Catastrophic Events, Part 2

Natural Hazards & Catastrophic Events A natural hazard is an event that results from Earth processes and that can cause damage and endanger human life. Natural hazards are the result of processes that take place in Earth systems. For example, hurricanes form over the ocean.

Natural Hazards 1.HurricanesHurricanes 2.FloodsFloods 3.TornadoesTornadoes 4.StormsStorms 5.EarthquakesEarthquakes 6.Volcanoes 7.Tsunamis 8.Droughts 9.WildfiresWildfires

Impact on Earth Some catastrophic events are the result of processes on Earth’s surface and in the atmosphere and oceans. Other catastrophic events are the result of processes inside Earth, such as earthquakes and volcanic eruptions.

Effects of Catastrophic Events Catastrophic events can affect the Earth in several ways: Speed up erosion Speed up deposition Change the Earth’s crust Erosion of beaches Wash away barrier islands

Human Activities Where people locate their activities can increase the damaging effects of natural hazards. How people use land can also alter Earth systems in ways that contribute to catastrophic events.

Potentially Catastrophic Non-Human Activity

Impact of How People Use Land Human activities that affect the environment can increase the impact of natural hazards. For example, one reason that Hurricane Mitch had such a catastrophic impact is that people had altered the land surface in ways that made the damage worse. Mountains and hills with steep slopes cover much of the land in Central America. Once, thick forests grew on these slopes. The forests held the soil in place and helped to absorb rainfall. But by the year Hurricane Mitch struck, people had cleared much of the forest for farming and ranching. This altered the Earth system in which trees protected the land surface from erosion and reduced the amount of runoff. As a result, huge amounts of runoff from the heavy rains quickly loosened the soil and mud flowed into river valleys.

Impact of Where People Locate You may have heard the saying “Location! Location! Location!” In real estate, this means that where a building is located is the main factor that determines its value. You could also apply this saying to human activities and natural hazards: Where people locate their activities — cutting forests or building towns — often determines the risks they face from different catastrophic events. For example, in many communities, people have located homes and other structures on flood plains or in low-lying coastal areas. Frequently, people think the land is safe for building because there has been no flooding for many years. But no one can predict when the next flood will be. Structures on a flood plain might be damaged or destroyed when the next major flood does occur. For example, structures in some low-lying coastal areas are at risk from tsunamis. A tsunami is a wave up to 20 meters high caused by an earthquake on the ocean floor.

THE END

This picture was taken in the Bitterroot National Forest in Montana on August 6, 2000 by a fire behavior analyst from Fairbanks, Alaska

Do NOT Burn during a Burn Ban!