The Restless Earth

EARTHS LAYERSTHREE LAYERS 1. The Core Made up of nickel and iron. Temperatures are hottest at the core. 2. The Mantle Is so hot that the rocks have melted into a semi molten state. This molten flows and moves in currents. At up to 4000 C 3. The Crust This is the earths skin and consists of solid rock. It is between 10 and 60km in thickness.

 The earths crust is broken into a number of different sections called plates.  These huge plates float on the semi molten rock of the mantle  The drift slowly on the mantle moving our continents with them! This is called continental drift  The plates constantly collide and separate from each other. This causes volcanic activity, earthquakes and folding.

 The plates of the earths crust float on the heavier, semi – molten rock of the mantle  The mantle is heated by the very hot core and this causes it to move in slow but constant currents.  Friction between the plates causes the plates to move – separate and collide!!

 When plates collide it causes??  Earthquakes  Fold mountains  When plates separate it causes??  Volcanic activity  Mid ocean ridges  Volcanic islands  Volcanic mountains

Plates moving in opposite directions cause? Volcanoes Plates colliding can cause? Earthquakes

 When plates collide and push together there is massive pressure at these zones of contact.  This pressure causes the crust to be forced upwards at these zones of contact. These are called fold mountains

 The Alps, the Rocky Mountains and the Andes are examples of fold mountains  These mountain ranges were formed during the “Alpine folding's” about 35 million years ago  Irelands fold mountains were formed hundreds of millions of years ago and are lower in stature because of years of being worn down (erosion)

What does this picture illustrate ?

Earthquakes occur when two tectonic plates move suddenly against each other. The rocks usually break underground and the earth shakes. Waves spread from the epicentre the point on the surface above the point of contact of the plates (hypocentre) if a quake occurs under the sea it can cause a tsunami.

California California in the United States suffers from severe earthquakes because it is situated where the Pacific and North American plates push past each other. These plates tend to stick together until enough pressure builds up for one plate to jerk forward a little. This jerking movement releases the shock waves of an earthquake. In 1906 a strong earthquake rocked the city of San Francisco. Buildings collapsed. Gas fires were broken, causing fires which destroyed much of the city. Wide streets and specially reinforced ‘earthquake proof’ buildings are expected to lessen the effects of further Californian earthquakes.

 When plates collide or slip past each other earthquakes are caused  The colliding and slipping causes such compression that the rock beneath the surface bends and then cracks suddenly  When this happens shock waves spread from the focus ( the place where the cracks occur)  This causes the earths surface to tremble for several seconds  The earthquake is usually strongest at the epicentre (the surface directly above the focus)

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Lava – molten magma Plate movement

Lav a Crater Vent

Haiti Earthquake The 2010 Haiti earthquake was a catastrophic magnitude 7.0 Mw earthquake, with an epicentre near the town of Léogâne. The earthquake occurred at 16:53 local time on Tuesday, 12 January By 24 January, at least 52 aftershocks measuring 4.5 or greater had been recorded. An estimated three million people were affected by the quake. The Haitian Government reported that an estimated 230,000 people had died, 300,000 had been injured and 1,000,000 made homeless. They also estimated that 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged. Many countries responded to appeals for humanitarian aid, pledging funds and dispatching rescue and medical teams, engineers and support personnel. Communication systems, air, land, and sea transport facilities, hospitals, and electrical networks had been damaged by the earthquake, which hampered rescue and aid efforts; confusion over who was in charge, air traffic congestion, and problems with prioritisation of flights further complicated early relief work. Port-au-Prince's morgues were quickly overwhelmed with many tens of thousands of bodies having to be buried in mass graves. As rescues tailed off, supplies, medical care and sanitation became priorities. Delays in aid distribution led to angry appeals from aid workers and survivors, and looting and sporadic violence were observed.