By completing these activities, the learner will:
This mountain in southwestern Washington is called Mt. Saint Helens. The first picture above was taken before May 18, 1980. The second picture was taken after May 18, 1980. There was a huge explosion caused by energy trapped beneath the ground. (movies)
Estimate the amount of mass Mt. Saint Helens lost after the explosion.
Volcanoes are found all over the world. Find current images for world-wide locations. (Click on the map for locations and descriptions of current volcanoes)..
Measuring Olympus Mons - A Model Lesson
Overview: In this activity you will investigate one of Mars' most spectacular features, the gigantic shield volcano called Olympus Mons. Located at 133 degrees West Longitude and 20 degrees North Latitude, Olympus Mons rises to an elevation of approximately 24,000 m, far above the thin Martian atmosphere. By contrast, Mt. Everest and the Hawaiian volcano Kilauea (measured from its base at the sea floor) are only about 9,000 m in height. The largest known volcano in the solar system, Olympus Mons is a true giant.
Procedure: Start NIH Image 1.55 (or later). When the program is loaded, move the pointer to the File pull-down menu in the upper left hand corner of the screen, depress the mouse button, drag down to Open, and release the button. Double-click on the file Mars. After a few seconds an image will appear.
1. What is your first impression of the planet Mars? How would you describe Mars to someone who has never seen it? ·When you are finished, select Close from the File pull-down menu. Next, Open the file Olympus Mons.
2. When the image appears, examine it carefully and make a sketch of what you see.Every satellite image is actually made up of small picture elements called "pixels." Click on the magnifying glass in the upper left hand corner of the Tools window and move it onto the image. Click the mouse button repeatedly until you can see the shape of the pixels.
3. All pixels have the same shape. Sketch that shape.Undo the magnification by double clicking on the magnifying glass in the Tools window.
4. Each pixel in the Olympus Mons image is 1850m on a side. How many kilometers is that?Move the pointer to the Analyze pull-down menu at the top of the screen, depress the mouse button, drag down to Set Scale, and let go. A new window will open. In the center of the window is a box labeled Units. Click on the down arrow in the box and select kilometers as your unit of measurement. At the top of the window enter 1 in the Measured Distance box and 1.850 in the Known Distance box. Click OK once you have done so. Now you are ready to measure Mars!
5. Suppose that a line on the image is 100 pixels long? How many kilometers is that?
Using the Segment Tool (Tools window, 5th icon from the top in the right hand column), draw the longest segment you can across the caldera of the volcano. Once the segment is drawn, return to the Analyze pull- down menu, drag down to Measure, and release the mouse button. Again, click on Analyze, drag down to Show Results, and release the mouse button. A Results window will appear with your answer in the column marked length.
6. Use the magnifying glass in the Tools window to zoom in on the caldera. Then take several additional measurements across the caldera using the Segment Tool. Once you have completed your measurements, circle the measurement that you think is the most reasonable estimate of the diameter of the caldera. Explain why you think that particular measurement is the best.
7. Repeat this procedure measuring the overall diameter of the volcano, not just the caldera. Record your results below.
8. Using a calculator, determine the area of each pixel in square meters (Recall that the image is made of pixels 1850m on a side).NIH Image has 4 tools for selecting regions for study.
9. Use your answer to question #4 and your calculator to compute the area of each pixel in square kilometers.
10. Is each pixel more than or less than one square kilometer?
12. Approximate the area of the entire volcano using each selection tool. After making each selection, first Measure then Show Results from the Analyze pull-down menu. Record your measurements below:
- using the rectangle tool
- using the oval tool
- using the polygon tool
- using the freehand tool (not the pencil in the left hand column)
Which measurement do you think is most accurate? Why?
13. How big is Olympus Mons compared to the state in which you live?
14. Reload the file Mars. The giant canyon cutting across the
planet just south of the equator is called Valles Marineris. The scale
for that image is approximately 7.4 km per pixel. Enter that figure in
the Set Scale option in the Analyze pull-down menu. Take a series of measurements
of Valles Marineris. Compare Valles Marineris to the Grand Canyon on Earth.
Which is longer? Wider?
Part 1: Find as much information as you can on the Mt. St. Helens volcano. This volcano in the Cascade range was quite active in 1980. Write an essay on this volcano that addresses the following: its origin and type, its magma source, potential hazards to people and the local environment, and its relationship to the "Big Picture" of global tectonics.