Earthquake By: Carlos, Frances, Valeska, Jason

What is an Earthquake? Earthquake – Is the vibration of Earth produced by the rapid release of energy

Cause of Earthquake Earthquake are naturally cause when the underground breaks into the fault. They sudden releases of energy causes the seismic waves that make the ground shake. Two blocks of a rock or two plates are rubbing against each other.

Focus and Epicenter The point within Earth where the earthquake starts is called focus. The released energy radiates in all directions from the focus in the form of waves. The impact of the stone sets water waves in motion.

Faults What causes Faults Tensional stress is when slabs of rock are pulled apart. Imagine stretching a rope out all the way and then continuing to pull on it from both ends. You're putting tension on the rope because it's being pulled in opposite directions. The same is true for tensional stress in rocks. Compressional stress is when slabs of rock are pushed together. They are literally being compressed into one another. This is like when two cars crash into each other - they're compressed into smaller, crumpled versions of what they were before. Shear stress is when slabs of rock slide past each other horizontally in opposite directions. The rocks are not smashed into each other or pulled apart, but their edges slide along each other with a lot of friction. This is like when you rub your hands together to warm them up. One hand goes forward and the other goes backward, rubbing against each other.

Elastic Rebound Hypothesis The springing back of the rock into its original place. They are like a stretched rubber band when it released. Is the explanation for the release of energy stored in deformed rocks.

Important information Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces. When the strength of the rock is exceeded, it suddenly breaks, causing the vibrations of an earthquake.

Aftershocks and Foreshocks Most of the movement along the fault occurred in short time period. The movement after an earthquakes is called an aftershock. Small earthquakes before a major earthquake is called a foreshock. The difference between an aftershock and a foreshock is that a foreshock is small and an aftershock can be any size.

1) Why is earthquakes caused? 2)What are earthquakes produced most ?