29487 natural disasters

They develop from easterly waves, which can later develop into a tropical depression... Later, it might develop into a tropical storm with winds up to 73 miles per hour, and eventually a

NATURAL DISASTERS

A disaster is an event that could hurt people and cause damages

Tornadoes: it is a violent wind movement They are also called twisters or cyclones Most people

recognize them as a towering black funnel extending downward from the base of a large cumulonimbus cloud It rotates at speeds up to three hundred miles per hour (480 kpm) or in some rare cases, even faster In the center of the tornado, the air pressure is very low in comparison to surrounding air pressure

The speed of the wind is the primary cause of deaths and destruction of property Many people are killed by flying objects and debris (missiles) They happened In certain parts of the world Australia, the Midwestern and Southern of United States

They also occur more frequently in the spring and summer months Tornadoes usually occur as part of a severe thunderstorm and often come in advance of cold fronts, however, they can also occur (although less frequently) ahead of warm fronts, and even behind cold fronts

The greatest killer tornado in the United States occurred during the year 1925 in Indiana, Illinois, and Missouri It killed six hundred ninety five people and injured over two thousand

Hurricanes: they are one of natures many destructive forces The word comes from West Indian;

huracan ("big wind") Hurricanes are seasonal storms and are most prevalent in August and September They develop from easterly waves, which can later develop into a tropical depression

with winds up to 31 miles per hour Later, it might develop into a tropical storm with winds up to 73 miles per hour, and eventually a hurricane Thunderstorms often form with hurricanes and then produce waterspouts

Hurricanes are huge tropical cyclones that originate over oceans near the equator, such as the Caribbean Sea and the Gulf of Mexico However, if they do reach land, destruction of property is imminent Wind speeds of a hurricane range from seventy to one hundred fifty miles per hour

One of the most destructive elements of a hurricane is the huge waves that are formed because of the strong winds and heavy rains These waves called a storm surge can rise several feet above water levels, especially during high tide

"Tsunami" is the Japanese word meaning tidal wave A tidal wave is a large sea wave caused by

a submarine earthquake or volcanic explosion When the ocean floor is tilted or offset during an earthquake, a set of waves is created These waves are similar to the concentric waves generated

Usually tsunamis move entirely across an ocean to the shore A tsunami can have wavelengths of

60 to 120 mi and may reach speeds of 800 km/h When the wave enters shallow waters, the wave,

which may have been half a meter high out at sea, grows rapidly When the wave reaches the shore, it may be 50 ft high or more Tsunamis have incredible energy because of the great volume

of water affected

Since the year 1819, more than 40 tsunamis have struck the Hawaiian Islands A tsunami warning system has been developed in areas such as Hawaii, where many devastating tidal waves occur Hawaii, the highest risk area, averages one tsunami every year with a damaging occurrence every

7 years Since 1945, more people have been killed as a result than as a direct result of an earthquake's groundshaking

Lightning: Lightning is characterized by the discharge of electricity between rain clouds or

between a rain cloud and the earth It is usually seen as an arc of extremely bright light which can

be many kilometers in length; however, there are other forms as well Accompanying the lightning

is the giant roar of thunder The thunder is caused by the expansion of air that has been heated by the lightning which then collides with cooler air, creating the sound of an explosion

Thunderstorms are the most common types of storms, and thunder itself, although frightening, is not dangerous It is the lightning that causes the problems Lightning and thunder occur together,

however we hear the thunder after we see the lightning Sound waves travel about one mile in five seconds, while light travels at more than 186,000 miles per second Therefore, lightning is seen immediately when it occurs, and thunder is heard a little later

The different sounds of thunder (deep roar/loud crash) is caused by the different types of lightning, for example, the thunder that has the sharp crackle like sound is caused when the large trunk of lightning forks into many branches

Earthquake: is a shaking of the ground caused by the sudden dislocation of material within the

earth's outer layer, or crust When forces pushing on a mass of rock overcome the friction holding the rock in place and blocks of rock slip against each other a earthquake may occur Some earthquakes are so slight, and some occur in such remote areas, that they are barely felt Others are so violent that they cause extensive damage

Earthquakes are caused by stresses below the earth's outer surface These stresses usually build

up until the rocks fracture along a "fault plane." This causes vibrations, also known as seismic waves Seismic waves will then travel in all directions from the area of fracture In large earthquakes seismic waves may be detected over the entire earth

Earthquakes can be caused by volcanoes in certain cases Nuclear explosions under the ground can create waves that are very similar to natural seismic waves The seismic energy created in a atomic bomb is one hundred-thousandth that of the largest earthquake

Earthquakes take place or have taken place in all parts of the world Frequent activity occurs along certain belts 80% of all seismic energy is generated from a belt that is found at the border of the Pacific Ocean The intensity of an earthquake is measured in terms of its geological effects and the overall damage it brings There are two major scales in which earthquakes are measured These two scales are the Mercalli Scale and the Richter Scale

Avalanche: they occurs when a mass of snow falls down a mountainside That is because new

snow (which is not wet) accumulates on a more heavy snow layer Since the new snow layer is not compact, it could slide down toward the base of the mountain

Avalanches could be triggered by loud noise (yells, firearm shots, etc.) Skiers, snowboarders and climbers could also cause an avalanche

There are two ways to reduce avalanche risks: by installing snowsheds or by triggering controlled avalanches These protection fences are made of rocks, soil and other materials They prevent avalanches to fill trails used by humans

Controlled avalanches cause the accumulated snow to fall down before it could trigger avalanches

by itself When nobody is in danger, explosives are used to produce a loud noise that causes an avalanche

Wildfires: (incendios forestales) they are dangerous for all people living near woodlands

In the wild, wildfires are ignited by lightning But some wildfires are caused by careless campers who did not extinguish their campfire or by walkers who threw their cigarettes in the woods 80% of wildfires are caused by careless people Wildfires move forward rapidly, even more if winds blow and the weather is dry To stop wildfires, firefighters use water bombers which carry water and drop it on wildfires Wildfires do not only have bad effects In fact, the many dead pin needles, leaves and tree trunks on the ground are burnt to ashes by wildfires These ashes are full of minerals and help the growth of new trees By burning trees, wildfires make “gaps” in the forest (called clearings) These clearings allow the sun to heat the ground up and help tree seeds to grow

Floods: they happen when a watercourse overflows They could be caused by rain, thaws or ice

jams

Heavy Rain: when it rains, water falling on the ground penetrates it But when the ground already

contains a lot of water, the falling rain could not seep through it The water then starts flowing toward a watercourse When it rains a lot on a region, all water flows toward the river, but this river can not contain it; therefore, the river overflows

Thaw: when spring arrives, snow and ice start to melt and the water flows toward the river If the

temperature rises too rapidly, a lot of water is produced in a short time; the river overflows and a flood happens

Ice Jam: In spring, rivers thaw out and big chunks of ice detach themselves and drift on the river

Sometimes these chunks get jammed against a bridge or rocks Consequently, these chunks of ice form a kind of dam

When water can not flow through this dam, it tries to find an alternate course to reach the river… and, sometimes, this new course is a field, a road or a house basement

Rockslide and Landslide: (deslizaminetos)

Rockslide is a downward and rapid movement of newly detached pieces of bedrock

Landslides are ground and rock movements They occur most commonly where the ground is made of soft material, like clay

When ground or cliffs collapsed, one calls them "scree"

The difference between a rockslide and a landslide is what is sliding:

• rockslide: big rocks and cliffs

• landslide: ground and mud

What to Do to Avoid Rockslide and Landslide

Of course, if you live outside rockslide hazard zones, accident risks will also be lower To reduce rockslide (or collapse) risks, rocksheds similar to snowsheds, as for avalanches, could be installed Another way is to trigger controlled rockslide risks, which means to cause less strong rocks to fall down after being sure nobody or nothing will be hit by them

Drought (sequia) : is a period or condition of unusually dry weather within a geographic area

where rainfall is normally present During a drought there is a lack of precipitation Droughts occur

in all climatic zones However, its characteristics vary significantly from one region to another Its seriousness depends on the degree of the water shortage, size of area affected, and the duration and warmth of the dry period In many underdeveloped countries, such as India, people place a great demand on water supply During a drought period there is a lack of water, and thus many of the poor die

Although drought cannot be reliably predicted, certain precautions can be taken in drought-risk areas These include construction of reservoirs to hold emergency water supplies, education to avoid overcropping and overgrazing, and programs to limit settlement in drought-prone areas The Southern Africa Development Community monitors the crop and food situation in the region and alerts the people during periods of crisis

Volcanic Eruption

Volcano is an opening in the earth's surface through which lava, hot gases, and rock fragments erupt (burst forth) Such an opening forms when melted rock from deep within the earth blasts through the surface Most volcanoes are mountains, particularly cone-shaped ones, which were built up around the opening by lava and other materials thrown out during volcanic eruptions Eruptions of volcanic mountains are spectacular sights In some eruptions, huge fiery clouds rise over the mountain, and glowing rivers of lava flow down its sides In other eruptions, red-hot ash and cinders shoot out of the mountaintop, and large chunks of hot rock are blasted high into the air

A few eruptions are so violent that they blow the mountain apart

The eruption of a volcano The gas-filled magma in the reservoir is under great pressure from

the weight of the solid rock around it This pressure causes the magma to blast or melt a conduit (channel) in a fractured or weakened part of the rock The magma moves up through the conduit

to the surface When the magma nears the surface, the gas in the magma is released The gas and magma blast out an opening called the central vent Most magma and other volcanic materials then erupt through this vent The materials gradually pile up around the vent, forming a volcanic mountain, or volcano After the eruption stops, a bowllike crater generally forms at the top

of the volcano The vent lies at the bottom of the crater

Once a volcano has formed, not all the magma from later eruptions reaches the surface through the central vent As the magma rises, some of it may break through the conduit wall and branch out into smaller channels The magma in these channels may escape through a vent formed in the side of the volcano Or it may remain below the surface

Practice

Read the definitions Fill in the blanks with the correct disaster Use the words from the box.

Flood, Tsunami, Hurricane, Earthquakes, Volcano, avalanche, Fire, lightning, meteorite, tornado,

landslide

1 It can start anywhere; it burns everything, it burns everything, and is very hot

_

2 A large amount of earth and rocks fall down the side of mountain

3 It is a large piece of rock or metal that lands on Earth from somewhere in space

_

4 It covers everything with snow

5 River overflow and there is water everywhere

6 Big storm with strong winds

7 Earthquake in the sea, it makes a big wave which destroy everything _

8 The ground moves, everything shakes, and buildings often fall down _

9 Its is a mountain that erupts and throw hot material everywhere

10 It is a very bright flash of light somewhere in the sky _

Hurricanes

They are one of natures many destructive forces The word comes from West Indian; huracan ("big wind") Hurricanes are seasonal storms and are most prevalent in August and September They develop from easterly waves, which can later develop into a tropical depression with winds up to 31 miles per hour Later,

it might develop into a tropical storm with winds up to 73 miles per hour, and eventually a hurricane Thunderstorms often form with hurricanes and then produce waterspouts

Hurricanes are huge tropical cyclones that originate over oceans near the equator, such as the Caribbean Sea and the Gulf of Mexico Usually they follow a parabola shaped path and sometimes do not reach any land at all However, if they do reach land, destruction of property is imminent Winds whirl in a counter clockwise direction in the northern hemisphere and clockwise in the southern hemisphere Wind speeds of a hurricane range from seventy to one hundred fifty miles per hour These winds blow circularly around a low-pressure center known as the eye of the storm Hurricanes cause numerous deaths in addition to the millions of dollars of property damage each year due to the intense winds and huge tidal surges.

2 What are the steps for a hurricane to be bigger? _

3 What is the fastest velocity for a hurricane winds?

4 When the hurricanes are most frequent?

5 Where do hurricanes originate? _

6 Another name for hurricanes?