An online-graphic computer program (ERISA-G) has been developed to facilitate engineering decision making concerning design earthquake loads. ERISA-G utilizes a simple Poisson model, together with historical data of past earthquake occurrences. The man-machine interactive system and its graphic display capability enable the engineer to understand not only the final results but also the process of earthquake risk analysis. The data files consist of mapping data (about 20000 points), active fault data (about 2000 segments) and two sets of earthquake data catalogues of different characteristics (each with about 1900 and 18900 earthquakes). Using a small number of input data and the choices made by the engineer at different stages of the program, ERISA-G produces some 40 different graphic displays in addition to a variety of line-printed output.