new topic: slopes

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New Topic: SLOPES

Colluvial - Related to Hill-Slope or Mountain-Slope Processes, Especially Those Driven Directly by Gravity

Colluvium - Gravity Driven Deposits

U.S. Landslide Risk

Landslides by U.S. Region

• California 40% of U.S. damage• West Virginia 13% of U.S. damage

WV Has 1st or 2nd Highest Landslide Damage Per Capita

• $100-300 /person/yr• ≈ UTAH

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Regional Causes of Landslides

• Steep Topography – Mountains – Incision by Rivers in Last 1 MY

• Materials– Red Shales - Expansive Clays

• Stupid or Ignorant People– Oversteepening of Slopes– w/o Geotechnical Consulting

Landslide Video ClipsDebris Slide on Sultan River, Dec 11, 2004http://www.kayakingsucks.com/sultan/sultan.html

http://www.kayakingsucks.com/Vid/landslide(hi-res).wmv

Kinki Landslidehttp://video.yahoo.com/video/play?vid=ba1f23a395748b6b08304eaeacf5bd2d.614434

Huge landslide Japan's Kinki region of the Nara Prefecture in August 2004 after heavy rains in the region.

Video by Japanese Ministry of Land

Landslide blocked a major mountain roadway, but nobody was injured in the incident.

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Rissa Landslidehttp://www.ce.washington.edu/~geotech/courses/cee522/RissaLandslide/rissa.html

In 1978 near Rissa, Norway, a landslide devastated an area of 0.127 sq miles, which included 7 farms. The slide contained about 7 to 8 million cubic yards of debris - the biggest slide in Norway in this century. Of the 40 people caught in the slide area, only 1 died.

The cause of this landslide was later determined to be the failure of a quick clay (marine clay) that was triggered by the excavation and stockpiling of 900 cu yards of soil placed by the shore of Lake Botnen. The stock-piled soil was generated by excavation work from the construction of a new wing being added to an existing barn. Note the relationship between the volume of the slide (~7.5 million yards) to the volume of the excavation that triggered it (~900 yards) - a ratio of over 8,000.

The slide started at the lake shoreline and developed retrogressively landward, occurring over a period of 6 minutes. About 70-90 m of shore slid into the lake.

The AVI clips below show portions of the slide in progress as filmed from a nearby vantage point. Look at the houses in the video clips to get a sense of the size of the failure - in the second clip, you can see houses and barns being carried away by the slide.

Part 1 - note the speed with which the landslide is moving

Part 2 - note that the slide is moving over great distances even though the ground is virtually flat

Campbell & others (1986) Classificationafter Varnes

“Soil”Debris Earth

Rock

Type

of M

otio

n

Fall

Topple

Planar Slide

RotationalSlide

Flow

Avalanche

Rock Fall Debris Fall Earth Fall

Rock Topple Debris Topple Earth Topple

Rock Slide Debris Slide Earth Slide

Rock Slump Debris Slump Earth Slump

Rock Flow Debris Flow Earth Flow

Rock Avalanche

Debris Avalanche

Earth Avalanche

Landslides

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Basic Landslide Classification

Material


Rock

Type

of M

otio

n

Material

“Soil” = Unconsolidated Material

Debris: >20 % Big Stuff (>2 mm)

Earth: <20 % Big Stuff (>2 mm)

“Rock” = Bedrock


Rock

Type

of M

otio

n

Fall

Topple

Planar SlideRotationalSlide

Flow

Avalanche

Landslides

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Rock

Typ

e of

Mot

ion

Fall

Topple

Planar Slide

RotationalSlide

Flow

Avalanche






Rock Avalanche Debris Avalanche Earth Avalanche

Landslides

Fall

Topple

ROCK FALL:

Talus = Landform (= Block Apron)

Scree = Deposit = Sediment (= Block Mantle)

70 Ton Boulder: “Mon”Blvd., 10 March 1994

S. Kite Photo

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Ice MountainTalus, W.Va.S. Kite Photo

Cacapon Mtn. Talus, W.Va. S. Kite Photo

Landslides -Topple

Pisa

http://www.endex.com/gf/buildings/ltpisa/ltpgallery/7Nov99/ltpgallery7Nov99.htm

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Rock

Typ

e of

Mot

ion

Fall

Topple

Planar Slide

RotationalSlide

Flow

Avalanche






Rock Avalanche Debris Avalanche Earth Avalanche

Landslides

Planar Slide

RotationalSlide

Planar Slide = “Slide”

Rotational Slide = “Slump”

Landslides

SLIDE (Translational)

Rock Slides may Parallel Weakness

SLUMP (Rotational Slide)



Landslides

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Landslides



Landslides

Seattle Shoreline

Debris (?) Slide

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Debris Slides, Venezuela, Dec 1999

Slump: the typical WV landslide. Slump scarp is at the head, and earthflow is at the toe. (Illustration by Paul Queen,WV Geol. Surv.)

http://www.wvgs.wvnet.edu/www/geohaz/geohaz3.htm

La Conchita, CaliforniaSlump

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“Slump”

Slump in McClure Pass, CO.

Tully Landslide, New York, 1994Jäger, Stefan, & Wieczorek, Gerald F., 1994, Landslide Susceptibility in the Tully Valley Area, Finger Lakes Region, New York: USGS Open-File-Report 94-615.http://www.usgs.gov/reports/open_file_reports/94-615/

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Rock

Typ

e of

Mot

ion

Fall

Topple

Planar Slide

RotationalSlide

Flow

Avalanche





Rock Flow Debris Flow Earth FlowRock Avalanche

Debris Avalanche

Earth Avalanche

Landslides

Flow

Avalanche

“FLOW” is Confined to Channel or Hollow

Debris Flow: “Slurry” Consistency

Part of Water Flood – Debris Flood – Debris Flow Continuum

AVALANCHE: Trapped Air&/or Water Reduces Friction

Snow Avalanche

Debris Avalanche: Rapidly "Sliding" Debris - Typically Originates as Debris Slide

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Twin Run & Simmons Run Debris Flows, Nov. 1985

~3 km

November 1985Debris Flow Track,

Twin Run, Pendleton Co., WV

Superelevation of Debris Flow, Twin Run

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Kanawha City Debris Flow

“Grain” Flow

Can of Planters Mixed Nuts Experiment

Do Large Nuts Rise to theTop of the Can?GEO 493F Class Experiment, 10 April 2003

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

Round I Round II Round III Dregs

Brazil Nuts Cashews Almonds Macademia Nuts Hazel Nuts Peanuts

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Props: DEBRIS FLOW VIDEOTAPES

Costa, John E., and Williams, Garnett P., 1984, Debris-flow dynamics: U.S. Geological Survey Open File Report 84-606, 1 VHS videotape.

Iverson, Richard M. 2001, Highlight from the Debris Flow Experiment Flume Studies, USGS informal document, 1 VHS videotape.

QUESTIONS ON DEBRIS FLOW VIDEOTAPES

Define Debris FlowWhat are the triggers for debris flows?What Source Area Conditions favor Debris Flow?Describe the 3 phases of a typical debris flow?Describe the sedimentology and geomorphology of debris

flows.The Coast and Williams videotape predates the USGS

Landslide Classification (Campbell, & Others, 1986) Which examples in the video are not true debris flows?

What happens to woody debris in a debris flowWhat happens to large rocks in a debris flow?Can you tell a debris flow from a flood flow deposit?

Gros Ventre Landslide, Wyoming.

Photo taken in 1931 of landslide triggered by rainfall & snowmelt in 1925. slide dammed the Gros VentreRiver, creating a lake that later drained catastrophically when the landslide dam failed, killing people downstream.

USGS, 1999, Geology and El Niño in the desert: Landslides, debris-flows, and flash floods during El Niño events, URL: http://geology.wr.usgs.gov/wgmt/elnino/deserten/processes.html

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Gros Vente Slide, Wyoming

Thistle Slide, Utah

>$400 million http://www.ldeo.columbia.edu/edu/dees/ees/ies2/masswasting/sld014.html

SlumgullionEarth flow-slide

Colorado

http://www.ldeo.columbia.edu/edu/dees/ees/ies2/masswasting/sld001.html

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Hebgen Lake Slide (Quake Lake) 1959, SW Montanawww.bikephotos.150m.com/Photos/ day22/6-29quake_mt.jpg

Hebgen Lake Slide (Quake Lake) 1959, SW Montanalandslides.usgs.gov/html_files/ landslides/slides/slide7.jpg

BFR

Person

S. Kite Photo, 2002

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Mt. Huascaran, Peru, 1970

Mt. Huascaran, Peru, 1970

Mt. St. Helens Lahar, 1982

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Debris Flow -Avalanche Hazard

Seattle Area

Landslides

CREEP

Slow Unconfined Flow of Soil or Rock

Typical Morgantown Wall vs. Good Retaining Wall

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Creep

SOLIFLUCTION: Soil Flow

Gelifluction: Solifluction Associated with Frozen Ground

0oC Thawed SoilFrozen Soil

Mean Annual

Winter Summer

PermafrostPermafrostZoneZone

Active LayerActive Layer


Rock

Type

of M

otio

n

Fall

Topple

Planar Slide

RotationalSlide

Flow

Avalanche






Rock Avalanche

Debris Avalanche

Earth Avalanche

Landslides

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Coulomb Equation

S = c + σ' tan Φ

Shear Strength =

Cohesion + Effective Normal Force XTangent of “Angle of Repose”

Φ = Angle of Internal Friction = "Angle of Repose"

Plane Friction +Interlocking Friction

tanΦ Increases from 0 to InfinityasΦ Increases from 0o to 90o

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Normal Force (σ ') Influenced byPore Pressure (μ) In Wet Soils

σ ' = σ - μμ > 0 in saturated zoneμ < 0 in unsaturated zone

Bearing Capacity:

Load/Area Without Yield

Ultimate Bearing Capacity:

Load/Area Without Rupture

Factor of Safety

Shear Strength/Shear Force

ATTERBERG LIMITS: Solid - Plastic - Liquid

Plastic: Continuous Deformation With Stress Without Rupture

Plastic Limit: Water Content at Which Solid Becomes Plastic

Liquid Limit: Water Content at Which Plastic Becomes Liquid

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QUESTIONS ON DEBRIS FLOW VIDEOTAPESDefine Debris FlowWhat are the triggers for debris flows?What Source Area Conditions favor Debris Flow?Describe the 3 phases of a typical debris flow?Describe the sedimentology and geomorphology of debris

flows.The Coast and Williams videotape predates the USGS

Landslide Classification (Campbell, & Others, 1986) Which examples in the video are not true debris flows?

What happens to woody debris in a debris flowWhat happens to large rocks in a debris flow?Can you tell a debris flow from a flood flow deposit?

hereClick to answer these questions!

Props: DEBRIS FLOW VIDEOTAPES

Costa, John E., and Williams, Garnett P., 1984, Debris-flow dynamics: U.S. Geological Survey Open File Report 84-606, 1 VHS videotape.

Iverson, Richard M. 2001, Highlight from the Debris Flow Experiment Flume Studies, USGS informal document, 1 VHS videotape.

CALTRANSRock Fall Video

http://www.maccaferri-canada.com/Scan123.jpg

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International Landslide Research Group

• 450 People in 55 countries interested in regional landslide research, applications, and solutions

• http://ilrg.gndci.cnr.it/

Editorial by Earl Brabb

1. MappingA. Prepare landslide susceptibility mapsB. Landslide inventories at 1:10,000 scale or largerC. Landslide inventories at 1:20,000 to 1:80,000 scaleD. Recon landslide inventories at 1:100,000 to 1: 500,000 scale

2. Sponsor workshops A. Local decision-maker awarenessB. Teach geologists how to identify landslidesC. International research conferences

3. Gather info on landslide costs4. Develop more applications for use of existing landslide info

Editorial by Earl E. Brabb

Suggested Priorities of an International Landslide Hazard Program

ILRG poll of 300 members in 1992(not in exact order of priority)

new topic: slopes

Documents