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As it spreads away from the ridge and cools and contracts, or becomes denser, it is able to sink into the hotter underlying mantle. When two oceanic plates collide, the younger of the two plates, because it is less dense will ride over the edge of the older plate. The density of the rock that makes up the subjecting plate determines the way in which a plate behaves. A plate with a greater density subjects into the mantle faster and at a steeper angle than a plate with a lower density. The age of the crust involved in the subsection also affects the rate at which it subjects.
Older crust is cooler and denser therefore it seduces at a steeper angle and faster than new crust at a subsection zone. The three key features associated with subsection zone are a deep ocean trench, a volcanic arc on the overriding plate parallel to the trench, and a plane of earthquakes, shallow near the trench and descending beneath and beyond the volcanic arc. Most earthquakes occur at tectonic plate boundaries. The largest earthquakes are associated with subsection zones because they have long continuous fault lines.
The depth of its focus can classify an earthquake. Earthquake depth range is divided into three zones: shallow, intermediate, and deep. Shallow earthquakes are between 0 to 70 km deep, intermediate earthquakes are between 70 to 300 km deep, and deep Ochs earthquakes have foci at more than 300 km. Terms Introduced and Defined: – Subsection zone: the place where two lithospheres plates come together, one riding over the other – Density: mass per unit volume Earthquake: the result of a sudden release of energy in the Earth’s crust that creates seismic waves. Subsection: the process in which one plate is pushed downward beneath another plate into the underlying mantle when plates move towards each other – Plate boundaries: found at the edge of the lithospheres plates and are of three types, convergent, divergent and transform Deep ocean trench: a portion of the Earth’s crust in which a tectonic plate is being sub-ducted (pushed down) below another plate – Shallow earthquake: more damaging than deeper earthquakes due to there being less rock to absorb the shaking – Deep focus earthquakes: occur within the subjecting oceanic plates as they move beneath the continental plates Hypothesis: The East Pacific Rise Material at the two convergent boundaries: the Tongs Trench and the Peru-Chile Trench is older than the crust created at the East Pacific Rise but the Tongs Trench material is older than the Peru-Chili Trench material. Materials: – Earthquakes and Subsection Zones Lab – Sharpened pencil with eraser – Graphing Paper – Ruler – Calculator Procedure: 1.
Take out a sharpened pencil, ruler, blank sheet of graph paper, and a calculator. 2. Pick up the earthquakes and subsection zones lab from your teacher. 3. Read the background information. 4. Read the hypothesis information. 5. View Figure 1 at the top of the Lab. 6. Form a hypothesis about the relative ages of the East Pacific Rise material at the two convergent obituaries: the Tongs Trench and the Peru-Chile Trench. 7. View table 1. 8. Divide your graph paper into two sections. . Label the left section Tongs Trench and the right section Peru-Chili Trench 10. Draw a vertical line (y-axis) and a horizontal line (x-axis) on each section of the graph paper. 11. Label both vertical lines (y-axes) Focus Depth (km). 12.
Label both horizontal lines (x-axes) Longitude (owe). 13. On both sections of the graph paper (Tongs Trench and Peru-Chile Trench) create a scale for the vertical axis (focus depth) ranging from 0-700 km. Going by intervals of 50 km, label zero at the top of the y-axis and 700 at the bottom of the y-axis. 14. On the left section of the graph paper (Tongs Trench) create a scale or the horizontal axis (longitude) ranging from 173-180 owe. Going by intervals of IOW, label the right end of the x-axis 173 and the left end of the x-axis 180. 15. On the right section of the graph paper (Peru-Chile Trench) create a scale for the horizontal axis (longitude) ranging from 61-71 owe.
Going by intervals of IOW label the right end of the x-axis 61 and the left end of the x-axis 71. 16. Plot the earthquake data from the region associated with the Tongs Trench from Table 1 on the left section of the graph paper, using a dot to represent each data point. 17. Plot the earthquake data from the region associated with the Peru-Chile Trench from Table 1 on the right section of the graph paper, using a dot to represent each data point. 18. Draw a best-fit line for the Tongs Trench data. A best fit line is a smooth line that shows the trend of the data; the line does not have to pass through the data points. 19. Draw a best fit line for the Peru-Chili Trench. 20.
On the left side of the graph (Tongs Trench) label the Pacific Plate (right side of the line of best fit) and the Indian Australian Plate (left side of the line of best fit) 21. Draw an arrow to show the direction of motion of the Pacific Plate (subjecting under the Indian Australian Plate) 22. On the right side of the graph (Peru-Chile Trench) label the NCAA Plate (left side of the line of best fit) and the South American Plate (right side of the line of best fit) 23. Draw an arrow to show the direction of motion of the NCAA Plate (subjecting under the South American Plate) 24. Complete analyze questions # 1-5 (4 & 5 completed in steps 20-23) 25. Check and analyze your hypothesis 26.
Answer conclude and apply questions # 1-2 Preparing a Lab Report: The lab report is to be written in the same format as any scientific publication. There is to be 5 minimum sections and they should be labeled: Introduction, Methods, Results, Discussion, and Literature Cited. The report must be composed on a word processor, printed, double spaced, Times New Roman, 12 apt. Font. The metric system should be used throughout the report. All parts of the report should be written using complete sentences in paragraph format. The first section of your lab report should be labeled with the word “Introduction. ” This section can be used to educate the reader so he or she can understand the rest of the report.
A hypothesis is proposed to explain an observation. It should be a statement, not a question. The next section is labeled “Methods. ” This section should provide enough information for readers to repeat the experiment if they desire. It should include the specific procedures and materials needed to carry out the lab. The next section should be labeled “Results. ” Put all results, statistical analyses, graphs, and tables in this section. Use sentences and paragraphs to describe general trends and summarize the tables and graphs. The next section should be labeled “Discussion. ” In this section discuss whether you accept or reject your hypotheses and explain why.
If you reject a hypothesis, state an alternative. Explain why your results came out the way they did. If your results did not come out as they expected, explain why and what should have happened. In addition, explain what your results mean. The last section is “Literature Cited. ” Everything mentioned in a scientific publication should be verifiable. This helps readers that have questions and it ensures that the information presented is accurate. The literature cited section contains a list of publications that you cited in the report. Instructions on Using a Table, Setting Up, and Preparing a Graph: To begin take a blank sheet of graph paper.
View Table 1, which includes the Longitude and Focus depths of the earthquakes at the Tongs Trench and Peru-Chile Trench. Divide the graph paper into two sections labeling the left side Tongs Trench and the right side Peru-Chile Trench. Draw a vertical line (y-axis) and horizontal line (x-axis) on each section of the graph paper. Label both vertical lines (y-axes) Focus Depth (km) and label both horizontal lines (x-axes) Longitude (owe). On both sections of the graph paper (Tongs Trench and Peru Chile Trench), create a scale for the vertical axes (focus depth) ranging from 0-700 km. Going by intervals of 50, label zero at the top of the y-axis and 700 at the bottom of the y- axis.
On the left section of the graph paper (Tongs Trench) create a scale for the horizontal axis (longitude) ranging from 173-180 0 W. Going by intervals of 1, label the right end of the x-axis 173 and the left end of the x-axis 180. On the right section of the graph paper (Peru-Chile Trench) create a scale for the horizontal axis (longitude) ranging from 61-71 ‘W. Going by intervals of 1, label the right end of the x-axis 61 and the left end of the x-axis 71. Plot the earthquake data from the region associated with Tongs Trench on the left section of the graph paper, and plot the earthquake data from the region associated with the Peru-Chili Trench on the right section of the graph paper, using a dot to represent each point.
Data and Results: Pacific Plate Indian-Australian Plate South American Plate NCAA Plate Analysis and Synthesis: Question: How far is the Tongs Trench from the East Pacific Rise? Note that one degree longitude equals about 100 km. If the seafloor spreads at 3 CM/year, how long would it take material on the plate to travel this distance? Answer: The Tongs Trench is 6,500 km from the East Pacific Rise. If the seafloor spreads at 3 CM/year, it would take material 216. 67 million years to travel this distance. Work: IOW = 65 x 100 km = 6,500 km. ,500 km x 100,000 CM = CM CM / 3 CM/year = years 2. Question: What is the depth of the deepest earthquake in the Tongs data set?
Estimate the rate of descent of the East Pacific Rise material at the Tongs Trench in centimeters per year. Answer: The depth of the deepest earthquake in the Tongs data set is 675 km. The rate of descent of the East Pacific Rise material at the Tongs Trench in centimeters per year is 0. 312 CM/year. Work: 675 km x 100,000 CM = R = CM / years R 0. 312 career 3. Question: Estimate the rate of descent of East Pacific Rise material into the Peru- Chile Trench in centimeters per year. Answer: IOW = 45 x 100 km = 4,500 km 4,500 km x 1 O,OHO CM = 45,000,000 CM 450,000,000 km / 3 CM/year = 150,000,000 years 540 km x 100,000 CM = CM R = 1 years R = 0. 6 CM/year Interpret and Explain Data The data represents the focus depths and longitudes (owe) of the earthquakes that occur at the Peru-Chile Trench subsection zone, and the Tongs Trench subsection zone. On the Tongs Trench as longitude (0 W) increases, or moves further from the prime meridian, the focus depth also increases, or becomes deeper. This creates a steeper slope, and the line appears to be moving upwards. On the Peru-Chile Trench as longitude (owe) increases, or moves rather from the prime meridian, decreases, or becomes shallower. This creates a smoother slope that appears to be moving downwards. On the Tongs Trench graph, the best-fit line is an estimate of the location of the boundary between the Pacific Plate and the Indian-Australian Plate.
The Pacific Plate is subjecting, or moving under the Indian-Australian Plate as this plate overrides the Pacific Plate. On the Peru-Chile Trench graph, the best-fit line is an estimate of the location of the boundary between the NCAA Plate and the South American Plate. The NCAA Plate is subjecting, or moving under the South American Plate as this plate overrides the NCAA Plate. The Peru-Chile Trench and Tongs Trench have similar earthquake focus depths (km), but the longitude (owe) of these earthquakes is different. Summary of Data As two tectonic plates converge, if one or both of the plates is an oceanic lithosphere, a subsection zone will form.
The Tongs Trench has a steeper profile than the Peru-Chile Trench. This is because older crust is cooler and denser than younger crust therefore it subjects at a steeper angle. The Tongs Trench has the steeper and older material. As observed from the charts, the Tongs Trench has a steeper profile than the Peru-Chile Trench. This means that the crust at the Tongs Trench is older and denser than the crust at the Peru-Chile Trench, therefore it subjects faster and at a steeper angle. The density of the rock that makes up the subjecting plate determines they way in that a plate behaves. A plate with a greater density subjects into the mantle faster and at a steeper angle than a plate with a lower density.
The age of the crust involved in the subsection also affects the rate at which it subjects. Older crust is cooler and denser therefore it subjects at a steeper angle and faster than new crust at a subsection zone. Conclusion: Check Your Hypothesis: My data supports my hypothesis. I predicted that the East Pacific Rise material at the two convergent boundaries: the Tongs Trench and the Peru-Chile Trench is older than the crust created at the East Pacific Rise but the Tongs Trench material is older than the Peru-Chile Trench. This is true because the Tongs Trench and Peru-Chile Trench will have older material, as they are further away from where the crust is created.
In addition, it is true that Tongs Trench has older material than the Peru-Chile Trench because it has a steeper slope, which means it is older and denser. Errors and Fixes: In this lab report, I researched more on my background information to enhance my understanding of the topic. In addition, I explained and analyzed my data to make it easier to understand the trends and what the data actually means. I also provided instructions on using a table of data, setting up, and preparing a graph, and preparing a lab report. The errors I had in my lab report were with the math work on the first three analyze questions, the direction in which the plates subjected, and my hypothesis did not clearly state an answer to my question.