 07:57 UTC (12:57 local time).[1][3] The largest in the area since 1990, the earthquake registered 7.3 on the moment magnitude scale and was centered approximately 270 kilometers (170mi) south of Mashhad on the village of Ardekul. The third earthquake that year to cause severe damage, it devastated the Birjand–Qayen region, killing 1,567 and injuring more than 2,300. The earthquake—which left 50,000homeless and damaged or destroyed over 15,000homes—was described as the deadliest of 1997 by the United States Geological Survey.[2] Some 155aftershocks caused further destruction and drove away survivors. The earthquake was later discovered to have been caused by a rupture along a fault that runs underneath the Iran–Afghanistan border.
Damage was eventually estimated at $100million, and many countries responded to the emergency with donations of blankets, tents, clothing, and food. Rescue teams were also dispatched to assist local volunteers in finding survivors trapped under the debris. The destruction around the earthquake's epicenter was, in places, almost total; this has been attributed to poor construction practices in rural areas, and imparted momentum to a growing movement for changes in building codes for earthquake-safe buildings. With 1 in 3,000 deaths in Iran attributable to earthquakes, a US geophysicist has suggested that a country-wide rebuilding program would be needed to address the ongoing public safety concerns.
Background and geology
Iran experiences regular earthquakes, with 200 reported in 1996 alone.[4] Like dozens that had preceded it, the 1997 Qayen event was of significant magnitude.[5] It occurred on Saturday, May 10, 1997 at 12:57 IRST in the Sistan region, one of the most seismically active areas of the country.[6] The first major earthquake in that region since 1979, it registered 7.3 on the moment magnitude scale (Mw), 7.2 on the surface wave magnitude scale (Ms), 7.7 on the energy magnitude scale (Me), and had a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale.[5]
The earthquake was caused by a rupture along the Abiz Fault, part of the Sistan suture zone of eastern Iran.[6] Located northeast of the main collision zone between the Arabian and Eurasiantectonic plates, the Sistan zone marks the eastern boundary of the Iranian microplate where it intersects with the Afghan crustal block.[3] Most of Iran is contained on one microplate, causing seismic activity mainly along its borders. Both the 1968 Dasht-e-Bayez earthquake (magnitude 7.3, resulting in 12,000–20,000deaths) and the Qayen earthquake were the results of strike-slip faults, meaning that the crustal blocks on either side of the faults shifted against each other horizontally.[7] The Qayen earthquake was caused by right lateral movement along the Abiz Fault.[8] In addition to the dominant strike-slip displacement, there was also local evidence of reverse faulting. The average displacement of about 2 m indicates a low static stress drop, more consistent with an interplate earthquake than an intraplate event.[6] The maximum horizontal acceleration during the quake was approximately 6.9 meters per second—nearly three-quarters of the acceleration an object would have in free fall—and occurred near the earthquake's epicenter. The crustal layer involved in the rupture was 20–25 kilometers (12–16mi) thick.[3] The ground rupture for the earthquake extended for 110 kilometers (68mi), which was longer than would be expected given the earthquake's magnitude.[8] There were at least 155aftershocks, reaching a magnitude of up to 5.5 on the Richter magnitude scale.[9] Many of the aftershocks occurred along the rupture up to 24 kilometers (15mi) below the surface.[3]
The earthquake's epicenter was within the village of Ardekul[5] in South Khorasan Province, which borders Afghanistan.[9] The village is isolated between mountains and hills. Although the Iranian government had distributed more than 800 seismographs throughout the country, few had been placed in the Qayen region due to its desert climate and the remoteness of the area.[8]
As a result of the dry climate, timber—a main component in building earthquake-resistant homes—is scarce in Qayen; homes are instead constructed of adobe.[8] The inhabitants of the poverty-stricken region rely on subsistence farming, raising livestock and crops such as wheat and saffron.[10] When the earthquake struck, much of the population was already working in the fields; for the most part, these people survived.[8] Many of those treated for injuries were found to be undernourished.[10]
Damage and casualties
The earthquake was felt over an area of 500,000 square kilometers (193,051sqmi), including in the cities of Mashhad, Kerman and Yazd. Destruction was most severe within a 100-kilometer (60mi) strip between the epicenter and Birjand. The tremors triggered landslides across the region and proved highly destructive to the region's mud-hut buildings. Entire streets were reduced to rubble,[9] and in one village, 110young girls were killed when their elementary school collapsed.[11]
An initial report in The New York Times claimed that more than 2,000 people had died in the worst-affected area, with a further 394 in Birjand and two in the small town of Khavaf. The earthquake was also said to have caused five fatalities in Afghanistan.[9] As rescue efforts proceeded these figures were revised; the United States Geological Survey states that 1,572[nb 1] people were killed and as many as 2,300 injured.[7] As bodies were retrieved, they were buried in mass graves.[9] Officials worried that a temperature fluctuation—from 5 to 29°C (41 to 84°F) on the day of the earthquake—would cause the corpses to rot more quickly, spreading infection.[10]
Southwest view of Qayen in 2006
Many villages lost both power and water, leaving survivors unable to fend for themselves.[11] The injured were often up to 140 kilometers (90mi) away from the nearest hospital.[9][11] One doctor, highlighting the desperate need for physicians to treat the injured, said "I don't know how many casts I have done today, but it seems like hundreds."[11] The extensive aftershocks prompted survivors to leave the vicinity of their homes and take to tents.[9] Several days later, another earthquake of magnitude 4.8 struck.[12] In the wake of the earthquake and its aftershocks, every one of the 700houses in the tiny village of Abiz, 90 kilometers (56mi) east of Qayen, was destroyed, and 400 of its 1,200 residents killed.[3]
According to an Iranian radio station report, 200 villages sustained severe damage or were totally destroyed.[11] The United States Geological Survey estimated that 10,533houses were destroyed; an additional 5,474 homes sustained varying degrees of damage. Fifty thousand people were left homeless.[7] Local officials initially estimated the cost of the damage at $67million 1997 US$ (roughly 89.5million 2008 USD).[9] The estimate was later raised to 100million 1997 USD (roughly 133.6million 2008 USD). One hundred schools and many health centers in the stricken areas were discovered to be in need of repair work.[12]
Many of the more seriously damaged homes were of simple construction, with walls made of mud, adobe, or brick packed 40–50cm (16–20in) thick. These materials are generally more vulnerable to the force of the earthquake, but some of the traditionally constructed homes sustained little or no damage. This was due to a range of factors, possibly including the height-to-width ratio, the lack of windows, and the quality of the materials used.[13] In general, reinforced concrete-framed homes, built after the 1979 earthquake, were better able to withstand the earthquake. Those near the epicenter still sustained severe damage due to the weight of the roofs and the weak joint connections between major structural elements of the buildings.[8]
Several thousand volunteers were brought in to join the search for survivors buried under mounds of brick and cement debris. Many volunteers used their hands. Local organizations, including the Iranian Red Crescent, sent 9,000tents, more than 18,000blankets, canned food, rice, and dates.[9] An additional 80 short tons (73t) of supplies were sent by the Iranian government to Mashhad, from where the relief efforts were being coordinated.[14]
The United Nations Secretary-General, Kofi Annan, pleaded that the international community "respond promptly and with generosity".[9] France dispatched a cargo plane filled with blankets, tents, clothing, and food, while Swiss authorities sent a rescue team with dogs trained in search-and-rescue.[9] Several aircraft carrying tents, blankets, and kerosene stoves from European and Arab countries arrived in Mashad on May 14.[15] Representatives from the United States, calling the disaster a "humanitarian issue", said that despite their strong differences with Iran they would donate supplies and other aid if requested.[9] The Mennonite Central Committee, an American relief agency stationed in Akron, Pennsylvania, redirected to the relief effort 400 metric tons (440 short tons) of lentils and cooking oils intended for immigrant refugees.[4] A specialist British disaster rescue organisation, the International Rescue Corps, offered to send a team but were refused visas (with the reasoning that "enough rescue crews had already arrived at the disaster site"),[9] and a Swiss offer of additional assistance was also turned down. Several countries within the Persian Gulf political region sent condolences to the families of victims and the government in the area.[9]
Because the affected area is extremely remote, distributing the relief supplies was difficult. Reaching some villages would require a five-hour drive over unpaved roads, some of which had collapsed or had been covered by landslides during the earthquake. Helicopters were used to provide supplies to some otherwise inaccessible areas.[11]
Although aid operations continued for some time, the Iranian government ceased rescue work on May 14. No more survivors were expected to be found in the rubble.[15]
Future threats
Iran was listed as "the worst offender" in a 2004 report on countries with poor earthquake engineering.[16] Professor Roger Bilham of the University of Colorado at Boulder, a geophysicist who specializes in earthquake-related deformation and hazards, blames construction practices for the fact that since the start of the 20th century, 1 in 3,000 Iranians has died in an earthquake-related incident. Bilham argues that "Most of Iran needs rebuilding."[16] The United Nations have prepared a Common Country Assessment for Iran, which likewise states that "While adequate building regulations exist for large cities, it is generally believed that they are not rigorously adhered to... most of those who have suffered in recent major earthquakes have lived in small towns and villages. Earthquake-proof construction is very rare in those areas and adequate building regulations are not yet in place".[17] An analysis of the performance of traditional buildings during the earthquake concluded that several factors, including high construction costs, poor materials, a shortage of skills in rural areas, and a lack of building regulations governing traditional construction techniques, have led to a deterioration in the quality of such buildings. The study recommended regulations to govern the construction of traditional arches and domes.[13]
The earthquakes of Iran are a large concern to the populace and are an impediment to economic development. Twelve earthquakes with a Richter magnitude of over seven have occurred within the last century. Three-quarters of the major cities of Iran are in areas prone to major earthquakes. The 1990 Manjil–Rudbar earthquake, with at least 42,000 fatalities, cost Iran roughly 7.2 percent of its Gross National Product (GNP) for that year and wiped out two years of economic growth.[17]
In 2007, the Asian Centre on Seismic Risk Reduction was formed in response to the regular earthquakes experienced by the southern, southwestern, and central Asian areas. This organization exists to "encourage regional and inter-regional networking and partnerships to reduce seismic damage". Earthquakes account for 73 percent of natural disaster deaths in the area.[18]
↑ 1,567 deaths in Iran and a further five in the Herat area of Afghanistan.[7]
Related Research Articles
An earthquake is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word tremor is also used for non-earthquake seismic rumbling.
The epicenter, epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates.
In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms.
The 1988 Armenian earthquake, also known as the Spitak earthquake, occurred on December 7 at 11:41 local time with a surface wave magnitude of 6.8 and a maximum MSK intensity of X (Devastating). The shock occurred in the northern region of Armenia which is vulnerable to large and destructive earthquakes and is part of a larger active seismic belt that stretches from the Alps to the Himalayas. Activity in the area is associated with tectonic plate boundary interaction and the source of the event was slip on a thrust fault just to the north of Spitak. The complex incident ruptured multiple faults, with a strike-slip event occurring shortly after the initiation of the mainshock. Between 25,000 and 50,000 were killed and up to 130,000 were injured.
An earthquake occurred on November 27, 2005, at 13:52 IRST on the sparsely populated Qeshm Island off Southern Iran, killing 13 people and devastating 13 villages. It was Iran's second major earthquake of 2005, following the one at Zarand in February. The epicenter was about 1,500 kilometers (930 mi) south of Tehran, close to Iran's southern borders. Initial measurements showed that the earthquake registered about 6.0 on the moment magnitude scale, although that was reduced to 5.8 after further analysis. More than 400 minor aftershocks followed the main quake, 36 of which were greater than magnitude 2.5. The earthquake occurred in a remote area during the middle of the day, limiting the number of fatalities. Iranian relief efforts were effective and largely adequate, leading the country to decline offers of support from other nations and UNICEF.
An earthquake struck the Kerman province of southeastern Iran at 01:56 UTC on December 26, 2003. The shock had a moment magnitude of 6.6 and a maximum Mercalli intensity of IX (Violent). The earthquake was particularly destructive in Bam, with the death toll amounting to at least 34,000 people and injuring up to 200,000. The effects of the earthquake were exacerbated by the use of mud brick as the standard construction medium; many of the area's structures did not comply with earthquake regulations set in 1989.
The 2002 Bou'in-Zahra earthquake occurred on 22 June 2002. The epicenter was near the city of Bou'in-Zahra in Qazvin Province, a region of northwestern Iran which is crossed by several major faults that is known for destructive earthquakes. The shock measured 6.5 on the Mwc scale, had a maximum Mercalli intensity of VIII (Severe), and was followed by more than 20 aftershocks. At least 230 people were killed and 1,500 more were injured.
The 1909 Borujerd earthquake also known as Silakhor earthquake occurred in Silakhor plain, Persia on January 23. Around 8,000 fatalities were caused directly from the magnitude 7.3 earthquake. An indefinite number of aftershocks continued for six months after the main shock. The section on this fault ruptured was the same as the main rupture zone of the 2006 Borujerd earthquake.
The 1984 Morgan Hill earthquake occurred on April 24 at 1:15 p.m. local time in the Santa Clara Valley of Northern California. The shock had a moment magnitude of 6.2 and a maximum Mercalli intensity of VIII (Severe). The epicenter was located near Mount Hamilton in the Diablo Range of the California Coast Ranges. Nearby communities sustained serious damage with financial losses of at least US$7.5 million.
The 2010 Baja California earthquake occurred on April 4 with a moment magnitude of 7.2 and a maximum Mercalli intensity of VII. The shock originated at 15:40:41 local time south of Guadalupe Victoria, Baja California, Mexico.
The 1995 Gulf of Aqaba earthquake occurred on November 22 at 06:15 local time and registered 7.3 on the Mw scale. The epicenter was located in the central segment of the Gulf of Aqaba, the narrow body of water that separates Egypt's Sinai Peninsula from the western border of Saudi Arabia. At least 8 people were killed and 30 were injured in the meizoseismal area.
The 1979 Imperial Valley earthquake occurred at 16:16 Pacific Daylight Time on 15 October just south of the Mexico–United States border. It affected Imperial Valley in Southern California and Mexicali Valley in northern Baja California. The earthquake had a relatively shallow hypocenter and caused property damage in the United States estimated at US$30 million. The irrigation systems in the Imperial Valley were badly affected, but no deaths occurred. It was the largest earthquake to occur in the contiguous United States since the 1971 San Fernando earthquake eight years earlier.
The 1968 Borrego Mountain earthquake occurred on April 8, at 18:28 PST in the geologically active Salton Trough of Southern California. The Salton Trough represents a pull-apart basin formed by movements along major faults. This region is dominated by major strike-slip faults one of them being the San Jacinto Fault which produced the 1968 earthquake. The mainshock's epicenter was near the unincorporated community of Ocotillo Wells in San Diego County. The moment magnitude (Mw ) 6.6 strike-slip earthquake struck with a focal depth of 11.1 km (6.9 mi). The zone of surface rupture was assigned a maximum Modified Mercalli intensity (MMI) of VII.
The 1994 Mascara earthquake occurred on August 18 at 02:13 local time with an epicenter in a rural part of Algeria. The earthquake measured 5.8 on the moment magnitude scale (Mw ) and had a depth of 10 km (6.2 mi). It caused the deaths of 171 people, left up to 12,500 homeless, and destroyed thousands of homes in Mascara Province. Many homes were damaged or destroyed due to poor building quality which collapsed on the inhabitants and resulted in a majority of the casualties. The national government launched a rapid response effort in its aftermath.
The 1979 Ghaenat earthquakes were a series of large earthquakes in Qaen County, Khorasan Province, northeast Iran, near the Afghanistan border. The first mainshock, known as the Korizan earthquake with a surface wave magnitude (Ms ) of 6.6 and moment magnitude (Mw ) of 6.8, struck on November 14, while the Ms 7.1 or Mw 7.2 Koli-Boniabad earthquake struck on November 27. The two mainshocks were assigned a maximum Modified Mercalli intensity of VIII (Severe) and X (Extreme), respectively. The earthquakes caused extensive damage throughout northeastern Iran, killing an estimated 297 to 440 people and left at least 279 injured.
The 1997 Bojnurd earthquake occurred on 4 February at 14:07 IRST in Iran. The epicenter of the Mw 6.5 earthquake was in the Kopet Dag mountains of North Khorasan, near the Iran–Turkmenistan border, about 579 km (360 mi) northeast of Tehran. The earthquake is characterized by shallow strike-slip faulting in a zone of active faults. Seismic activity is present as the Kopet Dag is actively accommodating tectonics through faulting. The earthquake left 88 dead, 1,948 injured, and affected 173 villages, including four which were destroyed. Damage also occurred in Shirvan and Bojnord counties. The total cost of damage was estimated to be over US$ 30 million.
The 1977 Bob–Tangol earthquake struck Kerman province of Iran on December 20, 1977 at 03:04 Iran Standard Time. The earthquake measured Mw 5.9 and struck at a depth of 22.7 km (14.1 mi). A maximum Modified Mercalli intensity of VII was evaluated based on damage. It had a strike-slip focal mechanism, which was unusual as the source structure was a thrust fault. It was part of a sequence of strong earthquakes along the 400 km (250 mi) Kuh Banan Fault. Between 584 and 665 people perished while a further 500–1,000 were injured; thousands were also made homeless. Casualties from the earthquake was considered moderate due to the sparsely populated area it affected. Preceded by foreshocks the month before, many residents became wary of a larger earthquake and took refuge outside their homes, contributing to the moderate death toll. However, there were none immediately before the mainshock so many were still in their homes when it struck. Aftershocks were felt for several months, some causing additional damage.
An earthquake struck Western Greece near the coastal city of Aigio at 03:15:48 local time on 15 June 1995. The second destructive earthquake to strike Greece in a month, it measured 6.4–6.5 on the moment magnitude scale (Mw ). It was assigned a maximum Modified Mercalli intensity of VIII (Severe) and EMS-98 intensity of IX (Destructive). The horizontal peak ground acceleration reached 0.54 g and ground velocity peaked at 52 cm/s (20 in/s)—the strongest ground motion ever recorded in Greece. Fifteen minutes after the mainshock, a large aftershock struck, causing further damage to Aigio. Faulting occurred on either the Aigion fault or an unnamed offshore fault. Other faults in the region have the potential to produce earthquakes up to Mw 6.9, which poses a risk to Aigio and the surrounding Gulf of Corinth.
The 1983 Kaoiki earthquake struck southern Hawaii Island on the morning of November 16, 1983. Measuring Mw 6.7, it was the largest to hit the island since 1975. The epicenter was located 50 km southeast of Hilo with an approximated depth of 12 km. The shallow strike-slip earthquake was assigned a maximum intensity of IX (Violent) on the Modified Mercalli scale. 6 people were injured, widespread damage and landslides were reported across the island.
The 1957 Farsinaj earthquake struck Hamadan, Iran on 13 December at 05:15 local time. The moment magnitude 6.5 earthquake destroyed 211 villages, killed approximately 1,130 people, and left another 900 injured.
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