The estimated total damage to housing units in Khorasan was over 500 million US dollars according to the International Institute of Earthquake Engineering Research in Tehran. Most construction in the area falls into one of a few catagories.

• Adobe buildings - Sun dried mud brick walls with wooden pole roofs.
• Masonry buildings - brick walls beam or slab roofs.
• Steel buildings - Typically larger buildings with steel frames, common in urban centers
• Reinforced concrete buildings - Concrete reinforced with steel

Adobe is one of the weakest building materials in an earthquake. But the dry weather in this region permits little greenery so timber is not an option for inexpensive shelter. The mud bricks are not baked - just dried in the sun. The roofs are either wooden poles supporting roofing material or more adobe. Thick adobe is needed to insulate houses from the hot desert sun. This makes the likelihood of failure even greater.

In the northern part of the region, which was hard hit by a quake in 1979, most of the traditional adobe buildings have been replaced by more modern construction. This resulted in far lower casualty rates in this area. Stone and brick masonry buildings are only as strong as the mortar which holds them together. When mud was used as mortar the results were as disastrous as adobe.

Few buildings in Khorasan were of steel construction. This class of structures are rare outside of urban centers or in poorer areas. Many buildings however were a combination of steel and masonry. Steel is used to form a strong frame around which the masonry is built. The photograph from New Abiz shows a house of this construction. Not surprisingly, the brick walls crumbled while the steel frame remained in place. This form of construction is only an improvement if it keeps the roof from collapsing which is not always the cases.

After 1979, reinforced concrete came into use for most public structures such as schools and administrative buildings. While this is generally considered to be a strong method of construction, it too fails when the roof is too heavy for the walls to support under stress. Though these structures were supposedly built to earthquake standards, construction short cuts often robbed the designs of their effectiveness. Reinforced concrete construction loses its effectiveness if the builder fails to anchor the walls to the foundation or if the steel beams are built into the concrete but then not anchored to one another. Close inspection following the May 10 earthquake revealed that an unusually high percent of reinforced concrete structures failed. This was blamed on construction short cuts and heavy loads of mud which had been placed on many roofs to help insolate from the hot sun.

Most all of the building failures could be attributed to structures that were built just strong enough to hold up their own weight but not tolerate the accelerations which accompany earthquakes. It is these accelerations which damage buildings. Peak accelerations during this quake reached 70% of the acceleration due to gravity (0.7 G's)

The general infrastructure faired well compared to buildings. Electricity and water lines were damaged severely in local areas but widespread damage was avoided. Electricity to most places was restored within a day. Since the more remote villages rely on springs for water, there were few major water lines to damage. Changes in the subsurface due to the shaking and displacement stopped flow in some wells. However, many new wells were created by the quake.

There are two dams in the area. Both experienced some cracking but neither dam broke and officials feel they can both be repaired adequately.

There are few bridges in the area most heavily hit so most road damage was easily repairable. Landslides over roadways were common but these were addressed immediately so relief crews could reach the region.

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Last update: October 1, 1998