Natural geological disasters such as earthquakes and volcanic eruptions are generated by activity occurring deep below the earth. Landslides, rockfalls, debris flows, and avalanches are examples of gravitational natural hazards, when rock, mud, or snow masses slide down the slope due to gravity. Earthquakes or harsh weather conditions might cause them. Heat, drought, forest fires, storms, floods, high water, and heavy rain are examples of meteorological natural hazards. Chain reactions, domino effects, and cascade effects, in particular, are a big issue in risk and disaster management, because correlations or causes are not always (early) recognized, and when highly sophisticated preventative measures must be adopted. Natural hazards are natural occurrences that have the potential to harm persons, infrastructure, and society. The effects of these catastrophes can be mitigated or exacerbated by human action. Natural hazards are categorized as geophysical, such as earthquakes or landslides, hydrological, such as flooding, or climatological, such as glacial changes or sea-level rise, in the geosciences.