Unit 4 The Restless Earth Part II Lessons 4, 5 & 6

1. Unit 4 The Restless Earth Part II Lessons 4, 5 & 6 The Big Idea: The movement of tectonic plates accounts for important features of Earth’s surface and for major geologic events. http://wondrouspics.com/volcano-photos/

2. Unit 4 Lesson 4 Volcanoes Magma Magic • Volcano- any place where gas, ash, or melted rock come out of the ground • Magma -melted rock is less dense than solid rock, so it rises to the surface. • Lava-magma that has reached Earth’s surface. Lava and ash erupt from a vent, or an opening of a volcano.

3. http://www.zeitnews.org/node/3350 Volcanic Flow • Viscosity- resistance to flow; shape and explosiveness of a volcano depend on the lava’s viscosity. • Pyroclastic material- hot ash and bits of rock, may also be ejected into the atmosphere. http://www.studyblue.com/notes/note/n/how-the-earth-works-final/deck/1690726

4. Unit 4 Lesson 4 Volcanoes Volcanic Landforms • Shield volcanoes-broad bases and gently sloping sides. • They are the result of mild eruptions. • Cinder cones-small volcanoes with steep slopes. • They form from ash and pieces of solidified lava that fall around a small vent.

5. Unit 4 Lesson 4 Volcanoes Volcanic Landforms continued • Composite volcanoes-built from alternating layers of hardened lava flows & pyroclastic material. • They generally develop into large, steep mountains. Have violent eruptions • Lava plateau-fissure eruptions produce flattened layer of cooled lava

6. Unit 4 Lesson 4 Volcanoes Volcanic Landforms continued • Caldera– magma chamber empties, the roof of the chamber can collapse, leaving a large basin-shaped depression • Magma chamber-expanded area of magma

7. Unit 4 Lesson 4 Volcanoes Eruption! Where do Volcanoes come from? • Tectonic plates-giant sections of lithosphere on Earth’s surface. Volcanoes can form at plate boundaries or within the middle of a plate. • Divergent boundaries-creates fissure eruptions & shield volcanoes, crust stretches & gets thinner. Most occur on ocean floor, creating undersea volcanoes, long underwater mtn range known as mid-ocean ridge. On land the crust stretches until a rift valley is formed. http://ajs-geo-blog.blogspot.com/2012/03/rift-valley.html

8. Unit 4 Lesson 4 Volcanoes http://www.eclp.com.na/demo/geography/mod1page24.html • Convergent boundaries- composite volcanoes or calderas can occur. Magma has high concentration of fluids, which form gas bubbles • Hot spots-far from any plate boundary, shield volcanoes, fissure eruptions & cinder cones can occur. • Ring of Fire –numerous explosive volcanoes that form on convergent boundaries surrounding the Pacific Ocean. http://volcanoworld.wordpress.com/2011/12/12/what-is-a-hot-spot-and-what-is-a-mantle-plume/

9. Unit 4 Lesson 5 Earthquakes Let’s Focus • Earthquakesare ground movements that occur when blocks of rock in Earth move suddenly and release energy. The energy is released as seismic waves that cause the ground to move. http://www.fhmindia.com/tag/earthquakes/

10. Unit 4 Lesson 5 Earthquakes What Causes Earthquakes? • Faults -release of energy that accompanies the movement of rock along a fault causes an earthquake. • Deformation-process by which the rock becomes deformed and changes shape caused by stress As the stress on rock increases, the energy stored in it increases. When the stress is released, the rock may return to its original shape. When rock returns to nearly the same shape after the stress is removed, its called elastic deformation. • Elastic rebound- return of rock to its original shape after elastic deformation

11. Unit 4 Lesson 5 Earthquakes http://pmikecolumbus.wordpress.com/2012/02/29/ripples-in-the-water/ What is an Earthquake? • Focus-place w/in Earth along a fault where the first motion of an earthquake occurs. Seismic waves flow outward in all directions • Epicenter- place on Earth’s surface directly above the focus http://geomaps.wr.usgs.gov/parks/deform/geqepifoc1.html

12. Unit 4 Lesson 5 Earthquakes Where do Earthquakes happen? • Divergent boundaries- tension stress causes normal faults to form. Earthquakes tend to be shallow because the crust is thin. • Convergent boundaries- rock is squeezed, & the stress is called compression. Reverse faults are formed, and earthquakes can be strong and deep. • Transform boundaries- shear stress pushes tectonic plates in opposite directions. Earthquakes tend to be relatively shallow.

13. Unit 4 Lesson 6 Measuring Earthquake Waves Shake, Rattle & Roll • Seismic waves-vibrations that cause different types of ground motion. Their speed depends on what they travel through • Surface waves- travel along Earth’s surface

14. Unit 4 Lesson 6 Measuring Earthquake Waves Seismic Waves continued • Body waves- travel through Earth’s interior • P waves– pressure waves or primary waves are the fastest • S waves- shear waves secondary, move side to side

15. Unit 4 Lesson 6 Measuring Earthquake Waves Wave Action! • Seismogram -tracing of earthquake motion. It also records the arrival times of seismic waves at a seismometer station. Page 259 to see triangulation. http://www.qrg.northwestern.edu/projects/vss/docs/navigation/1-what-is-triangulation.html

16. Unit 4 Lesson 6 Measuring Earthquake Waves http://www.panorama.am/en/society/2012/10/08/mes-az/ Earthquake Measurement • Magnitude- measure of the energy released by an earthquake, larger magnitude = stronger earthquake • Richter scale-measures ground motion from an earthquake to find the strength • Moment Magnitude scale-more accurate for large earthquakes, based on area of moving fault, avg distance the fault moves & rigidity of rocks in the fault.

17. Unit 4 Lesson 6 Measuring Earthquake Waves Did you feel that? • Intensity-effects of an earthquake and how the earthquake is felt by people Effects of an Earthquake • Magnitude • Local geology • Distance from the epicenter • Type of construction used http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/earthquake_effects.html http://www.ga.gov.au/ausgeonews/ausgeonews200606/sediments.jsp