Download Earthquakes

Earthquakes
Why do earthquakes happen?
Two of the crusts plates rub against each other and stick
in one place. Pressure builds up as they try and move
past each other.
Suddenly, the pressure is too much and the plates jerk
past each other. The place where this happens is called
the focus.
Vibrations go out in all directions through the rocks.
These vibrations are called shockwaves.
When the shockwaves reach the surface of the earth, they
cause the ground to shake. The most violent shaking is
directly above the focus at a point on the earth’s surface
called the epicentre.
The Richter Scale
1: Only felt by recording instruments
2: Felt by a few people especially in tall buildings
3: felt indoors, like a truck passing by
4: felt by most, windows shake, objects fall over/break
5: Damage to weaker buildings
6: Walls, monuments, chimneys, bookcases fall
7: Mostly all structures damaged, ground cracks,
landslides are caused.
8: The ground is moves like a wave, buildings fall and
massive damage.
What is an earthquake?
An earthquake is a trembling or shaking of the ground. Every
year, the earth is affected by over a million earthquakes .Most of
these vibrations are too weak to be felt. When they are severe,
however, earthquakes can have the deadliest impact of all
natural disasters. One of the most deadliest earthquakes was in
Haiti where a lot of damage happened.
What is the focus?
This is the place in the earth crust where the earthquakes starts.
Most focuses are less than 100km from the surface.
What is the epicentre?
This is the place on the earth’s surface directly above the focus.
From here the shock waves spread out over the earth’s surface
rather like ripples on a pond when a stone is thrown
The 2010 Haiti earthquake was a magnitude 7.0, with an
epicentre near the town of Léogâne, approximately 25
kilometres west of Port-au-Prince, Haiti's capital. The
earthquake occurred at 16:53 local time on Tuesday, 12 January
2010.