4.3 Correlation Between Damage and Injuries

Three types of building damage can lead to injuries and possible fatalities. The most severe building response is collapse. In past incidents, collapse has caused the most extensive fatalities. For the Oklahoma City bombing in 1995 (see Figure 4-3), nearly 90 percent of the building occupants who lost their lives were in the collapsed portion of the Alfred P. Murrah Federal Office Building. Many of the survivors in the collapsed region were on the lower floors and had been trapped in void spaces under concrete slabs.

Although the targeted building is at greatest risk of collapse, other nearby buildings may also collapse. For instance, in the Oklahoma City bombing, a total of nine buildings collapsed. Most of these were unreinforced masonry structures that fortunately were largely unoccupied at the time of the attack. In the bombing of the U.S. embassy in Nairobi, Kenya in 1998, the collapse of the Uffundi building, a concrete building adjacent to the embassy, caused hundreds of fatalities.

For buildings that remain standing, the next most severe type of  injury producing damage is flying debris generated by exterior cladding. Depending on the severity of the incident, fatalities may occur as a result of flying structural debris. Some examples of exterior wall failure causing injuries are listed below.

• In the Oklahoma City bombing, several persons lost their lives after being struck by structural debris generated by infill walls of a concrete frame building in the Water Resources building across the street from the Murrah building.
• In the Khobar Towers bombing in 1996 (see Figure 4-4), most of the 19 U.S. servicemen who loss their lives were impacted by highvelocity projectiles created by the failed exterior cladding on the wall that faced the weapon. The building was an all-precast, reinforced concrete structure with robust connections between the slabs and walls. The numerous lines of vertical support along with the ample lateral stability provided by the “egg crate” configuration of the structural system prevented collapse.

• In the bombing of the U.S. embassy in Dar es Salaam, Tanzania in 1998, the exterior unreinforced masonry infill wall of the concrete framed embassy building blew inward. The massiveness of the construction generated relatively low-velocity projectiles that injured and partially buried occupants, but did not cause fatalities.

Even if the building remains standing and no structural damage occurs, extensive injuries can occur due to nonstructural damage (see Figure 4-5). Typically, for large-scale incidents, these types of injuries occur to persons who are in buildings that are within several blocks of the incident. Although these injuries are often not life-threatening, many people can be affected, which has an impact on the ability of local medical resources to adequately respond. An example of nonstructural damage causing injuries is the extensive glass lacerations that occurred in the Oklahoma City Bombing within the Regency Towers apartment building, which was approximately 500 feet from the Murrah Building. In this incident, glass laceration injuries extended as far as 10 blocks from the bombing. Another example is the bombing of the U.S. embassy in Nairobi, Kenya. The explosion occurred near one of the major intersections of the city, which was heavily populated at the time of the bombing, causing extensive glass lacerations to passersby. The ambassador, who was attending a meeting at an office building across from the embassy, sustained an eye injury as a result of extensive window failure in the building.

A summary of the relationship between the type of damage and the resulting injuries is given in Table 4-1.