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You know how when you have a really bad day and it seems like everything is going wrong? It's just one thing after another, and you get so frustrated that by the end of the day you are ready to explode from frustration. In fact, you may get so frustrated that you have a sudden outburst or release of all that built-up energy. And those unlucky enough to be around you when that happens should watch out!
Earth also builds up and releases energy in this way. When this occurs, we have an earthquake, which is the shaking of the ground when rock below Earth's surface breaks. Energy builds up underground and once it builds up enough it just can't hold back any longer, and we get the same explosive release of energy as a person might at the end of a long, bad day.
When the energy is released it radiates outward in all directions. As the energy travels toward Earth's surface from underground it shakes the ground, sometimes so much that it can cause damage above the ground. A seismograph is a machine that records ground movement from earthquakes. The information recorded tells us about the strength and speed of the energy traveling from the breaking point underground.
We now know what an earthquake is, but what exactly causes the rock underground to break? This is the result of stress along plate boundaries on Earth. The plates are dynamic, so they are always moving. Sometimes they move enough that they push into each other or pull apart. Compressional stress occurs when rocks are pushed together - they're pressed into one another. Tensional stress occurs when rocks are pulled apart - they're being stretched farther than they would be otherwise. Shear stress is when rocks slide past each other in opposite directions - it's like rubbing your hands together; they don't push or pull, but there's a lot of friction there!
When the stress gets to be too much, like all of the events building up on a bad day, the rock breaks and the ground begins to shake. If the rock splits into separate pieces, we get a fault, which is the line of fracture along the split rock. One of the most famous faults on Earth is the San Andreas Fault in California. This fault runs almost the entire length of the state of California, and is well known for causing frequent earthquakes in this area.
Earth also builds up and releases energy in this way. When this occurs, we have an earthquake, which is the shaking of the ground when rock below Earth's surface breaks. Energy builds up underground and once it builds up enough it just can't hold back any longer, and we get the same explosive release of energy as a person might at the end of a long, bad day.
When the energy is released it radiates outward in all directions. As the energy travels toward Earth's surface from underground it shakes the ground, sometimes so much that it can cause damage above the ground. A seismograph is a machine that records ground movement from earthquakes. The information recorded tells us about the strength and speed of the energy traveling from the breaking point underground.
Earth also builds up and releases energy in this way. When this occurs, we have an earthquake, which is the shaking of the ground when rock below Earth's surface breaks. Energy builds up underground and once it builds up enough it just can't hold back any longer, and we get the same explosive release of energy as a person might at the end of a long, bad day.
When the energy is released it radiates outward in all directions. As the energy travels toward Earth's surface from underground it shakes the ground, sometimes so much that it can cause damage above the ground. A seismograph is a machine that records ground movement from earthquakes. The information recorded tells us about the strength and speed of the energy traveling from the breaking point underground.
Earth also builds up and releases energy in this way. When this occurs, we have an earthquake, which is the shaking of the ground when rock below Earth's surface breaks.