Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Name: Subduction Lab Period: The vast majority of earthquakes occur at plate boundaries. The deepest earthquakes occur at subduction boundaries where lithosphere is plunging down into the mantle. The behavior of the subducting plate is determined by the age of the rocks comprising the plate. Older crust is cooler, and therefore denser, than younger crust. Older, cooler, denser crust subducts faster and at a steeper angle than younger, warmer, less dense crust. In this lab activity, you will plot and compare actual earthquake depth data from two areas where subduction is currently occurring. One of the areas includes the Tonga Islands in the southwest Pacific Ocean. The other area is along the coastline of Chile. Procedure: On the graph on page 2, plot the data for Tonga and Chile trenches from the table. DON’T CONNECT THE DOTS, wait for teacher’s ok to do so. Assume the lines outline the converging plates Label the approximate location of the Tonga and Chile trenches on the graph Using your Plate Boundary Map, indicate the name of the two converging plates Using your Plate Boundary Map, indicate the relative movement of each plate using arrows Using your Plate Boundary Map, indicate the type of crust that makes up each plate. Earthquake Depth Data Tonga Trench Longitude Depth (°W) (km) 174 0 174.5 25 174 50 175 50 175.5 100 174 150 175 150 176 150 174.5 175 176 200 175.5 250 176 250 175.5 300 176.5 300 177 400 177.5 375 176.5 400 177.5 450 178 450 178 500 178.5 500 178 550 178 600 178.5 600 178.5 650 179 650 Chile Trench Longitude Depth (°W) (km) 69 25 68.5 50 65.5 50 68 50 67 100 70 25 69 75 66 100 65.5 100 69 125 67 150 65 150 66.5 150 65.5 200 64.5 175 68.5 125 65 225 62.5 275 68 100 66.5 200 66 225 64.5 300 62 300 61 350 62 425 65.5 250 Reflection Questions: 1. Which tectonic plate is being subducted at the Tonga Trench? 2. Which tectonic plate is being subducted at the Chile Trench? 3. Notice the direction that the Nazca and Pacific plates are moving. What process is occurring at the boundary of those two plates? 4. Look at your plate boundary map. Where do you usually find divergent boundaries (plates moving away from each other)? 5. The boundary between the Nazca and Pacific plate is part of the East Pacific Rise. If new rock (sea floor) is being formed at the East Pacific Rise, which trench (Tonga or Chile) should contain the oldest rock? Why? (Complete sentences) 6. What type of geologic feature is found at a subduction zone? 7. Based on the data you plotted in the lab, the collision of which two types of plates (oceanicoceanic, oceanic-continental, continental-continental) creates the deepest earthquakes? Use specific data from the lab to prove your statement. (complete sentences)