Earthquakes
A earthquakes is the shaking of the ground. There is a whole branch of Earth science dedicated to the research of earthquakes called seismology. Earthquakes can be very confusing and complex but they leave many questions for seismologists, or the scientist who study earthquakes to answer. Most earthquakes take place near the edges of tectonic plates. Tectonic plates push, pull, or slip past each other, which causes stress along the plates edges. Deformation is the change in a rock due to stress. Most rocks around a fault deform in two ways. The first is plastic deformation which resembles a piece of clay being molded. The other type of deformation is elastic deformation is the sudden return of deformed rock to its original shape. It resembles a rubber band being stretched and then it quickly returns to its unstretched position. A earthquake zone is where a large number of faults are located. Waves of energy that travel through the are called seismic waves. Seismic waves that travel through the earth are called body waves and seismic waves that travel along the surface are called surface waves. The speed of the wave depends on the objects it travels through. Waves that travel through solids, liquids, and gases are called P waves. P waves are the fastest seismic wave. They are also called primary waves because they are the first kind of wave to be detected when a earthquake hits. When a rock is deformed from side to side , the rock springs back to its original position and S waves are created. They are also known as shear waves and are the second fastest kind of seismic wave. S waves shear rock from side to side, which means they stretch the rock sideways. Another name for S waves are secondary waves because they arrive second. Surface waves move along the earths surface and the produce motion in the upper few miles of the earth. There are two types of seismic waves. One surface wave produces the up, down, and around motion and the other produces the back and forth motion. A seismograph is a instrument located at or near the earths surface and it records the seismic waves. A seismogram is the tracing of a earthquakes motion and is created by a seismograph. You can determine the time and location of a earthquake by finding the epicenter, or point directly above an earthquakes center ,or finding the focus, the focus is the point inside the Earth where a earthquake begins. The easiest way a seismologist can find the epicenter of a earthquake is the S-P time method. The S-P time method works by the seismologists uses multiple seismographs and they trace the first S wave with the S wave curve and the first P wave with the P wave curve. After finding out the distances, you can find the beginning of a earthquake by aligning the stations and reading horizontally to find the axis. The Richter Magnitude Scale measures the strength of a earthquake. The Modified Mercalli Intensity Scale measures the amount of damage caused by an earthquake otherwise known as intensity. Earthquake hazard is the measurement of how likely an area is to have a damaging earthquake in the future. Gap hypothesis states that sections of active faults that have had few earthquakes in the past are going to have many strong earthquakes in the future. Seismic gap is the complete opposite of gap hypothesis. Seismic gap is the area along a fault where few earthquakes have occurred recently but where strong earthquakes have occurred in the past. There are five types of earthquake resistance technology. A mass damper which is a weight placed at the top of a building and acts as motion sensors which tell the computer to correspond with the movement. An active tendon system works like a mass damper but it supports the bottom half of the building and shifts the weight to counteract the movement. A base isolator acts as a shock absorber during an earthquake. Steel cross braces are placed between the floors to help support the building. Flexible pipes help prevent waterlines from breaking. There are many ways you can be prepared for a earthquake. The most important thing to do is to have a plan and stick to the plan. (Holt Science and Technology Earth Science) ( http://hereandnow.wbur.org/2013/01/10/haiti-earthquake-book) ( http://framework.latimes.com/2011/02/22/6-3-earthquake-hits-new-zealand/#/0) ( file://localhost/Users/tholt19/Desktop/url-13.jpeg)