In order to analyze the cause, effect and relief efforts of the Johnstown floods of 1889,1936, and 1977, existing literature, journalistic accounts, and official documents concerning the floods were investigated.

At 4:00 PM on May 31, 1889, the South Fork Dam burst, releasing 60 million tons of water into the Conemaugh Valley. The flood destroyed Johnstown and the surrounding communities within a few minutes. The official totals were 2209 persons killed, 30,000 homeless, and 17.2 million dollars property damage. From Sang Hollow, a community four miles from Johnstown, the first description of the disastrous flood was sent to Pittsburgh by telegraph about two hours after the catastrophe. Several journalists set out by train for Johnstown immediately. A fire started in the flood debris and burned throughout the night. By morning rescue squads of survivors were trying to get through to those still marooned and to identify the dead.

The eruption of Mount Saint Helens in the Cascade Mountain Range of Washington State on 18 May 1980 resulted in a life-threatening and economically disruptive natural disaster that required the mobilization of supportive agencies from the State and Federal government for control. Because of the potential for further eruptions, the mechanism of death for those persons exposed to the initial blast was examined to aid in contingency planning.

Fatalities as a result of the eruption could be attributed to lack of understanding of the danger in the area of the mountain. Although several scientists were killed during the eruption, most were sight-seers who ignored the warning seismic activity and the precautionary blockade of the area. A few were outside of the well-publicized danger zone, but were caught in the rapidly moving mudslides or the ash cloud.

Cholera, which was unknown in Africa south of the Sahara, became an identifiable disease in South Africa in 1919. In the 1970's, 5 cases were diagnosed in people coming into South Africa from countries to the north. Instructions regarding Cholera surveillance were circulated in 1979 following an outbreak in Maputo. There was no evidence of any case of cholera acquired in South Africa before September 1980. Within 12 days, there were 23 proven cases of Vibrio cholera, El Tor biotype, among Africans who obtained drinking water from an irrigation canal off the Crocodile River midway between Nelspruit and Kaapmuiden. Five hundred forty-six cases had been identified by the end of February 1981 and more are expected.

On 13 October 1980, a team of health officials collected at Nelspruit to coordinate measures to contain the epidemic. They included chlorination of the irrigation canal, water surveillance of local rivers by sampling or leaving Moore pads in situ, increasing the number of staff and strengthening equipment at local laboratories, educating local medical and nursing staff in patient management and providing adequate stocks of intravenous fluids and tetracycline. Patients' contacts were traced, their homes inspected, their water supply sources and means of sewage disposal checked and the public educated in cholera prevention. There were regular press statements, radio talks, television programs and the broadcasting of educational leaflets to warn the population to take precautions. It was decided not to hold a mass immunization campaign nor to administer preventive antibiotics.