https://www.youtube.com/watch?v=DrwYtGf40hA
June 2 2013
AN EDUCATIONAL DOCUMENTARY ON PLATE TECTONICS
https://www.youtube.com/watch?v=1-HwPR_4mP4
June 2 2013
WHAT CAUSES AN EARTHQUAKE?
(Following the 5.7 magnitude earthquake which hit North Cotabato late last night, I am posting herewith some information which could help educate people on what causes earthquakes. I hope this will help. The picture and information were lifted from wikipedia.com and other internet sites.)
The processes of “plate tectonics” are what cause an earthquake.
An answer for young students:
Earthquakes are shakes and jiggles in the huge pieces of the Earth that form the outside of the big ball of our planet. We and the dirt and trees and other living things live on top of these big pieces of our Earth. These pieces are called plates. They “float” around on the Earth’s hot crust very very slowly, so slowly you can’t see them move. But as they creep along, they bump into each other sometimes. They can even get in a “traffic jam” and push real hard against each other.
When they bump and push together, the pressure builds up until something has to give and move from all the force. All at once when pieces find a way to get unjammed, the pressure that has made them squish together really tight lets go and a sudden jerk can happen as one plate gets on top of another or as they slide past each other. This jerking causes the scrunches and wrinkles of the plates that were jamming into each other to suddenly let go and “Boing!” Shakes and jiggles go rushing out of the tight spot as the plates move over or under or around each other. These jerks move in waves all across the huge plates to relieve the tension. These released forces are very powerful and they are what make the ground move, wiggle and vibrate so that we can feel it from very far away.
A basic answer for adults:
The surface of the earth is made up of great tectonic plates of rock. These plates are all moving 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.
The release of pressure caused by the grinding together of the tectonic plates creates the earthquake. Imagine the Earth’s outer layer as being cracked into many pieces. These pieces, called tectonic plates “float” on the melted core of the earth. Because of this, they shift around ever so slightly and as they shift, they can grind against each other. This builds up pressure until the two plates slip, releasing their energy in what we feel as an earthquake.
If you slowly but firmly rub your hands together you can feel how they seem to stick for a moment before finally sliding. It’s the same thing with the tectonic plates.
More Information:
Movement of the Earth’s crust along the plate margins causes up-heaving and instability in land or ocean masses. Plate Tectonics is what this movement of the Earth’s crust is called. The Earth’s plates are constantly moving and can push together in places. Sometimes they get into a “traffic jam”. As plates move and interact with each other, stress (pressure) builds up over time. When the stress increases to a certain point, it overcomes the tendency of the plates to press together and creates a sudden shift in the plate positions, resulting in what are called seismic waves. These waves are what we feel as an earthquake as they move out and away from the epicenter of the plate shift.
There are a few other occurrences that can cause earthquakes, including human activities (described below), but the majority are caused by plate tectonics.
Additional Information and Terminology:
Earthquakes are recorded with a seismometer. Seismologists can use the data to estimate the strength (more correctly termed the magnitude) of an earthquake; the distance to the center of the earthquake; and, if data from enough seismometer stations are available, the location of the earthquake’s epicenter. [An earthquake’s point of initial rupture is called its focus or hypocenter. The term epicenter refers to the point at ground level directly above the hypocenter.]
The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicenter of the earthquake.
The Earth’s tectonic plates are constantly moving very slowly (at a rate of cm/year).
Interesting Note:
The crack lines where this happens are called fault lines. Wherever there are fault lines, you normally find more earthquakes.
There are four tectonic plates near Japan: the Eurasian Plate, the Pacific Plate, the North American Plate and the Philippine Plate. The March 2011 earthquake involved the Pacific Plate diving under the North American Plate. This move of one plate below another is called subduction.
There are also big fault lines under Los Angeles. There are two main tectonic plates that meet under California. New Zealand also has large fault lines in the area.
That’s a reason why there are so many massive earthquakes and tsunami in those areas.
More Stories
Cotabato Food Republic: Master Plan 2025-2030
‘Billions For Ayuda Pero Bukid Walang Kalsada!’ (Last of 3 Installments)
Practical Cattle Raising In Backyard Paddocks (3rd of a Series) Brahman Best Breed For Tropical Countries