1. Volcanoes and Earthquakes Ms. Woodard

2. DAY 1 Objective: Objective: – I can explain how a volcano is structured – I can explain the differences in the types of volcanoes

3. What is a Volcano? A mountain formed of lava and/or pyroclastic material

4. Anatomy of a Volcano Vent – Opening in the crust Crater – Steep-walled depression at the top Magma Chamber – Where the molten rock waits Magma Tube – Links the vent to the magma chamber

6. Types of Volcanoes Determined by – Material that form the volcano – Types of eruptions that occur 3 types – Shield volcano – Cinder-cone volcano – Composition volcano

7. Shield Volcano Broad, gently sloping sides Nearly circular base Produced by lava flow Little explosive eruptions Ex: – Hawaiian Islands

8. Cinder-Cone Volcano Steep-sided slopes Small in size Built by pyroclastic materials ejected from a single vent Ex: Izalco Volcano

9. Composite Volcano Also known as Stratovolcano Large, nearly symmetrical structure Layers of lava and pyroclastic deposits Violently erupts Most Dangerous Ex: Mount St. Helens

10. Day 2 Objective Objective: – I can explain what happens when a volcano erupts

11. Magma vs. Lava Magma – Molten rock under the surface of Earth Lava – Molten rock on the surface of Earth

12. Factors Affecting Eruption Magma Composition Magma Temperature Amount of Dissolved Gases within magma

13. Viscosity of Magma Substance’s resistance to flow Hotter the magma, more fluid and less viscous Directly related to its silica content – More silica, greater its viscosity (slower movement)

14. Dissolved Gases Consist of water vapor and carbon dioxide More gases, the more violent the eruption

15. Volcanic Materials Lava Flow – Pahoehoe: lava flow resembles the twisted braids in ropes – Aa: lava flow that has a surface of rough, jagged blocks with dangerously sharp edges and spiny projections

16. Pyroclastic Material – Fragments ejected during eruptions – From very fine to several tons – Ex: Volcanic Ash Cinders (lapilli) Volcanic Bombs

17. Other Eruption Results Pyroclastic Flow – Consist of hot gases, glowing ash, and large rock fragments – Races down the steep slope Lahar – Mudflow that occurs when volcanic debris becomes saturated with water and rapidly moves down steep volcanic slopes

18. DAY 3 Objective – I can describe landforms that volcanic and igneous activities create – I can describe the locations of volcanoes and the relationship between volcanoes and plate tectonics

19. Volcanic Landforms Calderas – Large depression in a volcano – Forms Two Ways 1.Collapse of the top of a composite volcano after an explosive eruption 2.Collapse of the top of a shield volcano after the magma chamber is drained

20. Lava Plateaus – Formed by fissures – Fissures: low viscosity basaltic lava flow covering a wide area

21. Intrusive Igneous Activity This is also known as PLUTONS Plutons – Structures that result from the cooling and hardening of magma at depth – Classified according to shape size, and relationship to the surrounding rock layers

22. Types of Plutons Sills – When magma is injected along sedimentary bedding surface parallel to the bedding planes

23. Laccoliths – Magma is intruded between sedimentary layers close to the surface (lens shaped) Dike – Magma injected into fractures, cutting across preexisting rock layers

24. Batholith – Large intrusive igneous body that must have a surface exposure greater than 100 square kilometers

25. Plate Tectonics & Volcanoes Relationship – Plate movement provided the mechanism by which mantle rock melts to generate magma

26. Ring of Fire Area around the pacific ocean with extreme volcanic activity This shows the Pacific Plate Boarder

27. Intraplate Activity Occurs with a plate, not a plate boundary Hot Spots – Small volcanic region a few hundred kilometers across within a plate – Ex: Hawaiian Islands

28. DAY 4 Objective: Objective: – I can explain what an earthquake is – I can explain why earthquakes happen

29. What is an Earthquake? Vibration of Earth Produced by a sudden release of energy Movement along a fault line

30. Parts of an Earthquake Focus – Point within Earth where the earthquake starts Epicenter – Location on the surface directly above the focus Fault – Associated with earthquakes activity where movement has occurred

31. Causes of Earthquakes Elastic Rebound Hypothesis – Release of built-up energy – Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces – When the strength of the rock exceeded, it suddenly breaks, causing the vibrations of an earthquake

32. Foreshock vs. Aftershock Foreshock – Small earthquakes before the big quake Aftershock – Smaller earthquakes after the big quake

33. Seismic Science Seismology – Study of earthquake waves Seismograph – Instruments that record earthquakes Seismogram – The record made by a seismograph

34. Day 5 Objective: – I can explain how to locate origin of an earthquake – I can explain how to measure the strength of an earthquake

35. Earthquake Waves Two Main Types – Surface Waves – Body Waves P-waves S-waves

36. Surface Waves Seismic waves that travel along Earth’s outer layer Moves up & down and side to side Most destructive Last to arrive at the seismograph

37. Body Waves P-Waves (primary waves) – They push (compress) and pull (expand) rocks in the direction the wave travels – Can travel through solids, liquids and gases – Fastest waves – First to the seismograph

38. S-Waves (secondary waves) – Shakes particles at right angles to their travel – Can only travel through solids – 2 nd to the seismograph

39. Locating Earthquakes The difference in velocity of a P- Wave & S-Wave provides a way to locate the epicenter – Use a travel-time curve graph – Needs at least three seismograph station data

40. Strength of an Earthquake Two different types of measurements to describe the strength of an earthquake – Intensity – Magnitude

41. Earthquake Intensity A measure of the amount of earthquake shaking at a given location based on the amount of damage

42. Earthquake Magnitude A measure of the size of seismic waves or the amount of energy released at the source of an earthquake

43. The Richter Scale Measures magnitude Based on the amplitude of the largest seismic wave A TEN-FOLD system Largest earthquake record= 9.6 (CHILE)

44. Moment Magnitude Scale More precise Amount of displacement that occurs along a fault zone Most widely used – Estimates energy released by earthquakes

45. Mercalli Intensity Scale How much damage occurs Depends on: – Strength – Distance from the epicenter – Nature of the surface material – Building design

46. DAY 6 Objective: – I can describe the dangers of an Earthquake – I can explain how to make earthquake predictions

47. Earthquake Hazards Seismic Vibrations – Damage to building depends on several factors Intensity of vibration Duration of vibration What type of material built on Design of the structure

48. Liquefaction – Stable soil turns into a liquid that is not able to support building or other structures

49. Tsunami – Large ocean wave created by an earthquake – Tsunami warning system is active to monitor for them

50. Landslides – Greatest damage to structures – Sinking of the ground triggered by the vibration Fires – Caused by ruptured gas lines

51. Predicting Earthquakes Short Range – Measure uplift, subsidence and strain in the rocks – Short-range predictions has not been successful

52. Long Range – Based on the idea that earthquakes are repetitive – Seismic Gap An area along a fault where there has not been any earthquake activity for a long period of time