What is happening in this photograph??

1. What is happening in this photograph??

2. What do volcanic eruptions reveal about the earth’s interior??

3. What do you think the darker material floating on the molten lava is??

4. Earthquakes and Volcanoes Chapter 7

5. Section 1 Earthquakes • Objectives: • Describe what happens during an earthquake • Explain the difference between an earthquake’s focus and epicenter • Compare and Contrast the three types of waves produced by earthquakes

6. Skills Warm-up • This Just In …… • Imagine you are listening to the radio when the announcer says that a 5.8 earthquake has occurred in Alaska. • How do earthquakes happen?? • What does the 5.8 mean??

7. Earthquakes • Movements of the earth’s crust that occur when _______________and release stored _________ • Energy quickly travels out in ________ from the point of breakage • Energy can ______ and ________ rock and soil • Most occur at depths less than ____________ because the rocks are brittle

8. Earthquakes • Most earthquakes result from movements of the earth’s crust along ___________ • Faults are __________ in the earth’s crust • The 2 sides move in _________ _______ and earthquakes occur

9. Physics of Earthquakes • As the 2 sides of a fault move past each other, sometimes the rocks ________, _______ and become __________ • Tremendous ________ builds up in these areas

10. Physics of Earthquakes • ______ _____ – amount of stress a material can absorb • Example – rubber band stretched too far • When rocks are strained beyond elastic limit – _______ and ________ past each other • Huge amount of __________ released.

11. Physics of Earthquakes • As rocks break and move, __________ _______ is transformed into _______ _________ • _______ ________ – the vibrations produced by earthquakes • 3 Types: • ____________ • ____________ • ____________

12. Primary Waves • P Waves – _________ seismic waves • _____________ - the material through which the wave is travelling moves in the _________ direction as the wave • ___________________________the earth in direction of the wave

13. Secondary Waves • S Waves - second waves to arrive at a given point – _____ _________ • __________ – material moves at ______ ________to the wave direction • Like the up-and-down movement of a rope

14. Surface Waves • ____________– when P and S waves arrive at earth’s surface • Cause the earth’s surface to __________ ____________________________________________________________ • Cause the __________ damage during an earthquake

15. Activity • Earthquakes movie

17. Focus vs. Epicenter • _______ – area along a fault where _________ ______ ______________ – where earthquake begins • Seismic waves travel out in __________ from the focus • ___________ – point on earth’s surface directly __________________ – strongest shakes felt here

18. Detecting Seismic Waves • ________________ - detect and record seismic waves • Have a pen attached to a weight and a sheet of paper on a revolving drum • Seismic waves cause the pen to _______ and record a wavy line on paper • _________ of the peaks indicates the _________ of the earthquake

19. Locating an Epicenter • P, S, and L waves travel at _________ _________ • So, they reach a seismograph at __________ _________ • The difference between the arrival times of the waves helps scientists find the _______________

20. Locating an Epicenter • Calculated distance to the epicenter becomes the ________ of a circle that is plotted on a map • Epicenter lies ______________ on the circle • Plotting circles from ___ ____________ _______ _________ pinpoints the epicenter – why do you need 3 stations??

21. Rating Earthquakes • _______ _________– compares the size of earthquakes using data from seismograph stations • Each increase of _____ magnitude number equals an increase of ______ in ground motion • A magnitude 7 earthquake causes 10 times more damage than a magnitude 6 and 100 times more damage than a magnitude 5

23. Rating Earthquakes • ________ ________– measures the effects of an earthquake on • ________________ • ________________ • ________________ • ________________ • Data gathered from people who have experienced the quake are used to determine an intensity value for their location

25. Activity • Comparing earthquake scales • Textbook page 136

27. Earthquake Zones • Most of the world’s earthquakes occur along or near the edges of ________ ______________ • At these spots, ______ is the greatest • 3 Major earthquake zones: • 1. ________________ • 2. ________________ • 3. ________________

28. Ring of Fire • Accounts for ______ of world’s seismic activity • Goes all the way around the _________ _________ • Includes east coast of Asia and west coasts of North and South America • Active spots in the U.S. • __________________ • __________________

29. Mid-Atlantic Ridge • Hypothesis – ________________ __________ is being made along the mid-Atlantic ridge • This causes many earthquakes

30. Mediterranean-Asiatic Belt • _____________ _________ are colliding • Causes very destructive _____________

31. Far from Plate Boundaries • Small number of earthquakes occur far from plate boundaries (strong) • ______________________________________ • ______________________________________ • Even quiet parts of earth can conceal large amounts of ____________

32. Hidden Faults • 1983 – Coalinga, Ca (between LA and SF) • Magnitude __________ earthquake • Surprised scientists: • __________________ • __________________ • __________________

33. Hidden Faults • Team of scientists studied what happened • Found several faults ___________ beneath • They were hidden inside of __________ in the earth • The determined these faults are ______ very active

34. Questions • 1. Explain what causes earthquakes. • 2. What is the difference between an earthquake’s focus and epicenter? • 3. How do the 3 types of seismic waves differ? How are they similar? • 4. Would using 4 seismograph stations to locate the epicenter of an earthquake be any more accurate than using 3? Explain.

36. Lab Activity – How to Model the Richter Scale • Page 139 in Textbook

38. Section 2 EarthquakeEvidence • Objectives: • Describe some features produced by earthquakes • Discuss factors that determine earthquake damage • Explain what causes tsunamis • Make Inferences about ways to build structures that could withstand major damage from earthquakes

39. Ground-Level Evidence • Earthquake evidence is sometimes preserved in ________ or ____________ changes to the ground • Strong earthquakes leave _________ evidence

40. Ground-Level Evidence • At some faults changes are _____ but ________________ – no earthquakes • ____________ – slow, continuous, steady motion • Creep rate of 1 cm/year – ground levels would be displaced by 1 meter after __________ • Can break structures

41. Landscape Evidence • Powerful earthquakes can cause ____________ damage • ____________ earthquake of 1964 – ______ magnitude • Upheaval of >260,000 square km of ground • ___________ moved sideways!

42. Landscape Evidence • Earthquakes affect poorly compacted sediments more: • __________ • __________ • __________

43. Slides • Rapid down slope movements of ________, ________, and _________ • Can occur on a _______ or far away • Large sections of mountain may ________ and race downward • Some continue for ____________, destroying all in their paths (homes and roads)

44. Scarps • Sudden earth movements that _________ ________ • Height depends on the _____ of material uplifted and the ___________ and ___________ of uplift

45. Fissures • Long ________ in rock or soil • May extend for _______ _____________ • If fissures occur on hill or mountain – massive ____________ can occur

46. Factors of Earthquake Damage • ____________ of epicenter to ______________ area • Moderate quake in a crowded city causes _________ damage than a large quake in a desert

47. Factors of Earthquake Damage • _______ ___ _________ where structures are built affects amount of damage • Soft, wet, loose soils can ___________ seismic waves • Buildings on more solid ground have better chance of survival

48. Factors of Earthquake Damage • Building ________ and _____________ affect damage • ________ __________ buildings may move with and withstand ground motion • Brick and cement may ________ and _____________

49. Factors of Earthquake Damage • __________ – an ocean wave caused by ________________ • __________ water – tsunamis are low and fast-moving • __________ water – they slow down and increase in height (30 meters) • Few structures survive a large tsunami

50. Earthquake Prediction • Past – changes in animal behavior and well levels • Now – seismologists look at • __________________ • __________________ • __________________