Natural Hazards

● Natural Hazards are the result of naturally occurring processes caused by rapid or slow onset events.

● Most natural hazards result from geologic processes.● Natural Hazards are most noticeable when they cause loss of life or property. If the

process that poses the hazard occurs and destroys human life or property, then a natural disaster has occurred.

Earthquake

1. Definition/Cause: The sudden release of energy in the Earth’s lithosphere due to the movement of tectonic plates, causing the shaking of Earth’s surface.

2. Frequency: ~500,000 earthquakes occur each year; only ~100,000 of these can be felt3. Technology Used: Tiltmeters measure ground tilt near faults and volcanoes. If a change

is recorded, it can indicate a possible earthquake. Also, seismographs draw lines which indicate ground motion.

4. Scale Used/Range: Richter Scale; measures from 1 (light) to 10 (severe)5. Area Most likely to occur: Along the edge of the oceanic and continental plates. (Ring of

Fire)6. Why does it occur in this area: The constant motion of the plates may cause them to

bump into each other or slide past each other, releasing energy in the Earth.

Tornado

1. Definition/Cause: By severe thunderstorms, in which the maritime tropical (mT – hot) and the continental polar (cP) air masses meet; The air in the thunderstorm rises and the surrounding air races to fill the gap. This results in a funnel-shaped, whirling column of air extending downward from the cloud.2. Frequency: United States leads the list, with an average of over 1,000 tornadoes recorded each year. Canada is a distant second, with around 100 per year.3. Technology Used: Scientists can predict the tornado over a wide region but cannot tell exactly where it will touch down and even the exact path is not very predictable. Meteorologist use weather predicted tools to determine if a tornado will form, such as satellites, Doppler radar (measures rain, wind direction and speed), as well as barometers

to measure changes in air pressure.4. Scale Used/Range: Enhanced Fujita Scale categorized by wind speed5. Area Most likely to occur: Tornado Alley, Midwest of US6. Why does it occur in this area: The area is relatively flat, which allows the cold air from Canada to meet the warm air from the Gulf of Mexico.

Hurricane and Floods

1. Definition/Cause: Hurricanes arise in the tropical latitudes (between 10° and 25° N) in summer and autumn when sea surface temperature are 28°C (82°F) or higher.The warm seas create a large humid air mass. The warm air rises and forms a low pressure cell, known as a tropical depression. When the temperature exceeds 28°C (82°F) the air begins to rotate.Cause an overflowing amount of water, also known as a flood.2. Frequency: Usually, there are less than 21 tropical storms in each region's hurricane season.3. Technology Used: Hurricane hunters pass through a storm 4-6x via planes which carry radars and weather instruments to track the direction of the hurricane.4. Scale Used/Range: Saffir Simpson Hurricane Scale5. Area Most likely to occur: In the Atlantic region, hurricanes form anywhere from the tropical central Atlantic to the Gulf of Mexico.6. Why does it occur in this area: Hurricanes almost always form over ocean water, warmer than about 80°F. Hurricanes that form in the Atlantic start moving westward, which is North American mainland. This why we do not see many hurricanes on the west coast as they move westward into the Pacific Ocean.

Volcano

1. Definition/Cause: Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface due to movement of tectonic plates. At the surface, it erupts to form lava flows and ash deposits.2. Frequency: On average, there are about 50-70 volcanoes that erupt every year. Some of them erupt multiple times, while others only have one eruption. During the past 10,000 years, there are about 1500 volcanoes on land that are known to have been active, while the even larger number of submarine volcanoes is unknown.3. Technology Used: Scientists need to know the past history of the volcano to predict future activity. If there are more earthquakes occurring, scientist can assume it is because of the moving magma. Changes in slope; measured using tiltmeters because as the magma and gas push inside the earthquake it slopes upward. Gas emissions such as Sulfur dioxide and carbon dioxide. Infrared cameras to measure heat.

4. Scale Used/Range: Volcanic Explosivity Index (VEI)5. Area Most likely to occur: Near plate boundaries and hot spots; the Ring of Fire in Pacific Ocean6. Why does it occur in this area: The movement of the plates creates zones of subduction, which leads to the formation of volcanoes. Hot spots are where a lot of heat is concentrated in a small area. The heat causes the overlying rock to melt. Since the magma is liquid and is lighter than the surrounding rock it "floats" to the surface and forces its way out of fissures in the crust.

Blizzard/Avalanche

1. Definition/Cause: A blizzard is a long-lasting snowstorm with very strong winds and intense snowfall, limited visibility. It does not necessarily need to be snowing to have a blizzard. The fresh loose snow can be blown around reducing visibility. An avalanche is a moving mass of snow that may contain ice, soil, rocks, and uprooted trees. Avalanches begin when an unstable mass of snow breaks away from a mountainside and moves downhill.2. Frequency: about 19 blizzards per year in the US; avalanches are difficult as some occur and do not affect humans, and some we cause to avoid tragedies.3. Technology Used: weather satellites used to help make computer models.4. Scale Used/Range: No scale for a blizzard, but measured according to amount of snowfall as well as wind speed. 3 criteria needed to classify a blizzard: Issued for sustained or gusty winds of 35 mph or more, and falling or blowing snow creating visibilities at or below 1/4 mile. These conditions should persist for 3 hours.5. Area Most likely to occur: Blizzards occur in the dead of winter when temperatures are the coldest. United States, blizzards are most common in the Great Plains and upper Midwest. Avalanches are most common during and in the 24 hours right after a storm that dumps 12 inches (30 centimeters) or more of fresh snow. Avalanches are triggered by skiers and snowmobiles.6. Why does it occur in this area: The northern plains, however, are the perfect location for blizzard conditions: The flat terrain allows the wind to reach blizzard-speed requirements.

Tsunami

1. Definition/Cause: large ocean wave usually caused by an underwater earthquake or a volcanic explosion, landslides on the seafloor, meteorite crashing.2. Frequency: Two tsunamis occur per year throughout the world which inflict damage near the source. Approximately every 15 years a destructive, ocean-wide tsunami occurs.3. Technology Used: Deep-ocean tsunami detection buoy and mareograph measure changes in sea level. Cannot be predicted, Pacific Tsunami Warning System, based in Hawaii, in the USA. Its network of detectors can track quakes that may cause a tsunami.

4. Scale Used/Range: New 12 category Tsunami Intensity Scale, also use the Richter Scale (same as earthquake scale)5. Area Most likely to occur: Ring of Fire along the Pacific Ocean, near coast, ocean/harbor6. Why does it occur in this area: tectonic plate movement along the boundaries.

Wildfires/Drought

1. Definition/Cause: Common causes of wildfires include lightning, human carelessness, arson, volcano eruption, and pyroclastic cloud from active volcano. Heat waves, droughts, and cyclical climate changes such as El Niño can also have a dramatic effect on the risk of wildfires. Drought – period of below average precipitation in a given region.2. Frequency: On average, more than 100,000 wildfires clear 4 million to 5 million acres land in the U.S. every year. In recent years, wildfires have burned up to 9 million acres of land.3. Technology Used: Firefighters use a tool known as a pulaski. Its a combination of an ax and hoe used to dig a fireline. A fireline is a strip of land from which all brush and debris have been cleared to rob a wildfire of its fuel. Firefighters also use hotshots and smoke jumpers to clear a large path in a big circle around the fire so the blaze is contained in a ring of dirt. When the fire reaches this area, it runs out of fuel and starves to death. If the fire is too large, however, planes and helicopters fly overhead, dropping water and special chemicals that smother the flames. Also uses drones and satellite imaging.4. Scale Used/Range: Wildland urban interface (WUI) hazard scale, a tool that will help predict the threat and measure the severity of wildfire. The proposed scale would range from E1 to E4 with E4 being a location’s highest exposure to fire. Building codes and buffer zones between homes and forest could then be set.5. Area Most likely to occur: common in the forested areas of the United States and Canada. The Santa Ana winds are hot, dry winds that aggravate the fire danger in forests and bush lands. These winds characteristically appear in Southern California and Northern Baja California weather during autumn and early winter. In southern California, under the influence of Santa Ana winds, wildfires can move at tremendous speeds, up to 40 miles in a single day, consuming up to 1,000 acres per hour.6. Why does it occur in this area: The climates are sufficiently moist to allow the growth of trees, but feature extended dry, hot periods. Fires are particularly prevalent in the summer and fall, and during droughts when fallen branches, leaves, and other material can dry out and become highly flammable.

Landslides and Mudslides

1. Definition/Cause: Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Landslides are induced by climatic conditions such as heavy rainfalls, snowfalls or natural phenomena such as volcanic activity or earthquakes. Human activities such as deforestation, mining, constructions, vibrations from big machines, etc. may also cause a landslide. Deforestation also is an important cause of landslides. The roots of trees hold the soil in place. Without trees, the stability of a slope is decreased greatly and with a large or even a small change, a landslide can be caused.

30-45 degree slope is the most optimal for a landslide/mudslide to occur.2. Frequency: result in 25-50 deaths per year.3. Technology Used: Fibre-optic sensors embedded in shallow trenches within slopes could help detect and monitor both large landslides and slow slope movements. Electronic inclinometers are used to provide warnings of impending landslides. The devices are placed on the slope in question, and notify officials when the angle of that slope changes significantly.4. Scale Used/Range: no scale used to measure landslides and mudslides5. Area Most likely to occur: The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. Alaska and Hawaii also experience all types of landslides. Burned areas charred by wildfires are particularly susceptible to debris flows, given certain soil characteristics and slope conditions.6. Why does it occur in this area: mountainous regions with unstable layers of earth.