1 / 21

Earthquakes

Earthquakes. 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.

jason
Download Presentation

Earthquakes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

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

More Related