LabAssignment 3

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(Revision 4) Assignment 3 Tectonic Earthquakes and Associated Hazards Complete Units 4, 5, and 6 before attempting this assignment. This assignment (worth 100 marks) makes up 5% of your final grade. Materials To complete this assignment, you will need the following materials. Please collect them now, before you proceed.  Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.). Upper Saddle River, NJ: Prentice Hall.  Keller, E. A. (2012). Introduction to Environmental Geology (5th ed.). Upper Saddle River, NJ: Prentice Hall. Overview Following a brief look at geologic hazards, this assignment examines basic characteristics of tectonic earthquakes. You will become acquainted with methods that can be used to locate earthquake epicentres and procedures for measuring earthquake intensity. After examining earthquake shaking hazard maps and fault detection, the final part of the assignment addresses earthquake preparation, hazard reduction techniques, and earthquake prediction. Geologic Hazards: Introduction Reading Assignment Keller, E. A. (2012). Introduction to Environmental Geology (5th ed.).  Review “Hazards, Disasters, and Natural Processes” (pp. 142–149). Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “Introduction to Geologic Hazards” (pp. 45–51). Questions (20 marks) Answer questions 1–4 under “Questions Introduction II—Geologic Hazards” (p. 48) in Investigations in Environmental Geology (3rd ed.). 1. Give the definition of a geologic hazard (in your own words or that provided in the Introduction). A geologic hazard is a geologic condition, process, or potential event that poses a threat to our safety, health, structures, the functions of human society, and the economy. Geology 207: Introduction to Environmental Geology 1

(Revision 4) 2. List 5 geologic hazards. Earthquakes, Volcanoes, Floods, Landslides, Tsunamis. 3. What types of hazards have been omitted from this book? Biological hazards (disease, pests, overpopulation), Weather hazards (tornadoes, storms, wildfires), Magnetic storms, Asteroid impacts, Technological hazards (air pollution, nuclear accidents, terrorism), Slow geologic processes (erosion, permafrost thawing, desertification) 4. Can human activity induce a geologic hazard? Explain your answer. Yes, the chapter gives us an example of human activities like diverting rivers, undercutting slopes, over- using groundwater, etc. That can trigger or worsen geologic hazards like landslides, floods, ground subsidence that may not have otherwise occurred or been as severe. Humans can be geological agents altering hazard risk. Earthquakes A. Earthquake Epicentre Reading Assignment Keller, E. A. (2012). Introduction to Environmental Geology (5th ed.).  Review “Introduction to Earthquakes,” “Earthquake Magnitude,” and “Earthquake Intensity” (pp. 170– 177). Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “Introduction” (p. 82).  “Earthquake Waves” (p. 82).  “Part A. Epicentre, Intensity, and Seismic Risk: Epicentre” (p. 83). Questions (40 marks) Answer questions 1–4 (A1, pp. 83–84) in Investigations in Environmental Geology (3rd ed.). Geology 207: Introduction to Environmental Geology 2

(Revision 4) 1- 2- To determine the distance from the earthquake to each seismograph station we must first determine the time lag between P and S wave arrivals at a given distance from an earthquake, say 100 km, knowing the average velocities of the P and S waves. If the average velocity of the P wave is 6.1 km/sec and the average velocity of the S wave is 4.1 km/sec, what is the time required for each wave to travel 100 km? (It may help to think of this problem like a very fast driving trip: if you want to go 100 km, and you drive at a rate of 6.1 km/sec, how long, in seconds, will it take you to get to your destination?) P waves (6.1 km/sec) travel 100 km in 16.4 seconds. S waves (4.1 km/sec) travel 100 km in 24.4 seconds. Thus, the time lag between the arrival of P and S waves at a distance 100 km from the hypocenter (T100) is 8 seconds. 3- Geology 207: Introduction to Environmental Geology 3

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(Revision 4) 4. a. The epicenter of the earthquake can be pinpointed by drawing compass arcs from three of the stations with radii corresponding to the distances calculated in Question 3. The intersection of these radii marks the epicenter. Do this in Figure 6.3. Geology 207: Introduction to Environmental Geology 4

(Revision 4) b. Where is the epicenter? (Give location within a state.) Missouri c. Label it on the map (Figure 6.3). See above. d. At what time did the earthquake occur? (Refer to Figure 6.2.) 3:10-09 CST B. Earthquake Intensity Reading Assignment Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “Intensity” (pp. 84–85). Questions (20 marks) Answer questions 1 and 2 (A2, pp. 85–87) in Investigations in Environmental Geology (3rd ed.). Geology 207: Introduction to Environmental Geology 5

(Revision 4) 1. Following are some historical descriptions of earthquakes (a-d). Such statements, made to scientists or reporters or recorded in diaries or on survey forms distributed by government agencies, allow scientists to determine the intensity of an earthquake. Using the Modified Mercalli Intensity Scale (Table 6.1), assign each of the quakes an intensity number. Pick the lowest number exhibiting the characteristics given. The first quotation describes the observations of an eyewitness to a California earthquake around 1913. The second, third, and part of the fourth descriptions are from data gathered by the U.S. Coast and Geodetic Survey after the Daly City, California, earthquake of 1957 (Richter magnitude 5.3). a. “There was a keen frost, and when we reached the water-hole a thin film of ice was seen upon the water. I dismounted and led my horse by the bridle, and walked to the edge of the water. Just as I reached it, the ground seemed to be violently swayed from east to west. The water splashed up to my knees; the trees whipped about and limbs fell on and all around me. I was affected by a fearful nausea, my horse snorted and in terror struggled violently to get away from me, but I hung to him, having as great a fear as he had himself. The lake commenced to roar like the ocean in a storm, and, staggering and bewildered, I vaulted into the saddle and my terrified horse started, as eager as I was to get out of the vicinity.” (Eisman 1972) Intensity: VII b. “The shock seemed to be a sort of gentle swaying back and forth, causing hanging fixtures to swing, but doing no damage.” (Iacopi 1971) Intensity: II c. “The earthquake was very intense. . .a heavy oak china cabinet and massive table moved 2 to 3 inches away from original positions; kitchen stove moved 2 inches; furnace in basement moved two inches off base and water heater tilted off base.” (Iacopi 1971) Intensity:VI d. “It was as if giant hands took the house and shook it ... the pea soup jumped out of the pot and the grandfather clock was silenced.” (modified from Iacopi, 1971) Intensity:V 2. Not all earthquakes occur in areas where high levels of risk have been identified. On July 27, 1980, an earthquake of Richter magnitude 5.1 shook Kentucky, Ohio, and adjacent states. The earthquake epicenter was determined to be at latitude 38.2° N, longitude 83.9" W, near Sharpsburg, Kentucky(approximately 30 miles southwest of the Ohio River town of Maysville, Kentucky). It had a focal depth of 13 km. Damage to structures along the Ohio River in Maysville, Kentucky, and in the Ohio communities of Aberdeen, Manchester, Ripley, and West Union, consisted of chimneys being knocked down, cracks in plaster and concrete blocks, and merchandise being toppled from store shelves. In Cincinnati a cornice reportedly fell from city hall. a. Based on the reported damage, what was the intensity of this earthquake along the Ohio River? VIII Geology 207: Introduction to Environmental Geology 6

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(Revision 4) b. C. Earthquake Shaking Hazard Maps Reading Assignment Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “Earthquake Shaking Hazard Maps” (p. 91). Questions (20 marks) Answer questions 1, 3, 4, and 5 (A4, pp. 91–92) in Investigations in Environmental Geology (3rd ed.). For a colour map of Figure 6.3, see the link: http://pubs.usgs.gov/fs/2008/3018/pdf/FS08-3018_508.pdf 1. Which areas of the country have the lowest hazard from earthquake shaking (where 4% g, or less, peak acceleration is expected)? Whole or parts of Florida, Texas, Wisconsin, Minesota, Michigan, North and South Dakota, and Montana. 3. What three or four regions of the country have the highest accelerations? West Coast, Hawaii, South Carolina and near the border of Tennessee, Kentucky, Arkansas, Missouri, and Illinois. Geology 207: Introduction to Environmental Geology 7

(Revision 4) 4. What geologic processes, other than shaking and fault displacement, could produce a hazard in an earthquake? List two. Liquefaction and Landslides 5. The geologic material on which a building rests plays a role in the type of shaking that occurs during an earthquake. Weak materials amplify the shaking. Which of the following foundation materials would most likely result in less shaking and a safer building? unweathered bedrock Geology 207: Introduction to Environmental Geology 8

LabAssignment 3

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