Earthquake region

  • The greatest concentration of earthquakes is found around the Pacific Ocean.

  • Another stretches from the Mediterranean sea to the Hilmalayas.

  • Both areas are the plates moving towards each other.

  • The volcanic belt coincide with the major earthquake zone.THE EARTHQUAKE REGIONS

THE PLATES AND THE RING OF FIRE REGION


AN EARTHQUAKE

WHAT IS AN EARTHQUAKE?

The vibration or tremors in the earth’s crust , caused by a sudden release of energy when the rock displaced along a fault.

THE FORMATION OF AN EARTHQUAKE

When two plates move towards or away from each other or slide movement is not smooth cause the friction between the moving plates cause stress to build up in the crust and eventually faulting occurs.  The rock breaks and move in sudden jerks along the fracture. The energy which has been stored up in the rocks is suddenly released as shock waves. This cause vibration or tremors of the earth’s surface known as an earthquake.

THE FORMATION OF EARTHQUAKE

THE PLATE MOVES AND BREAK PRODUCED SHOCK WAVES

Shockwaves of the earthquakes

During an earthquake the shock waves spread out in all directions from the point where the earthquake starts.

The point in the earth’s crust at which an earthquake starts is called the focus.

The point on the earth’s crust that is directly above the focus is the epicentre.

The shock waves are the strongest at the epicentre and so the greatest damage in that area.

PLATE MOVEMENT- TRANSFORM

Slide past each other ( Transform plate)

When the two plates past  slide each others. This will change the location of the original plate. Earthquakes commonly take place along the plate boundary. The Pacific plate and the North American slide past each other.

Transform plate between Pacific Plate and North American Plate

PLATE MOVEMENT- DIVERGENT

Move away from each other (DIVERGENT PLATE)

When the two plates move away from each others.  As the plate moves apart, the rocks break and form fractures in the crust when an earthquake occur along the plate boundary. Magma from the mantle rises to the ocean floor through these fractures and solidifies at the plate boundary, form new crust. The boundaries where the plates move apart are described as “CONSTRUCTIVE PLATE BOUNDARIES” because new crust is being formed and added to the ocean floor. As the result, the ocean floor gradually extends and increases in size.This will make the sea floor spreading and extended the Oceanic ridges. Oceanic ridges is form when the magma continues to rise on the ocean floor and piles up and solidifies forming a long chain of mountains on the ocean floor.

a) the formation of ocean ridges b) the ocean floor spreading and extended

PLATE MOVEMENT- CONVERGENT

MOVE TOWARDS EACH OTHER    (CONVERGENT PLATE)

When the two plates move towards or collide each others. This will make the subduction where one plate ( oceanic crust) move downwards beneath the other plate into underlying mantle and form block of mountain ( Continental crust) and oceanic ridges ( Oceanic crust). Subduction is the process which a plate is pushed downwards beneath another plate into the underlying mantle. The boundaries where plates move toward each other are described as “Destructive Plate boundaries” because part of the plate melts during the subduction and is destroyed. Some magma forces its way upward through the fracture crust and reaches the surface forming Volcanoes.

Subduction process as the arrow goes downward

THE PLATE TECTONIC MOVEMENT

How the plate moves?

The convection current in the mantle inside the earth is very hot. The heat cause the magma in the mantle to expand and rise. The magma cause risen and spread out beneath the plates. As the result of this the plate moves. The repeated heating and rising of the magma set up continuous convection currents in the mantle causing the plate to move.

PLATES

What is a PLATE?

Plate is a crust together with the upper part of mantle is divided into pieces. Plate is like a jig-saw puzzle frame to the earth’s crust. There are many major plates and several smaller ones can be found.  The earth is made up of moving plate is put forward in the Plate Tectonics Theory.