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Volcanoes and Earthquakes

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Presentation on theme: "Volcanoes and Earthquakes"— Presentation transcript:

1 Volcanoes and Earthquakes

2 DAY 1 Objective: I can explain how a volcano is structured

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

4 Anatomy of a Volcano Vent Crater Magma Chamber Magma Tube
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 Day 2 Objective: I can explain what happens when a volcano erupts

7 Magma verse Lava Magma Lava Molten rock under the surface of Earth
Molten rock on the surface of Earth

8 Factors Affecting Eruption
Magma Composition Magma Temperature Amount of Dissolved Gases

9 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)

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

11 Gases 70% water vapor 15% carbon dioxide 5% nitrogen 5% sulfur

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

13 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

14 DAY 3 Objective I can describe the locations of volcanoes and the relationship between volcanoes and plate tectonics

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

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

17 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

18 DAY 4 Objective: I can explain what an earthquake is
I can explain why earthquakes happen

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

20 Parts of an Earthquake Focus Epicenter Fault
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

21 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

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

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

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

25 Earthquake Waves Two Main Types Surface Waves Body Waves P-waves

26 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

27 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

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

29 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

30 Strength of an Earthquake
Two different types of measurements to describe the strength of an earthquake Intensity Magnitude

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

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

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

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

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

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

37 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

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

39 Tsunami Large ocean wave created by an earthquake

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

41 Predicting Earthquakes
Short Range Measure uplift, subsidence and strain in the rocks Short-range predictions have not been successful

42 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

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