An earthquake of magnitude 8 hit and destroyed the city of Damghan, Iran, in 856 AD. Damghan is in the north central part of what is now Iran. Both the city of Damghan and many areas around it were destroyed.
On December 22, 856, an earthquake of magnitude 8 struck the city of Damghan, at that time the capital of the area we now know as Iran. While the earthquake was centered on Damghan and destroyed most of that city, damage to neighboring areas extended east and west over a two-hundred-mile stretch of countryside. Every village in this area was destroyed. One third of the town of Bustam, about fifty miles east of Damghan, collapsed. In mountain areas close to the center of the earthquake the surface of the ground parted in several places. Overall, 200,000 people lost their lives. The memory of the event was so vivid that, two generations later, detailed memories of all that had happened were still being recounted.
Iran has always been known as a place of earthquakes because of its location along fault lines and between two major tectonic plates that are always colliding. In earlier times, news of earthquakes in this remote region east of Mesopotamia was almost nonexistent. Not until the early Islamic Period, after 622, was it possible to locate reliable records of events. Of the significant earthquakes reported after 622 and before 922, Damghan was the most powerful. There were about forty others within this period with magnitudes ranging from 5 to 7. At this early stage of scientific thinking, explanations for earthquakes among the more educated Muslims were based on Aristotle’s thinking, a sort of philosophy of nature based on mathematics or on orderly patterns observed in nature. Unfortunately, earthquakes are anything but orderly. We know their causes but not their timing. For the vast majority of people in 856, earthquakes were viewed with awe and their origins attributed to the actions of a supernatural power.
Even in modern times, this theological interpretation of earthquakes is a common view. One group regards them as punishment from their god for bad behavior. Another sees them as omens of contemporary political events; that is, they indicate what is about to happen in a particular country. This view is so common in China today that the government of that country delayed for three years the detailed reporting on an earthquake that came in 1976. In the case of Iran, there was a fairly large earthquake in that country on the sixteenth of January 1979, in which several hundred people were killed. That particular day happened to be the one on which Shaw Pahlavi departed from Iran, leaving the government of the country in the hands of the theological leaders who replaced him. To many people in the country, the earthquake was evidence of the behavior of their god in rearranging the nation’s government. With our present knowledge of the causes and outcomes of earthquakes, Iranian patterns can be identified across time and space, some because of local records and traditions seen to be repeating every thousand or even every five thousand years.
The Eurasian and Arabian tectonic plates converge at an average rate of a little over one and a half inches every year. Iran is in the middle all of this activity and its numerous fault lines bear the evidence. Across a line that stretches east and west for more than six hundred miles strike slip and reverse faults are the places where plate movements are expressed. In earlier times, as in the Damghan earthquake, most of the country consisted of small farming settlements in which homes were built of simple mud-walls, a type of construction that easily collapses when an earthquake strikes. Some commentators have suggested that people built simple inexpensive homes because they knew that there would be new earthquakes and they would lose whatever they built. In places like these ancient Iranian ones, most of the deaths in an earthquake are caused by the collapse of homes. As a result, it often happens that huge numbers of deaths are reported from developing countries, where buildings are incapable of withstanding even low magnitude earthquakes; while developed countries report fewer deaths when hit with similar magnitude earthquakes.
Much of the history of homes in Iran is typical of conditions in other developing nations, so a closer examination of how single homes and clusters of buildings are constructed in Iran is worthwhile. In addition, their failure until very recent times to make buildings earthquake resistant is also typical of many other countries. In December of 2003, the ancient Iranian city of Bam was destroyed in an earthquake. It was clear in reports from the British Broadcasting Corporation (BBC) that failed buildings were the main cause of the large number of deaths. According to the BBC, Bam experienced a strong earthquake at four in the morning when most of the residents were in bed. One-third of its population of 200,000 was either killed or seriously injured. Most of the buildings, including two of the city’s hospitals, were destroyed. The BBC’s reporter told of intense scenes of grief as survivors stood beside corpses wrapped in blankets or buried beneath rubble. This story in all probability was very much like the one that was recounted in Damghan twelve and a half centuries ago.
Homes built a thousand years ago and those built today in most rural areas are built of dried mud or adobe bricks, rarely with a type of clay that gives significant strength to the building. Where timber is available, beams can be installed for the support of flat roofs in spite of the fact that the kind of timber available is often warped or weak from repeated use in previous constructions. Typically, a flat roof is very heavy. It consists of some kind of boarding on which two feet of earth is laid. A flat roof is always preferred because it provides a cool place in which to sleep during the hot summer months and can also be used for drying crops. In mountain villages, a common sight in a country that has one third of its land area higher than ten thousand feet above sea level, houses are built with stones and held in place with a clay mortar. Where slopes are steep the roof of one house becomes the ground floor and outdoors of the next home above it. On lower elevations homes are built close together with very little space between them. When a home is damaged, the repair work rarely tries to make the place stronger and, therefore, better able to withstand the next earthquake.
The concept of making buildings as earthquake resistant as possible was unknown until recently. Heavy rainfall still destroys hundreds of homes in the course of a few hours. The idea of changing both the appearance and shape of a home to make it better able to resist an earthquake began to appear for the first time in the second half of the twentieth century. There is one group of Iranians who have no need to make their homes earthquake resistant—the nomadic tribes who need homes that can be dismantled and remounted in a short time as they move from place to place. Their homes are yurts and they are perfect examples of earthquake resistant homes. These structures are dome-shaped, circular, tents made of collapsible walls of willow poles, known as yurts. The roof of a yurt is domed and both roof and walls are covered with a kind of felt made from animal wool. Dried grass and strips of leather are used for holding the structure together. In summer, the felt sides are rolled up to admit air and, in winter, extra sheets of felt are added to the outside for warmth. The whole structure can be taken apart and reassembled in an hour, a vital feature for nomadic life. A yurt can provide a comfortable home for at least fifty years.