1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, and 1987. International Heat Flow Commission, International Association of Seismology and Physics of the Earth's Interior, and Oklahoma State University. Department of Geography. Cartography Service. This point shapefile contains heat flow data for Sudan compiled from sources dating from 1974 to 1987. Heat flow is a measure of heat loss across t... International Heat Flow Commission.