Natural hazards
Introduction
New Zealand is situated on the ring of fire, where 80 percent of earthquakes occur it is important to be educated on how earthquakes work and how to stay safe during an earthquake. This is why when we got the opportunity to investigate a natural hazard we chose earthquakes. In this inquiry we will be looking at how earthquakes are formed, the effects of earthquakes, and how we can mitigate the negative effects of earthquakes. We found four possible solutions for our fertile question ‘How can we mitigate the negative effects of an earthquake’. And came to a conclusion that having an isolated base on all houses is more effective.
What is an earthquake?
An earthquake is the result of a sudan slip on a fault. This causes a giant release of built up energy that we feel as a violent shaking called an earthquake. This energy is built up by the tectonic plates. As the tectonic plates are constantly moving under the earth's crust. they occasionally bump into each other and get stuck. As the plates try to keep moving they build up a significant amount of energy. Then when the plates are released all the energy is released in waves causing the destructive earthquakes.
What causes an earthquake?
So how is an earthquake caused?. Earthquakes are caused by movement in the tectonic plates. Tectonic plates are pieces of the earth's crust constantly moving.
There are seven tectonic plates on earth, African, Australian, Antarctic, Eurasian, North American, South American and Pacific. When these gigantic plates crash against each
Other they are under a huge amount of stress. Eventually they are forced to release, this movement creates waves of friction that shakes the earth. New Zealand is located on the edge of the pacific plate and the australian plate. This means we have a fault line that runs through the middle of the country. This makes the country vulnerable to earthquakes, tsunamis and volcanic eruptions.
Where do earthquakes occur?
Earthquakes occur where fault lines occur. Fault lines are lines that split tectonic plates and give them room to move or if a plate is going under another plate. These fault lines are the reason we get earthquakes. But there are three main places where these earthquakes occur. The first one is the mid-atlantic ridge, this is a fault line that runs through the atlantic ocean. Not very big earthquakes happen here but Iceland has felt a few magnitude 6 earthquakes. The second main place where they occur is the alpide belt; this is a fault that runs from the mediterranean to South East asia. About 5 to 6 percent of earthquakes happen here this fault has been the cause of 17 percent of Earth's largest earthquakes happen in this area. The third place where earthquakes usually occur is circum-pacific belt also known as the ring of fire. This is where 80 percent of earthquakes happen. New Zealand is located on the edge of the ring of fire and has a fault line that runs along the east coast and is where most or all of New Zealand's earthquakes occur. &
What does an earthquake do?
Most people think that earthquakes are the reason that so many people die. But it's the buildings we build that kills everyone. Because of the way we build buildings. If a magnitude 9 earthquake hit and you went to stand in the middle of the field the chances of you dying would almost be 0 percent. But if you were surrounded by skyscrapers and buildings the probability of you being crushed is very high.
How big can an earthquake get?
In the past earthquakes have done a lot of damage to cities and towns. But just how big can an earthquake get? According to scientists an earthquake cannot get bigger than magnitude 10 or above.When a magnitude 2.5 or less earthquake hits it’s very unlikely anyone's going to feel it, a magnitude 1 earthquake is equivalent to 500 grams of explosives. Any magnitude from 2.5 to 5.4 is often felt but only causes minor damage. An earthquake from 5.5 to 6.0 will only cause slight damage to buildings. An earthquake with the magnitude from 6.1 to 6.9 may cause major damage in populated areas. Any magnitude from 7.0 to 7.9 can cause serious damage. However a magnitude 8.0 or greater earthquake is equivalent to 500 million tons of explosives. And can destroy communities near to its epicenter.An earthquake cannot rea The biggest earthquake in recorded history was of magnitude 9.5 in Valdivia, chile. This earthquake left about 2 million people homeless and approximately 2,000 people died. In 2011 Japan was hit with a magnitude 9.1 earthquake that left 500,000 people homeless and killed 20,000 people. Our expert Mark Stirling said that we could be expecting a magnitude 9 earthquake (M9) along the Hikurangi subduction zone. This is a fault line that caused the Christchurch earthquake, it also triggered a tsunami warning a few weeks ago when the seafloor was hit with a magnitude 8 quake.
Numerical nata
What are the potential negative effects of and earthquake
The main negative effects of an earthquake are the large amount of lives earthquakes take. The enormous amount of buildings and belongings that are destroyed. The changing of the landscape and the causing of tsunamis and landslides.
This graph shows the amount of deaths in five different earthquakes across the world. As this graph shows, the Sendai earthquake in Japan on 3/11/2011 killed a lot more people than any other earthquake that has been recorded in this graph.
What are some positive effects of earthquakes?
What are some of the positive effects of earthquakes? One of the positive effects is land, without earthquakes there would be no land which would mean there would be no plants and there would be hardly no oxygen in the atmosphere. Another positive effect is when an earthquake occurs it can sometimes lift land out of the ocean making more space to build structures. And the other main positive is it helps humans extract oil, water and natural gases from the earth.
What can we do to mitigate the negative effects of an earthquake?
We found four main ways to reduce the negative effects of earthquakes.
The first out of the tree is base isolation. This design was created by a New Zealand scientist called Bill Robeson. His idea was to have a rubber block with a hole in the middle and then have a led core in the middle. The energy from the earthquake is absorbed by the led. And the led starts to act like plastic and lets the building move with the earthquake. With only simi contact with the ground. This design is widely accepted in California and Japan, however only 10 buildings in New Zealand have used this technique in their design and only one in Christchurch. As this design is extremely effective and reliable also this design is between 5 to 10 presents cheaper than a conventional. &
Our second solution to help reduce the negative effects of earthquakes. Is to make the building wave with the earthquake and then return to its original form after the earthquake has passed. Professor Stefano Pampanin at the University of Canterbury used the example of having two boxers. He said the worst way to receive a punch is to go straight into it. But the best way is to move with the punch because when you get hit there will be less impact. This design is based on flexibility and uses prefabricated blockers and high strength steel which acts as elastic under pressure. This theory or design was tested extensively at the University of Canterbury.&
Our third design to help reduce the negative effects of earthquakes. Is to have a fuse so the building breaks in the right place. These fuses will break when too much pressure is applied causing the building to collapse in a safer way causing less damage and less harm.&
As our fourth and final possible solution for reducing the negative effects of earthquakes. We thought of having a warning system to tell people there was going to be an earthquake so they can get away from danger. However this is not possible because there is no technology to tell when an earthquake is going to occur.
base isolation
making buildings wave with the quake
warning system
fuse so the building can breakin the right place
Cost
3
4
2
4
Effectiveness
1
2
5
3
effecancy
1
3
4
3
resources
4
4
1
3
time taking to make changes
4
4
3
4
Total
13
17
15
17
About our expert
Mark stirling was our expert. When he was a teenager in 1976 he experienced an earthquake in blenheim. He told me it was between a 6 and a 6.5 magnitude earthquake. He is now the professor/chair of earthquake science at the University of Otago. He specialises in earthquake statistics, active faults and seismic hazard analysis. When he went tranming in the local mountains near Blenheim he used to look down on the Wairau Fault. This inspired him to study geology at University. This later evolved into a speciality in faults and earthquakes.he then went on to teach and give talks at the University of Otago.
Conclusion
After looking into earthquakes and finding out more about them. We found that as most earthquakes effects are negative like building destruction, death and landscape changes. But also earthquakes can be positive in some ways. We found that having all new buildings built with base isolation would be the best way to mitigate the negative effects of earthquakes significantly, And could save thousands of lives.
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