EAR 105 Study Guide Test 3
n Read the book, use the guide below to focus your reading along with lecture slides and your notes
n Know how to read and use various charts/tables/figures – as demonstrated in lectures (you don’t need to memorize the charts)
n Read over your geotours exercises/study guide
n Look over your homework
EAR 105 Earth Science: Material covered/study guide
Test 3 will cover chapters 8, 9, 10, and Interludes D (all of these are listed below).
~50 questions.
Chapter 8: Metamorphism
• Metamorphism and methamorphic facies (Box 8.1, lecture slides)
• Metamorphic processes (Figure 8.3)
• Relationship between pressure, depth and metamorphism (know how to read Figure 8.4, 8.14, 8.15)
• Grades of metamorphism
• Where does metamorphism occur, discussed in class (Sec. 8.5)
• Classifying metamorphic rocks, foliated vs non-foliated
• Common metamorphic rocks
• Meaning of a protolith and common protoliths discussed in class
Skip: Box 8.2, 8.3
Chapter 9: Volcanoes
• Products of volcanism:
o pyroclastic flows (nuee ardent)
o lava bombs, lapilli
o lava flows types: pillow basalts, aa, pahoehoe
o gasses and lahars
• Melting and magmatism,
o composition of magmas
felsic vs mafic
viscosity
temperatures
o Geotherm, Solidus (Melting Curve), Liquidus
• Volcano Architecture (Anatomy)
o Types of volcanoes, slopes, lava types, size, etc..
• Caldera vs crater
o Caldera formation
• VEI, eruption types
o Table 9.1: effusive/Hawaiian, Strombolian, Plinian
• Explosive eruptions to remember Box 9.1
o Mt St Helens (1980), Krakatau (1883), Pompeii (79AD)
• Different types of Volcanoes and their Geological Settings
o subduction zones, hot spots, ridges/rifts
o shield volcanoes, stratovolcanoes, cinder cones
o Ring of fire
• Intra-plate volcanism
o hotspots, large igneous provinces
• Super volcanoes e.g. Yellowstone
• Volcanic Hazards
• Volcanoes in our solar system
o (lunar Mare – on the moon), Olympus Mons on mars (largest in solar system, 3x higher than Everest), Sulphur volcanoes on Io (moon of Jupiter).
Chapter 10 Earthquakes
• What is an earthquake?
• What is a seismometer?
• What is a seismogram?
• Describe an earthquake and explain where the energy released during an earthquake comes from.
o Seismic waves radiate from the focus of the EQ (what is the difference between a focus and the epicenter)
o What is an asperity?
• Distinguish among the different kinds of seismic waves
o Body Waves (P & S) and Surface waves (Lateral or Love Waves, and Vertical or Rayleigh waves).
o What are the differences between these?
o What is a P-wave and a S-wave: how do they propagate through the Earth?
• Arrange seismic waves in order of arrival (i.e. speed of wave travel and amplitude)
• What controls the speed of waves through the Earth (material properties: compressibility and rigidity)
• Show how the arrival times of seismic waves can indicate where an earthquake occurred.
o Using the P&S-wave travel time plots to determine the locations (epicenter) of earthquakes (from multiple seismometers). Understanding seismograms and what they record (arrival of waves P, S then surface waves)
o Understand how one obtains precise location of an earthquake (triangulation).
• Relate earthquakes to specific geologic settings, in the context of plate tectonic theory.
• Explain the difference between the intensity and magnitude of an earthquake and how these indicators of earthquake size can be determined.
• Distinguish between tsunamis and storm waves, and explain how large tsunamis can cause so much damage.
• Types of faults
o Normal fault (dip-slip) (tensional fault, results in extension): Footwall vs hanging wall, fault plane..
o Reverse fault (dip-slip) or thrust fault, results in compression.
o Strike-slip fault (a shearing motion, fault plane is vertical)
A strike-slip fault, right-lateral (dextral fault) and left-lateral (sinistral)
• Which type of waves are most destructive, what wave type is used for early warning systems?
• Magnitude and Intensity of Earthquakes
o Richter scale (developed in 1935) but only accurate close to the EQ epicenter
o Moment magnitude scale (eg EQ of magnitude 7 is 10x more powerful than a
magnitude 6 and is 100x (10x10) more powerful than a magnitude 5. 1 magnitude unit = 32x energy).
o How does intensity compare to amplitude?
• Earthquakes at Plate Boundaries and Plate Interiors
o Convergent plate boundaries –
o Define Wadati-Benioff zones
o The greatest, most powerful EQs occur at subduction zones (megathrust EQs)
o deep vs shallow earthquakes
o Strike-slip faults (transform. boundaries, eg San Andreas fault)
o Continental rifts (normal faults) – eg Basin and Range province, Rio- Grande rift, East Africa rift
o Continent-continent collision zone (eg Himalayas)
o Intraplate settings – eg New Madrid EQ (1811-12)
• San Andreas movie – in which a M9.6 EQ splits California – however this is not possible
• Earthquake Hazards:
• aftershocks (for periods of weeks-years) often follow the main event, foreshocks often precede larger EQs but hard to know if any EQ is actually a foreshock
• Earthquake safety
• EQ damage – eg buildings sited of different bedrock (solid bedrock, sediment, water-
saturated sand and mud) – waves slow down and increase in amplitude in softer material
• Sec. 10.6 only Sediment Liquefaction and Tsunamis
o Liquefaction (what is this?)
o How do tsunamis form? (megathrust EQs at subduction zones produce the big ones): 3 examples 2011 Japan 9.0 EQ and tsunami, 2010 Chile M8.8 EQ and tsunami, 1964 Alaska M9.2 EQ and tsunami, 2004 Sumatra M9
EQ and tsunami
o Tsunamis waves vs storm waves
o Characteristics of tsunami (retreat of water is often first sign, multiple waves)
• Can we predict EQ’s – yes we can, but in probabilities, not in the short-term, develop risk-maps
Interlude D: Earth's Interior revisited
• Structure of the Earth (crust, mantle core)
• Seismic waves and their propagation
• What effects seismic wave propagation (rock type, solid/liquid, type of wave),
• Reflection (Snell’s law) and refraction (if move from faster to slower material the wave is refracted to a steeper angle, if move from slower to faster (normal in the Earth with increasing depth) the wave is refracted to a shallower angle.
• Because of the core-mantle boundary there is a P-wave shadow zone (103-143°) and a S- wave shadow zone (103 to 103°). The S-wave shadow zone is larger because S-waves do not travel through liquid (ie the liquid outer core)
• Seismic tomography: Seismic wave velocities in the earth – variable due to compositional changes (red = slower than expected (hotter or less dense), blue = faster than expected
(cooler or denser) – example of subducting Pacific plate under Japan