Recommended
More Related Content
What's hot
What's hot (20)
Similar to Lithosphere 2: Tectonics
Similar to Lithosphere 2: Tectonics (20)
More from Robin Seamon
More from Robin Seamon (20)
Recently uploaded
Recently uploaded (20)
Lithosphere 2: Tectonics
- 1. LITHOSPHERE 2 Tectonics ppt. by Robin D. Seamon
- 2. Plate Tectonics VOCABULARY: Continental Drift Alfred Wegner Plate tectonics asthenosphere mantle convection ridge push slab pull deformation magnetic reversals sea floor spreading normal fault reverse fault
- 3. Continental Drift: 1912 Alfred Wegner proposed the idea that the continents were moving away from one another, breaking from one giant protocontinent he named (Pangaea); he but didn’t know why. Today we know that the Earth’s plates float upon the semi-liquid mantle and move due to: The Lithosphere moves & changes.
- 4. http://www.bucknell.edu/x17758.xml Plate Tectonics- theory that the Earth’s lithosphere is composed of 10+ plates that fit together like a puzzle • plates move about 5 cm a year
- 7. The plates move slowly on the upper mantle (asthenosphere) http://kids.britannica.com/comptons/art-156130/A-diagram-shows-the-relationship- between-volcanic-activity-and-Earths
- 8. Movement is caused by mantle convection inside the Earth • Hot, less dense fluids go up while cold, more dense ones go down
- 9. ridge push: sliding plate force; occurs at mid- ocean ridges; caused by gravitational force • spreading happens at the hot magma exit; less dense = greater volume = higher elevation than the cooler ocean floor beside it • As plate moves from the boundary, it also cools, condenses & sinks, creating a SLOPE • lithosphere slides down • the PUSH is applied to the tectonic plate due to gravity
- 10. slab pull: part of the tectonic process caused by subduction • weight of cold, dense oceanic plate dropping under another plate • PULLS the oceanic plate down into the mantle
- 12. Continental “fit” The continents look like they fit together like a puzzle EVIDENCE:
- 13. Correlation of rocks & minerals Coastal regions of different continents have the same rocks & minerals EXAMPLE: Rocks in the Uwharries of NC near Albemarle are of the same rhyolite found on the western coast of Africa EVIDENCE:
- 14. Correlation of fossils Coastal regions of different continents have the same fossils EXAMPLE: fossils of ancient species crossing continents EVIDENCE:
- 15. Finding fossils in unusual locations If we find fossils of a species unable to live in that location today, the plates must have moved EXAMPLE: whale & marine fossils found in Andes mountains EVIDENCE:
- 17. Ocean Floor Evidence • Age of rocks get older away from the divergent boundary • Magnetic Reversals recorded in ocean floor match on opposite sides of the divergent boundary EVIDENCE:
- 18. EVIDENCE: Crustal deformations • Faulting normal fault: hanging wall move down reverse fault: hanging wall moves up
- 19. Plate Interactions VOCABULARY: Continental crust Oceanic crust convergent boundary divergent boundary transform boundary subduction uplift compression tension shear ridge trench rift
- 20. • Two Types of Crust • Float on the asthenosphere Oceanic Crust Density: 2.7 g/cm3 -Cooler -Sinks below continental crust Continental Crust Density: 3.0 g/cm3 -Warmer GRANITE BASALT
- 21. Convergent boundaries- plate boundaries where the force of compression pushes two plates together Divergent boundaries- plate boundaries where the tension pulls plates away from one another Transform boundaries- plate boundaries where one plate slides past another plate through shearing Which subducts? Continental vs. Oceanic What happens in the space? What happens at these faults?
- 22. CONVERGENT BOUNDARIES: Forms volcanic mountain range, trench & sudden earthquakes OCEAN CRUST & CONTINENTAL CRUST SUBDUCTION UPLIFT FORCE: compression
- 24. CONVERGENT BOUNDARIES: Forms oceanic trench & volcanic island chain OCEAN CRUST & OCEAN CRUST SUBDUCTION FORCE: compression
- 26. CONVERGENT BOUNDARIES: Forms mountains CONTINENTAL CRUST & CONTINENTAL CRUST SUBDUCTION UPLIFT FORCE: compression
- 27. Folded Mountains http://freddoty.com/folded-mountains Near the Sullivan River in the Canadian Rockies The Cape Fold Belt Mountains, S Africa http://www.geocaching.com/geocache/GC2CEJP_steytlerville-arch?guid=ff36205a-b979-422c-8266-f7f83ec4d884 FORCE: compression
- 28. DIVERGENT BOUNDARIES: Creates sea-floor spreading: Mid-Atlantic Ridge FORCE: tension OCEAN CRUST & OCEAN CRUST
- 30. DIVERGENT BOUNDARIES: Forms rifts & normal faults: CONTINENTAL CRUST & CONTINENTAL CRUST FORCE: tension Iceland Rift Valley Rift
- 33. TRANSFORM BOUNDARIES: Creates earthquakes: San Andreas Fault CONTINENTAL CRUST & CONTINENTAL CRUST FORCE: shear
- 34. EARTHQUAKES VOCABULARY: earthquake tsunami focus initiation epicenter split seismograph amplification Richter Scale seismic waves P-wave S-wave surface wave shadow zones National Earthquake Information Center Global Seismographic Network Pacific Tsunami Warning Center
- 35. Earthquakes: tension builds up at plate boundaries until the plates slip & tension is released- we feel earthquakes
- 36. • Pressure builds within the crust at the focus and suddenly breaks along a fault • The sudden release of energy causes seismic waves that make the ground shake • epicenter: place on the surface above the focus
- 37. Seismograph- strength of an earthquake is measured with this tool that records the vibrations from sensors placed in the earth http://sydney.edu.au/science/uniserve_science/school/Seismograph/menu.html http://sydney.edu.au/science/uniserve_science/school/Seismograph/menu.html
- 39. Seismic waves: waves of energy are radiated from an earthquake as both body & surface waves; 2 kinds: BODY WAVES travel through earth’s inner layers; faster; arrive first 1. P-wave- primary wave; compressional wave; FIRST WAVE: fastest
- 40. BODY WAVE 2. S-wave- SECOND WAVES slower; can only move through solid rock (not liquid) (this is why scientists deduce the earth’s outer core is liquid) • moves particles up and down or side to side perpendicular to the direction the wave is traveling
- 41. SURFACE WAVES travel only through the crust; • lower frequency; seismographs pick up • damaging waves, sending movement in any direction on the surface; tearing apart structures • deeper earthquakes are less destructive
- 42. Shadow zones- places on Earth’s surface that will not receive seismic waves because of density of material • S-waves are absorbed by the liquid outer core • P-waves care refracted by the liquid outer core ANIMATION
- 44. • Closer a seismic station is to the epicenter 1. The sooner the P-wave will arrive 2. The smaller the difference between P & S waves Determining distance from the Epicenter
- 45. Measure the distance between the first p wave and the first s wave for each station. 1. Which is the closest station? CLOSEST 2nd CLOSEST FARTHEST
- 46. Earthquake Monitoring • National Earthquake Information Center- US (NEIC) determines size & location of significant earthquakes worldwide & sends information out, & maintains a database • Global Seismographic Network (GSN) worldwide seismic network
- 48. Locating the epicenter Determining the location requires distances from three stations. • This will determine the location on a circle with the radius being the distance from that station to the epicenter. • Using data from 3 stations, scientists can triangulate where the epicenter is: • Where the 3 circles intersect = epicenter
- 49. Deadly Hazards • Shaking ground causes buildings, roads and bridges to shake, roofs cave in • Poorly constructed buildings in underdeveloped countries, especially devastating Haiti Earthquake 2010 Magnitude 7.2 230,000 died
- 50. 15,900 + died Japan Earthquake Pictures, Video (9 min) Tohoku Earthquake, Japan 2011 Magnitude 9.1
- 51. Causes of Earthquakes: 1. natural pressure buildup 2. groundwater extraction 3. wastewater injection Destruction dependent upon: 1. Intensity & duration of the vibrations 2. Nature of the material where a structure is built 3. Design of the structure
- 52. Earthquake Protection • Build on stable ground • Use modern earthquake-stable designs for houses and bridges
- 53. IN HOME: seek cover against an interior wall; protect head; avoid mirrors/windows & tall furniture
- 54. Tsunami: when an earthquake or volcanic eruption happens under the ocean 1. Initiation: under-ocean earthquake 2. Split: created wave splits: one moving towards ocean, one towards shore 3. Amplification: front of wave gets taller as it moves toward shore
- 55. Deadly Hazards • Speeds faster than a jet liner • Heights rise 40 feet or more before crashing on shore • 50,000+ people killed this century • 1998 Paupa New Guinea earthquake: 2,200 killed
- 56. • On shore, a person would see the water receding from shoreline as it gathers with the upcoming tidal wave.
- 57. • Pacific Tsunami Warning Center- 1948; collects seismic data from 26 member countries; keeps watch for suspicious shaking that might trigger tsunamis; • Palmer, Alaska- warning center that monitors coasts specific to British Columbia, Washington, Oregon, & California • When an earthquake of 7/5 magnitude or greater near/under the ocean occurs, these warning centers send out initial alerts to all local authorities within 3 hours of tsunami travel time • Local authorities decide on evacuation plans
- 62. VOLCANOES VOCABULARY: volcano shield volcano cinder cone volcano composite volcano caldera Ring of Fire hotspot lava lahar ash acid plumes glass shards
- 63. Pressure under the crust becomes great within a magma chamber & must come out… volcanoes Volcanoes: cracks in the crust where lava flows 1. shield volcanoes 2. cinder cone volcanoes 3. composite volcanoes
- 64. Mauna Kea, Hawaii (shield volcano) http://www.uhh.hawaii.edu/~csav/gallery/decker/hawaii_mauna_kea.php http://www.the-vu.com/2010/05/mauna-kea-in-hawaii-driving-to-the- summit-of-this-grand-volcano/ Shield volcano: layers of lava released from non- explosive eruptions Hawaiian islands are on a hot spot in the center of the Pacific plate
- 65. Paricutin, Mexico photo2.si.edu/mexvolc/volcmex. htm Cinder cone volcano: pyroclastic material- dust & ash explodes out
- 66. Mt. Fuji Mount St . Helens ruby.colorado.edu/.../Volcanix/Volc anix.html Composite volcano: pyroclastic explosions followed by slower, longer flowing-lava (Mt. St. Helens
- 67. Caldera: large, semicircular pit that forms when the chamber supplying magma to a volcano partially empties, then the roof collapses; sinks the ground thinkgeoenergy.com/archives/747
- 69. Ring of Fire Major area in Pacific Ocean basin where many earthquakes and volcanic eruptions occur
- 70. Yellowstone Volcano, Wyoming Enormous caldera & super-volcano under the surface • 40 mile crater • last eruption: 640,000 ya • 1000-2000 earthquakes a year (most below 3 magnitude) • an eruption would be 1000X more powerful than Mt St. Helen’s in 1980 • hydrothermal water features are evidence it is still active • most scientists believe that weeks of warning signs will alert us; 1/700,000 chance a year it will erupt CURRENT CONDITIONS LINK:
- 71. Yellowstone Hotspot hotspot- thermally expanded buoyant mantle that lifts an overlying plate -used to track motion of tectonic plates: hot plate stays put as plate moves across it
- 72. Craters of the Moon National Monument, Idaho -final stage of the Yellowstone hotspot volcanism -result of volcanic flow and a rift valley (62 miles in the park)
- 76. VOLCANIC GEOHAZARDS • lava- magma that reaches the surface
- 77. GEOHAZARDS • lahar- destructive mudflow on the slopes of a volcano
- 78. GEOHAZARDS • ash- volcanic ash clouds the sky and adds to acid rain & air pollution Ontake, Japan 2014
- 79. GEOHAZARDS • acid plumes & glass shards – sulfur dioxide gas & very fine glass shot into the sky as Mt. Kiauea volcano vents 7/2018 VIDEO 1 min
- 80. Mt. Saint Helens, Washington
- 83. • Scientists study and monitor seismic activity at a volcanic hot zone • In scientific observatories & through field work, scientists look for warning signs of an eruption • small earthquakes • inflation/swelling of the land • increased emission of heat/gas from vents Kilauea Observatory, HI
- 84. Official Volcano Warnings • color codes & alert levels • specific for each volcano • warning systems are based on probability of eruption
- 85. Safety After a Volcano • cover mouth &nose • wear goggles/protect eyes • cover skin • clear roofs from heavy ash