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Earthquakes 101

Apr 28, 2015

Thousands of earthquakes happen across the US each year. The good thing is, almost all of them are too small to feel. Most earthquakes in North America happen west of the Rocky Mountains, but there are still 39 states that are at serious risk for quakes.

Plate Tectonics

Our planet is divided into a three main layers: a solid core, a liquid magma mantle and a crust , which floats on top. That top crust is made up of individual plates, which are kept in constant motion by convection currents in the magma.

Tectonic PlatesTectonic Plates

Types of Plate Boundaries

Earthquakes mostly occur at the boundary where one plates meets another. Plates either converge, collide, diverge or move past each other when they meet. When plates "converge," it means that one plate is slowly pushed beneath the other over the span of several thousand years. Plates that collide push rock layers upward, which creates mountains. When plates move away from each other or "diverge," lava comes up from the mantle and cools to form new sections of crust. Other plates simply move slowly past each other.

Earthquake!

In some places, the plates become locked together. Energy builds up in the locked plates, which is released in the form of an earthquake when the plates finally give. The place where the earthquake originates beneath the surface is called the hypocenter. The point on the surface directly above the hypocenter is called the epicenter - a word you've probably heard many times in the news whenever a major earthquake is reported.

Ride the Waves

An earthquake emits its power as three waves of energy. Primary waves (a.k.a. P-Waves) are felts as a sudden jolt. Secondary waves (a.k.a. S-waves) arrive moments later and are felt as a more ongoing side-to-side shaking. Surface waves arrive after the main P and S waves, and radiate outwards from the epicenter.

Earthquake WavesEarthquake Waves

Recording Zigzags

A seismograph is a machine that records the ground vibrations during a quake. A needle keeps drawing straight lines until the earth trembles, then the lines start to zigzag. The bigger the zigzags, the bigger the quake. The strength of an earthquake is measured by the Richter scale. Based on the seismograph readings, the Richter scale rates a quake using numbers 0-9, nine being the mother of all quakes.

Home-Made SeismographHome-Made Seismograph

Earthquakes: The Richter Scale

  • 1: Generally not felt, except by instruments.
  • 2: Generally not felt, except by instruments.
  • 3: Sometimes felt by people, but no damage.
  • 4: Sometimes felt by people, but no damage.
  • 5: Felt by most people, damage near epicenter (where the plates actually smashed into one another).
  • 6: Damage to buildings within six miles (10 km) of the epicenter.
  • 7: Serious damage to buildings within 60 miles (100 km) of the epicenter. Loss of life.
  • 8: Major earthquake with damage being caused to a huge area. Loss of life over 120 miles (200 km).
  • 9: Very rare. Major damage and loss of life up to 600 miles (1,000 km) away.

The Richter ScaleThe Richter Scale

Are They Predictable?

So far, scientists have yet to develop a reliable way of predicting earthquakes. There are, of course, many factors that they believe lead up to earthquakes, like change in groundwater chemistry, foreshocks (small, insignificant quakes) and strain in underground rocks. Because each quake seems to be caused by a different combination of these factors, it makes it very difficult to make predictions far enough in advance to help people. Seconds before a quake, pets like dogs and cats might get a little freaky, as they seem to be able to feel the trembling well before we do.!

What To Do In An Earthquake

One of the biggest quake dangers is being hit on the head or trapped under something. If you are indoors, stay put. Place something protective on your head and crouch under a table or stand in a doorway. If you are outside, quickly find an open space and stay away from things that will fall on you. After an earthquake, be prepared for aftershocks. Aftershocks follow earthquakes and are usually smaller than the actual quake. They are dangerous because they can cause things that were weakened from the original earthquake to fall down.

Earthquake Preparedness KitEarthquake Preparedness Kit

For more information on earthquakes check out check out www.fema.com.

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Disaster You'd Least Like to Get Caught In?

  • Hurricane.
  • Flash flood.
  • Avalanche.
  • Earthquake.

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drowning
drowning posted in Debating:
It's questions like this that make me lose a little more hope in humanity as each day passes by.
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cubicfairy
Kawaii Chan P.O.V Kawaii waited at the bus stop after leaving the house, only just hearing what Katelyn said, she was tempted to go back and finish the cupcake... No, she had to see Zane. The bus came and she went in "where you goin' today sugar?" Kawaii Chan smiled at the man "kawaii Chan is going to the hospital" she said, giving the man a few dollars "please take a seat" kawaii Chan nodded as the bus driver tipped his hat at her, and they started up the road Zane P.O.V Zane felt the wheel chair go over a bump and into the air-conditioned hospital, he shivered, hearing doctors speak, kids crying and adults grunting, groaning and moaning made him nervous, thinking he had to look proper, he sat up straight, instantly regretting it, his back cracked and the nurse laughed "you know, you don't have to be fancy to be at a hospital, right?" Zane sighed "well it sure felt that way" the nurse laughed again, not responding though, then he heard running footsteps behind him, slightly screaming, then a voice "Zane kun!" He realised who it was, "k-kawaii Chan?" Kawaii Chan laughed "of course it's kawaii Chan, silly!" He bit his lip "okay.." he felt himself going over another bump, probably his hospital room, "uh, Zane, you'll need to get up to get on the bed, though you can't see, you think you'll be alright?" Zane shook his head "no" someone took his hand "kawaii Chan can help!" He realised kawaii Chan holding his hand, but he knew he was okay, it was kawaii Chan, he would be safe with her, he realised he was muttering "miss, you're blushing, are you alright?" The nurse said, and kawaii Chan giggled "I'm okay"
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AlphaT
AlphaT posted in Say Anything:
"Ritterkreuz" wrote: I would become president of Israel and enforce an open borders policy to culturally enrich the land. Their walls are too great to be broken in one day, plebe.
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XxRuby_PhoenixxX
America.
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Shadeleaf
Shadeleaf posted in Debating:
"boredlol" wrote: First there will be the Rapture. Then the ########## will sign a seven year treaty with Israel. When the ########## signs the treaty, the start of the Tribulation will commence. Then will begin the judgments. When three and a half years pass, the great Tribulation will start. After three and a half more years, the Lord will descend from the heavens. The earth will be destroyed and and new, perfect world will be created by the Lord. You can read about this in the book of Revelation. A really interesting book series I read is based on this. It's called Left Behind. There is Left Behind the kids and Left Behind (adults). Left Behind the kids is the story of four teenagers. Left Behind is the story of adults. I read the whole fifty book kids series twice. I'm in the middle of reading the sixteen book adult series. The kids series is more for teens and teens. As for the adult series, twe######d teens can probably read it, but you can decide. The adult series is more graphic, but still good nonetheless. Sorry for doing this super long post. Bye! Ohhhh I love that series! Anyways,  I should say this is how I imagined the Apocalypse, the End of Days, Armeggedon.
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