Chapter 9 : Earthquake and Volcano
It is the shaking of earth due to movements of rocks along a fault.
An earthquake is caused by the release of energy built up in the earth.
When this energy is released it travels out in all directions (including up and down).
These earthquake waves cause the ground to shake and shatter causing plenty of damage.
The study of earthquake and the waves they create is called seismology.
The surface of the earth is made up of great tectonic plates of rock.
These plates move slowly towards, or away from, each other.
Sometimes when they push together they slip and there is a jolt, and that is what we feel as an earthquake.
There are basically two types:
Topics covered in this snack-sized chapter:
Some earthquakes are related to volcanoes, earthquakes are along the edges of tectonic plates. This is where most volcanoes too occur.
The release of pressure caused by the grinding together of the tectonic plates creates the earthquake.
The plates are made of rock and drift all over the globe; they move both horizontally (sideways) and vertically (up and down).
Over long periods of time, the plates also change in size.
The Earth's surface is covered by a series of crustal plates.
The ocean floors are continually moving, spreading from the center, sinking at the edges, and being regenerated.
This theory explains the movement of the Earth's plates and also explains the cause of earthquakes, volcanoes and many other geologic phenomenon’s.
The top layer of the Earth's surface is called the Continental crust.
The thin crust under the oceans is called Oceanic crust.
Oceanic crust is thinner and denser than continental crust.
Crust is constantly being created and destroyed.
Oceanic crust is more active than continental crust.
A volcano is an opening, or rupture, in a planet's surface or crust.
It allows hot magma, volcanic ash and gases to escape from below the surface.
Volcanoes can also form where there is stretching and thinning of the Earth's crust in the interiors of plates.
Material which erupts during volcanic eruption is lava.
Lava: It is a molten rock erupted from volcano, also, such rock that has cooled and hardened.
The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases.
When the part of earth’s upper or lower crust melts, magma forms.
A volcano is essentially an opening through which this magma and the dissolved gases are discharged.
Volcanoes erupt when rock releases pressure.
It spreads and creates magma.
There are plates that are always shifting around in the ground.
They move 1cm every day. When the plates collide, they make a big BOOM which causes the things in the volcano to heat up.
Then the heat pushes everything to the opening in the volcano which causes it to erupt and shoot out.
Volcanoes are formed when the hot lava (magma) shoots out of the earth's crust.
The lava becomes hard on cooling down to form a volcanic mountain.
Drop down; take cover under a desk or table and hold on.
Stay indoors until the shaking stops and you're sure it's safe to exit.
Stay away from bookcases or furniture that can fall on you.
Stay away from windows. In a high-rise building, expect the fire alarms and sprinklers to go off during a quake.
If you are in bed, hold on and stay there, protecting your head with a pillow.
If you are outdoors, find a clear spot away from buildings, trees, and power lines. Drop to the ground.
Cover your mouth and nose. Volcanic ash can irritate your respiratory system.
Wear goggles to protect your eyes.
Keep skin covered to avoid irritation from contact with ash.
Ash fall is very heavy and can cause buildings to collapse. Exercise great caution when working on a roof
Wear long-sleeved shirts and long pants.
Use a dust mask or hold a damp cloth over your face to help breathing