Аннотация:Geothermal exploration and development of geothermal sites requires the investigation of their engineering geological setting and an assessment of the hydrothermal activity impact on the environment. Hydrothermal alteration of rocks and changing in their physical-mechanical properties promotes a broad range of geological phenomena that is indicated by many researchers on various geothermal sites all over the world. There are slope instability with the initialization of landslides or rock avalanches, changes in relief, hydrothermal explosions, migration of thermal manifestations, changes in temperature and the hydrodynamic regime of a hydrothermal system, reduction of well production, surface deformation and subsidence, discharge of wastewater from production wells to the creeks with formation of silica deposits etc. These processes have an impact on the environment and influence on exploitation of the geothermal field, and in some cases, they could be hazardous for the economic or tourist development of the geothermal site. In the paper we discuss the environmental impact problems induced by hydrothermal activity, which may occurred during natural evolution of hydrothermal systems or due to the geothermal development and utilization, and describe the geological phenomena associated with hydrothermal activity on the most well-known hydrothermal systems of Kamchatka Peninsula (Far East, Russia).
