Do Now - 9/30/15 1)Which type of boundary creates new lithosphere? 1)Which type of boundary is associated with oceanic ridges and rift valleys? 1)Stephen is visiting the mountains in Colorado. What type of tectonic plate boundary is Stephen most likely near? 1)Riddle: The more of me you take, the more you leave behind. What am I?
What is an Earthquake? Instructions 1.Close both eyes. 1.Sit up straight in your chair. 1.Place both hands palm down on the desk.
What is a focus? The point beneath the Earth’s surface where rock under stress breaks to cause an earthquake.
What is an epicenter? The point on the surface directly above the focus.
The farther the distance between the focus and the epicenter, the weaker the earthquake. Therefore, the closer the focus is to the surface, the stronger (and more damaging) the earthquake. Distance from Focus to Epicenter
Elastic Rebound Hypothesis Instructions 1.Do and touch nothing until instructed to do so. 1.Follow Mr. Marosy’s verbal instructions. 1.Draw what you just observed, and then use your observations to answer the question in your notes: What is the Elastic Rebound Hypothesis?
What is a fault? It is the break in the crust where the earthquake began, between two pieces of rock that have moved past each other.
The 3 Types of Faults NormalReverseStrike-slip When the hanging wall drops down. When hanging wall moves up. Walls move sideways Creates outward forcesCreates inward forcesCreates horizontal forces
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What are seismic waves? Seismic waves are the energy-packed vibrations caused by earthquakes
During an earthquake, vibrations called seismic wave move away from the focus in all directions similar to the ripples created by a pebble in a pond.
Seismic waves carry the energy of an earthquake away from the focus, through the Earth’s interior, and across the surface.
What are the three types of seismic waves? ■ Primary waves (P waves) ■ Secondary Waves (S waves) ■ Surface waves (L waves)
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When the P & S waves reach the surface, they move more slowly creating the most severe ground movements.
Seismographs are used by scientist to detect, measure & record the vibrations of seismic waves. An earthquake’s magnitude is a measurement of its strength based on seismic waves and movement along faults.
What are 2 rating scales used to measure an earthquake?
Richter scale This scale rates earthquakes according to the size of seismic waves as measured by the seismograph.
Moment Magnitude scale This scale rates earthquakes by estimating the total energy they release. The moment magnitude scale can be used to measure earthquakes of all sizes, near or far!
How do scientists determine the location of an earthquake’s epicenter?
■ When an earthquake strikes, P waves are the first to arrive at a seismograph followed by the S waves. ■ The farther away the epicenter is, the greater the difference between the two arrival times.
This difference in time tells scientists how far the seismograph is from the epicenter. This information is then used to plot a circle on a map.
The circle shows the distance from one seismograph station to all points where the epicenter could be located.
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■ To determine the exact location of the epicenter, at least THREE stations need to find their distance from the epicenter and draw a circle on a map
The single point where the 3 circles intersect is the location of the earthquake’s epicenter.
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