natural disasters ppt by muzzammil ghayas

Natural DisastersGroup Members:-1. Tahira Jabbar Shaikh (4377)2. Shahid Hussain (4422)3. Sana Laiq Ali (4384)4. Kamran Mehmood (4424)5. Muhammad Muzammil Ghayas (4338)

Course Instructor:-Miss Mehvish Saleem

Disaster:-

An occurrence causing widespread

destruction and distress.

A catastrophe.

A grave misfortune.

Definitions

A natural disaster is an event caused by

natural forces.

It often has a significant effect on human

populations.

Typically the human populations either are

displaced (left homeless) or killed.

Natural Disasters

Have economic and emotional effect on

people.

Directly affect life and property.

Contd…

Natural disasters occurs in all three broadareas:

Land Air Water

Occurrence & Affects of Natural Disasters

There are 4 kinds of natural disasters whichoccurs on land:

Earthquakes Volcanic Eruptions Lahars Avalanches

Disasters on Land

Earthquake is a sudden shock of earth’s crust.

The underground point of origin is called the

focus.

The point directly above the focus is called

the epicenter.

They are measured with a seismometer.

The scale is called the Richter Scale.

Earthquakes

An earthquake that occurs after the main

shock.

It occurs in the same area or region of the

main shock.

Its magnitude is relatively smaller than the

main shock.

The Aftershocks

If the magnitude of an after shock is greater

than the main shock:

After shock is designated as the main shock.

The main shock is redesignated as the fore

shock.

Designation of Main Shock & The After Shock

Earthquake itself does not kill any one.

Usually the secondary events kill the

people.

Secondary events include:

Tsunami

Building Collapse

Fires

Volcanoes

Earthquakes does not Kill People

A volcano is an opening in earth’s crust.

It allows hot magma, ash and gasses to

come out from below the surface.

They are generally found where tectonic

plates are diverging or converging.

Volcanic Eruptions

Volcanoes can be destructive.

Can be harmful for the life and property.

Icelandic volcanic eruption continued for

nearly 3 months.

Caused thousands of

flights to be cancelled.

Contd…

A type of mudslide/landslide composed of

pyroclastic material & water.

It is liquid while moving and becomes solid when

the activity is stopped.

Can flow 100 km/hour.

Can cover a distance of more than 300 km.

Can be deadly due to their energy & speed.

Killed 23000 people in Armero , Columbia in 1985.

Lahars

An avalanche is a rapid flow of snow down a

slope.

Primarily composed of flowing snow.

It occurs in mountainous regions.

It can mix air and water with descending snow.

Most destructive natural disaster in the

mountainous regions.

Avalanches

Wellington Avalanche (1910)

Blons Avalanches (1954)

Some Notable Avalanches

There are basically three types of naturaldisasters which occurs in or due to the water:

Floods Tsunami Limnic eruptions

Water Disasters

A flood is an overflow of water.

They occur when the flow of water exceeds

the capacity of river.

Heavy rain is another reason.

Can be destructive for life and property.

Floods

A tsunami is a series of water waves.

It is caused by the displacement of a large

volume of a water body.

Caused by the underwater earthquakes,

volcanic eruptions and

underwater explosions.

Can destroy coastal areas.

Tsunami

Frequent in Japan.

In 2004, Indian Ocean Tsunami caused widespread

destruction.

Hundreds of thousands of people were killed in different

countries.

During 2nd World War, New Zealand army tried to create

an artificial tsunami.

New Zealand army was failed to create the artificial

tsunami.

Contd…

Can not be predicted correctly even if magnitude

and place of quake is known.

Pacific tsunami warning system monitors Pacific

Ocean’s seismic activities.

People can save their lives by going

to the places higher than the land.

Sign boards are placed in US to

show the people where to go.

Countering Tsunami

A rare type of natural disaster.

Occurs in lakes.

Occurs when a gas (carbon dioxide) erupts deep

under the water.

Large cloud of carbon dioxide forms above the lake.

Killed 37 people in Cameron at Lake Monoun in 1984.

Killed 1700-1800 people in Cameron at Lake Nyos.

Limnic Eruptions

Air Disasters

Tornado

A rotating column of air.

In contact with both surface of earth and

the cloud.

Approximate length is 250 feet (80 m).

Usually wind speed is 110 miles/hour.

Can attain wind speed of more than 300

miles/hour.

Tornado

Multiple-Vortex Tornado

Water Spout

Dust Devil

Fire Whirls

Steam Devil

Some Other Types of Tornadoes

Multiple-Vortex Tornado

2 tornadoes moving simultaneously

Waterspout

A tornado over the Water

Dust Devil

A Dust Devil

Fire Whirls

A tornado of fire

Steam Devils

Multiple tornadoes of Smoke

Humans can not control the nature.

Better understanding of natural disasters

and causes can help us in minimizing the

damage.

By proper disaster management thousands

of lives can be saved.

Conclusion

Q & A