Saturday 23 June 2012

Earthquake Written Report


Earthquakes

By
Geoffrey
5L

Definition
An earthquake is a movement in the earth’s crust that is caused by a build-up of pressure. This sends out a series of shock-waves.  
  
Components

- Types of earthquakes
There are three types of earthquakes; strike-slip, normal (reverse) and thrust. Strike-slip is when the tectonic plates rub together. Normal (reverse) is when the tectonic plates try to pull apart. Thrust is when two tectonic plates crash together. 

-Tectonic plates
Tectonic plates are part of the Earths crust which is driven around by the mantles heat. There are 12 tectonic plates on the Earth; 8 massive ones and 4 small ones.   

-Aftershocks
Aftershocks are mini earthquakes which happen after the main earthquake. Sometimes the aftershocks are bigger than the main earthquake.

-Measurement
We measure earthquakes with the Richter scale and sometimes with the seismograph. Seismographs can detect very small earthquakes that we cant feel. The Richter scale can measure very high earthquakes. The Richter scale was named after Charles Richter because he invented it.  

-Effects
The effects of earthquakes are shaking of the ground, ground rupture, landslides, avalanches, fires, soil liquefaction, tsunamis, floods and human impacts. Human impacts are buildings being destroyed, people dying and roads being completely destroyed.

-Major earthquakes
An earthquake in China was believed to be 9.0 on the Richter Scale in 1556. Another big earthquake was in North America which was 9.0 on the Richter Scale around the year 1700. The biggest earthquake ever heard of was a 9.5 killer earthquake in Chile, in 1960. A smaller quake was a 9.2 in 1964, in Alaska, which was on Good Friday.

-Predictions
No one ever knows when an earthquake is going to happen.

-Preparation for earthquakes
You cant really prepare for an earthquake because you cant predict an earthquake. If you know an earthquake is going to happen you should nail bookshelves to the wall, keep books secure on the book shelves and put things in the bottom shelves. You should also lock up cupboards and put beds in the middle of the room. During an earthquake you should keep away from trees, glass, and walls.
 Case study
The 1811 to 1812 the New Madrid earthquake interested me because it was an earthquake over 8.0 on the Richter Scale. This earthquake was in the night and it threw people out of their beds. The aftershocks happened for five months. Sand geezers came out of the ground, the Mississippi river ran backwards, lakes dried up and three earthquakes happened in that year.

Positives of earthquakes

 

Earthquakes are good because they reshape the earth so we get more hills, mountains, valleys, lakes and rivers. 

Negatives of Earthquakes
Earthquakes do more bad than good. Evidence of this is that hundreds and thousands of people die each year. Billions of dollars are wasted because of earthquakes and many buildings are damaged.

 Living with or Surviving Earthquakes
To live and survive in an earthquake prone area you should build wooden houses rather than brick houses because wooden houses are more flexible and brick houses normally crash down during earthquakes.


 Interesting facts about earthquakes
An interesting fact about earthquakes is that earthquakes don’t have to happen on fault lines. Stress can build up in the middle of tectonic plates. Then the tectonic plate tries to pull apart which causes an earthquake. If you dig down 35 kilometres into the Earth you will find the mantle, and if you dig down 5 kilometres under the sea you will also see the mantle.

Summary
In summary, this book talks about earthquakes and what they do to us. This report can tell us lots about earthquakes. It tells about the definition of earthquakes, the different types of earthquakes, tectonic plates, aftershocks, measurement of earthquakes, effects of earthquakes, major earthquakes and the positives and the negatives of earthquakes.