The earth’s crust is made of about 30 huge plates, called tectonic plates, that float on the semi-liquid mantle are surrounding the earth’s core. There are currents and movements in the mantle, so these plates move very slowly in relation to each other.
Earthquakes are evidence of this movement. Most of the area where earthquakes take place are along the edges of these plates. Friction holds the plate edges together for a while but continuing movement means that huge stresses build up. The tension is suddenly released when the plates shift sharply, but this causes an earthquake. There are other causes of earthquakes, but they all involve sudden movement of the crust along a fault or crack.
A tornado is formed when huge masses of clouds moving in different directions meet. The air starts to spin in a spiral and a funnel of twisting air reaching out towards the ground. The low pressure inside the funnel sucks up the soil, dust and anything else it touches.
Tornados are violent destructive whirlwind whose force is concentrated into a much smaller area than a hurricane. They travel across land at very high speeds and the roaring noise the make can be heard 40km away.