The risk to humans from geologic hazards can be minimized by human behavior.
Geology deals with various aspects of the Earth's composition and structure, geological processes that modify the Earth's surface and are responsible for mineral and rock formation and accumulation of raw-material deposits. A geologic hazard can be broadly defined as an actual or threatened landslide, land subsidence, earthquake, or any other natural or unnatural movement of land or earth. Geologic hazards are responsible for great loss of life and destruction of property. In the twentieth century more than a million people worldwide have been killed by earthquakes alone, and the value of the property destroyed by earthquakes, volcanoes, and tsunamis amounts to scores of billions of dollars. Unfortunately, with the exception of landslides, most geologic events cannot be prevented or even predicted with any precision. Nevertheless, appropriate mitigation measures can enormously reduce the damage caused by geologic hazards. .
Although landslides are a hazard in all 50 States there is currently little national effort to reduce landslide hazards and damage. There are, however, local examples of successful landslide hazard mitigation. For example, the Los Angeles area has reduced over 90% in landslide losses by implementing appropriate zoning regulations. Two approaches can be taken to mitigate landslide hazards. The "hard" approach includes constructing debris dams, retaining walls, and drainage systems in landslide-prone areas. The "soft" approach focuses primarily on avoiding landslide hazard areas by using proper zoning and land-use regulations. Although both approaches could potentially mitigate landslide hazard, soft approaches most efficiently reduce the long-term hazard potential. Furthermore, zoning and land-use regulations are more cost-effective measures over the long-term than constructing debris dams and retaining walls.