CRJU245 - Security in 21st Century

Week 3 Lecture

General Hazards

Hazards are processes that create danger to human life and infrastructures. Risks are the potential or possibilities that something bad will happen because of the hazards.

All natural hazards have occurring processes that have been around throughout the Earth’s history. Most of the hazardous processes are called Geologic Processes. Geologic Processes can, and will, affect humans, and are most noticeable when they cause loss of life or property. If the geologic process that poses the hazard strikes human life and/or property then a natural disaster has ensued.


Below are some natural hazards and possible disasters:

  • Earthquakes
  • Volcanic Eruptions
  • Tsunami
  • Landslides
  • Floods
  • Droughts
  • Hurricanes
  • Tornadoes

Natural Hazards and Disasters Classification

Natural disasters can be divided into three categories. Those categories are:


  • Geologic Hazards – Geologic hazards are responsible for significant loss of life and destruction of property. In the 20th 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 billions of dollars.

  • Atmospheric Hazards – This hazard is also considered a natural hazard. Each of the atmospheric hazards (hurricanes, tornadoes, blizzards, etc.) may have its own natural characteristics, geographic area where it occurs (areal extent), time of year it is most likely to occur, severity, and associated risk. While these characteristics allow identification of each, many atmospheric hazards are interrelated. In most cases, a natural disaster or event involves multiple hazards. During severe thunderstorms wind is often a factor which can cause tornadoes and tropical cyclones. Severe winter-storms and hailstorms including snowfall from severe winter-storm can prompt avalanches.

  • Hydrologic Hazards - Hydrologic hazards include floods, storm surges, coastal erosion, and droughts. It is important to realize the relationship of hydrologic hazards with the different hazard groups. For example, extreme rainfall from a thunder and lightning event can cause flooding, and winds from a tropical cyclone can exacerbate storm surge and coastal erosion. Other causes of flooding include locally intense thunderstorms, snowmelt, ice jams, and dam failures. Flash floods, which are characterized by rapid on-set and high velocity waters, carry large amounts of debris. Floods are capable of undermining buildings and bridges, eroding shorelines and riverbanks, tearing out trees, washing out access routes, and causing loss of life and injuries

  • Seismic Hazard - Seismic hazard is a natural phenomenon such as ground shaking, fault rupture, or soil liquefaction that is generated by an earthquake. Seismic risk is the probability that humans will incur loss or damage to their built environment if they are exposed to a seismic hazard. In other words, seismic risk is an interaction between seismic hazard and vulnerability (humans or their built environment).

United States and Hazards

People often associate natural hazard deaths with dramatic events, such as large earthquakes, volcanic eruptions, floods, hurricanes, or tornadoes. However, some of the most dramatic natural hazards occur infrequently or in restricted areas, so they cause fewer deaths than more common and less dramatic hazards.

In the United States, heat and drought account for the largest numbers of deaths. In fact, there were more deaths in the United States from heat waves between 1997 and 2008 than from any other type of natural hazard. In addition to heat stress, summer heat wave fatalities can result from dehydration and other factors; the very young, the very old, and the poor are affected the most. The same populations are vulnerable during the winter weather, the third most deadly hazard in the United States. Winter deaths often involve hypothermia, but some surveys include, for example, auto accidents caused by icy roads.


Flooding is the second most deadly hazards in the United States accounting for 16 percent of fatalities between 1986 and 2008. Fatalities from flooding can result from hurricane-driven floods; some surveys place them in the hurricane category rather than floods. The number of deaths from a given hazard can vary significantly from year to year due to rare, major events. For example, there were about 1,800 hurricane related deaths in 2005 when Hurricane Katrina struck.

Hazard ID and Risk Assessment

References and Supplemental Resources

Hyndman, D. & Hyndman, D. (2010). Natural Hazards and Disasters. Cengage Learning.


https://youtu.be/Us32wyFi5Hg