Almost every day, newspapers, radio and television channels carry reports on disaster striking several parts of the world. But what is a disaster? A natural hazard is a threat of a naturally occurring event that will have a negative effect on humans. This negative effect is what we call a natural disaster. Natural Hazards (and the resulting disasters) are the result of naturally occurring processes that have operated throughout Earth’s history. Natural hazards are caused either by rapid or slow onset events which can be geophysical (earthquakes, landslides, tsunamis and volcanic activity), hydrological (avalanches and floods), climatological (extreme temperatures, drought and wildfires), meteorological (cyclones and storms/wave surges) or biological (disease epidemics and insect/animal plagues). Risk is characteristic of the relationship between humans and geologic processes. The risk from natural hazards, while it cannot be eliminated, can, in some cases be understood in such a way that we can minimize the hazard to humans, and thus minimize the risk. To do this, we need to understand something about the processes that operate, and understand the energy required for the process. Then, we can develop an action to take to minimize the risk. Such minimization of risk is called hazard mitigation. Although humans can sometimes influence natural disasters, other disasters that are directly generated by humans, such as oil and toxic material spills, pollution, massive automobile or train wrecks, airplane crashes, and human induced explosions, are considered technological disasters, except when they occur as a secondary result of a natural disaster. Vulnerability refers the way a hazard or disaster will affect human life and property. In general, less developed countries are more vulnerable to natural hazards than are industrialized countries because of lack of understanding, education, infrastructure, building codes, etc. Poverty also plays a role - since poverty leads to poor building structure, increased population density, and lack of communication and infrastructure. Human intervention in natural processes can also increase vulnerability by development and habitation of lands susceptible to hazards. Risk and vulnerability can sometimes be reduced if there is an adequate means of predicting a hazardous event.