Similarly, the large fire that occurred after the 1906 San Francisco earthquake was responsible for much of the death toll following that event. More recently, the 1994 Northridge earthquake in southern California showed that strong vibrations may sever underground fuel lines or gas connection points, causing spills of volatile or explosive mixtures and resultant fires (10,59). Similarly, during the first 7 hours following the 1989 Loma Prieta earthquake in northern California, San Francisco had 27 structural fires and more than 500 reported incidents of fire (18). Furthermore, the city water supply was disrupted, significantly impairing the city's ability to fight these fires (63).

Perhaps the most vulnerable areas of all are the informal housing sectors on the periphery of many rapidly growing cities in developing countries (so-called "squatter housing" or "shanty town" settlements). Many of these have the potential for catastrophic conflagrations following an earthquake.