INDEX FOR YOU TO KNOW

• 1 : INTRODUCTION

• 2 : FLOODS & DROUGHTS

• 3 : EARTHQUAKES

• 4 : HURRICANES

• 5 : GENERAL CONCLUSION

• 6 : THE END

INTRODUCTION

• We have always known about the high destructive power that our planet has.

• Earhquakes, tsunamis, floods, droughts, hurricanes have caused hundreds of thousands of deaths as well as damage valuated in billions of dollars in the last century. Many of them seem to have increased in frequency and intensity.

• Is this a natural fact or, do human beings have something to do with?

FLOODSFloods temporary covering of water

of land that is not normally covered by water.

heavy rainfalls

Caused snow melt

by hurricanes

tsunamis

Prevent move away from rivers

WAYS OF PREVENTING FLOODS

FRANCE:

GREAT FLOOD, PARIS 1910

RESERVOIRS TO REMOVE PRESSURE FROM THE SEINE

• LONDON: protected from sea flooding by mechanical barries

• VENICE:

EXAMPLE• FLOODING OF BIESCAS:

7th of August of 1996

• JAPAN – 11th of March 2010

DROUGHTS

• Droughts extended period of months or years when a region notes a deficiency in its water supply.

reduction in water quality

consequences famine

malnutrition &

dehydratation

migration

wars

wildfires

EARTHQUAKES AND TSUNAMIS

What is an Earthquake?

• Ground movement caused by the sudden release of seismic energy due to tectonic forces.

The focus of an earthquake is the location of the energy released inside the Earth’s crust.

The epicentre is the point on the Earth’s surface directly above the focus.

Where that it takes place ?

• This commonly occurs due to movement along tectonic plate boundaries.

Magnitude

Earthquake Effects Approx. number each

year< 2.5 Usually not felt, but recorded 900,000

2.5-5.4 Often felt, only minor damageOften felt, only minor damage 30,000

5.5-6.0 Slight damage to buildings and other structures

500

6.1-6.9 May cause a lot of damage in very populated areas

100

7.0-7.9 Major earthquake. Serious damage.

20

> 8.0 Great earthquake. Can be totally destructive near the epicentre.

1 every 5-10 years

• Magnitude 7.7 - 8.3

How do we mitigate the hazard from earthquakes?

• Reinforcing buildings• Education• Disaster plans

Earthquakes and Tsunami’s

• An earthquake under the ocean has the potential to form a tsunami.

• The earthquake must vertically displace overlying water (extensional or compressional faults - not transform)

Extension CompressionTransform

2004 South Asian Boxing Day event

• Biggest earthquake in 40 years!

• Magnitude 9.2• 150 km off the west

of Northern Sumatra

• Generated a disastrous tsunami in 12 countries

Tsunami

Animations of the Boxing Day tsunami showing how the tsunami radiated from the entire length of the 1,600 km (994 miles) rupture.

Above: Countries most effected by the tsunami

A village near the coast of Sumatra lays in ruin after the tsunami.

A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain.

“Tropical”comes from the fact that they usually develop in the tropics, while “cyclone” comes from their typical shape: a round amount (group) of rotating clouds and winds surrounding a clear area in the center, known as “eye”.

Tropical cyclones are seasonal. In the northern hemisphere the season is usually from August-November. In the southern hemisphere the hurricane season is usually between March-May.

According to their winds speed, tropical cyclons are clasiffied into three types:

If its wind speed is higher than 118 kph, then the cyclone is considered a hurricane.

If the wind speed is lower than 63 kph, then the cyclone is known as tropical depression.

If it is between 63 and 118 kph, then it is called tropical storm.

The high insolation of the zones between tropics increases the ocean’s temperature, making a lot of water to evaporate, mainly at the end of the summer. The air above the ocean is heated too and, as a result, convenction currents start when the air moves from the cool zones, which have high atmospheric pressure, to the hot ones. These currents, combined with high evaporation, promote the formation of big storm clouds, which start spinning due to air currents and the Coriolis effect.

As the pressure in the center drops, the cyclone grows. If the cyclone grows enough, in the center it develops a low pressure clear area known as “eye”, due to the rotational forces that prevent anything from staying there.

A typical hurricane structure

Hurricanes are the biggest, strongest and so, most destructive type of tropical cyclone. They can reach more than 700 km wide, and

have wind speeds over 300 kph.

For this reason, it isn´t odd that they are one of the most destructive natural

disasters. It is estimated that about 10.000 people die every year due to tropical

cyclones some of which are hurricanes

Hurricanes destructive effects are mainly caused by:

-Theirs strong, fast winds, that can reach speeds over 200kph.

-Theirs heavy rainfalls, very likely to cause floods.

-The possibility to create tornadoes as a result of the pressure differences inside the storm.

-The increase in the sea level when landfalling, which causes floods and can cut off scape routes.

One good example of a highly destructive hurricane was Hurricane Katrina.

THANK YOU FOR

LISTENING!

By: Javier Casatorres Mon-puo Lee Shu Ana Casas