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Ring of Fire and Quakes Original Source: Dr. Leslie Sautter (Dept. of Geology, College of Charleston) Grade Level: SC Standards: National Standards: 8th 8th – IIIB3c,d,g,j Earth and Space Science Content Standard D . Focus Question Teacher Preparation What are the relationships among the locations of earthquakes, active volcanoes and plate boundaries? If this activity will be presented using an LCD projector, the powerpoint presentation “Ring of Fire and Quakes” should be downloaded. Objectives If this activity will be presented using an overhead projector, the following preparations are necessary: 1. Photocopy Figures 1-5 onto overhead transparencies. Students will: compare distributions of shallow and deep focus earthquakes. compare distributions of volcanoes with earthquakes. compare earthquake and volcano distributions with plate boundary locations. make inferences of what is occurring at different plate boundary locations. 2. If the overheads are in black and white: a. Figure 3: With a yellow transparency marker, color over the areas where there are dots that represent deep focus earthquakes. b. Figure 4: With a red transparency marker, fill in the circles that represent sites of recently active volcanoes. Key Words earthquake focus epicenter Pacific Ring of Fire Time Frame divergence One 50-minute class period convergence Suggested Learning Environment Materials This activity is written for the teacher to conduct with the entire class, using either an LCD or overhead projection. “Ring of Fire and Quakes” powerpoint presentation, (by L. Sautter) computer LCD projector Relevant pages in Of Sand and Sea or Chapter I, The Ocean Planet, pp. 7-16. overhead transparency copies of Figures 1-5 overhead projector physiographic map of the continents red and yellow overhead transparency markers (not necessary if overheads are printed in color) tape COASTeam Program, Project Oceanica, College of Charleston 1 Ring of Fire and Quakes TEACHER PAGES Teacher Background Information Procedure The teacher should review basic information about earthquakes: An earthquake is the sudden release of a tremendous amount of energy from within the earth‟s interior. This release of energy is often from a location where tremendous friction has prevented rocks under stress from fracturing or moving. When the stresses exceed the force of friction, the built-up energy is suddenly released. Earthquake energy travels through the earth in the form of seismic waves. The point of origin of an earthquake (i.e., where the energy is released) is called the earthquake focus. The plural of “focus” is “foci.” Earthquake foci occur at depths ranging from the earth‟s surface to approximately 700 km below the surface. Scientists group the foci into three broad groupings, based on the depth of the earthquake. These groups and their approximate depth ranges are: o shallow focus (0-50 km), o intermediate focus (50-300 km) o deep focus (300-700 km) The point plotted on a map directly above the earthquake focus is called the earthquake‟s epicenter. Therefore, on a map, different symbols will indicate the epicenter locations of shallow, intermediate, and deep focus earthquakes. The following instructions are intended for the teacher to use as a classroom demonstration, using the powerpoint “Ring of Fire and Quakes,” or using overhead transparencies. Text in blue italics and in parentheses relate to instructions if the teacher is using overhead transparencies. The lettered items (a, b, c, etc.) are the instructions or questions the teacher might pose to the class. 1. Slide 1 - “Physiography of the seafloor.” (Show overhead Figure 1.) a. Review the large-scale seafloor features of the Pacific and Atlantic Ocean basins. 2. Slide 2 - “Distribution of shallow focus earthquake epicenters.” (Remove Figure 1 and show Figure 2 by itself.) a. What is a shallow focus earthquake? b. What is an epicenter? c. Make observations regarding the shallow focus earthquake distribution. Observations should pertain ONLY to the information being viewed on the figure. Do not make interpretations as to why the epicenters are distributed as they are. d. Is the concentration of these epicenters the same everywhere? 3. Slide 3 – “Overlay of shallow focus earthquake epicenter on the seafloor physiography.” (Overlay Figure 2 onto Figure 1. You may wish Note that there are no student sheets with this activity, as it is done as a class, with the teacher leading the guided inquiry. Students should write their observations and responses to the questions posed by the teacher in their science notebooks. to tape the edges of the overheads to the projector, but this is only temporary.) a. Where are the greatest concentrations of shallow focus earthquakes? b. With what type of seafloor feature are they associated? Students are asked to make observations. Stress that observations are what they can see, not the how or why of the data presented. They should not interpret the data (e.g., explain why volcanoes are in a ring around the Pacific) when asked to make observations. 4. Slide 4 – “Distribution of deep focus earthquake epicenters.” (Remove Figures 1 and 2 from the overhead COASTeam Program, Project Oceanica, College of Charleston 2 Ring of Fire and Quakes TEACHER PAGES projector. Show Figure 3 by itself. Separate Figures 1 and 2 if they were taped together.) c. Are they associated with any continental features? d. Generally, how are the volcanoes distributed in the Pacific Ocean? The line of volcanoes around the rim of the Pacific is called the “Ring of Fire.” e. Generally, how are the volcanoes distributed in the Atlantic Ocean? Is there a “Ring of Fire” in the Atlantic Ocean? a. What is a deep focus earthquake? b. Make observations (not interpretations) regarding the deep focus earthquake epicenter distribution. (Note: observations should pertain ONLY to the information being viewed.) 5. Slide 5 – “Overlay of deep focus earthquake epicenters on seafloor physiography.” (Overlay Figure 3 onto Figure 1. You may wish 9. Slide 9 – “Distribution of shallow focus earthquake epicenters and active volcanoes.” to tape the edges of the overheads to the projector, but this is only temporary.) (Overlay Figure 2 on Figure 4.) a. a. Where are the greatest concentrations of deep focus earthquakes? b. Are they associated with any seafloor features? c. Are they associated with any continental features? 10. Slide 10 – “Distribution of deep focus earthquake epicenters and active volcanoes.” (Remove Figure 2, and overlay Figure 3 on Figure 4.) 6. Slide 6 – “Distribution of shallow and deep focus earthquake epicenters.” a. (Remove Figure 1. Overlay Figure 3 onto Figure 2). a. Make observations to compare the distribution of shallow focus earthquakes to the distribution of deep focus earthquakes. Make observations to compare the distribution of deep focus earthquakes to the distribution of recently active volcanoes. 11. Slide 11 – “Distribution of shallow focus earthquake epicenters, deep focus earthquake epicenters, and active volcanoes.” 7. Slide 7 – “Distribution of recently active volcanoes (approximated).” (Add Figure 3 to Figures 2 and 4. Tape these three overheads together, as they will be used as a group in the next steps.) (Remove Figures 2 and 3, and show Figure 4 by itself.) a. Make observations to compare the distribution of shallow focus earthquakes to the distribution of recently active volcanoes. Make observations of the distribution of active volcanoes. a. Summarize your observations regarding the distributions of and associations among deep and shallow focus earthquakes and volcanoes. b. Complete the following sentence: “Volcanoes are more strongly associated with ____ focus earthquake epicenters.” 8. Slide 8 – “Overlay of recently active volcanoes on seafloor physiography.” (Overlay Figure 4 onto Figure 1.) a. Where are the greatest concentrations of volcanoes? b. Are they associated with any seafloor features? COASTeam Program, Project Oceanica, College of Charleston 3 Ring of Fire and Quakes TEACHER PAGES 12. Slide 12 – “Overlay of shallow and deep focus earthquake epicenters, and volcanoes on seafloor physiography.” 14. Toggle back and forth between Slide 13 and Slide 14 several times so that students can visualize the associations among earthquakes, volcanoes and the different types of plate boundaries. (Place Figure 1 underneath the taped stack of Figures 2, 3, and 4). (Overlay Figures 2,3, and 4 on Figure 5.) a. What earthquake/volcanic activity is occurring at the mid-ocean ridges (e.g., the Mid-Atlantic Ridge and East Pacific Rise)? b. What earthquake/volcanic activity is occurring at Iceland? c. What earthquake/volcanic activity is occurring at trenches (e.g., the Aleutian Trench, the Mariana Trench, The Tonga Trench, the Peru-Chile Trench)? d. What earthquake/volcanic activity is occurring at the Andes Mountains? e. What earthquake/volcanic activity is occurring at the seamount chains such as the Aleutian Islands and the Mariana Islands? f. What earthquake/volcanic activity is occurring at Hawaii? g. What earthquake/volcanic activity is occurring at the San Andreas Fault? a. What type or types of earthquakes do you find associated with divergent plate boundaries? b. What type or types of earthquakes do you find associated with convergent plate boundaries? c. Compare divergent and convergent plate boundaries with respect to the distribution and abundance of volcanoes. d. Find the San Andreas Fault. What type of plate boundary is it? What type or types of earthquakes are associated with it? e. Is Hawaii on a plate boundary? What type or types of earthquakes are associated with it? 15. Students should be challenged with the following questions, which are intended to provoke brainstorming. Students may be broken into small discussion groups to devise some hypotheses to answer the questions. 13. Slide 13 – “Tectonic plates, showing divergent, convergent and transform plate boundaries.” (Remove Figures 1-4 and show only Figure 5.) What does a high concentration of earthquakes occurring along a line indicate? This figure shows the locations of the tectonic plate boundaries. Examine the legend and make observations as to where divergent, convergent and transform plate boundaries occur. a. Define the terms divergence, and convergence. b. What seafloor and/or continental feature(s) are found associated with divergent plate boundaries? c. What seafloor and/or continental feature(s) are found associated with convergent plate boundaries? d. Where is the largest transform plate boundary on the Pacific Plate? Deep focus earthquakes are usually not located directly beneath the shallow focus earthquakes, but they are almost always offset. Any ideas why this might be occurring? Most volcanoes occur above deep focus earthquakes, rather than shallow focus earthquakes. Is there a possible association between these „quakes and volcanoes? Why are there few to no deep focus earthquakes associated with mid-ocean ridges? COASTeam Program, Project Oceanica, College of Charleston 4 Ring of Fire and Quakes TEACHER PAGES Assessment Use the students‟ responses to the previous questions as assessment of their understanding of the Ring of Fire and Quakes as well as the relationship between plate boundaries and the locations of earthquakes and volcanoes. Source: Dr. Leslie Sautter, Project Oceanica, Dept. of Geology and Environmental Geosciences, College of Charleston, SC. website: http://oceanica.cofc.edu email: [email protected] phone: 843-953-5586 Funding for the COASTeam Program was provided by the South Carolina Sea Grant Consortium. http://oceanica.cofc.edu/coasteam/ COASTeam Program, Project Oceanica, College of Charleston 5 Ring of Fire and Quakes TEACHER PAGES COASTeam Program, Project Oceanica, College of Charleston 6