Crossing Disciplinary Boundaries between

Stratigraphy and Geomorphologyto analyze Slope Stability

Kyle C. Fredrick, PhDCalifornia 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 andLocation, 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.”

(Photos by: Matthew R. Baird and USGS)

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

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

• 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

• High-intensity development within the city of Pittsburgh and along the Monongahela, Allegheny and Ohio Rivers

Pittsburgh Metropolitan Area:

RED BEDS!

Was

hing

ton

Way

nesb

urgPERM

IAN

Dun

kard

Gro

upM

onon

gahe

la G

roup

Uni

onto

wn

Pitt

sbur

gh

Cone

mau

gh G

roup

Cass

elm

an

PEN

NSY

LVAN

IAN

Gle

nsha

w

Alle

ghen

y G

roup

(Mark A. Evans)

Slope

Aspect

Reclassification Process

Land Cover

Lithology

Reclassification Process

Soil Texture

Soil Depth

Reclassification Process

Distance from State Roads

Distance from Streams

Reclassification Process

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?