7.24 mass-movement style, activity state, and...

7.24 Mass-Movement Style, Activity State, and DistributionRH Guthrie, Calgary, AB, Canada

r 2013 Elsevier Inc. All rights reserved.

7.24.1 Mass-Movement Style 2307.24.1.1 Falling 2307.24.1.2 Toppling 2317.24.1.3 Sliding 2317.24.1.4 Flowing 2327.24.1.5 Spreading 2347.24.1.6 Creeping 2347.24.2 Activity State 2347.24.2.1 Pre-Failure Movement 2347.24.2.2 Failure 2347.24.2.3 Reactivation 2347.24.2.4 Activity State 2357.24.3 Mass-Movement Distribution 2357.24.3.1 Distribution of Mass-Movement Disasters 237References 237

Abstract

The collection and analysis of mass-movement data and the broader dissemination of results requires the adoption of

standard methods for describing mass-movement style or type and activity state. Main mass-movement styles, such asfalling, toppling, sliding, flowing, spreading, and creeping, are defined herein. Well-known substyles are explained and

different activity states of mass movements are described. Activity states may be related to the immediate behavior (pre-

failure, failure, and reactivation), or to the morphological status (active, suspended, dormant, and inactive). Finally, the

global distribution of landslides is discussed, including the prevalence of mass movements along convergent plateboundaries, climatologically wet regions, and mountainous highlands. The global distribution of mass-movement disasters

is shown, concentrated in the Asia Pacific, and in South America.

7.24.1 Mass-Movement Style

The collection and analysis of mass-movement data and the

broader dissemination of results require the adoption of

standard methods for describing mass-movement style or type

and activity state. Mass movements have been classified in

several ways (Shroder et al., 2005), including rheology (i.e.,

Pierson and Costa, 1987), engineering properties (Hoek and

Bray, 1981), shear type and grain size (i.e., Sassa, 1989), and

velocity (Nemcok, 1977). The most common type of classifi-

cation is a combination of mass-movement style and material

type. Sharpe (1938) proposed a mass-movement classification

system based on four major mass-movement styles: slow-

flowage types, rapid-flowage types, landslides, and subsidence.

Varnes (1978) developed what has become perhaps the most

widely used classification system based on five movement

styles (falls, topples, slides, spreads, and flows; see Chapters

7.13, 7.14, 7.15, 7.16, and 7.17) (Figure 1) and on material

type (rock debris and earth). Varnes’ (1978) classification has

been since modified by several authors (i.e., Hutchinson,

1988; EPOCH, 1993; Cruden and Varnes, 1996); however, in

general, changes have been limited in nature. One potential

drawback of Varnes’ (1978) classification is the lack of dis-

tinction for creep as a mass-movement style. Cruden and

Varnes (1996), however, suggested that creep can be in-

corporated into Varnes’ (1978) classification by a description

of velocity behavior. Others, Sidle and Ochiai (2006), for in-

stance, consider creep and similar behaviors (such as soli-

fluction) to be definitive styles in their own right. Several

distinct mass-movement styles are described herein: falling,

sliding, flowing, spreading, and creeping.

7.24.1.1 Falling

Falling involves the detachment of soil or rock from a steep

slope or cliff (Figure 2). This describes a process where there

is effectively no shear displacement along the failure surface

and where material is transported through the air by falling,

rolling, or bouncing. True falling – that is, objects in freefall –

typically occurs on slopes steeper than 761, whereas slopes

flatter than 451 are dominated by bouncing and rolling

(Hungr and Evans, 1988; Cruden and Varnes, 1996). Falling

may lead to more complex mass movements as the rock and

Guthrie, R.H., 2013. Mass-movement style, activity state, and distribution.

In: Shroder, J. (Editor in Chief), Marston, R.A., Stoffel, M. (Eds.), Treatise on

Geomorphology. Academic Press, San Diego, CA, vol. 7, Mountain and

Hillslope Geomorphology, pp. 230–238.

Treatise on Geomorphology, Volume 7 http://dx.doi.org/10.1016/B978-0-12-374739-6.00172-X230

soil disintegrate downslope and transform in character to

another primary style (such as a rockfall avalanche).

7.24.1.2 Toppling

Toppling is the forward rotation of rock or soil around an

axis or point that lies below the center of gravity of the

displaced mass (usually at or near the base of the slope).

Toppling typically occurs in rock masses that are strongly

jointed, fractured, or characterized by pervasive discontinuity

sets into a series of steeply dipping slabs or columns (Fig-

ure 3). Rock masses of this type include columnar basalts,

well-foliated metamorphic rocks (schists, slates, and phyl-

lites), and rock masses with pervasive joints or discontinuities.

Toppling may be primarily of the flexural type or the

block type:

• Flexural toppling occurs in hard rock mass with steeply

dipping discontinuities following loss of toe support

through sliding or erosion.

• Block toppling occurs in individual columns divided by

wide orthogonal joints where shorter toe columns are

forced forward and outward by overturning longer col-

umns behind (Figure 4). Several complex variations of the

toppling mechanism exist in addition to those already

described.

7.24.1.3 Sliding

Sliding is the downslope movement of a rock or soil mass

along a rupture surface (the relatively thin zone of intense

strain). Slides are characterized by a well-defined shear surface

and relatively coherent displaced mass. Sliding is commonly

divided into two substyles: translational slides and rotational

slides (Figure 5).

In translational slides, a rock or soil mass is displaced along

a planar or undulating surface (i.e., a discontinuity, bedding,

contact, joint, fault, or weathering surface) that is shallow

relative to the length of the mass movement (depth-to-length

ratio o0.1). Translational slides may break up and lose struc-

ture as velocity increases and with increased travel distance

from their source (Figure 6) and may transform into a flow or

an avalanche. Mass movements along a single planar surface are

generally simply called planar slides (Hoek and Bray, 1981) or,

in the case of a large displaced rock mass, block slides.

Wedge slides are a special case of translational mass

movements where two intersecting discontinuities, or a dis-

continuity and a rupture surface, form a deeper wedge-shaped

failure surface upon which the displaced mass slides. Wedge

failures are common in steep rock masses with several inter-

secting joint sets, bedding planes, and other discontinuities.

Rotational slides fail along a circular concave rupture sur-

face with little internal deformation. The head of a rotational

slide is generally characterized by a vertical drop of the dis-

placed material with an upper displaced surface that is tilted

back toward the scarp. The toe of a rotational landslide

commonly bulges outward and onto the original ground

Rock fall

Rock fall debris

ScreeScree

Debris fall

Debris cone

Debris

Rock

Figure 2 Mass-movement styles: falling. Modified with permissionfrom Geomorphological Services Limited, 1986. Review of Researchinto Landsliding in Great Britain. Reports to the Department of theEnvironment, London, UK.

Cracks

Rock topple

Cracks

Soil or debris topple

Figure 3 Mass-movement styles: toppling. Modified with permissionfrom Geomorphological Services Limited, 1986. Review of Researchinto Landsliding in Great Britain. Reports to the Department of theEnvironment, London, UK.

Coarse FineRock fall Debris fall Earth fall

Rock topple Debris topple Earth toppleTranslational Rock slide Debris slide Earth slideRotational Rock slump Debris slump Earth slump

Flowing Water as pore fluid Rock flow Debris flow Earth flowAir as pore fluid Rock avalanche Debris avalanche

(deep creep)Rock spread Debris spread Earth spread

(soil creep)

Complex movements

Toppling

Sliding

Spreading

Type of materialEngineering soils

Bedrock

Mass-movement style

Falling

Figure 1 Mass-movement styles: a landslide classification. Modified with permission from Varnes, D.J., 1978. Slope movement types andprocesses. In: Schuster, R.L., Krizek, R.J. (Eds.), Landslides: Analysis and Control. TRB Special Report 176. Transportation Research Board,National Research Council, Washington, DC, pp. 11–33.

Mass-Movement Style, Activity State, and Distribution 231

surface. The vertical displacement at the landslide head may

result in unsupported rock or soil mass above the landslide,

which in turn causes retrogressive failure upslope. Rotational

landslides are considerably deeper than their translational

counterparts, and occur in deeper, relatively homogeneous

materials. Rotational slides are commonly called ‘slumps’.

7.24.1.4 Flowing

Flows are characterized by the spatially continuous turbulent

movement of disaggregated rock or soil over a rigid bed

(Figure 7). Flows typically behave as a viscous liquid, with

short-lived, closely spaced shear surfaces (distributed shear),

and either water or air acting as the pore fluid. Generally, a

gradation develops between translational sliding and flowing,

dependent on slope (mobility) and water content. Like

translational slides, flows generally have low depth-to-length

ratios. Flows often have long runouts and travel at high vel-

ocities, thereby making them exceptionally hazardous.

Several substyles of flows are recognized, including

channelized debris flows, debris floods, debris avalanches,

block streams, and earth flows. Debris flows and channeli-

zed debris flows are rapid to extremely rapid flows of high

density (generally over 80% solids by weight) that are dis-

tinguished by whether they create their own path or run along

a preexisting channel. Both are commonly associated with

t1

t3

t2

t4

Figure 4 Proposed mechanism for the block topple of the Chaco Canyon sandstones onto the ancient remains of Pueblo Bonito (Bryan, 1954).Water seeps into the mesa surface, daylights at the base of the cliff causing sapping. Loss of support at the toe develops into a full blockrotation away from the cliff, and the process begins anew. Photograph by Bob Adams.

232 Mass-Movement Style, Activity State, and Distribution

extreme precipitation events, and channelized debris flows in

particular may extend many kilometers before stopping

(usually at the end of the channel confines). Debris floods are

hyperconcentrated sediment flows, a transitional step between

debris flow and a purely hydrologic flood.

Earth flows are the term given to slow-moving mass

movements in plastic soils. Limited internal deformation, with

most of the movement occurring along shear surfaces like a

slide, means that earth flows are likely misnamed. However,

the term ‘earth flow’ is used extensively to describe mass-

movement styles that vary from flow-like behavior to slide-like

behavior with discrete basal and lateral shear surfaces

(Figure 8).

Avalanches are extremely rapid flows where a significant

content of the pore space of the disaggregated mass is air ra-

ther than water. They have low depth-to-length ratios and vary

in size from small open slope debris avalanches to colossal

rock and debris avalanches traveling at more than 100 km h�1,

and they are among the world’s deadliest hazards (Figure 9).

Rock avalanches have been called ‘sturzstroms’ across much of

Europe. Debris slides, avalanches, and flows may all grade into

one another depending on the local morphology and mois-

ture conditions.

Figure 6 The disastrous 1963 Vajont rock slide in northeastern Italykilled 2500 persons and made Vajont Europe’s deadliest singlelandslide. Although the rupture surface is clearly identifiable, thedeposit has lost much of its original coherence. Other mass-movementstyles at Vajont included initial creep attributed to the filling of thereservoir, and block rotation on the north face may have contributed tothe failure (Mueller, 1968).

Figure 7 Flowing. Modified with permission from GeomorphologicalServices Limited, 1986. Review of Research into Landsliding in GreatBritain. Reports to the Department of the Environment, London, UK.

Figure 8 This landform in the southern Caucuses is often called anearth flow. The actual mechanism may vary between flowing andsliding. Photograph by R.H. Guthrie.

Figure 9 The deadly Guinsaugon (Southern Leyte Province,Philippines) rock slide–debris avalanche of 2006 that killed 1221people and displaced thousands. Like other types of flows,avalanches commonly have long runout zones. Photograph by R.H.Guthrie.

Debris slidetranslational

Debris sliderotational

Figure 5 Mass-movement styles: sliding. Modified with permission fromGeomorphological Services Limited, 1986. Review of Research intoLandsliding in Great Britain. Reports to the Department of theEnvironment, London, UK.


7.24.1.5 Spreading

Spreading is the spatial dilation or extension of a cohesive

rock or soil mass coupled with a subsidence into underlying

material (Figure 10). Spreads may extend many kilometers

and often occur on terrain that otherwise appears benign. Two

main substyles are common. Block spreads occur where thick

rock layers overlie softer materials. The poorly supported hard

upper layer fractures, and underlying material is squeezed up

into resulting cracks and joints in the rock. This style of spread

is extremely slow.

Liquefaction spreads occur in sensitive clays that lose

cohesive strength as a result of some sort of disturbance. This

disturbance may be seismic but may also be a removal of

toe support (e.g., lacustrine clays along the outward bend

of a river), overloading, or some other disturbance. Lique-

faction spreads will often retrograde inland as subsidence

of the disturbed ground removes support for ground that is

still intact.

7.24.1.6 Creeping

Creep is the slow, plastic, downslope deformation of rock or

soil without definite bounding shear or slip surfaces. Creep

affects rock and soil masses at very large and very small scales.

Particle creep occurs in individual stones and soil particles,

whereas rock creep may occur at depths 4300 m below the

rock surface. The Vajont slide (Figure 6), for example, under-

went years of creep before accelerating catastrophically as a rock

slide with a definable shear failure surface. In general, creep

occurs in soils at speeds o5 mm yr�1 and in rock at speeds

o10 mm yr�1. Creep is also associated with freeze/thaw cycles

and periodic mobilization of recently thawed ground. These

forms of creep result in greater displacement of soils (m yr�1)

and are known as solifluction, gelifluction, or frost creep.

7.24.2 Activity State

The identification of mass movements may nevertheless pre-

clude their actual state of activity. Mass movements can be

divided into three basic stages of movement: pre-failure

movements, failure, and reactivation. Several activity states

describe known mass movements, including active, sus-

pended, dormant, and inactive.

7.24.2.1 Pre-Failure Movement

One of the difficult challenges faced by geoscientists is deter-

mining the likelihood of first-time failures. As shear strength

progressively decreases, relative to stresses, many landslides

show signs of movement that precede their overall failure. This

movement occurs during the development of shear surfaces,

joints and fractures, and any other displacements that ultim-

ately lead to the mass movement. Morphological character-

istics of pre-failure movements include tension cracks, toe

bulging, slickensides, jack-strawed and pistol-butt trees, lean-

ing or displaced infrastructure, and changing drainage pat-

terns. Pre-failure movements are generally correctly classified

as rock or soil creep, such as the activity that preceded the

Vajont slide (Figure 6); however, they generally portend a

greater hazard to follow (Kilburn and Petley, 2003). In falls

and topples, the mechanism is generally not creep but pro-

gressive failure and the long coalescing of planes of weakness.

Lee and Jones (2004) called this stage a late incubation stage

of landslide hazard, and its importance lies in the correct

identification and interpretation of both the pre-failure

movements and the predicted mass-movement event.

7.24.2.2 Failure

Failure is simply the stage where the driving forces (stresses)

overcome the resisting forces (strength) and the mass move-

ment occurs. Failure may be liquid, plastic, or brittle, de-

pending on the nature of the material, but it refers to a

nonrecoverable displacement of rock or soil. In complex mass

movements, failure includes the transformation between

mass-movement styles as the displaced mass may behave

differently from initiation to runout (the common transfor-

mation, e.g., from a rockfall into a rock or debris avalanche).

In addition, many large mass movements exhibit ongoing

activity beyond what is normally considered to be the main

failure. This activity may include slumps (rotational sliding) or

debris flows in the path of the larger mass movement and

rockfall or toppling at the peak. These movements could be

mapped out individually but are usually ignored or simply

understood as relatively inconsequential post-failure adjust-

ments to the changes in slope morphology.

7.24.2.3 Reactivation

When failure involves the plastic or nonbrittle deformation of

a rock or soil mass along a shear surface, the shear surfaces

typically remain intact and exhibit lower residual shear

strength (Figure 11). Consequently, the entire mass or por-

tions of the mass may be subject to periodic displacement,

Figure 10 The 20 June 1993 Lemieux landslide was a liquefactionspread of B3 million m3 that blocked the South Nation River in theSaint Laurence Lowlands of Canada. Photograph by Greg Brooks.


generally associated with rainfall or increased groundwater

tables. Landslides that are periodically reactivated tend to be

slow moving with limited displacements; however, they can

transform into sudden catastrophic events. Landslides that

undergo reactivation may be predictable, at least in terms of

location and triggering conditions, but they still present a

substantial hazard.

In 1998, in Kelso Washington, for example, a slow-moving

landslide destroyed 120 houses and became one of the most

expensive landslides in United States. This event took place on

the site of an ancient landslide, reactivated by three years of

higher than normal rainfall.

7.24.2.4 Activity State

In general, known landslides can be described using various

activity states (Table 1). Active landslides are those that are

currently moving or, in the case of reactivated landslides, those

that move with a regular, measurable periodicity. Active

landslides may also be first-time landslides that have not yet

reached a stable condition, or whose failure has reduced

overall slope stability, thereby creating subsequent retro-

gressive failure at the same location. Suspended landslides are

known failures with the potential to reactivate under con-

ditions that are comparable to current conditions, but for

which no pattern has yet been determined.

Dormant landslides, on the other hand, are landslides that

require a change from current conditions, usually some sort of

extreme event, to reactivate. Finally, landslides that are not

likely to reactivate are simply called inactive. The causes may

be several: remediation, engineering works, different geo-

morphic or climatologic regimes from when they occurred, or

the removal of cause. Correct identification of the activity state

of landslides is critical to hazard and risk mapping and at the

planning stages of land management.

7.24.3 Mass-Movement Distribution

Mass movements occur on every continent on the planet, even

in Antarctica where recent headlines of geomorphic activity

include large blocks of ice calving off into the ocean. However,

the reporting of mass movements is inconsistent: landslides

are historically underreported in remote, sparsely populated

areas and in underdeveloped countries, or grouped with other

natural hazards such as floods, earthquakes, and volcanoes.

The deadly 1556 earthquake in Shanxi province of China, for

instance, had a massive death toll (B830 000), many of which

came from the mass movement of loess deposits. Nevertheless,

advances in remote image acquisition and processing are

leading to a more complete picture of mass-movement dis-

tribution, and generalizations can be made regarding the

requisite conditions for widespread mass movements.

Convergent fault boundaries tend to produce steep

mountainous terrain, active seismic regimes, volcanism, and

complex geology, all of which combine to make those areas

particularly susceptible to landslides. The Asia-Pacific region

combines the features of convergent fault boundaries with

intense high rainfall in the form of typhoons to produce

landscapes particularly susceptible to landsliding. These

countries (including China, Taiwan, India, and Indonesia) are

among the most frequently impacted countries by mass

movements in the world (Figure 12). Falls, topples, slides, and

flows are common features of mass-movement styles.

The convergent boundaries at the Indian plate create con-

ditions that contribute to mass movements in central Asia. In

Tajikistan, for instance, in the 1949 Khait earthquake, a

landslide traveled over 20 km burying 20 villages along its

path; 7000 people died in that event and from landslides in

adjacent valleys (Evans et al., 2009).

North and South America are bound along their western

edge by the Cordillera, a range of mountains formed by the

Table 1 Activity states of mass movements

Activity state Description

Active Currently moving or failing with ameasurable periodicity of displacemento5 years.

Suspended Known mass movements with potential tomove, but currently stationary or withoutmeasurable displacement for 45 years.

Dormant An inactive landslide under normal currentconditions. May be reactivated underextreme conditions.

Inactive – abandoned An inactive landslide that is unlikely to bereactivated because the original cause nolonger applies.

Inactive – stabilized An inactive landslide that is unlikely to bereactivated because the original cause hasbeen remediated. Remediation can be byman or by nature (i.e., vegetation cananchor the landslide).

Inactive – relict An inactive landslide that originated under adifferent climatic or geomorphologicalregime than present; also called ancient.

Displacement (strain)

She

ar s

tren

gth

Peak (failure)

Residual

Pre

-failu

re

Figure 11 Diagram showing the strength–strain relationship oflandslides. The ability of a material to recover from strain is governedby its strength. Once peak strength has been exceeded, the materialfails along a shear surface. In landslides, particularly deep, slow-moving landslides, the driving forces of failure may abate (pore-waterpressures may drop as the material fails for example) anddisplacement may stop. However, the new shear surface represents aplane of weakness, and new movements (reactivation) are governedby its residual strength. This is particularly true for clay soils.


subduction of the Pacific and Nazca plates, respectively. Mass

movements on this steep rugged terrain are exacerbated by

moist air coming off the Pacific Ocean and falling as snow or

rain. Flows, falls, topples, and slides are common. Large rock

and ice avalanches occur in the highest mountains where

melting snow and ice contribute to the mobility and volume

of events. One of the most famous landslide disasters of all

time occurred in Nevados Huascaran (Peru) in 1962 and again

in 1970. Both events began as rock/ice falls and transformed

into high-velocity (up to 85 m s�1) debris flows by incorpor-

ating sediment and ice from the glacier and moraines below,

killing thousands of people. Debris floods triggered by the

1970 landslide continued for an additional 180 km. A recent

(2010) 45 Mm3 rock avalanche from Mount Meager in the

Canadian Cordillera also reached high velocities (460 m s�1)

and traveled several kilometers, burying or partially burying

the Capricorn, Meager, and Lillooet river valleys below

(Figure 13).

In Europe, high mountains of the Alps and Caucasus also

form conditions for mass movements. The conditions are

similar to those in the Cordillera, including the less common

ice–rock avalanche. In 2002, in the Kolka–Karmadon region of

Russia, 100 Mm3 of rock and ice traveled B20 km at speeds of

up to 80 m s�1 and destroyed everything in its path.

However, not all mass movements are so large; but many

are instead shallow debris flows or localized slumps (ro-

tational slides). They are caused commonly by earthquakes,

such as the 1994 Northridge earthquake in the United States,

or by hurricanes and extreme precipitation events, such as the

1999 storms that caused hundreds of debris flows and debris

floods to impact Caracas and neighboring cities in Venezuela.

In fact, smaller landslides are so common that for most steep

landscapes an argument may be made that small landslides do

most of the geomorphic work, shaping the hillslopes (Guthrie

and Evans, 2007).

Spreads, slumps, and slow earth flows occur where plastic

soils or salt-rich soils dominate or where weathered regoliths

occur: deep lacustrine or marine sediments, generally in more

stable slope positions and in the interior of continents.

These mass movements may be triggered by any change in the

present ground condition, including vibration (mechanical

or seismic) or toe erosion (e.g., along the outer bend of

a river).

1−5

6−14

15−28

29−42

43−60

No reports

Figure 12 The number of major landslides reported to the international disaster database 1900–2009. Light gray lines are divergent plateboundaries, medium gray lines are transverse plate boundaries, and dark gray lines are convergent plate boundaries. Data with permission fromEM-DAT, 2010. The OFDA/CRED International Disaster Database. Universite Catholique de Louvain, Brussels, Belgium. http://www.emdat.be(accessed January 2011).

Figure 13 The 2010 rock avalanche from Mount Meager in theCanadian Cordillera. This event corresponds to several other steepmountainous areas in the world where the incorporation of ice androck from steep collapsing slopes can result in catastrophic massmovements with velocities in excess of 50 m s�1. Photograph byR.H. Guthrie.


7.24.3.1 Distribution of Mass-Movement Disasters

The global distribution of mass movements is not complete

unless it takes into account the distribution of mass-move-

ment-related disasters. These disasters are a combination of

the location of the hazard and of the proximity of people and

infrastructure to those hazards. In this respect, the Asia-Pacific

region once again dominates the distribution (Figure 14).

However, the proximity of mass movements to populated and

developing areas in South America makes it a disaster hot spot

as well. Land-use change in the Americas is increasing the

frequency of mass movements, and global population pres-

sure puts more and more people in the path of detriment.

References

Bryan, K., 1954. The Geology of Chaco Canyon, New Mexico in Relation to the Lifeand Remains of the Prehistoric Peoples of Pueblo Bonito. SmithsonianMiscellaneous Collections 122, No. 7. The Smithsonian Institution, Washington,DC, 65 pp.

Cruden, D.M., Varnes, D.J., 1996. Landslide types and processes. In: Turner, A.K.,Schuster, R.L. (Eds.), Landslides: Investigation and Mitigation. TRB SpecialReport 247. Transportation Research Board, National Research Council, pp.36–75.

EM-DAT, 2010. The OFDA/CRED International Disaster Database. UniversiteCatholique de Louvain, Brussels, Belgium. http://www.emdat.be (accessedJanuary 2011).

EPOCH, 1993. Temporal Occurrence and Forecasting of Landslides in the EuropeanCommunity. European Commission, Bruxelles, 3 vols., Contract No. 90 0025.

Evans, S.G., Roberts, N.J., Ischuk, A., Delaney, K.B., Morozova, G.S., Tutubalina, O.,2009. Landslides triggered by the 1949 Khait earthquake, Tajikistan, andassociated loss of life. Engineering Geology 109, 195–212.

Guthrie, R.H., Evans, S.G., 2007. Work, persistence, and formative events: thegeomorphic impact of landslides. Geomorphology 88, 266–275.

Hoek, E., Bray, J., 1981. Rock Slope Engineering, Revised. Institution of Miningand Metallurgy, Third ed. Routledge, London.

Hungr, O., Evans, S.G., 1988. Engineering evaluation of fragmental rockfall hazards.In: Bonnard, C. (Ed.), Proceedings of the Fifth International Symposium onLandslides, pp. 685–690.

Hutchinson, J.N., 1988. General report: morphological and geotechnical parametersof landslides in relation to geology and hydrogeology. In: Bonnard, C. (Ed.),Proceedings of the Fifth International Symposium on Landslides, pp. 3–35.

Kilburn, C.R.J., Petley, D.N., 2003. Forecasting giant, catastrophic slope collapse:lessons from Vajont, northern Italy. Geomorphology 54, 21–32.

Lee, E.M., Jones, D.C.K., 2004. Landslide Risk Assessment. Thomas TelfordPublishing, London, 454 pp.

Mueller, X.X., 1968. New considerations on the Vaiont slide. Rock Mechanics andEngineering Geology 6, 4–91.

Nemcok, A., 1977. Geological/tectonic structures: an essential condition for genesisand evolution of slope movement. Bulletin of the Association of EngineeringGeology 16, 127–130.

Pierson, T.C., Costa, J.E., 1987. A rheologic classification of subaerialsediment–water flows. In: Costa, J.E., Wieczorek, G.F. (Eds.), Debris Flows/Avalanches: Process, Recognition, and Mitigation. Reviews in EngineeringGeology 7. Geological Society of America, Boulder, CO, pp. 1–12.

Sassa, K., 1989. Geotechnical classification of landslides. Landslide News 3,21–24.

Sharpe, C.F.S., 1938. Landslides and Related Phenomena, a Study of Mass-Movement of Soil and Rock. Columbia University Press, New York, NY, 137 pp.(Reprinted by Pageant Books, Paterson, NJ.)

Shroder, J.F., Jr., Cverckova, L., Mulhern, K.L., 2005. Slope-failure analysis andclassification: review of a century of effort. Physical Geography 26(3), 216–247.

Sidle, R.C., Ochiai, H., 2006. Landslides: Processes, Prediction, and Land Use.Water Resources Monograph 18. American Geophysical Union, Washington, DC,312 pp.

Varnes, D.J., 1978. Slope movement types and processes. In: Schuster, R.L., Krizek,R.J. (Eds.), Landslides: Analysis and Control. TRB Special Report 176.Transportation Research Board. National Research Council, Washington, DC, pp.11–33.

1−10

11−100

101−1000

1001−10 000

10 444

No reports

Figure 14 The distribution of mass-movement disasters: the cumulative global distribution of deaths by country for mass-movement disastersnot recorded as another disaster type (flood, volcano, and earthquake).


Biographical Sketch

Dr. Richard Guthrie is an internationally recognized geomorphologist with particular expertise in landslides,

hazard and risk assessment. He provides geoscience expertise to natural resource management, urban develop-

ment, parks management, environmental assessment, and public safety in British Columbia, Canada and around

the world.

With 18 years of leading applied geomorphology, his work has included quantification of landslide hazard

and risk, magnitude and frequency, runout and mobility, and management and communication. He has exam-

ined landslides in Europe, Asia and North America, and recently led the investigation of the 2010 Mount Meager

landslide (Canada’s biggest historical landslide).

With over 60 publications, Dr. Guthrie is the Director of Geohazards and Geomorphology at SNC Lavalin

Environmental, an adjunct professor at the University of Waterloo, an associate editor of the Quarterly Journal of

Engineering Geology and Hydrogeology, and author of three upcoming chapters on landslides and landslide

disasters in national and international compendiums.


7.24 mass-movement style, activity state, and...

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