Social and Environmental Impacts of Landslides

Transcription

1 Social and Environmental Impacts of Landslides Latsis Symposium 2007 Research Frontiers in Environment and Sustainability ETH-Zurich September 18, 2007 Dr. A. Keith Turner Emeritus Professor Geological Engineering Colorado School of Mines

2 Landslide: the movement of a mass of rock, debris, or earth down a slope

3 Classification of Landslides TWO WORDS used: Material: rock debris, earth Type of Movement: (failure mechanism)

4 Classification of Landslides TWO WORDS used: Rotational Earth Slide Translational Earth Slide Rock (Block) Slide Earth (lateral) Spread Rock Fall Rock Topple Debris Flow Earth Flow

5 Landslide Velocities Velocities range over 10 orders of magnitude Danger zone: people cannot escape Zone of Property Damage: Minimum Damage Zone: constant maintenance possible

6 Landslide Volume and Frequency Volume: From very small ( a single rock!) To very large (million m 3 ) Frequency: Small landslides are frequent Large landslides are rare

7 Landslide Size-Frequency Model

8 Assessing Landslide Danger Volume x Speed POWER or Energy: Extremely large and rapid landslides ( sturzstroms( sturzstroms ) are the most dangerous Elm Landslide deaths Illustration from Buss and Heim, 1881

9 Landslides and Society Landslides are natural phenomena: Societal issues result only when humans and their built environment are located in the path of landslides Prior to the Industrial Revolution in late 1700 s s and early 1800 s s landslide studies rare: No economic incentive No scientific basis

10 Early Landslide Studies - 1 Bindon Landslide December 25, 1839:

11 Early Landslide Studies - 2 Landslide Caused First Railway Fatality, 1841: Sonning Cutting, near Reading, Great Western Railway (illustration from 1846)

12 Early Landslide Studies - 3 Clay Slopes on French Canals, 1846: Landslides in Clays, Alexandre Collin, 1846

13 Landslides Impacts on a Global Scale Recent World Bank report states: Global land exposed to landslides = 3.7 million km 2 Population exposed = 300 million (5% world pop.) Land area in high risk zones = 820,000 km 2 Population in high risk zones = 66 million

14 Landslides Impacts on a Global Scale Recent World Bank report states: Global land exposed to landslides = 3.7 million km 2 Population exposed = 300 million (5% world pop.) Land area in high risk zones = 820,000 km 2 Population in high risk zones = 66 million

15 Landslides and Population Growth Increased urbanization Increased development in mountainous regions

16 Landslide Impacts Landslides are local events: Under the radar rarely receive attention of hurricanes, floods, earthquakes, volcanic eruptions Often little government aid provided Disastrous impact on individual Neighbours oppose hazard zonation lowers property values.

19 Estimating Landslide Losses Regional or National losses hard to determine Mixed with other causes hurricanes, earthquakes, etc. Losses are significant: USA annual landslide losses = $3.5billion & killed Direct vs Indirect Losses

20 Thistle, Utah Landslide (1983) Most expensive landslide in USA (total loss = $688 million)

21 Dams and Landslides Landslides may partially block valleys: These narrow area sometimes chosen as dam sites At least 254 large dams interact with landslides (USGS Prof. Paper 1723; Schuster, 2006) Reservoirs may be subject to landslides: Vaiont,, Italy, October 5, 1963 Reservoir mostly filled with 270-million m 3 Downstream wave caused 2,500 fatalities

22 Dams and Landslides VAIONT LANDSLIDE Landslides may partially block valleys: These narrow area sometimes chosen as dam sites At least 254 large dams interact with landslides (USGS Prof. Paper 1723; Schuster, 2006) Reservoirs may be subject to landslides: Vaiont,, Italy, October 5, 1963 Reservoir mostly filled with 270-million m 3 Downstream wave caused 2,500 fatalities (Image: Professor E. Bromhead, University of Kingston)

23 Dams Built on Landslides Bonneville Dam, Columbia River, USA

24 Landslides As Dams Landslides can dam rivers: another hazard Pakistan Earthquake: October 8, 2005 Hattian Bala debris avalanche created two lakes in the Karli and Tang valleys. USGS Open-File Report (Harp and Crone)

25 Landslides and the Environment Landslides Affect Environmental Issues: They cause: Terrain Modification Environmental Degradation They may be triggered by: Volcanoes Earthquakes Extreme Precipitation Events (huricanes( huricanes) Wildfire Human Activities Landslides and Global Climate Change?

26 Landslides Produce Terrain Modification Very large,ancient debris flow (300,000 years B.P.) at Mount Shasta, California produces hummocky topography.

27 Landslides Produce Terrain Modification Slumgullion Very large,ancient debris flow (300,000 years B.P.) at Mount Landslide, Shasta, California produces hummocky topography. Colorado This earth flow began some 700 years ago. About 350 years ago, a second earth flow started from the top of the mountain. The new flow is still moving, sometimes as much as twenty feet in a year. The first flow was so large and cataclysmic, it blocked the Lake Fork of the Gunnison River and created Lake San Cristobal, Colorado's second largest natural lake.

28 Landslides Cause Environmental Degradation Severe slope denudation by landslides in the Rio Malo drainage, northeastern Ecuador, following the Reventador earthquake. Downstream channels were clogged with debris.

29 Landslides may be Triggered by Volcanoes Volcanoes produce lahar lahar flows Examples from Mount St. Helens eruption of View of North Fork Toutle River valley (northwest of St. Helens) shows part of the debris avalanche that traveled approximately 24 km downstream at a velocity exceeding 240 km/hr. Deposit averages 45 m thick (max = 180 m.) (USGS Photo by L. Topinka,, Nov. 30, 1983)

30 Landslides may be Triggered by Volcanoes Volcanoes produce lahar lahar flows Examples from Mount St. Helens eruption of View of North Fork Toutle River valley (northwest of St. Helens) shows part of the debris avalanche that traveled approximately 24 km downstream at a velocity exceeding 240 km/hr. Deposit averages 45 m thick (max = 180 m.) (USGS Photo by L. Topinka,, Nov. 30, 1983)

31 Landslides may be Triggered by Volcanoes Volcanoes produce lahar lahar flows Examples from Mount St. Helens eruption of View of North Fork Toutle River valley (northwest of St. Helens) shows part of the debris avalanche that traveled approximately 24 km downstream at a velocity exceeding 240 km/hr. Deposit averages 45 m thick (max = 180 m.) Downstream destruction (USGS Photo by L. Topinka,, Nov. 30, 1983)

32 Landslides may be Triggered by Volcanoes Volcanoes produce lahar lahar flows Examples from Mount St. Helens eruption of View of North Fork Toutle River valley (northwest of St. Helens) shows part of the debris avalanche that traveled approximately 24 km downstream at a velocity exceeding 240 km/hr. Deposit averages 45 m thick (max = 180 m.) Downstream destruction (USGS Photo by L. Topinka,, Nov. 30, 1983)

33 Landslides may be Triggered by Earthquakes Earthquake-induced landslide damage to a house built on artificial fill, after the 2004, Niigata Prefecture, Japan earthquake. (Photo by Prof. Kamai, Kyoto Univ.)

34 Landslides may be Triggered by Earthquakes Earthquake-induced 500,000 m 3 landslide Earthquake-induced landslide damage to a house built on artificial fill, after damaged the 2004, the Pan Niigata American Prefecture, Highway, Japan El earthquake. Salvador, (Photo by (Photo Prof. Kamai, by Ed Harp, Kyoto USGS) Univ.)

35 Landslides may be Triggered by Earthquakes LAS COLINAS, El Salvador, 2001 A magnitude 7.3 earthquake- induced a landslide at Las Colinas, El Salvador. More than 600 lost their lives due to the landslide, while 300 died of other causes. (Photo USGS)

36 Landslides may be Triggered by Extreme Precipitation Events GONDO, Switzerland October 14, 2000 Following 3 days of precipitation, a mudflow of 10,000 m 3 destroyed a concrete wall designed to stop rock falls. The wall slid with the mudflow and destroyed ten buildings of the village and 14 fatalities resulted.

37 Landslides may be Triggered by Extreme Precipitation Events Bluebird Canyon, Laguna Beach, California June 1, 2005 (18 million-dollar homes damaged/destroyed) No rainfall or earthquake activity occurred during or immediately before the landslide movement. Landslide is almost certainly related to the extremely heavy winter rains that occurred December 2004 February 2005.

38 Landslides may be Triggered by Wildfire Debris Flow blocked Interstate-70 at Glenwood Springs, Colorado, shortly after area was burned by Wildfire.

39 Landslides may be Triggered by Wildfire Debris Flow blocked Interstate-70 at Glenwood Springs, Colorado, shortly after area was burned by Wildfire. Debris flow deposits from Hot Creek Fire, Idaho, Photo by Sue Cannon, USGS)

40 Landslides may be Triggered by Wildfire Debris Flow blocked Interstate-70 at Glenwood Springs, Colorado, shortly after area was burned by Wildfire. Debris flow deposits from Hot Creek Fire, Idaho, Photo by Sue Cannon, USGS) Debris flow deposits Durango, Colorado, after Missionary Ridge Fire, (Photo by Sue Cannon, USGS)

41 Landslides may be Triggered by Human Actions xx A 75-foot foot-high stone retaining wall built in 1908 collapsed onto the Henry Hudson Parkway in Upper Manhattan on May 13, 2005

42 Landslides and Global Climate Change? (Source: IADB, 2007)

43 Responding to Landslides Mitigation Activities: prevent/reduce adverse effects Developed Countries: Assessment of Hazard and Risk Increasingly quantitative approach Political, Legal, Administrative measures Landslide insurance a doubtful solution Structural & Geotechnical measures Stabilization both internal and external Drainage

44 Slope Stabilisation Options

45 Buttress Can Stabilise Landslide

46 Drainage Methods

47 Drainage Methods Installing Horizontal Drains

48 Rock Slides along Roads

49 Rock Slides along Roads

50 Two Solutions: Rock Removal and Rock Slope Reinforcement

51 Two Solutions: Rock Removal and Rock Slope Reinforcement

52 Rock Fall Hazards in Yosemite National Park

53 Rock Fall Hazards in Yosemite National Park

54 Definition of Hazard Zones

55 Rock Fall Hazards in The Yosemite Valley

56 Rock Fall Hazards in The Alps One Example: Randa

57 Rockfall A Concern for Motorists Washington State October 30, 2004 Glenwood Canyon May 8, 2003

58 Rockfall A Concern for Motorists Glenwood Canyon Thanksgiving 2004 Washington State October 30, 2004 Glenwood Canyon May 8, 2003

59 Rockfall A Concern for Motorists Glenwood Canyon Thanksgiving 2004 Rockfall Damaged Bridge Deck Over $1-million repair cost Washington State October 30, 2004 Glenwood Canyon May 8, 2003

60 Rockfall A Concern for Motorists Glenwood Canyon Thanksgiving 2004 A rock climber parked his car near CSM Rockfall Damaged Bridge Deck Over $1-million repair cost Washington State October 30, 2004 Glenwood Canyon May 8, 2003

61 Landslides in the Developing World

62 Landslide Response in the Developing World Lack resources, capacity, or technical expertise to apply landslide risk-reduction reduction measures React to emergencies and disasters VULNERABILITY POVERTY Deterioration of the environment and natural resources DISASTERS International collaboration and support vital

63 South American Examples Caraballeda, Venezuela, 1999

64 South American Examples Caraballeda, Venezuela, 1999 La Paz, Bolivia

65 South American Examples Carmen de Uria, Venezuela, 1999 Caraballeda, Venezuela, 1999 La Paz, Bolivia

66 Thank you. Questions??