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Exercise 8 • Landslides and Avalanches 117
FIGURE 8.4 On an oblique photograph, contours on the upper, scarp, area of a landslide bend into the hill, and contours on the lower,
hummocky, area of the landslide bend out from the hill. See Figure 8.3 for the parts of this landslide. Photograph courtesy of http://www
. geog.ucsb.edu/- j eff/projects/la_conchita/1995/95_slideshots.html
3. Abrupt and irregular changes in slope and drainage
pattern
4. Hummocky irregular surfaces
5. Smaller landslide deposits that are commonly younger
and form within older and larger landslide deposits (in
other words, if an area has slid in the past, it is subject to
both small and large renewed slides)
6. Steep, arcuate scarps at the upper edge
7. Irregular soil and vegetation patterns
8. Disturbed vegetation
9. Abundant flat areas
QUESTIONS (8, PART A)
La Conchita, California
Figure 8.4 shows a landslide that occurred in 1995 above
the small town of La Conchita, California. This landslide
reactivated in the wet winter of 2005, with disastrous conse-
quences. Note the shape of contours as they cross the land-
slide. Figure 8.5 shows a vertical aerial photograph of the
same site, and note how contours appear on this photograph.
1. a. Can you recognize the shape of contours that may indicate
a landslide? Check with your Teaching instructor before going
on to the next question.
FIGURE 8.5 Contours that cross landslides, as shown on vertical
photos, bend to follow concave part of slope in the upper scarp area
of the slide. Contours in the lower part of a landslide will be con-
vex and irregular over hummocky terrain. La Conchita, California,
1995; Same site as in Figure 8.4. Photograph courtesy of Pacific
Aerial Surveys, http://www.geog.ucsb.edu/- jeff/projects/
la_conchita/1995/95_slideshots.html
b. In Figure 8.4 and 8.5, were any homes damaged? Explain.
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