Mass Wasting
-
Upload
jordan-david -
Category
Documents
-
view
51 -
download
0
description
Transcript of Mass Wasting
![Page 1: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/1.jpg)
Mass Wasting
![Page 2: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/2.jpg)
Mass wasting / slope failure / landslides refers to all downslope movement of rock, regolith, and soil under the direct influence of gravity. Speeds range from extremely fast to extremely slow.
![Page 3: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/3.jpg)
Landslide
• General term for rapid downslope movements/failure
![Page 4: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/4.jpg)
Classification of Landslides
• Based on the type of MATERIALS involved, the SPEED (velocity) of movement, and the TYPE or mechanism of downslope movement.
![Page 5: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/5.jpg)
Downslope Movements
• Types– Fall
– Topple
– Flow
– Slide
– Subsidence
![Page 6: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/6.jpg)
What types of material are involved?1. ROCK – a hard or firm mass that was
intact and in its natural place before the initiation of movement.
2. SOIL – an aggregate of minerals and rocks that either was transported or was formed by the weathering of rock in place.a) Earth – 2 mm particles 80% b) Debris –2 mm particles < 20%
![Page 7: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/7.jpg)
How fast does a landslide move?
• Very Slow – e.g. Creep
• Moderate – e.g.Slumps and earthflows
• Rapid to Very Rapid - e.g. Rockfalls and
Avalanches
![Page 8: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/8.jpg)
FallHalsema Highway
H. Cabria, 2002
www.goodearthgraphics.com/photo/ geology/rockfall.jpg
Colorado River
http://anaheim-landslide.com/types.htm
http://www.science.ubc.ca/~geol351/imgset.html
Similkameen Valley, BC
![Page 9: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/9.jpg)
Topple
http://anaheim-landslide.com/types.htm
http://www.science.ubc.ca/~geol351/imgset.html
Chaco Canyon, NM
www.charmouth.org/html/geology/ geology%20gallery/gallery.ht
Charmouth, UK
![Page 10: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/10.jpg)
Slide
http://anaheim-landslide.com/types.htm
Halsema Highway
H. Cabria, 2002
http://www.science.ubc.ca/~geol351/imgset.html
http://www.science.ubc.ca/~geol351/imgset.html
Liard River, BC
Valtellina, Italy
![Page 11: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/11.jpg)
Flow
http://anaheim-landslide.com/types.htm
http://www.science.ubc.ca/~geol351/imgset.html
http://www.science.ubc.ca/~geol351/imgset.html
South Nation River, Ontario Mt. Pinatubo Lahars
Mt. Pinatubo Lahars
El Salvador www.brookes.ac.uk/geology/ 8361/images/mudflow.gif
![Page 12: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/12.jpg)
Creep
http://anaheim-landslide.com/types.htm
Halsema Highway
H. Cabria, 2002
Black Hills, South Dakota
academic.emporia.edu/aberjame/ struc_geo/primary/prim31.jpg www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 13: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/13.jpg)
Complex typesFrank Slide, Alberta
Huascaran Avalanche, Peru
Thistle Slide, Utah
Colalo Landslide
http://www.science.ubc.ca/~geol351/imgset.html
http://www.science.ubc.ca/~geol351/imgset.html
S. Catane, 1999
![Page 14: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/14.jpg)
Triggers: water input
Mudslide after hurricane Mitch,Fall 1998
Millbrae CA, March 2000
Water infiltrating into unstable slope increases pore pressure (“loosens” particles) and adds more weight to slope, favoring failure.
www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 15: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/15.jpg)
Triggers: earthquake
Ground shaking due to earthquake activity can facilitate slope failure.
Nevados Huascaran, Peru, 1970(18 000 dead)
Northridge earthquake, CA, 1994
www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 16: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/16.jpg)
How human activities increase the
frequency of landslides? • Logging operations • Construction leads to oversteepening of
slopes - road cuts, quarrying or open-pit mining operations
• Buildings and structures on a naturally unstable slope
• Irrigation, watering the lawn, using septic tank for sewage disposal
![Page 17: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/17.jpg)
Landslide ControlZoning is an effective way of reducing landslide-related risk, by keeping people from building and living in, or controlling the type of structure built in landslide-prone areas. This approach however is not always viable.
Slope stabilization measures can greatly reduce the risk of catastrophic slope failure. In some cases, however, this only serve to delay the inevitable.
Riprap wall to control undercutting by stream
www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 18: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/18.jpg)
Slope Stabilization
![Page 19: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/19.jpg)
Slope stabilization: ground anchoring
Drilling to install rock bolts and water pressure monitors (piezometers)
Drilling and bolting across plane of weakness
Ground anchoring (bolting)
www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 20: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/20.jpg)
Slope stabilization:retaining structures
Wire mesh
Geogrid holds unconsolidated material in place
Wire baskets filled with rockwww.geol.umd.edu/~nathalie/GEOL120.htm
![Page 21: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/21.jpg)
Slope stabilization: keeping the water out
Drains and trenches keep water from infiltrating the top of a slump
Short-term precaution against further water input and erosion
Revegetation and drainagewww.geol.umd.edu/~nathalie/GEOL120.htm
![Page 22: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/22.jpg)
SheltersIn some landslide- or avalanche-prone areas, slope stabilization is impractical due to the scale of the unstable slope. This is particularly true for roads in mountainous areas. In this case, sheds are used to divert slides from the road (and people on it).
(Note use of old tires to absorb shock of falling rock.) www.geol.umd.edu/~nathalie/GEOL120.htm
![Page 23: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/23.jpg)
Slope StabilizationMarcos Highway
Rock fence
Rockshed
Shotcrete
Fly-over
H. Cabria, 2002
Tuba Fault
![Page 24: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/24.jpg)
Mankayan Landslide
S. Catane, 1999
![Page 25: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/25.jpg)
H. Cabria, 2002
Mankayan Landslide
S. Catane, 1999
S. Catane, 2000
Aurora Street - 1999
2000
2002
![Page 26: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/26.jpg)
Mankayan Landslide
PVC pipes are used to prevent waste water from infiltrating the slope.
The small PVC pipes were connected to a bigger pipe that directly drains into the creek located below the slope.H. Cabria, 2002
H. Cabria, 2002
![Page 27: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/27.jpg)
Miag-ao Landslide
![Page 28: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/28.jpg)
Cherry Hills Landslide
(Photo by R. S. Punongbayan)
![Page 29: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/29.jpg)
Photo of landslide in Punta, San Francisco, Panaon Island, Southern Leyte, Central Philippines. December 17 – 20, 2003
![Page 30: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/30.jpg)
![Page 31: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/31.jpg)
![Page 32: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/32.jpg)
The andesites are moderate to highly weathered while the matrix of the breccia is completely weathered. Soil thickness including highly weathered rocks is about 10 m.
![Page 33: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/33.jpg)
Land Subsidence: Causes
Man-made: Withdrawal of subsurface support (removing water, petroleum, rocks voids)
Downwarping due to sedimentation, ice loading, dewatering and compaction of sediments
Folding or faulting or earthquakeCollapse of underground cavern (sinkhole)
![Page 34: Mass Wasting](https://reader035.fdocuments.net/reader035/viewer/2022062408/5681369b550346895d9e38b2/html5/thumbnails/34.jpg)
Sinkholes
Winter Park, Florida sinkhole (100m across x 34 m deep) formed1981
“December giant” sinkhole,Alabama (130 m long x 46m
deep) formed 1972