Study Guide for Earth Systems Ch 8 & 9 Test
1. Define fault. A fracture in the Earth where movement has occurred
2. What is the relationship between a fault and an earthquake? Earthquakes are associated with
faults.
3. What causes earthquakes? Elastic rebound
4. Define aftershock. Smaller earthquakes that follow a major earthquake
5. Define creep. The slow continuous movement that occurs along some fault zones
6. The San Francisco earthquake of 1906 occurred along what fault? San Andreas fault
7. Which seismic wave travels most rapidly? P waves
8. Which seismic waves compress and expand rocks in the direction the waves travel? P waves
9. The distance between a seismic station and the earthquake epicenter is determined from what?
Arrival times of P and S waves
10. What is the scale most widely used by scientists for measuring earthquakes? moment
magnitude scale
11. What is the amount of shaking produced by an earthquake at a given location called? Intensity
12. The trace that records an earthquake from seismic instruments is called what? Seismogram
13. The Richter magnitude of an earthquake is determined from what? Measurement of the
amplitude of the largest seismic waves
14. What affects the amount of destruction caused by earthquake vibrations? 1) The design of
structures, 2) the intensity and duration of the vibrations and 3) the nature of the material on
which structures are built
15. What areas have the greatest damage from earthquakes? Area with older brick structures
16. What are tsunamis? Tidal waves often generated by movements of the ocean floor
17. Define liquefaction. In areas where sediments are saturated with water, earthquakes can turn
stable soil into a fluid through this process
18. How does a tsunami occur? There is vertical movement of a fault under the ocean floor
19. What causes a landslide? Violent shaking from an earthquake causes soil and rock on slopes to
fail
20. Why do earthquakes often cause damaging fires? Earthquake vibrations can break gas lines,
water lines, and electrical lines.
21. What layers of Earth make up the lithosphere? the crust and upper mantle
22. Be able to label Figure 8-2 in the book (layers of the Earth).
23. What is Earth’s thin, rocky, outer layer called? Crust
24. What is the Moho? The boundary between the crust and the mantle
25. What is Earth’s core made of? Iron and nickel
26. Evidence that Earth’s core has a high iron content comes from what? meteorites
27. List the evidence that supports Wegener’s hypothesis. 1) fossils of the same organism have
been found on different continents, 2) climate changes and 3) mountain ranges
28. What does evidence about ancient climates indicate? glacial ice once covered much of what is
now India and Australia
29. What does the geographic distribution of the swimming reptile Mesosaurus provide evidence
of? South America and Africa were once joined
30. What layers of the Earth does a tectonic plate consist of? the crust and uppermost mantle
31. In the plate tectonic theory, a plate can be made up of what? both continental and oceanic
lithosphere
32. What happens in a transform fault boundary? two plates grind past each other without
destroying or producing lithosphere
33. What is a geographic example of a transform fault boundary? the San Andreas Fault
34. At which boundary is new ocean crust formed? divergent boundaries
35. What results when divergence occurs between two oceanic plates? seafloor spreading
36. Be able to label Figure 9-1 (convergent oceanic-continental boundary).
37. What occurs at a subduction zone? 1) Oceanic crust is pushed down into the mantle,
2) A continental plate moves over an oceanic plate and 3) One oceanic plate moves beneath
another oceanic plate.
38. If a deep ocean trench is located adjacent to a continent, active volcanoes would likely be found
where? landward from the trench
39. What happens to the lithosphere at a transform fault boundary? It is neither destroyed nor
produced
40. What do magnetic reversals provide evidence for? seafloor spreading
41. The Hawaiian Islands were formed when the Pacific Plate moved over what? A hot spot
42. The age of the rocks in the ocean basins was determined by what? ocean drilling
43. What plate boundary is the formation of the Hawaiian Islands associated with? No plate
boundary. They were formed over a hot spot.
44. Define slab-pull. The main source of downward convection flow in the mantle
45. Be able to read Figure 9-2 (convergent oceanic-oceanic boundary)