Earth Science: Geology, the Environment, and the Universe

Chapter 8: Mass Movements, Wind, and Glaciers

Problem of the Week

Slipping and Sliding: Landslides

Resources:

1. Use of Air Temperature Data to Anticipate the Onset of Snowmelt-Season
   Landslides - Open-File Report 98-124
   By Alan F. Chleborad
   
   
2. U.S. Geological Survey Fact Sheet 020-98 Online Version 1.0
   Popular Beach Disappears Underwater in Huge Coastal Landslide
   
   
3. Debris-Flow Hazards in the United States
   By Lynn M. Highland, Stephenson D. Ellen, Sarah B. Christian, and William M. Brown III
   USGS
   
   
4. REPORT OF THE LANDSLIDE HAZARD TEAM

Executive Summary: The CEOS Group

*Skills: Estimation, reading graphs, analyzing data, calculating percentages, inferring, forming conclusions.

Answers:

Key information: 27 total events.

To find Percentages: Take sample number of events and divide by the total number of events, then multiply by 100.
Ex: X/27 = .YY x 100 = YY%

1. At 1 week 10 events had occurred - 37% of the total number of events.

10/27 = .37 x 100 = 37%

2. At 3 weeks approximately 24 events had occurred – approximately 89% of total.

24/27 = .88 (repeating so round to .889) x 100 = 88.9% or 89%

3. 62°F
   
   
4. 69°F; 6 events

4. The researcher, Alan F. Chleborad found that 85% of the landslide events in this study occurred within 2 weeks after the first yearly occurrence of the threshold temperature – 58°F; 27 or 100% had occurred within 3 weeks of the first occurrence of the threshold temperature– 58°F This was the identified as the "optimal temperature threshold."