At present the problem of ensuring the seismic safety on the large urban areas is becoming of extreme importance. As the gross damage during a lot of earthquakes is a result of secondary reasons (fires in Tokyo in 1923, landslides in Anckorage in 1964, etc.), the problem being discussed is a versatile and
complex one, especially in the old large cities. In general case the solution of the problem of ensuring the seismic
safety on the urban areas comes to the following sequence of stages: composing the informational data base about the urban areas including a man-made hazard block as well as the social concrete, planning, structural, economic and ecological blocks; multifunctional analysis of influence of different factors on vulnerability of population, economic and ecology of the area being investigated; development (creation) of geoinformational system for analysing the complex vulnerability of the urban areas, estimation of probable losses of human beings
and economic damage at different probable scenarios of seismic events, i.e. knowledge of probable consequences of the earthquakes; revealing the effective preventive measures for seismic disaster mitigation and development of operation and long-term program of preparation for the earthquakes.
The paper is concerned with all stages of solving this complex problem. GIS and different scenarios of violent earthquake for Petropavlovsk-Kamchatsky where secondary dangers both natural tsunami, snow avalanches, rockfalls, liquefication of soils) and man-made (fires, propagation of toxic and radioactive substances, explosions, etc.) are presented.