Layers of the Earth
Earth is made up of three layers: crust, mantle and core. The outer layer is the crust, the middle layer is the mantle and the inner layer is the core. Earth's crust and upper mantle are broken into large plates that move slowly. Figure 1 shows the layers of the Earth. Figure 1: Layers of the Earth
The Earth's surface is formed of large pieces of rock called plates that are also called tectonic plates. These plates are always moving; sometimes they slide past one another at other times they collide with one another.
In geologic terms, a plate is a rigid, large and massive piece of solid rock. The word tectonics is derived from Greek word ‘tektonikos’ and it means ‘pertaining to build.’ These two words …show more content…
Strike-slip fault: This fault is caused due to shearing. The rocks tend to push each other horizontally in opposite directions. Ex: San Andreas Fault. Figure 6: Types of faults
The magnitude of an earthquake is measured using Richter’s scale with the help of an instrument called a seismograph, which measures and records the intensity of earthquakes.
There are three types of earthquake waves:
1. Primary waves: These are the waves that reach the surface of the earth first immediately after the energy is released in the earth’s crust.
2. Secondary waves: The waves reaching the surface after the primary waves are called secondary waves.
3. Surface waves: Primary and secondary waves affect the surface resulting in the generation of waves called surface waves. These waves are considered to be the most destructive waves.
Plate movement can also cause another natural disaster called volcano. Under certain conditions, when plates are pushed or pulled together, volcanoes are created thus, both earthquakes and volcanoes tend to occur in the same place.
A volcano is a cone-shaped hill formed by materials from the mantle being forced through an opening in the Earth's