Download
earthquakes n.
Skip this Video
Loading SlideShow in 5 Seconds..
Earthquakes PowerPoint Presentation
Download Presentation
Earthquakes

Earthquakes

138 Vues Download Presentation
Télécharger la présentation

Earthquakes

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Earthquakes

  2. A natural vibration of the ground caused when the stress built up between tectonic plates is suddenly released. • There are three types of stress: • Compression – caused by two plates being push together. • Tension – Pulls plates apart. • Shear – causes plates to twist. Earthquakes

  3. There are three types of Faults • Normal fault • caused by tension. • Reverse fault • caused by compression. • Strike-slip fault • caused by shearing. Types of faults

  4. Primary waves (p-waves) • Longitudinal waves – these vibrate by the compression of material in the direction of the wave’s motion. These can travel through the core. • Secondary waves (s-waves) • Transverse waves (Like in water) – these vibrate by moving the particles perpendicular to the direction of wave’s motion. These cannot travel through the core. • Surface waves • Vibrate in all directions. Three Types of Seismic Waves

  5. Richter Scale • Based on size of the largest seismic waves generated by the Earthquake. • Each level increase represents an increase of energy by a factor of 32 and a wave size of 10 times. Measuring Earthquakes

  6. Moment of Magnitude Scale • Based size of fault rupture, amount of movement, and rock characteristics. • More accurate than Richter scale. • Modified Mercalli Scale • Measures the amount of damage caused by the Earthquake. Measuring Earthquakes

  7. Chile (Feb 27th) Mag. 8.8 • Indonesia (April 6th) Mag. 7.7 • Vanuatu (May 27th) Mag. 7.7 • Indonesia (May 9th) Mag. 7.2 • Mexcali Valley, California (April4th) Mag. 7.2 • Solomon Islands (Jan 3rd) Mag. 7.1 • Haiti (Jan 12th) Mag. 7.0 • Ryukyu, Japan (Feb 27th) Mag. 7.0 There have been 7460 earthquakes so far this year. Most are below a magnitude of 4.9. Strongest Earthquakes of 2010

  8. 7th Strongest in History • 130 after shocks over the next week. • The focus ground at epicenter moved 3.0 up and 10 m west. • 500 times more powerful than Haiti • Called a megathrust quake because it is in a subduction zone Chili

  9. Focus • The location in the Earth’s crust where the earthquake occurs. • It can occur anywhere between the surface and a depth of 700 km. The closer to the surface it occurs, the more powerful the earthquake is. • Epicenter • The location on the Earth’s surface above the focus. Location of the Earthquake

  10. Epicenters are found using triangulation from three or more seismograph stations. • P-waves travel a lot faster than s-waves. The difference between the arrival time of each type of wave tells you the distance to the epicenter. • The speed of each wave is a constant factor. Finding the Epicenter

  11. Determine the difference in time between the arrival of the s & p waves. Steps for finding the Epicenter

  12. Use the travel-time graph at which the p-curve and s- curve have the same separation. • Record this distance. Steps for finding the Epicenter

  13. Repeat the steps #1-3 for two other stations Steps for finding the Epicenter

  14. Use a compass to draw a circle around each station with the radius in step #3. • The epicenter is located where all three circles intersect. Steps for finding the Epicenter

  15. P. 499 #1-4 • p. 504 #2, 4 • P. 510 #1-4 Homework