Crossing Disciplinary Boundaries
between
Stratigraphy and Geomorphology
to analyze Slope Stability
Kyle C. Fredrick, PhD
California University of PA
Clarissa Enslin
(BS CalU ‘14), MS Candidate, Idaho State
University
Geomorphology Course
• EAS 343
– Sophomore and Junior-level w/ a few seniors, offered
every other Fall
• Generally pre-dates Sed/Strat, Tectonics, Structure
– Pre-requisites
• Required: Introductory Geology
• Recommended: Historical Geology, Hydrology, GIS
– Major content topics
• General Processes (Weathering and Erosion, Deposition), Tectonic
landforms, Fluvial systems, Glacial geomorphology, Mass Wasting
• Relevant Objectives: “Students should be able to…”
– Explain the interrelationships of Earth processes and the
evolution of landscapes;
– Interpret the origin and history of landscapes as they
appear on air photos and topographic maps.
Relevance and
Location, Location, Location!
• Landslides in the United States account for approximately
$3.5 billion in damages annually (USGS)
– And between 25-50 fatalities
• 1970-1976: Total public and private costs of landslides in
Allegheny County averaged at least $4 million per year
(DCNR)
Regional Relevance
From the Pittsburgh Post-Gazette:
• “In Pittsburgh, the Public Works Department uses
a "three-tiered system" to oversee hillsides that
are on city property, spokesman Tim McNulty
said in an email.
• The city has a two-page "watch list" of all hillsides
known to have the possibility of landslide issues.
• And then it has an immediate list of hillsides that
engineers have determined could be at risk of
landslides or other problems, Mr. McNulty said.
• For those hillsides, the city will pre-emptively
close the surrounding streets to stabilize them.”
Common landslide issues in SW PA
(clockwise from above): (1) Soil Creep
on a relatively gentle slope (2)
landslide of 2006 on Route 65 in
Kilbuck, and (3) a construction-related
failure near Pittsburgh
(Photos by: Matthew R. Baird and USGS)
Local Relevance
Examples of common landslide issues
near CalU (clockwise from above): (1)
Freeze-thaw at seeps in outcrops and
roadcuts, (2) Poorly maintained/
constructed municipal roads, and (3)
variable sedimentary lithologies with
shales and siltstones creating
cantilevered layers.
(Photos by: Matthew R. Baird)
Title: Indexing Geological Factors for
Determining Landslide Susceptibility
• Goal: Students develop a multi-layered model of factors
that effect slope stability to construct an updatable, flexible
model of landslide susceptibility
• Logistics
– Placed late in the semester
– Two weeks to complete first map
• One week road check
– Third week for group presentations and manipulation of final
map
• Products
– Final map (7 map essentials, 50 points)
– Write-up (4-5 pages, 50 points)
•
•
•
•
Brief Intro
Methods (factors and weights with justification) including map layers
Analysis
Conclusion and future work
Objectives
• Understand the interplay of controlling factors on
landslide development
• Analyze varying data sources, scales, types
– Evaluate and Integrate data of varying “quality”
• Construct active maps in GIS to incorporate
updated information and manipulate model
inputs
• Iterate with peers to establish consensus
• Consider geotechnical issues related to slope
stability
Benefits
• Indexing
– Available map layers (or
new ones?)
– Map calculations
• Factor scaling and Weights
• Real-world application
with a useful product
• Students are responsible
for determining outcome
based upon…
– Geologic knowledge
– Proficiency with GIS (or
other methods)
– Ability to work with others
(Mark A. Evans)
Washington
Dunkard Group
Waynesburg
Pittsburgh
Monongahela Group
Uniontown
PERMIAN
Casselman
Conemaugh Group
Glenshaw
• High-intensity development
within the city of Pittsburgh
and along the Monongahela,
Allegheny and Ohio Rivers
Allegheny Group
• Deeply incised valleys with
steep slopes
• Shallow soils with silt loam and
urban soils dominant
• Limestone, sandstone and
shale inter-bedded with coal,
much of it mined
PENNSYLVANIAN
Pittsburgh Metropolitan
Area:
RED
BEDS!
Aspect
Reclassification Process
Slope
Lithology
Reclassification Process
Land Cover
Soil Depth
Reclassification Process
Soil Texture
Distance from Streams
Reclassification Process
Distance from State Roads
Conclusions
• Students are responsible for…
–
–
–
–
Acquiring maps
Establishing categories and weights
Producing their own maps through calculation
Assessing and Validating their final susceptibility map
• Potential “Issues”
– Lack of GIS proficiency
– Poor working groups
– Time management
• Benefits: Students end with a self-constructed,
relevant product related to a geotechnical topic
they are likely to face in their early careers
Questions?
• By the way, what is the background?