Building a seismograph
This report is about earthquakes and plates tectonic. It discusses what causes earthquakes, how they work, what people use to measure earthquakes, and how plates move. I think it is cool.
The composition of the earth includes a solid center called the core. On the outside it has a really thin crust over it. The crust is broken into giant puzzle pieces called tectonic plates. In between it has melted rocks with lava called magma.
The magma slowly moves due to convection currents. For example, boiling water is moving, the hot water goes up and the cold goes down. In the same way, the uneven heat of the mantle creates currents underground. That is why convection makes plates move.
Plate tectonics is the earth crust moving on top of the moving magma. The earth crust is divided into plates. A plate tectonic is a piece of earth crust. Plates can include both landmasses and areas of ocean floor. These plates are moving very, very slowly. The earth mantle is like a thick liquid of hot rocks, it flows very slowly. The earth crust floats on this thick liquid, the plates are carried along in the top of magma.
This movement causes earthquakes, volcanic formation and the formation of mountains. For example, sometimes, instead of pushing into one another, two plates move against each other. Friction holds the upper layers of crust together. But the plates continue to move deeper down and pressure builds up on the surface. When the strain has more force than the friction can hold, the plates slip. The movement sends shock waves through the earth. This is an earthquake. When two plates move by each other lateral earthquakes can be the result.
A seismograph is the device that scientist use
to measure earthquakes. The main problem that must be solve in creating a
seismograph is that when the ground shakes, so does the instrument. Therefore,
most seismographs involved a large mass of some sort. There is a very simple
seismograph, by hanging a large weight from a rope over a table. By attaching a
pen to the weight and taping a piece of paper to the table so that the pen can
draw on the paper. The seismograph
measure how strong is the earthquake, and which direction came from.