2. Stress on the Crust “Listen…you think YOU have it bad! I am under more stress than you can possibly imagine. I lead a really hard life you know.” Mr. Rock a force that acts on crust rock stress- a force that acts on crust rock 1. - push together 1. compression- push together 2. - pull apart 2. tension- pull apart 3. - side by side tearing 3. shear- side by side tearing

3. Deformations- “Strain” deformation- any change in the shape or volume of Earth’s crust in response to a stress. Types of Deformations: Faulting (breaking), folding (bending), tilting, sliding, weathering, erosion

4. Folding result of compression result of compression Types of Folds 1. 1. monocline 2. 2. anticline 3. 3. syncline

5. Folding- Las Vegas Nevada

6. Faulting - a break in the earth’s crust where movement has occurred fault- a break in the earth’s crust where movement has occurred Parts of Faults 1. fracture / break line 1. Fault plane- fracture / break line 2. rocks above fault plane 2. Hanging wall- rocks above fault plane 3. rocks below fault plane 3. Footwall- rocks below fault plane HW HWHW FW FW

7. Types of Faults 1. - hanging wall moves downward 1. Normal- hanging wall moves downward = tension cause = tension 2. - hanging wall moves upward 2. Reverse- hanging wall moves upward = compression cause = compression rides up and over Thrust Fault- HW rides up and over FW 3. side by side movement 3. Strike-Slip- side by side movement = shear cause = shear fault plane vertical fault plane vertical

8. “Oh no!! The ground shakes again!! The gods must be angry with us! Quick.…sacrifice something!!” Panicking Villager Earthquakes!!!

9. Earth’s Crust in Motion! Earthquake: shaking of the Earth’s crust caused by a release of energy. Ex. erupting volcanoes, plate movement

10. How Earthquakes Happen… 1. 1. Friction keeps plates from moving. 2. 2. Stress builds up. plates “deform” plates reach their elastic limit (amount of stress something can absorb) 3. 3. Rocks rupture (break) at weakest point. plates move suddenly- earthquake! 4. 4. Plates “rebound”

11. Parts of an Earthquake - the spot along the fault where rock occurs focus- the spot along the fault where rock slippage (break) occurs - the point on the earth’s surface directly above the epicenter- the point on the earth’s surface directly above the focus

12. Review: Seismic Waves 1. 1. Body Waves a. a. P-Waves- (Primary) 5-14 km/s compresses and stretches crust (compression wave) b. b. S-Waves- (Secondary) 3.5-8 km/s vibrates crust side to side (shear wave) 2. 2. Surface Waves- “L-Waves” 2.5-4.5 km/s combination of P & S waves travel along the surface; cause most damage; slowest

13. Locating an Earthquake Seismograph device used to detect seismic waves different wave types = different seismographs

14. Locating an Earthquake P, S, L waves travel at different speeds each then arrives at the seismograph at different times time difference between P and S waves used to calculate distance to epicenter distance to epicenter = radius of a circle drawn around the station Need 3 seismograph stations at 3 different locations.

15. Measuring Earthquakes 1. 1. Mercalli Intensity Scale: I to XII based on intensity- amount and type of damage caused 2. 2. Richter Magnitude Scale: 1 to 10 + based on magnitude- amount of energy released (9.5 biggest) 3. 3. Moment Magnitude Scale: based on the size of many types of seismic waves, amount of movement, size of rupture, and rock strength along the fault.

16. Earthquakes Effects Aftershocks- small EQ’s after a major EQ; due to the release of more stress Liquefaction- ground becomes “soft”; creates mudslides and landslides Fault Scarps- a cliff made by an EQ Tsunamis

17. Tsunami ocean wave caused by earthquakes, massive landslides, meteor impacts ocean wave caused by earthquakes, massive landslides, meteor impacts Japanese for “” Japanese for “harbor wave” In deep water: low / very fast moving low / very fast moving In shallow water: slows down due to drag on bottom slows down due to drag on bottom increases in height- up to 90+ ft increases in height- up to 90+ ft

18. Earthquake Zones ”Seismic Belts” 1. 1. Circum-Pacific Belt…“Ring of Fire” 2. 2. Mediterranean-Asian Belt 3. 3. Mid-Ocean Ridges

19. Earthquake Prediction Earthquake-Recurrence Rate (history) Animal Behavior Seismic Gap Theory- “Strain Accumulation” areas along a fault where few EQ’s have occurred could be areas where A LOT of stress is building up.