Presentation on theme: "EARTHQUAKE In terms of earth movements we live in one of the most active areas on earth. Earthquakes are one of the results of earth."— Presentation transcript:
In terms of earth movements we live in one of the most active areas on earth. Earthquakes are one of the results of earth movements, volcanoes are another. New Zealand has plenty of the former and a few of the latter. Can you name any volcanoes in NZ?
EARTHQUAKE How many earthquakes do you think NZ has each year? The Institute of Geological and Nuclear Sciences locates about 10,000-15,000 each year but only are large enough to be felt by people. The biggest NZ earthquake was the magnitude 8.2 earthquake in 1855 which was centred on the WAIRARAPA! We live in a quake zone and should understand how they happen and what we can do to reduce the impacts of earthquakes. The Wairarapa is well overdue for another big shake down.
EARTHQUAKE Earthquakes are a result of the structure of the earth. Structure of the Earth The earths crust is broken into lots of pieces which ‘float’ on the magma in the mantle. They all fit tightly together so magma doesn’t escape. Just like a giant jigsaw puzzle.
Earthquakes generally occur at or near plate margins. The plates are pulled about by the movement of magma underneath them. The magma is moved by convection currents. As a result there are different types of margin or boundary between plates. There are 4 main types of margin: ConstructiveConservative DestructiveCollision
EARTHQUAKE Destructive margin Plate Margins
EARTHQUAKE Collision margin
EARTHQUAKE Conservative margin
EARTHQUAKE Constructive margin
EARTHQUAKE New Zealand sits on the margin between the Pacific and Indo-Australian plates.
EARTHQUAKE NZ is a fractured country with fault lines running from the north to the south. These are weaknesses in the rock and some are where the plates meet. Masterton
EARTHQUAKE The main fault line is the Alpine fault which runs through South Island. North Island has a fault line that runs along side the motorway and then comes up through the Rimutakas and along the bottom of the hills up past Masterton. This fault line is less than 20km from where we are at school. If the plates decide to move what will happen to us here?
EARTHQUAKE What causes the earthquake? As plates move they build up pressure between them. After a while the pressure gets too much for the plate margin to hold and so there is a release of pressure as the plates snap into their new position. BBC NEWS | Science/Nature | How earthquakes happen
EARTHQUAKE During an earthquake the ground shakes and buildings move. Solid structures like concrete and brick built houses and offices tend to be more affected than wooden structures. Why do you think this is? Wooden structures are able to flex with the ground whereas concrete has no flexibility so cracks and breaks. Anything not fixed to walls or other surfaces will fall off or over and may harm anyone nearby.
EARTHQUAKE The first shocks in a big earthquake do lots of damage. Some building may be destroyed, others are seriously weakened. Some earthquakes have aftershocks which may be as big as the main earthquake. These often do more damage and kill more people than the initial ‘quake. During an earthquake many of the services that we take for granted may be damaged. Can you name any?
EARTHQUAKE Without water it is hard to put out the fires that have started due to electrical faults or burst gas pipes. If roads are damaged it is hard for the emergency services to get to the places where they are needed. If you can get to the hospital because you are injured will it be there or will it be a pile of rubble? Are the fire station and ambulance stations operational or are the vehicles trapped inside? What can you do?
EARTHQUAKE During the earthquake: Get under a door frame or desk Stay where you are if possible Don’t panic Before the earthquake: Make a plan Prepare an emergency kit which will have food, water and clothing in it as well as a medical supplies Strap things down in your house so they don’t fall on you
Earthquakes are measured using seismographs which record the energy of the quake. This energy is reported using one of two scales: Richter scale – goes up to 10 Meracalli scale – goes up to 12 Meraclli scale activity Survival guide activity Earthquake crossword
EARTHQUAKE Case study: Pakistan Earthquake 2005
Saturday 8:50AM, Oct 8th, 2005: A powerful 7.6 magnitude earthquake struck the India- Pakistan border with more than 140 aftershocks, causing extensive damage in Pakistan, India and Afghanistan.
Reports indicate more than 82,000 people have been killed and more than 3.3 million people have been left injured or homeless and more than 1,000 hospitals destroyed.
The death toll is expected to rise, a spokesman said, because rescue workers and the military have been unable to access some of the remote areas hit by the quake. He said entire villages and many roads have been wiped out by landslides. "The army has fully mobilized to handle this situation. This disaster is by far the biggest in its magnitude and scale so far that we have witnessed in Pakistan's history," a general said.
Earthquakes happen mostly where the earth's tectonic plates collide. In Pakistan, quake activity is mainly concentrated in the northern and western sections of the country, along the boundary of the Indian, Iranian and Eurasian plates. The Indian plate is moving north at about 5cm a year, resulting in a force on the southern edge of the Tibetan plateau—the force that generates the Himalayas. Why did the Pakistan earthquake happen? This is a collision boundary.
Now it’s your turn…. Complete the exercise on the handout sheet. You will have 3 sessions in the computer room to do research etc then a week to complete the final piece of work.