Catastrophic Events - Mrs. Grigar-Family & …...caused by an imbalance between positive and...

Catastrophic

Events

http://environment.nationalgeographic.com/environment/natural-disasters/forces-of-nature.html

What is a catastrophic event?

It is any natural or manmade incident, including terrorism, which results in extraordinary levels of mass causalities, damage, or disruption severely affecting the population, infrastructure, environment, economy, national morale and/or government functions.

http://www.nationalgeographic.com/forcesofnature









Natural Catastrophic Events

Hurricanes

Tornadoes

Earthquakes

Volcanoes

Avalanches

Lighting

Tsunamis

Forest fires

Floods

Landslides










Avalanche

Huge mass of ice and snow that breaks away from the side of a mountain and surges downward at great speed.

Three main kinds: wet-snow, dry-snow and slab avalanche

Wet-snow avalanches usually occur in the spring

Dry-snow avalanches are the more deadly ones.

In slab avalanche, a huge chunk of solid snow breaks away from a slope, sliding across a layer of loose snow crystals lying beneath










Formation of an avalanche

Formation of an avalanche requires only a mass of snow and a slope for it to slide down.

Most avalanches begin either during or soon after a snowstorm.

As each new layer of snow settles on the ground, it binds itself to the existing layers that are anchored to the mountainside.

Additional weight of a heavy snowfall prevents the snow from gripping onto the layers of snow underneath--This triggers an avalanche










Other factors causing avalanche formation include:

Explosions

Heavy snowfalls

Cornices

Earth tremor

Snow on ice

Yet in 90 percent of avalanche incidents, the snow slides are triggered by the victim or someone in the victim's party. Avalanches kill more than 150 people worldwide each year. Most are snowmobilers, skiers, and snowboarders.










Damages

Every year many people are killed from avalanches. About half of the buried victims will die if they are not rescued

within 30 minutes Others die due to the severe shock of hitting boulders or trees

during the slide Or are crushed by massive blocks of snow more than 130 million cubic yards of snow and ice slides down a

slope or mountainside. Ice mass collects large amounts of debris such as rocks and tree

stumps In populated mountain areas, whole villages are crushed Hundreds of people and animals are buried alive Power and water supplies are cut off and the roads disappear in

only a few minutes.










Floods

when there is more water than the lakes, rivers, oceans, or ground can hold.

Many different types of floods

Named for how often they occur 10 years floods,

100 years floods,

500 years floods,

Monsoon floods










Causes and effects

Causes Effects

Too much rainExcessive melting of snow

Too much water for the ground to absorb water

Ice or other objects block the flow of the river

Damage property and homes

Kill people and animals

Communities in flood zones must be rebuilt with proper flood controlling equipment.










Flood Safety

Have knowledge on it

Flood watch and flood warning

Flood watch: "flooding [that] is possible within a certain area"

Flood warning: "a flood [that] is imminent or one that has already been reported".

Recognize environmental clues that indicate an upcoming flood










A tsunami is a series of ocean waves that sends surges of water, sometimes reaching heights of over 100 feet (30.5 meters), onto land. These walls of water can cause widespread destruction when they crash ashore.

These awe-inspiring waves are typically caused by large, undersea earthquakes at tectonic plate boundaries. When the ocean floor at a plate boundary rises or falls suddenly it displaces the water above it and launches the rolling waves that will become a tsunami.

Tsunami-Killer Waves










Most tsunamis, about 80 percent, happen within the Pacific Ocean’s “Ring of Fire,” a geologically active area where tectonic shifts make volcanoes and earthquakes common.

Tsunamis may also be caused by underwater landslides or volcanic eruptions. They may even be launched, as they frequently were in Earth’s ancient past, by the impact of a large meteorite plunging into an ocean.

The best defense against any tsunami is early warning that allows people to seek higher ground. The Pacific Tsunami Warning System, a coalition of 26 nations headquartered in Hawaii, maintains a web of seismic equipment and water level gauges to identify tsunamis at sea. Similar systems are proposed to protect coastal areas worldwide.

The most infamous tsunami of modern times hit Indian Ocean shorelines on the day after Christmas 2004. That tsunami is believed to have packed the energy of 23,000 Hiroshima-type atomic bombs. Some 150,000 people were killed in a single day.










Lightning Lightning can and often does strike the

same place twice, especially tall buildings or exposed mountaintops

This enormous electrical discharge is caused by an imbalance between positive and negative charges. During a storm, colliding particles of rain, ice, or snow increase this imbalance and often negatively charge the lower reaches of storm clouds. Objects on the ground, like steeples, trees, and the Earth itself, become positively charged—creating an imbalance that nature seeks to remedy by passing current between the two charges.










Lightning is extremely hot—a flash can heat the air around it to temperatures five times hotter than the sun’s surface. This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.

About 2,000 people are killed worldwide by lightning each year. Hundreds more survive strikes but suffer from a variety of lasting symptoms, including memory loss, dizziness, weakness, numbness, and other life-altering ailments.










Wild Fires/ Forest Fires Uncontrolled blazes fueled by weather, wind, and dry underbrush,

wildfires can burn acres of land—and consume everything in their paths—in mere minutes.

On average, more than 100,000 wildfires, also called wildland fires or forest fires, clear 4 million to 5 million acres of land in the U.S. every year. In recent years, wildfires have burned up to 9 million acres of land. A wildfire moves at speeds of up to 14 miles an hour, consuming everything—trees, brush, homes, even humans—in its path.

There are three conditions that need to be present in order for a wildfire to burn, which firefighters refer to as the fire triangle: fuel, oxygen, and a heat source.

Fuel is any flammable material such as trees, grasses, brush, even homes.

Heat source-spark which helps light the fire ex: lightning, burning campfires or cigarettes, hot winds, and even the sun can all provide sufficient heat to spark a wildfire.

Air supplies the oxygen a fire needs to burn.










Landslides the movement of a mass of rock, debris, or earth down

a slope a type of “mass wasting” which denotes any down slope

movement of soil and rock under the direct influence of gravity

The term “landslide” encompasses events such as rock falls, topples, slides, spreads, and flows

can be initiated by rainfall, earthquakes, volcanic activity, changes in groundwater, disturbance and change of a slope by man-made construction activities, or any combination of these factors.

can also occur underwater, causing tidal waves and damage to coastal areas. These landslides are called submarine landslides.










Tornadoes Tornadoes are vertical funnels of rapidly spinning air. Their

winds may top 250 miles an hour and can clear-cut a pathway a mile wide and 50 miles long.

Twisters are born in thunderstorms and are often accompanied by hail. Giant, persistent thunderstorms called supercells spawn the most destructive tornadoes.

These violent storms occur around the world, but the United States is a major hotspot with about a thousand tornadoes every year.

"Tornado Alley," a region that includes eastern South Dakota, Nebraska, Kansas, Oklahoma, northern Texas, and eastern Colorado, is home to the most powerful and destructive of these storms.

U.S. tornadoes cause 80 deaths and more than 1,500 injuries per year.










A tornado forms when changes in wind speed and direction create a horizontal spinning effect within a storm cell.

Tornadoes are classified as weak, strong, or violent storms. Violent tornadoes comprise only about two percent of all tornadoes, but they cause 70 percent of all tornado deaths and may last an hour or more.

People, cars, and even buildings may be hurled aloft by tornado-force winds—or simply blown away. Most injuries and deaths are caused by flying debris.










Hurricanes Hurricanes are giant, spiraling tropical storms that can pack

wind speeds of over 160 miles an hour and unleash more than 2.4 trillion gallons of rain a day. These same tropical storms are known as cyclones in the northern Indian Ocean and Bay of Bengal, and as typhoons in the western Pacific Ocean.

Hurricanes begin as tropical disturbances in warm ocean waters with surface temperatures of at least 80 degrees Fahrenheit. These low pressure systems are fed by energy from the warm seas.

If a storm achieves wind speeds of 38 miles an hour, it becomes known as a tropical depression.

A tropical depression becomes a tropical storm, and is given a name, when its sustained wind speeds top 39 miles an hour.

When a storm’s sustained wind speeds reach 74 miles (119 kilometers) an hour it becomes a hurricane and earns a category rating of 1 to 5 on the Saffir-Simpson scale.










Hurricanes spin around a low-pressure center known as the “eye.” Sinking air makes this 20- to 30-mile-wide (32- to 48-kilometer-wide) area notoriously calm. But the eye is surrounded by a circular “eye wall” that hosts the storm’s strongest winds and rain.

A hurricane’s high winds are also destructive and may spawn tornadoes. Torrential rains cause further damage by spawning floods and landslides, which may occur many miles inland.

The best defense against a hurricane is an accurate forecast that gives people time to get out of its way. The National Hurricane Center issues hurricane watches for storms that may endanger communities, and hurricane warnings for storms that will make landfall within 24 hours.










Volcanoes

Volcanoes are awesome manifestations of the fiery power contained deep within the Earth.

These formations are essentially vents on the Earth's surface where molten rock, debris, and gases from the planet's interior are emitted.

When thick magma and large amounts of gas build up under the surface, eruptions can be explosive, expelling lava, rocks and ash into the air.

Less gas and more viscous magma usually mean a less dramatic eruption, often causing streams of lava to ooze from the vent.










About 1,900 volcanoes on Earth are considered active, meaning they show some level of activity and are likely to explode again.

Many other volcanoes are dormant, showing no current signs of exploding but likely to become active at some point in the future.

Others are considered extinct










Earthquakes

Earthquakes, also called temblors, can be so tremendously destructive, it’s hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors.

Some 80 percent of all the planet's earthquakes occur along the rim of the Pacific Ocean, called the "Ring of Fire" because of the preponderance of volcanic activity there as well

Most earthquakes occur at fault zones, where tectonic plates—giant rock slabs that make up the Earth's upper layer—collide or slide against each other

Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves A quake measuring 3 to 5 is considered minor or light 5 to 7 is moderate to strong 7 to 8 is major 8 or more is great










On average, a magnitude 8 quake strikes somewhere every year and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis.

Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.



























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Catastrophic Events - Mrs. Grigar-Family & …...caused by an imbalance between positive and...

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