Portland Community College | Portland, Oregon

Earthquakes (G 209) is a one-term introductory course in earthquakes/seismology, which is a branch of the science of geology. The student will develop an understanding of the causes, activity, effects, and hazards of earthquakes as well as an understanding of the various methods of measuring the size/energy of an earthquake. The course will use case studies of historical earthquakes to examine ways to minimize earthquake damage, with emphasis on earthquakes in the Pacific Northwest.

Students are expected to be able to read and comprehend college-level science texts and perform basic mathematical operations in order to successfully complete this course.

Earth and space sciences are based on observations, measurements and samples collected in the field. Field-based learning is recommended by numerous professional Geology organizations, including the American Geological Institute and the National Association of Geoscience Teachers. Field-based learning improves both metacognition and spatial/visualization abilities while helping to transfer basic concepts to long-term memory by engaging multiple senses at the same time. Spatial thinking is critical to success in STEM (Science, Technology, Engineering, and Math) disciplines. Field work may include:

• Å·ÖÞ±­¾öÈü¾º²Âapp_Å·ÖÞ±­×ãÇòÍø-Ͷע|¹ÙÍøing skills in site characterization
• Application of key terms and concepts
• Measurement and data collection
• Interpretation of data and observations, and fitting them to a larger context

Field work may be physically challenging and may require overland travel on foot or other means to field sites, carrying equipment and supplies, and making measurements in unusual or awkward positions for a length of time.  Field work may include inherent risks (uneven terrain, variable weather, insects, environmental irritants, travel stress, etc.). Field work can be adapted to individual abilities.

Regarding the teaching of basic scientific principles (such as geologic time and the theory of evolution), the Portland Community College Geology/General Sceinces Subject Area Committee  stands by the following statements about what is science.
 

• Science is a fundamentally non-dogmatic and self-correcting investigatory process. A scientific theory is neither a guess, dogma, nor myth. The theories developed through scientific investigation are not decided in advance, but can be and often are modified and revised through observation and experimentation.
• “Creation science,” also known as scientific creationism, is not considered a legitimate science, but a form of religious advocacy. This position is established by legal precedence (Webster v. New Lenox School District #122, 917 F.2d 1004).
• Geology/General Science instructors at Portland Community College will teach the generally accepted basic geologic principles (such as geologic time and the theory of evolution) not as absolute truth, but as the most widely accepted explanation for our observations of the world around us. Instructors will not teach that “creation science” is anything other than pseudoscience.
• Because "creation science", "scientific creationism", and "intelligent design" are essentially religious doctrines that are at odds with open scientific inquiry, the Geology/General Sciences SAC at Portland Community College stands with such organizations such as the National Association of Geoscience Teachers, the American Geophysical Union, the Geological Society of America, and the American Geological Institute in excluding these doctrines from our science curriculum.

Upon completion of this course students should be able to:

1. Evaluate the probability of future earthquake activity in a particular area based on tectonic setting, past recurrence intervals, elastic rebound theory and the stick slip behavior of faults.
2. Explain the geographic distribution of Earth’s earthquake activity using an understanding of plate tectonics. 
3. Evaluate the earthquake-related hazards and risks impacting our communities using scientific reasoning based on field and/or laboratory and/or remote measurements and observations. 
4. Assess the contributions of seismology to our evolving understanding of global change and sustainability while placing the development of seismology in its historical and cultural context.

The material in this course will be presented in a lecture/discussion format. Other educationally sound methods may be employed such as guest lectures, field trips, research papers, presentations, and small group work.

At the beginning of the course, the instructor will detail the methods used to evaluate student progress and the criteria for assigning a course grade. The methods may include one or more of the following tools: examinations, quizzes, homework assignments, research papers, small group problem solving of questions arising from application of course concepts and concerns to actual experience, oral presentations, or maintenance of a personal work journal.

1. Describe what is meant by "earthquake".
2. Define the following terms: focus, epicenter, refraction, reflection.
3. Describe the different types of seismic waves.
4. Describe the relationship of earthquakes to plate tectonics.
5. Define the following terms: strain accumulation, creep, foreshock, main shock, aftershock, interplate earthquake, intraplate earthquake.
6. Describe how a seismograph works.
7. Locate an earthquake epicenter using travel-time curves and three seismic records.
8. Describe how earthquakes can be used to study the interior of the earth.
9. Locate underground faults and describe crustal structure using a seismic profile.
10. Classify the different types of faults that result from earthquakes.
11. Define the following terms: strike-slip, dip-slip, oblique-slip, hanging wall, foot wall.
12. Describe the landforms produced along faults.
13. Describe the causes of earthquakes.
14. Define the following terms: compression, dilation, elastic rebound, compressive stress, tensile stress, fault-plane diagram
15. Identify the different types of seismic waves on a seismogram and determine the motion along the fault from the first motion of the p-wave.
16. Describe the relationship between earthquakes, volcanoes and tsunamis.
17. Define the following terms: soil liquefaction, slickensides, sand boils, clastic sills.
18. Discuss a number of historical earthquakes and determine the major cause of destruction for each case.
19. Describe the events that precede earthquakes.
20. Describe the evidence for past earthquakes along the Cascadia subduction zone.
21. Describe steps that an individual can take to protect against earthquake damage
22. Describe methods for making buildings and other structures more earthquake resistant.

Topics to be covered include:
 

1. Global Earthquake Activity
   1. Major historic earthquakes and their impact on society (e.g. San Francisco 1906, Mexico City 1985, Nisqually 2001 etc.)
   2. Number and geographic distribution of major historic earthquakes
2. Observational Seismology
   1. Eyewitness observations during earthquakes
   2. Effects of earthquakes; ground rupture, ground displacement, fault scarps, sand boils, liquefaction, damage to buildings and structures
   3. Mercalli intensity scale
   4. Foreshocks and aftershocks
3. Faults and Earthquakes
   1. Relationship between faults and earthquakes, elastic rebound theory of earthquakes
   2. Stress (compressive, tensional, shear) and strain (brittle, ductile and elastic)
   3. Types of faults: strike slip, dip slip, oblique slip, right lateral, left lateral, normal, reverse, thrust and detachment, footwall vs. hanging wall, relation between fault type and stress
   4. Small scale features of faults; slickensides, fault gauge, mineralization.
   5. Geomorphology of faults; scarps, shutter ridges, sag ponds, linear valleys, faceted spurs
   6. Evidence for cumulative displacement along faults
   7. Causes of earthquakes not associated with faults; landslides, volcanic eruptions, atomic tests
4. Instrumental Seismology
   1. Seismometers; principles of operation, sensitivity
   2. Seismograms; identification of P, S and surface waves
   3. Properties of waves; wavelength, amplitude, period, wave speed, particle motion
   4. Behavior of waves; constructive and destructive interference, standing waves, refraction, reflection
   5. Interpretation of P, S and surface waves, typical velocities of each
   6. Use of P-S wave gap to determine distance to earthquake, pinpointing the point of origin of an earthquake by triangulation, epicenter vs. focus
   7. Use of first motion studies to determine the sense of motion along a fault, use of 'beach ball diagrams' to represent fault plane solutions
   8. Determining the magnitude of an earthquake; Richter magnitude vs. moment magnitude
   9. Frequency of various size earthquakes, depth distribution of earthquakes
5. Mechanics of Faults
   1. Creep and asperities, stick -slip models of faults
   2. Earthquakes triggered by earthquakes; changes in stress and strain caused by earthquakes
6. Earthquakes and the Earth's Internal Structure
   1. Refraction and reflection of seismic waves, application to determining subsurface structure and thickness of crust
   2. Velocity of seismic waves through different materials, effects of pressure and temperature on seismic velocity
   3. Variation of seismic velocity with depth; evidence for the low velocity zone
   4. Shadow zones as evidence for the outer and inner core.
7. Plate Tectonics and Earthquakes
   1. Basic idea of plate tectonics, evidence for plate motion, difference between continental and oceanic crust, internal structure of the earth, heat loss and plate tectonics
   2. Types of plate boundaries: stresses associated with each, first motions of earthquakes observed at each, depths of earthquakes associated with each type of plate boundary
8. Living with Earthquakes
   1. Primary hazard from earthquakes; ground shaking, ground deformation, liquefaction
   2. Secondary hazards from earthquakes; landslides, tsunamis, fire
   3. Construction of earthquake hazard maps
   4. The methods of paleoseismology, the reoccurrence intervals of faults
   5. Preparing for earthquakes, personal preparedness, societal preparedness
   6. The design of earthquake resistant buildings, the retrofitting of existing buildings
   7. Predicting earthquakes, possible precursors, periodicity, seismic gaps
   8. Successes and failures of earthquake prediction in China and Parkfield, CA.
9. Earthquakes in the Pacific Northwest
   1. Historic earthquakes in the Pacific Northwest
   2. Tectonic setting of the Pacific Northwest and the possibility of large earthquakes
   3. Evidence for prehistoric subduction zone earthquakes in the Pacific Northwest
   4. Comparison of causes, effects and frequency of shallow, deep and subduction zone earthquakes
   5. "Silent' earthquakes in the Pacific Northwest