Bam earthquake

Earthquake

Date: December 26, 2003

Place: Bam, Iran, and the surrounding area

Magnitude: 6.5

Result: More than 26,000 killed, about 75,000 left homeless, including 30,000 injured; more than 85 percent of the buildings in Bam destroyed, including the historic Citadel

The Earth’s crust is cracked and broken into large segments called plates. These plates may be 25 to 320 kilometers (15 to 200 miles) thick and a few hundred to thousands of kilometers wide. The plates dip into the mantle, a global layer of hot, dense rock that is generally not molten but plastic. In a simplified view, convection currents in the mantle rise, move across the top, and then cool and sink at the glacial speed of a few centimeters (1 or 2 inches) per year. The motion of the mantle carries the plates on chaotic journeys so that some plates slide by, pull away from, or crash into other plates. This movement is the source of earthquakes. Large quakes occur when one plate is locked against another, allowing stress to build for years or centuries until the weakest link gives way and that part of the plate lurches forward.

With about 130 major earthquakes during recorded history, Iran ranks among the most seismically active countries of the world. It is spanned by a network of faults at the boundary between the Arabian plate and the Eurasian plate. On Friday, December 26, 2003, a segment of the Arabian plate broke loose and ground northward. A small precursor quake struck at 4:00 a.m., and some residents of Bam, Iran, rushed out into the streets. Unfortunately, since small quakes occur there often and nothing further happened immediately, most went back to bed. The magnitude 6.5 quake struck at 5:26 a.m., releasing energy equivalent to 5.6 megatons of TNT. The quake’s focal point was almost directly beneath Bam. Seen from above, the sand-colored houses, walls, towers, and arches gave Bam the look of a fantastically intricate sand castle. After the quake, it looked as if vandals had kicked down the walls, stomped on the towers, and sat on the castle. Most of Bam was rubble.

Aftermath. The ancient city of Bam was built on a desert plateau in the southeastern region of Iran. The old city was made of adobe, bricks of mud mixed with straw or animal dung and dried in the sun. Thick walls were constructed with bricks plastered together with layers of clay, and roofs were decked with heavy tiles or more bricks built into cupolas and vaults. Adobe works well in a country where it rarely rains, and the thick walls helped to keep the interiors of the houses cooler during the heat of the day. During the quake, however, the adobe disintegrated, turning walls and roofs into tons of dirt that cascaded down onto the sleeping inhabitants. Those who freed themselves or were quickly pulled from the rubble by family members or neighbors had a good chance of survival, but after the first few hours, searchers found very few survivors. There were two miracle survivors: a 97-year-old woman, Sharbānou Māndarāī, was trapped for eight days in the airspace beneath a table near a ventilation pipe and was rescued in amazingly good condition, but a 56-year-old man pulled from the rubble after 13 days was in poor condition.

The final toll was 26,271 killed, more than 30,000 injured, and more than 75,000 left homeless. Approximately 85 percent of the buildings were completely destroyed. It made little difference if the buildings were ancient or modern, since building codes had not been followed. For example, two modern hospitals, supposedly built to withstand such quakes, collapsed in ruins. All of Bam’s 131 schools were destroyed, and about a third of the teachers were killed. A prison at the edge of the city collapsed, setting the prisoners free. After standing guard for nearly 2000 years, the largest adobe building in the world, the Citadel, or Arg-e-Bam, a magnificent warren of ramparts, towers, arches, courtyards, and narrow passages, was now largely rubble. Most of the date palms that were claimed to have produced the world’s best dates were lost.

Iranian president Mohammed Khatami announced that the disaster was more than one nation could handle, and he appealed for international aid. This was a dramatic change from the quake of June, 1990, when foreign aid was refused in spite of 50,000 killed and 60,000 injured. More than 60 nations responded to President Khatami’s appeal, sending supplies and workers. Only aid from Israel was refused. The United States had broken off diplomatic relations with Iran during the 1980-1981 hostage crisis, dealing with the country only through third parties, but in this situation U.S. officials spoke directly with their Iranian counterparts to arrange aid. U.S. military airplanes brought emergency supplies on December 28, and 80 American doctors and aid workers arrived in Bam on December 30. Noting Iran’s new openness, the U.S. government proposed a high-level humanitarian mission to be headed by Senator Elizabeth Dole, a past president of the American Red Cross, but the Iranian government was not ready for this step and “held it in abeyance.” Iran accused the United States of trying to turn the situation to its own advantage, although the tone was far less strident than it had been in the past. Eventually, medical care, food, water, temporary shelter, blankets, a sanitation system, and more were provided by Iran and other nations.

Cultural Heritage. President Khatami promised that Bam would be rebuilt, and in July, 2004, the World Heritage Committee of the United Nations Educational, Scientific, and Cultural Organization (UNESCO) declared Bam a World Heritage site, stating that it represented a historical culture of which Iranians were justifiably proud. With this declaration, UNESCO became the head of the international efforts for the cultural preservation of Bam. Under its direction, experts from Japan began helping to reconstruct the Citadel, a project expected to take fifteen years.

Bam was a trading center as early as 250 b.c.e. and became a pilgrimage site when a Zoroastrian fire temple was built there. After the temple was destroyed, it was replaced in the ninth century c.e. by one of the earliest mosques in Iran, the Jame Mosque. Built on the ancient Silk Road, the old trade route between Europe and Asia, Bam was a convenient place for traders with silk from China or carved ivory and gold baubles from India to bargain with traders bringing fine Roman glass and other goods from the west. Bam became famous for textiles and for garments of silk and cotton. As water became available for farming, Bam also became famous for its dates and other fresh fruit.

Ingenuity allowed the inhabitants to live in a region that can reach 50 degrees Celsius on a hot summer day. Bam is built beside a river that seldom has water, but water is available to those who know how to find it. It comes from deep wells and from underground channels called qanats, which were invented in Iran perhaps 3,000 years ago. They are channels built by hand underground to minimize evaporation of the water into the dry desert air. They begin in the aquifer at the base of the mountains many kilometers away. The qanat is constructed with only a shallow slope so that water flows nicely, but not so rapidly that it erodes the tunnel. Vertical shafts every 20 or 30 meters provide air as well as access to construct and maintain the qanat. Bam has some of the oldest qanats in Iran. Before the quake, 126 qanats supplied about half of the water used by Bam and its surroundings, but most were damaged in the quake, and 40 percent were severely damaged.

Windcatchers (badgir) have been used for more than 1,000 years. The simplest is a vertical shaft from the ceiling of a room to the outside. The top of the shaft has a roof supported by columns or perforated walls. Wind blowing across the top of the shaft will reduce the pressure there and suck the warmest air from the room below. If the room has thick adobe walls that were chilled by the windcatcher drawing in cold night air, the room may remain cool all day. If the windcatcher has a scoop that diverts the wind down its shaft, over a pool of water, and into a room, the air will be chilled by evaporative cooling. It will be even cooler if the windcatcher forces dry air through a qanat so that it undergoes evaporative cooling and also draws chilled air from the underground chamber. In fact, if this combination is used to chill a well-insulated building, ice can be harvested in winter and kept in such a building well into the summer.

Outlook for the Future. In an opinion piece for The Iranian called “Ready for Future Bams?” on January 3, 2003, Sassan Pejhan writes that as he watched the television coverage of the Bam quake, he could not help but recall previous earthquakes in Iran: Roudbar in 1990, where 50,000 were killed and 60,000 were injured, and the Tabas earthquake in 1978, in which 25,000 were killed. The Tabas quake reminded Pejhan’s parents of the 1968 earthquake at Khorasan, where 12,000 were killed, and Pejhan’s grandparents were reminded of the earthquake at Salmas, where 4,000 were killed. Pejhan wonders what can break this vicious cycle of tragedy and concern followed by apathy and little progress.

Four days before the Bam quake, a quake of the same magnitude struck California’s central coast and killed only 2 people in the town of Paso Robles. On October 23, 2004, a series of quakes, the first of magnitude 6.8 (several times more powerful than the Bam quake), struck northern Japan, killing 35 and injuring 1,300. Simply put, Iran has not invested in building earthquake-resistant structures to the extent that more developed countries have. It is not merely a matter of mud brick construction, since modern buildings in Iran also collapsed. After the quake, Investigators found that fired bricks were often so weak that they disintegrated when struck sharply. Weak bricks had not been fired hot enough or long enough. Had buildings been constructed to the standards required by the Iranian building code, most probably would have survived. It is not simply a matter of money, since Iran has a great deal of oil money but has chosen to spend it elsewhere.

The Ayatollah Ali Khamenei visited Bam three days after the quake and comforted the people by assuring them that the quake was not a punishment from God but instead a test to see if they would remain faithful during difficulties. Too many people have taken this statement to mean that they should not work to prevent future tragedies. In fact, a consensus has been expressed by many writers both inside and outside Iran that a prevalent submissive and fatalistic mind-set keeps the people from making necessary changes. Those who are trying to implement steps to make buildings more earthquake-resistant find it difficult to institute change because of these attitudes.

Research shows that adobe homes could be greatly strengthened by using iron straps to tie walls to foundations, floors, ceilings, and roofs. Some horizontal and vertical concrete beams would also greatly strengthen adobe buildings. Covering adobe with a layer of adhesive, fiber-based polymers (quake wrap) has been shown to help. Even placing adobe bricks in sandbags and putting barbed wire between layers of bricks greatly strengthened test buildings. Enforcing building codes is probably the most effective step that could be taken.

Locals complained that money donated by other nations for the rebuilding of Bam was being withheld by the government and that the rebuilding was proceeding too slowly. The government responded that donor nations have been slow to fulfill their pledges. They also pointed out that before rebuilding could be started, it took more than six months to develop a plan for a modern city that would solve some of the problems with the old city. By 2006, although there were still many piles of rubble waiting to be cleared, the rebuilding was well underway, but ensuring that the new buildings are built to code requires constant vigilance.

Bibliography

Campi, Giovanni. “The Bam Earthquake: The Tragedy of a Cultural Treasure ‘Depicted in the Faces of People.’” UN Chronicle 41 (December 1, 2004): 40.

Earthquake Engineering Research Institute. 2003 Bam, Iran, Earthquake Reconnaissance Report. Oakland, Calif.: Author, 2006.

Ghafory-Ashtiany, Mohsen, et al. Journal of Seismology and Earthquake Engineering: Special Issue on Bam Earthquake. Tehran: International Institute of Earthquake Engineering and Seismology, 2004.

Hough, Susan Elizabeth, and Roger G. Bilham. After the Earth Quakes: Elastic Rebound on an Urban Planet. New York: Oxford University Press, 2006.

Lawler, Andrew. “Earthquake Allows Rare Glimpse into Bam’s Past—and Future.” Science 303 (March 5, 2004): 1463.