EXERCISE 1: Landslides
Using the search bar at the top left corner of Google Earth Pro, navigate to the village of Tskneti, Georgia. On Sunday 14 June 2015, a significant landslide occurred on a hillslope approximately 2.5 km southwest of the village (41°40’37″N, 44°40’36″E).
In combination with heavy rains this landslide contributed to mudflows and flooding impacting the communities downstream, where there were >400 reported injuries and was notable damage to the Tbilisi Zoo.
In Exercise 1 we are going to use Google Earth Pro to explore imagery of the region before and after the landslide and make some basic measurements of the landslide length, width, and area.
1. Use the Time Slider tool to find clear, cloud free images of the area before and after the landslide occurred. Use the screenshot tool on your computer (Mac Users: Type Command + Shift + 4; Windows Users: Type Windows + Shift + S to access “Snip & Sketch”) to capture and present the before and after scenes of the site. Submit photos of before and after the landslide and include a full caption including the two imagery dates (given at the bottom of the Google Earth Pro page beside the latitude, longitude, elevation data). (3 marks)
2. Use the ruler tool to determine the approximate width and length of the landslide. With this information, overlay pin marks on your “after” image to indicate the length and width of the slide. Based on these measurements, estimate the total area of the slide. (3 marks)
3. Finally, use the Area tool to delineate and calculate the area of the landslide. Provide a screenshot of your area coverage and comment on the estimated vs. measured area. (3 marks)
4. As described above, a flash flood triggered the landslide. In your own words, write approx. 200 words describing the events of Sunday 14 June 2015. Be sure to touch on the trigger and the forces at play. Cite your sources for the event in APA style. (4 marks)
5. Based on the imagery in Google Earth and your knowledge of the event, would you categorize this landslide as a slump or a flow, and why? (4 marks)
6. Explore Google Earth to find the location of another landslide and take screenshots before and after the event as in Question 1. How does the size and type of the landslide you found compare to that near Tskneti? Would the event be categorized as a slump or a flow, and why? Make sure to include the dates and coordinates of your images and cite any external sources you use in APA style. (5 marks)
EXERCISE 2: Mining Sites
Navigate to Tasu, BC, Canada. Tasu was an iron and copper open pit and underground mining operation and townsite in Haida Gwaii along the North Coast of British Columbia that was active from 1918 until the 1960s. If you view the mine site obliquely from northeast, you can see evidence the tailings that were deposited as part of the mining activity.
In this exercise, we are going to use the Google Earth Pro Path tool to determine the Angle of Repose of the tailings slope remaining at Tasu. Note that when calculating the angle of repose, it is important to measure the steepest slope. This is often along a line that is perpendicular to the headwall; streaks in the debris along the length of the slope can also help indicate the steepest path.
7. Choose the Path Icon . A cursor will show up allowing you to click along a path of interest, for example from the bottom to the top of a slope. When you have selected your path by clicking two or more points, select OK on the Path window and you will see your “Untitled Path” in the navigation bar to the left.
Highlight your path by clicking on in in the left- hand navigation bar, then choose Edit > Show Elevation Profile. Here you will be provided a cross section of your path, showing slope as a percentage (Recall: Slope = Rise / Run). Provide a screenshot of the path you selected and elevation profile that results from it and an appropriate caption. (3 marks)
8. While slopes exhibited as a percentage are helpful for some geotechnical applications, we are interested in the specific angle of repose associated with these deposits. Calculate the angle of repose for this tailing material by calculating the tangent of the elevation change divided by the horizontal length of the path; include your calculation in your answer. (4 marks)
Recall → tan θ =
*Be sure to use the same units (e.g. meters) for both measurements and report your angles
in degrees
9. Pretend there is a 3 kg boulder sitting at the top of the headwall of the tailings slope. Calculate the values of the normal force N and the shear force T for the boulder, based off the angle of repose you determined in Question 2. Show your work. NOTE: Your calculator likely has multiple angle-related options: DEG (degrees), RAD (radians), or GRAD. Given that the formula you are using inputs and angles in degrees, you should use degrees (DEG) to calculate your answers. See page 405 of the textbook for examples. (5 marks)
EXERCISE 3: Reflection
10. How can the tools you used in Google Earth for this assignment be useful in the analysis of landscape features and events? Use the examples of Tasu, BC and Tskneti, Georgia as well as at least two other examples of your own. Cite your sources for the events in APA style. (6 marks)