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Climate change, manifested by an increase in mean, minimum, and maximum temperatures and by more intense rainstorms, is becoming more evident in many regions. An important consequence of these changes may be an increase in landslides in high mountains. More research, however, is necessary to detect changes in landslide magnitude and frequency related to contemporary climate, particularly in alpine regions hosting glaciers, permafrost, and snow. These regions not only are sensitive to changes in both temperature and precipitation, but are also areas in which landslides are ubiquitous even under a stable climate. We analyze a series of catastrophic slope failures that occurred in the mountains of Europe, the Americas, and the Caucasus since the end of the 1990s. We distinguish between rock and ice avalanches, debris flows from de-glaciated areas, and landslides that involve dynamic interactions with glacial and river processes. Analysis of these events indicates several important controls on slope stability in high mountains, including: the non-linear response of firn and ice to warming; three-dimensional warming of subsurface bedrock and its relation to site geology; de-glaciation accompanied by exposure of new sediment; and combined short-term effects of precipitation and temperature. Based on several case studies, we propose that the following mechanisms can significantly alter landslide magnitude and frequency, and thus hazard, under warming conditions: (1) positive feedbacks acting on mass movement processes that after an initial climatic stimulus may evolve independently of climate change; (2) threshold behavior and tipping points in geomorphic systems; (3) storage of sediment and ice involving important lag-time effects. Copyright © 2011 John Wiley & Sons, Ltd.
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State of Science
Is climate change responsible for changing
landslide activity in high mountains?
Christian Huggel,
1
*John J. Clague
2
and Oliver Korup
3
1
Glaciology, Geomorphodynamics & Geochronology, Department of Geography, University of Zurich, Zurich, Switzerland
2
Department of Earth Sciences, Simon Fraser University, Vancouver, BC, Canada
3
Earth and Environmental Sciences, Potsdam University, Germany
Received 8 March 2011; Revised 29 July 2011; Accepted 6 August 2011
*Correspondence to: Christian Huggel, Glaciology, Geomorphodynamics & Geochronology, Department of Geography, University of Zurich, Zurich, Switzerland. E-mail:
christian.huggel@geo.uzh.ch
ABSTRACT: Climate change, manifested by an increase in mean, minimum, and maximum temperatures and by more intense
rainstorms, is becoming more evident in many regions. An important consequence of these changes may be an increase in landslides
in high mountains. More research, however, is necessary to detect changes in landslide magnitude and frequency related to
contemporary climate, particularly in alpine regions hosting glaciers, permafrost, and snow. These regions not only are sensitive
to changes in both temperature and precipitation, but are also areas in which landslides are ubiquitous even under a stable climate.
We analyze a series of catastrophic slope failures that occurred in the mountains of Europe, the Americas, and the Caucasus since the
end of the 1990s. We distinguish between rock and ice avalanches, debris flows from de-glaciated areas, and landslides that involve
dynamic interactions with glacial and river processes. Analysis of these events indicates several important controls on slope stability
in high mountains, including: the non-linear response of firn and ice to warming; three-dimensional warming of subsurface bedrock
and its relation to site geology; de-glaciation accompanied by exposure of new sediment; and combined short-term effects of
precipitation and temperature. Based on several case studies, we propose that the following mechanisms can significantly alter landslide
magnitude and frequency, and thus hazard, under warming conditions: (1) positive feedbacks acting on mass movement processes that
after an initial climatic stimulus may evolve independently of climate change; (2) threshold behavior and tipping points in geomorphic
systems; (3) storage of sediment and ice involving important lag-time effects. Copyright © 2011 John Wiley & Sons, Ltd.
KEYWORDS: climate change; landslides; glaciers; permafrost
Introduction
Many regions of the world are experiencing increases in mean,
maximum, and minimum air temperatures and more frequent
heavy precipitation (IPCC, 2007). Of particular concern are ex-
treme events such as heat waves, droughts, exceptional rainfall,
and floods (Füssel, 2009; Smith et al., 2009), that are assessed
in detail in the Intergovernmental Panel on Climate Change
(IPCC) Special Report on Managing Risks from Extreme Events,
published in late 2011. Landslides are another process with
causal links to climate change, primarily through precipitation,
but in some cases also through temperature (Figure 1A; Sidle
and Ochiai, 2006; Crosta and Clague, 2009). A large body of
literature is concerned with rainfall as a trigger for shallow
landslides (Corominas, 2000; Wieczorek and Glade, 2005),
and empirical intensity-duration thresholds have been estab-
lished for rain-induced landslides in various regions throughout
the world (Caine, 1980; Larsen and Simon, 1993; Guzzetti
et al., 2008). How contemporary climate change could affect
landslide activity, however, remains largely unresolved. One
key area of uncertainty is how climate change will alter the
probability of damaging slope failures during a specified period
(Cruden and Varnes, 1996; Lateltin et al., 2005). This probabi-
listic measure has direct application in quantitative risk assess-
ments and appears to be a useful metric for quantifying effects
of contemporary climate change on landslide occurrence.
Observations of recent large landslides in some mountain
regions suggest that climate change is having an effect on slope
stability (Evans and Clague, 1994; Geertsema et al., 2006;
Jakob and Lambert, 2009), but the evidence is typically ambig-
uous, and physical causeeffect relationships remain specula-
tive or conceptual (Huggel, 2009).
The attribution of a climatic effect to a given sample of land-
slides requires that non-climatic and anthropogenic causes and
triggers be eliminated. Inconsistency or bias in landslide
reports, however, makes statistically rigorous analysis challeng-
ing. Here we focus on high-mountain areas where anthropo-
genic effects are absent or minimal, and where snow,
glaciers, and permafrost sensitive to temperature changes may
compromise slope stability (Evans and Clague, 1994; Haeberli
et al., 1997). Climate change may alter rates of physical and
chemical weathering or degrade permafrost, all of which may
EARTH SURFACE PROCESSES AND LANDFORMS
Earth Surf. Process. Landforms 37,7791 (2012)
Copyright © 2011 John Wiley & Sons, Ltd.
Published online 28 September 2011 in Wiley Online Library
(wileyonlinelibrary.com) DOI: 10.1002/esp.2223
change the bulk strength properties of slope-forming materials
(Figure 1A; Davies et al., 2001; Arenson and Springman,
2005; Harris et al., 2009). A change in the frequency or magni-
tude of precipitation affects infiltration rates and pore-water
pressures, as well as the erosional efficacy of fluvial processes.
An increase in rainfall may thus affect hillslope stability through
dynamic loads during high-intensity rainstorms, slope undercut-
ting, or redistributions of topographic-induced stresses in rock
slopes (debuttressing effects) (Augustinus, 1995; Ballantyne,
2002). Clearly, the timescale on which climate change affects
slope stability and landslide hazards is important (Figure 2). For
instance, debuttressing effects can have lag times of the order of
millennia (post-glacial), but can also act on timescales as short as
decades (see section on Lower Grindelwald Glacier, Swiss Alps).
Similarly, ice unloading due to widespread glacier shrinkage is sug-
gested to have effects on seismicity on timescales of millennia, but
also over periods of decades, as recent studies in Alaska have
shown (Sauber and Ruppert, 2008).
The approach we use here is a hybrid one, integrating review
elements and case studies. In the second section we distinguish
between large landslides in rock and ice, in the third section
alpine debris flows, and in the fourth section coupled processes
among landslides, glaciers, and rivers. Each section is intro-
duced by a review and theory, followed by a limited number
of case studies that highlight specific aspects of climate change
and landslides.
We focus on identifying potential characteristic signals of
climate change in a number of large (>10
5
m
3
), catastrophic
Shear strength
Shear stress
FS = 1
t0
t1
t2
t3
t4
stable
unstable
Rock
Soil
Frequency
Magnitude
1
2
3
AB
Figure 1. (A) Simplified relationship between shear strength and shear stress for a hillslope. Factor of Safety (FS) = 1 delineates a force equilibrium
where the hillslope is at the threshold of failure. Vertical arrow is a time trajectory starting at t
0
and ending at t
4
, during which shear strength gradually
decreases to the point of failure through, for example, weathering, static fatigue, or permafrost degradation. Horizontal arrows mark dynamic loading
events (i.e. potential triggers) such as earthquakes or rainstorms. Event at t
1
produces sufficient additional shear stress to trigger slope failure, whereas
the event at t
2
does not. However, a subsequent event comparable to that at t
2
may trigger failure in a sufficiently weakened hillslope (t
3
). (B) Sche-
matic diagram highlighting inverse scaling relationship between landslide frequency and magnitude, such as area or volume (both axes are log-
scaled). For simplicity, a simple power-law scaling is assumed. Line 1 is a reference state prior to climate change; line 2 is a possible scenario related
to climate change, where larger landslides begin to dominate at the expense of smaller ones; line 3 is a scenario where smaller landslides begin to
dominate at the expense of larger ones.
10-1 101
10-2 100102
(days)
Rock / ice slope failures
Increasing mean temperature
Warm extreme temperatures
Periglacial debris flows
Heavy precipitation
Short-term effects
Seasonal melt water
production, snow fall
elevation
Enhanced melt
water and
thawing
Water
infiltration
into rock and ice
Increasing mean temperature
Warm extreme temperatures
Heavy precipitation
Higher snow line,
enhanced runoff,
soil saturation
Enhanced melt
water and soil
saturation
Rapid soil
saturation, enhanced
surface runoff
101103
100102104
(years)
Lag-time effects
Conductive heat transport
to subsurface, latent heat
effects, debuttressing effects
due to glacier retreat
Conductive
heat transport
to subsurface
Uncovering of glacial
sediments due to glacier
retreat, thawing permafrost,
sediment input
Possibly alteration
of sediment input
systems
Possibly alteration
of sediment input
systems
Figure 2. Temporal relationships between processesthat affect slope stability and climate drivers. Short-term effects, ranging from minutes to months
are distinguished from lag effects on the order of years to millennia. The timescales indicated by the grey bars are only approximate, but highlight the
variability in the different processes. The spatial scale, although not shown here for the sake of simplicity, is closely related to the temporal scale. For
example, the effect of colder late Pleistocene climate may still exist at depths of several hundred metres in rock (Noetzli and Gruber, 2009).
78 C. HUGGEL, J. J. CLAGUE AND O. KORUP
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
landslides that have occurred over the past 15 years in
glacierized or formerly glaciated areas in the European Alps,
the Americas, and the Caucasus. Table I provides a summary
of the described case studies plus a few additional events.
Our sample includes rock slides, rock avalanches, debris flows,
and icerock avalanches (sensu Cruden and Varnes, 1996) that
were not triggered by earthquakes. Although relatively rare dur-
ing the historic period, such landslides have caused much de-
struction and loss of live (Eisbacher and Clague, 1984; Haeberli
et al., 1989; Huggel et al., 2005; Pralong and Funk, 2006). Large
and catastrophic bedrock landslides also produce more persistent
geomorphic evidence than smaller slope failures and thus offer
Table I. Summary of selected recent slope failure events and their relation to climate and climate change
Location
Date of
occurrence
Approximate mass failure
volume (10
6
m
3
)
Maximum failure
elevation (m a.s.l.)
Relation to climate or
climate change
Large rock slope failures
Monte Rosa, Italy 21 April 2007 03 4000 Massive ice loss and bedrock failures in
adjacent areas during previous years and
decades; permafrost occurrence; very
warm temperatures days-weeks
before failure
Kolka, Caucasus, Russia 22 September 2002 130 4300 Probably warming permafrost and
warming steep glacier ice
Mount Steele, Yukon 24 July 2007 2780 4640 Permafrost occurrence; warm, melting
temperatures days-weeks before failure
Mount Steller, Alaska 14 September 2005 50 3100 Probably warming permafrost and steep
glacier ice; warm, melting
temperatures days-weeks
before failure, ridge situation
Mount Miller, Alaska 6 August 2008 22 2200 Probably warming permafrost and steep
glacier ice; warm, melting temperatures
days-weeks before failure
Mount Cook,
New Zealand
14 December 1991 60 3755 Probably warming permafrost and steep
glacier ice; very warm temperatures
days-weeks before
failure, ridge situation
Thurwieser, Italy 18 September 2004 25 3725 Probably warming permafrost at several
meters bedrock depth, ridge situation
Mount Munday, BC MayJuly 2007 3 3100 Probably warming permafrost; warm
temperatures days or weeks
before failure
Alpine debris flows
Rotlaui, Switzerland 22 August 2005 05 2400 Abundant glacial sediment in source
zone due to recent glacier retreat;
permafrost occurrence in sediment body;
extremely high rainfall intensity
Salcantay, Peru 27 February 1998 25 4200 Abundant glacial sediment in source
zone due to glacier retreat; high
accumulated rainfall amounts,
warm temperatures implying high
snowfall line and further liquid water
from ice and snowmelt
Tambo de Viso, Peru 16 January 1998 04 24005600 Abundant unconsolidated sediment;
intensive rainfall during the 1997/1998
El Niño event
Gerkhozhansu River /
Tyrnyauz
18 July 2000 10 3500 Abundant glacial sediment in source
zone due to recent glacier retreat; likely
permafrost occurrence in sediment
body and remnants of dead ice
Process coupling
Ritzlihorn, Switzerland 20092010 >03 (total) 3260 Warming permafrost in rock fall source
zone, days of high temperatures precede
failures and debris flows
Lower Grindelwald
glacier, Switzerland
20062010 3000 Long-term glacier retreat leads to glacier
lake formation, debuttressing and
moraine and bedrock failures, probably
warming permafrost in rock
fall source zone
Mount Meager, BC 6 August 2010 48 2400 Long-term glacier retreat leads to
debuttressing effects; probably
warming permafrost in rock slope
failure source zone
Mount Harold
Price, BC
2224 June 2002 1 1720 Warming of steep rock slope; rockslide
transformed into a debris flow
79CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
the possibility of recording past climate change (Dapples et al.,
2002; Korup and Clague, 2009; Borgatti and Soldati, 2010).
Catastrophic Landslides Involving Bedrock
and Ice
A recent spate of large slope failures in rock and ice, resulting
in rock and ice avalanches with volumes of the order of 10
5
to 10
8
m
3
have raised questions about the extent to which they
are related to climate change (Gruber and Haeberli, 2007;
Huggel et al., 2008b). The best documented events are in the
European Alps and include, for example, the 2510
6
m
3
rock
avalanche from Punta Thurwieser, Italy, in 2004 (Sosio et al.,
2008); the 2310
6
m
3
Brenva rock avalanche, Mont Blanc,
Italy, in 1997 (Barla et al., 2000); the ~10
6
m
3
rock slides from
Dents du Midi and Dents Blanches, Switzerland, in 2006; and
the rock avalanche from the east face of Monte Rosa, Italy, in
2007. Other high-mountain regions with large numbers of
recent large rock and ice avalanches include the Southern Alps
of New Zealand (Allen et al., 2009), British Columbia, Canada
(Evans and Clague, 1988; Geertsema et al., 2006), Yukon and
Alaska (Lipovsky et al., 2008; Huggel et al., 2010), and the
Caucasus (Haeberli et al., 2004). Most of these rock slope
failures have sources in areas of warm permafrost.
In spite of such evidence, the role of permafrost thaw in
rock-slope failure is difficult to demonstrate conclusively.
Research in this field is formative, but important progress has
been made during the past several years. It is now understood,
for example, that heat conduction and advection of heat by
water moving in fractures are important processes of permafrost
degradation (Gruber and Haeberli, 2007). Ridges, spurs, and
peaks experience more rapid permafrost degradation than flat
and gentle surfaces, because atmospheric heat can enter the
subsurface from several sides (Noetzli and Gruber, 2009). In
this context, we observe that several recent large rock slope
failures had sources in such ridge and spur locations. Thawing
effects due to advection by running water are not yet suffi-
ciently understood, but are subject to ongoing research. Recent
findings suggest that this process can produce thaw corridors
along fractures on annual timescales (Hasler et al., 2011).
Moreover, warming or thawing of ice-filled clefts can reduce
shear strength of the materials underlying the slope (Davies
et al., 2001; Günzel, 2008). Increases of hydrostatic pressure in
previously ice-filled fractures can result from infiltration of water.
Yet it remains difficult to attribute individual slope failures con-
clusively to permafrost degradation, given the impediments to
measuring subsurface properties and thus distinguishing the
effects of permafrost from other factors that control slope stability
(Fischer and Huggel, 2008; Fischer et al., 2010). It is possible,
however, to determine the location and extent of permafrost on
rock slopes and to identify where thaw is most likely to occur.
Measurements and models of subsurface temperature fields have
greatly helped shape our understanding of impacts of climate
change on alpine permafrost and related slope stability
(Wegmann et al., 1998; Gruber et al., 2004a; Noetzli et al.,
2007; Hasler, 2011).
Climate change affects permafrost in rock slopes on different
spatial and temporal scales. Due to the large time lag of heat
diffusion, permafrost may persist at depth, even where surface
temperatures are no longer favorable (Wegmann et al., 1998;
Noetzli et al., 2007). The recent warming signal has penetrated
into bedrock to depths of decametres, and will continue to
reach further depth in coming decades.
The concept of the para-glacial cycle (Ballantyne, 2002) has
been applied to hillslope stability in formerly glaciated regions.
Augustinus (1995), for example, argues that slopes gradually
adjust to altered stress regimes following glacier downwasting
and retreat. The idea that glacial debuttressing decreases the sta-
bility of slopes has been influential and has led many authors to
conclude that some large bedrock landslides are a lagged re-
sponse to major climate change (Abele, 1974; Cossart et al.,
2008). Proposed lag times following de-glaciation are of the order
of millennia (Ivy-Ochs et al., 2009; Prager et al., 2009), but may
also be as short as decades (see section on Lower Grindelwald
Glacier, Swiss Alps).
Here we highlight two case studies that further support the
notion of a causal relationship between glacier retreat, permafrost
degradation, and slope failure. A third example demonstrates po-
tential ambiguities of attributing large failures in ice and bedrock
to climate change.
Monte Rosa, Italy
The Monte Rosa east face, Italian Alps, extends from 2200m
to >4500 m above sea level (a.s.l.) and is one of the largest rock
walls in the Alps. It is formed of gneissic rocks and is partly cov-
ered by steep glaciers that have thinned and retreated consider-
ably over the past 30 years (Figure 3; Haeberli et al., 2002;
Fischer et al., 2006). Frequent slope instability involving both
ice and rock has been documented since about 1990 (Fischer
et al., 2006). The largest slope failure was a 1110
6
m
3
ava-
lanche of ice and snow that detached from the middle section
of the east face at ~36003800 m a.s.l. in August 2005. The
avalanche reached the foot of the rock face, where a large
supra-glacial lake had formed in 2002 but had drained in 2003.
Had the lake still existed in 2005, the avalanche would have
generated a displacement wave with likely catastrophic conse-
quences for the downstream community of Macugnaga. The av-
alanche, which occurred at night, buried much of a pasture near
an alpine hut frequented by tourists during daytime. Less than two
years later, in April 2007, ~0.3 10
6
m
3
of rock detached from
the east face at ~4000 m a.s.l. and fell to its base at ~2200 m a.s.
l. The rock mass detached from a dip slope on which a large
amount of ice had been lost in recent years, likely altering the
local temperature and stress fields (Fischer et al., 2011). High-
resolution photogrammetry and LiDAR-based topographic studies
revealed that smaller, more frequent rock and ice avalanches dur-
ing the last two decades of the twentieth century were responsible
for ~20 10
6
m
3
of mass loss from the east face of Monte Rosa
(Fischer et al., 2011). This loss predominantly occurred from about
3300 to 4100 m a.s.l., corresponding to areas of warm to cold
permafrost.
Meteorological observations at high elevations on Monte
Rosa and other sites in the Alps have shown that atmospheric
warming can cause strong, non-linear increases in firn and
ice temperature. Melting initiates at temperatures of greater
then 10C, and subsequent refreezing can strongly affect
warm firn and ice due to latent heat production (Suter and
Hoelzle, 2002; Hoelzle et al., 2010). In this manner cold ice
can transform into polythermal or temperate ice within several
years (Haeberli and Alean, 1985). This effect, together with
enhanced infiltration of melt water to the base of steep glaciers,
could change the potential source zones of ice avalanches.
The spatio-temporal analysis of landslide activity at Monte
Rosa indicates that the primary onset of mass loss at the end
of the 1980s and early 1990s occurred in tandem with a strong
increase of local air temperatures (Fischer et al., In press). The
large mass losses imply changes in mechanical stress and ther-
mal surface and subsurface fields that influenced subsequent
landslide activity, including the 2007 rock avalanche. The
lesson learnt from Monte Rosa thus is that slope instability
initially may be triggered by climate change, but then can
develop further independently of additional climatic stimuli.
80 C. HUGGEL, J. J. CLAGUE AND O. KORUP
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
Kolka-Karmadon, Caucasus
The 2002 icerock avalanche in the Kasbek region of the Russian
Caucasus is emblematic of a complex long-runout landslide.
Approximately 1020 10
6
m
3
of rock and glacier ice detached
from a steep slope of intensely fractured rock below the summit
of Dzhimarai-khokh (4780 m a.s.l.; Haeberli et al., 2004;
Kotlyakov et al., 2004; Huggel et al., 2005; Evans et al., 2009).
The failure zone extended from about 3500 to 4300 m a.s.l. The
rock mass fell onto Kolka Glacier and sheared off most of it. More
than 100 10
6
m
3
of rock and ice avalanched down the
Genaldon valley for 19 km before coming to rest above the
narrow Karmadon gorge. A debris flow continued downvalley
another 15km before stopping 4km above the town of Gisel.
The avalanche and the debris flow devastated the valley and
killed 120 people. The ice-rich debris formed a dam at
Karmadon, impounding several lakes in tributary valleys
with up to 5 10
6
m
3
of water. Potential floods from these
lakes were a threat to downstream areas (Haeberli et al.,
2004), but the lakes emptied non-catastrophically.
The thermal state of the source area was studied by Haeberli
et al. (2003) and Huggel (2009), who concluded that mean
annual air temperatures in the detachment zone were about 5
to 10C, suggesting the presence of cold permafrost. Ten
temperature loggers were installed on rock faces around Kolka
Glacier to monitor seasonal ground temperatures at 10 cm depth.
Preliminary results indicate that the lower limit of permafrost on
the north-northeast face of Dzhimarai-khokh, where the failure
occurred, is ~3000 m a.s.l. and that the temperature range in
the detachment zone is between 3and8C (Huggel, 2009).
Historic climate trends for the region are poorly known, but
the observed rapid retreat of glaciers, which has accelerated
since the mid-1990s, attests to recent warming (Stokes et al.,
2006). Changes in glacier cover on the north-northeast face of
Dzhimarai-khokh are not nearly as well documented as for
Monte Rosa. However, the two large mountain walls are strik-
ingly similar, and the assumption that hanging glaciers in the
Caucasus have undergone comparable changes to those in
the Alps is not unreasonable. A large loss of glacier ice would
have changed temperature and stress regimes in the underlying
bedrock. Thermal modeling has shown that ice may have a
deep warming effect on bedrock through latent heat dissipation
due to freezing of meltwater, reaching instability when tem-
peratures approach the melting point (Huggel et al., 2008a;
Huggel, 2009). The currently still-limited understanding of the
mechanics of failure and entrainment of Kolka Glacier warrant
future research (Haeberli et al., 2004; Kotlyakov et al., 2004;
Evans et al., 2009).
Mount Steele, Canada
A large rock-ice avalanche occurred within a steep gully system
on the precipitous north face of Mount Steele (5067 m a.s.l.),
southwest Yukon Territory, Canada, on July 24, 2007 (Figure 4;
Lipovsky et al., 2008). Two days before this event a large (~ 3
million m
3
) ice avalanche occurred on the same slope. The
leading edge of the ice avalanche traveled across Steele Glacier
below the gully, up a 275-m-high rock ridge, and then down
onto another glacier below. The total horizontal travel distance
is about 8 km. The July 24 event involved several tens of
millions of cubic meters of ice and rock. The headscarp is about
540 m wide and exposes a wall of glacier ice ~70 m thick. The
failed material accelerated down a 44slope from about 4600
to 2800 m a.s.l., before running onto Steele Glacier. The debris
descended up to 2160 m and traveled a maximum horizontal
distance of almost 6 km, leaving a deposit about 37km
2
in area
on the glacier. In the distal part of its travel path, the landslide
reached, but did not overtop, the ridge crested by the earlier
ice avalanche. Some of the debris at the northwest edge of the
deposit and much of the debris that climbed the ridge slid back-
wards on reverse slopes after reaching its limits of travel.
The seismic magnitude estimated from long-period surface
waves (M
s
)is52. Modeling of the waveforms suggests an esti-
mated duration of approximately 100 seconds and an average
velocity of between 35 and 65 m s
1
(Lipovsky et al., 2008).
This landslide is one of 18 large rock avalanches known to
have occurred since 1899 on slopes adjacent to glaciers in
western Canada.
Based on long-term (19712000) temperature data from
Burwash Landing, located at 807 m a.s.l. 76 km northeast of
Mount Steele, and a lapse rate of 065C/100 m, mean annual
air temperatures at the Mount Steele detachment zone
(~ 30004650 m a.s.l.) are estimated to range between 18 to
29C. Such temperatures indicate cold ice, possibly with a
zone of recrystallization and infiltration during summer, espe-
cially in the lower part.
The Burwash Landing temperature record furthermore indi-
cates an increase of mean temperature of 065C per decade
over the past 40 years (19662007), amounting to as much as
26C in total (Figure 5). For 10 days prior to the landslide, daily
maximum temperatures were about 3C above the 19712000
July monthly average maximum temperature. The average daily
temperature for the month of July was ~2C higher than
Figure 3. Significant changes in the Monte Rosa east face between
1985 (background) and 2004 (photo insets). Areas demarcated by the
dotted and full line arrows indicate, respectively, the failure zones of
the 2005 and 2007 avalanches. The area enclosed by the dashed line
is a zone that became completely de-glaciated between 1985 and
2004. The ellipse at the toe of Monte Rosa on Belvedere Glacier is
the location of a supra-glacial lake that formed in 2002 and generated
a non-catastrophic outburst in 2003 (as a reference for scale, the diam-
eter of the lake is approximately 500 m). (Photographs courtesy of J.
Alean and L. Fischer.)
81CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
normal, suggesting that maximum daily air temperatures were
between 3C and 75C, respectively, for the upper and lower
ends of the detachment zone (Figure 6). We find that, although
the upper part of the source zone remained a few degrees
below freezing, the lower part was above freezing for several
days before failure. Photographs taken shortly after the event
appear to show frozen water on the rupture surface (Figure 4),
raising the possibility that sensible heat, solar radiation, or
geothermal heat was sufficient to produce free water. However,
the possible role of long-term climate change and short-term air
temperature variations on the slope failure remains to be
studied in more detail.
Debris Flows in Peri-glacial Environments
Debris flows are common processes and hazards in mountains
(Chiarle et al., 2007). Most debris flows are triggered by pro-
longed or intense rainfall, in some cases with snowmelt (Jakob
and Hungr, 2005), or by catastrophic drainage of naturally
dammed lakes (Clague and Evans, 2000; Korup and Tweed,
2007). Other triggers include alluvial bulking of debris along
steep stream courses and erosion of debris cones on steep rock
slopes (Rickenmann and Zimmermann, 1993). In recent
decades, glacier retreat due to atmospheric warming has ex-
posed large amounts of poorly consolidated sediment prone
to slope failure and debris flows. Some of the largest debris
flows in the Alps in recent years have had sources in newly
de-glaciated areas (Zimmermann and Haeberli, 1992; Chiarle
et al., 2007; Scheuner et al., 2009). There and elsewhere, large
debris flows have occurred when glacier- and moraine-dammed
lakes suddenly drained (Haeberli, 1983, 2008; Grove, 1987;
Evans and Clague, 1994; Clague and Evans, 2000; Richardson
and Reynolds, 2000; Korup and Tweed, 2007).
There are two basic approaches to predicting rainfall-triggered
landslides. The first involves physically based models that simu-
late the physical processes that are relevant to landslide initiation
in order to determine landslide occurrence in space and time
(Montgomery and Dietrich, 1994; Iverson, 2000; Crosta and
Frattini, 2003). The second approach uses empirical models that
statistically relate rainfall measurements, such as intensity and
duration, to documented landslide events (Wieczorek and
Glade, 2005; Guzzetti et al., 2007). Several landslide-triggering
precipitation thresholds have been developed for mountain
ranges in Europe and North America (Zimmermann et al.,
1997; Marchi et al., 2002; Jakob and Weatherly, 2003).
There is not yet clear evidence for an increase in the frequency
or magnitude of debris flows in peri-glacial areas during recent
decades, which precludes an unambiguous attribution to climate
change. However, extreme rainfall events, which are common
Figure 4. The 2007 ice and rock avalanche, Mount Steele, Yukon, Canada. Left: Overview of the landslide scar and landslide material deposited on
Steele Glacier. Dashed lines indicate the upper and lower end of the detachment zones at 4650 m and 3000m a.s.l., respectively. The arrow points to
the location of the enlarged image at the right hand. Right: Close-up of the failure zone in bedrock and glacier ice. There is evidence of seepage sur-
facing at the icebedrock interface of the failure zone. (Photographs taken on August 2, 2007, by P. Lipovsky.)
1967 1977 1987 1997 2007
-50
-40
-30
-20
-10
0
10°C
Mt. Meager, 1800 m asl
Mt. Steele, 3000 m asl
Mean annual air temperature
Figure 5. Mean annual air temperatures extrapolated to the lower end
of the landslide detachment zones at Mount Meager and Mount Steele.
Data were extrapolated from the Whistler meteorological station at
657 m a.s.l., 70km southeast of Mount Meager, and the Burwash Land-
ing meteorological station at 807 m a.s.l., 76 km northeast of Mount
Steele, using a lapse rate of 065C/100 m. Linear trends show warming
of 225C (19772007) and 26C (19672007) for Mount Meager and
Mount Steele, respectively.
-30 -20 -10 0 days
-20
-10
0
10
20
30°C
Mt. Meager, 1800 m asl
Mt. Meager, 2400 m asl
Mt. Steele, 3000 m asl
Mt. Steele, 4650 m asl
Air temperature
Figure 6. Extrapolated air temperature records for the 30 days prior to
the Mount Meager and Mount Steele landslides, for the upper and
lower ends of the detachment zones. Temperatures were extrapolated
as described for Figure 5.
82 C. HUGGEL, J. J. CLAGUE AND O. KORUP
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
debris flow triggers, have increased in many regions of the world
over the past several decades (Trenberth et al., 2007). Although
projections differ depending on the climate model used and the
specific region of interest (Kysel`y and Beranová, 2009), heavy
precipitation events are generally forecast to increase in the
twenty-first century (Meehl et al., 2007). Beniston (2006), for
example, forecasts a shift of precipitation extremes to spring
and autumn in the Swiss Alps by 2100. Other models, however,
show an increase in extreme precipitation events in winter (Frei
et al., 2006). These projections carry implications for debris flow
activity, but factors other than precipitation may also affect debris
flow frequency and magnitude. Sediment supply, for example,
may be equally important, as case studies in the Valais, Swiss
Alps, have shown (Rebetez et al., 1997; Lugon and Stoffel, 2010).
Few researchers have examined the effect of future changes
in precipitation on landslide activity. Jakob and Lambert
(2009) forecast an increase in total monthly rainfall in coastal
British Columbia by the end of the twenty-first century, with a
likely corresponding increase in landslides. Other researchers
have linked downscaled climate model output to slope stability
models [Buma (2000) and Malet et al. (2007) for the French Alps;
Dehn et al. (2000) for the Italian Alps; Collison et al.(2000)for
southeast England; and Crozier (2010) for New Zealand].
Bathurst et al. (2005) used scenario runs of the Hadley Center
global circulation model HadRM3 for 20702099 as input to a
physically based model to assess changes in landslide activity
at a site in the Italian Alps. They found slightly reduced debris
flow activity in a warmer drier climate.
Rotlaui-Guttannen, Swiss Alps
On August 28, 2005, following a period of intensive rainfall, a
large debris flow occurred in the upper Aare valley and crossed
the main Grimsel highway close to the village of Guttannen.
Damming of the Aare River by debris flow deposits and
subsequent overflow and flooding of the village caused major
damage and closed the highway. The debris flow initiated at
~2400 m a.s.l. in an area of glacial sediment that had been
exposed by recession of Homad Glacier during the past several
decades (Figure 7).
The Rotlaui-Guttannen event is typical of large debris flows
sourced in de-glaciated areas with large reservoirs of glacial sedi-
ment (Zimmermann and Haeberli, 1992; Rickenmann and
Zimmermann, 1993). With a total volume of ~ 500,000 m
3
,itis
the largest debris flow in the Swiss Alps over the past two decades.
Permafrost that existed in its source sediments promoted rapid sur-
face runoff (Scheuner et al., 2009). The snowline was high
(over 3000 m a.s.l.) during the days of heaviest rainfall, thus all
precipitation in the catchment was rain, of which about 170 mm
were recorded in 48 hours between August 21 and 22, 2005
(Scheuner et al., 2009). One remarkable aspect of the Rotlaui-
Guttannen event is that it entrained more than half of the total
flow volume (~ 300 000 m
3
) along its path as it crossed and
eroded a Holocene debris fan (Figure 8). Debris-flow bulking
of a similar magnitude has rarely been documented. Yet, large
debris flows that originate in glacier forefields during heavy
rainfall may entrain large quantities of sediment along their
paths, even on fans or other relatively low-gradient surfaces if
critical erosion thresholds are exceeded. Debris flow volumes
and hazard can be greatly increased under these circumstances
(Huggel et al., 2011).
Salcantay, Peru
Instability induced by recent glacier retreat and exposure of un-
stable glacial sediment is illustrated by a large landslide on
Nevado Salcantay (6264 m a.s.l.), about 20 km south of Machu
Picchu, Peru, in 1998. On February 27, during the rainy sea-
son, a slope with a large volume of unconsolidated sediment
failed in the Quebrada Rayancancha, on the north slope of
Nevado Salcantay, forming a debris flow with a volume of
~25 10
6
m
3
. The landslide scar was 1 km wide and 1 km
long, and was located between 3950 and ~4200 m a.s.l.
(Figure 9). The debris flow traveled along the Ahobamba valley,
reaching up to 60 m on the valley sides and scouring the stream
bed to a depth of ~30 m (Huggel et al., 2004b). Upon reaching
Vilcanota River, the debris flow dammed it to a height of 70 m.
A hydroelectric power plant was flooded and covered with fine
alluvium, causing damages of about 100 million US dollars.
The Salcantay landslide is extremely large by Alpine standards
about two orders of magnitude larger than otherwise similar
events in the European Alps (Rickenmann and Zimmermann,
1993; Zimmermann et al., 1997; Scheuner et al., 2009).
Extrapolation of mean annual air temperatures from regional
climate stations at elevations of 2500 to 3500 m a.s.l. suggests
that permafrost is absent at the elevation of the source area.
Persistently high temperatures during several weeks prior to
the event may have contributed large amounts of melt water
from snow and ice on the surrounding mountain flanks, saturat-
ing soils in the source area (Figure 10). Likely more important,
however, was the saturation of sediment by persistent anteced-
ent rainfall. We used ground- and satellite-based rainfall mea-
surements to reconstruct the precipitation record in the
remote area where the landslide initiated (Figure 10), based
on the Tropical Rainfall Measurement Mission (TRMM)
Multi-satellite Precipitation Analysis (TMPA), available at
025grid spatial and three-hourly resolution (Huffman et al.,
2007). The rainfall data, analyzed and integrated over the four
closest 025tiles, show that several days of intense rainfall pre-
ceded the landslide. Cumulative rainfall of the 40 days prior to
the event amounted to 170 mm, likely implying soil saturation.
Recent studies evaluating the performance of TRMM in the
same Andean region have shown that correlation between
TRMM-TMPA and ground rainfall gauge stations increases over
longer periods of time, with a correlation of about 08 for
seven-day periods (Scheel et al., 2010). For the Salcantay land-
slide, but for many other cases as well, cumulative rainfall is
therefore a more reliable measure than rainfall intensity, espe-
cially when using TRMM data (Figure 10). On a more general
level, the Salcantay event demonstrates the importance of both
precipitation and temperature for triggering large landslides in
high mountains since high temperatures and large precipitation
amounts together imply runoff generation and soil saturation up
to high elevations. Although the unusual amount of rainfall and
high air temperatures at Salcantay reflect climate variability, the
relation of this case to climate change is primarily through the
effects of long-term glacier retreat that exposed large amounts
of unconsolidated sediment to erosion.
Process Coupling Among Landslides, Glaciers,
and Rivers
Dynamic interactions among landslides and glacial and river pro-
cesses in high mountains include: (i) outburst floods from
glacier- and moraine-dammed lakes that have formed in
response to recent glacier thinning and retreat; (ii) slope failures
in rock, ice, or moraines that impact glacial lakes, causing out-
burst floods; (iii) damming of rivers by landslides, resulting in po-
tentially unstable dams that may fail within hours, days, months,
or years; (iv) deposition of landslide debris in channels of rivers or
torrents, altering debris flow magnitude and frequency.
83CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
Many lakes dammed by ice and unstable moraines have
formed in recent decades in high mountains around the world
(Ames, 1998; Gardelle et al., 2011), as glaciers retreated and
downwasted at rates of up to 510 m yr
1
(Schiefer et al., 2007;
Paul and Haeberli, 2008). Many of these lakes have drained sud-
denly, producing huge downstream floods (Clague and Evans,
2000; Richardson and Reynolds, 2000). Others are bordered by
slopes that show signs of instability and might fail. Landslides that
enter these lakes or artificial reservoirs could generate displace-
ment waves that overtop the dams. In April 2010, an icerock av-
alanche from the flanks of Hualcán (~5400 m a.s.l.) in the
Cordillera Blanca in Peru generated a massive impact wave in a
glacier lake; the wave overtopped the bedrock dam and flooded
downstream communities (Carey et al., In Press). Similar cases
are also known from other mountain regions (Clague and Evans,
2000; Huggel et al., 2004a; Kershaw et al., 2005).
Landslides can interact with river processes by forming
short- or long-lived dams in valleys. Water impounded behind
these dams poses significant flood hazards for downstream
populations and infrastructure. An extensive literature exists
on processes, hazards, remedial measures, and landslide
dam case studies (Costa and Schuster, 1988; Korup and
Tweed, 2007). Landslides can also alter the sediment budget
of rivers (Hewitt et al., 2008) and steep mountain torrents. Be-
cause sediment supply is an important control on debris flow
magnitude and frequency (Lugon and Stoffel, 2010), both
Figure 7. Area of initiation of the 2005 Rotlaui-Guttannen debris flow. The white line delineates the lower margin of a frozen body of glacial sed-
iment. Remnants of Homaf Glacier are visible at the foot of the rock face at the right side of the photograph. The glacier formerly extended to the white
line and left large amounts of sediment during its retreat. The sediment probably only became permanently frozen after retreat of the glacier. The ar-
row indicates the direction of debris flow propagation.
Figure 8. Cascades of landslide processes at Ritzlihorn-Guttannen, central Swiss Alps: black curved lines on the northeast flank of Ritzlihorn indi-
cate rockfall source areas from frozen bedrock. The trapezoid marks the area where rockfall debris and avalanche snow accumulates, and debris
flows initiate and propagate along the Spreitlaui channel to run out to the Aare River. The inset image on the right highlights the critical risk situation
with the debris flow channel running over (1) the highway gallery, and (2) the transnational gas pipeline. Also shown on the main image is the runout
zone of the 2005 Rotlaui-Guttannen debris flow, with the inset indicating a heavily eroded channel cross-section along the debris fan. (Photograph by
C. Huggel and image by GoogleEarth.)
84 C. HUGGEL, J. J. CLAGUE AND O. KORUP
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
slowly and rapidly moving mass movements can change
debris flow hazards over many years.
The following case studies refer to the aforementioned inter-
actions and serve as examples of what is likely to occur in the
future with continued warming.
Ritzlihorn-Guttannen, Swiss Alps
Repeated rock falls began to occur in 2009 from the northeast
face of Ritzlihorn (3263 m a.s.l.), ~2km northwest of the
Rotlaui-Guttannen event described earlier (Figures 7 and 8).
The rock face consists of strongly shattered and weathered gneiss,
and its upper part is frozen (permafrost). Many couloirs carry wa-
ter, possibly derived from thawing permafrost. Further field obser-
vations provide evidence of frozen bodies of shattered rock that
have become increasingly unstable and are the source of the rock
falls (D. Tobler, personal communication, 2011). Blocky debris
and avalanched snow accumulate at the apex of the large
Holocene debris fan on which the community of Guttannen is lo-
cated (Figure 8). Some of the accumulated snow persists through
the summer. The debris fan is drained by the Spreitlaui torrent,
which enters Aare River at 940 m a.s.l.. No damaging debris
flows are known to have occurred prior to 2009 (Hählen,
2010), although the morphology and sedimentology of the fan in-
dicate considerable debris flow activity earlier in the Holocene.
In the summer of 2009, debris flows began to occur in the
Spreitlaui torrent. The initiation zone is the apex of the fan,
where rock debris and snow accumulate. Saturation of the sed-
iment by water derived from melting of avalanched snow is
likely an important factor in triggering the debris flows. The
largest debris flows, in July and August 2010, had volumes of
~100 000 m
3
and peak discharges of ~500 m
3
s
1
(Hählen,
2010). The debris flows entrained large amounts of fan sediment
along the Spreitaui channeland obstructed the flowof Aare River.
Just before reaching the river, they passed over a gallery of the
main highway and a transnational gas pipeline. Both structures
were heavily damaged by debris flows in 2009 and 2010; traffic
and transport of gas had to be temporarily suspended (Figure 8).
Field observations indicate that thawing permafrost has
played an important role in the recent rock fall activity.
The accumulated rock debris, in turn, plays a major role
in the generation of debris flows, as illustrated by the histor-
ically unprecedented large events on the Holocene fan in
2009 and 2010. These events illustrate the dynamic interac-
tions between rockfall and debris flow activity at Ritzlihorn.
Figure 9. Left: Scarp of the 1998 landslide on the northern slope of Salcantay (6264 m a.s.l.) in the southern Peruvian Andes. The landslide initiated
in thick glacial sediments. For scale, the black bars indicate the height of a person. Right: Aster satellite image from July 4, 2002 showing the landslide
initiation area (white rectangle) relative to the glaciers of Salcantay (summit at lower right of the image). (Photograph courtesy of Reynolds Geos-
ciences Ltd.)
Figure 10. Rainfall and temperature record for the 40-day period prior to the Salcantay landslide. Locations of tiles for the TRMM satellite rainfall
data are shown on the map at the left. The Carhuasi meteorological station is 30km southwest of the landslide at 2763 m a.s.l. Maximum air tempera-
tures were extrapolated to the top of the landslide failure area at 4000 ma.s.l. The cumulative rainfall record for TRMM tile 3 and an average of all four
TRMM tiles are highly correlated, whereas daily rainfall amounts can differ considerably among TRMM tiles and the ground station.
85CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
More research is currently being conducted to better understand
the implications of permafrost degradation on rock fall activity at
this site. The Ritzlihorn events could be a model case for a major
change in mass-movement frequency and magnitude related to
atmospheric warming. An initial stimulus, in this case an increase
in air temperature and its effect on ground surface temperatures,
may have critically disturbed the system, leading to a process
cascade that evolves independently of climate (see also the
Monte Rosa case earlier). An additional perspective is the
possibility that the Ritzlihorn system displays a threshold or
tipping-point behavior, with changes in permafrost likely being
at the head of a chain of subsequent landslide processes.
Lower Grindelwald Glacier, Swiss Alps
Changes in Lower Grindelwald Glacier have been well docu-
mented since at least the mid-nineteenth century, when tourism
started to become popular in the Alps. Since it achieved its
maximum Little Ice Age extent around 1860, the glacier has
retreated ~2 km (Zumbühl et al., 2008). The terminal area of
the glacier downwasted 60 m to >80 m between 1985 and
2000 (Paul and Haeberli, 2008). The glacier presently termi-
nates at the upper end of a gorge in a glacially overdeepened
trough flanked by steep rock slopes.
In recent years, the steep rock slopes near the snout of the
glacier have shown signs of instability that probably are related
to glacier downwasting and permafrost degradation. In 2006,
210
6
m
3
of rock at the toe of the east flank of the Eiger, at
the entrance of the glacial gorge (Figure 11), became unstable
(Oppikofer et al., 2008). The rock slope spectacularly collapsed
later that year and still remains unstable. About the same time,
a glacial lake started to form in the trough at the terminus of
the glacier. Since 2005, the lake has grown, achieving volumes
of ~024 10
6
m
3
in 2007, ~1310
6
m
3
in 2008, and
~2610
6
m
3
in 2009 (Werder et al., 2010). The lake is
dammed by rock debris emplaced by the 2006 and more recent
landslides and by stagnant glacier ice. In late May 2008,
~0810
6
m
3
of water suddenly drained from the lake, with a
peak discharge of 110 m
3
s
1
. Like the face of the Eiger, the mo-
raine at the northeast margin of the glacial lake has been destabi-
lized by glacier downwasting in recent years. This instability
culminated in a ~0710
6
m
3
failure of the proximal flank of
the moraine in 2005. Additional moraine failures in 2009 gener-
ated impact waves in the lake, but did not cause an outburst flood.
Rockfalls started to occur on the Mättenberg, northeast of the
glacier terminus, in 2000. The source area is located between
2500 and 3000 m a.s.l., likely in warm degrading permafrost
(Städelin, 2008). The accumulating rock debris is periodically
evacuated by large erosive debris flows; ~0710
6
m
3
of sedi-
ment was eroded from the debris cone between 2000 and 2005
(Städelin, 2008). Many of these debris flows reached the lake.
The lake is also vulnerable to impacts by ice avalanches from
steep snouts of Challifirn and Fiescher Glacier. To date, ice
avalanches from Challifirm have been restricted mainly to the
glacial gorge and the dam impounding the lake, and those from
Fiescher Glacier have come to rest before reaching the lake.
Less favorable scenarios, however, are possible.
Lower Grindelwald Glacier is likely to continue to retreat, with
a potential for significant enlargement of the lake. In late 2009,
authorities completed the construction of a drainage tunnel more
than 2 km long to lower the level of the lake and reduce the
danger of outburst floods to people and property in the corridor
between Grindelwald and Interlaken, 25 to 20 km downstream.
The coupling of hazardous processes around Lower
Grindelwald Glacier is remarkable. Yet it remains to be seen
whether the Grindelwald situation is representative or an
exceptional case of landscape instability in de-glacierizing
high-mountain areas. The experience at Grindelwald has
nevertheless shown that hazard assessments are consider-
ably complicated where multiple processes operate and
interact.
Mount Meager, Canada
One of the largest historic landslides in western Canada
occurred at Mount Meager in southwest British Columbia on
August 6, 2010. Approximately 48 10
6
m
3
of highly fractured
and weathered, Pleistocene volcanic rocks detached from the
southwest flank of the mountain between about 1800 and
2400 m a.s.l. (Figure 12). The detached rock mass, which
contained large amounts of water, rapidly fragmented as it im-
pacted the base of the mountain slope in the headwaters of
Capricorn Creek, a steep tributary of Meager Creek. The im-
pact, however, was sufficient to trigger seismic waves that were
recorded by seismographs up to hundreds of kilometers from
the source. As it struck the base of the steep mountain slope,
the landslide transformed into a debris flow that traveled 7 km
down Capricorn Creek at an average speed of 60 m s
1
to
Meager Creek. The debris flow dramatically super-elevated at
bends along this part of its path. It then entered the valley of
Meager Creek and climbed 270 m up the northwest-facing wall
of that valley. There it bifurcated into two lobes: one lobe ran
nearly 4 km to the southwest up Meager Creek valley, and the
other traveled northeast down Meager Creek to Lillooet River,
about 12 km from the source. Landslide debris blocked Meager
Creek at the mouth of Capricorn Creek for about 19 hours,
impounding a lake that reached up to 15 km long. Debris in
Lillooet River valley stemmed the flow of Lillooet River for
about two hours. Concern over a possible outburst flood from
the lake in the valley of Meager Creek led to the evacuation
of 1500 people in the town of Pemberton.
The landslide is the third large landslide in the Capricorn
Creek watershed since 1998 and the fifth such event in the
Meager Creek watershed since 1930 (Jordan, 1987). Landslides
at the head of Capricorn Creek in 1998 and 2009 were sourced
in a colluvial apron near the toe of the 2010 failure and may
Figure 11. Interacting slope instability processes at Lower Grindelwald
Glacier. (1) Rock slope failure at Schlossplatte, at the head of gorge.
(2) Frequent rock falls from warm permafrost areas of Mättenberg.
(3) Debris flows along ravines cut into the debris fan/moraine complex.
(4) Lateral moraine slope failures. (5) Ice avalanches from Challifirn and
Fiescher Glacier/Heissi Platte. (6) Glacier lake at terminus of Lower
Grindelwald Glacier. (7) Outburst flood from the glacier lake. This area
shows the complex interaction of processes that are closely linked to gla-
cier retreat and downwasting and to permafrost degradation. Background
image is from 1997 (Google Earth).
86 C. HUGGEL, J. J. CLAGUE AND O. KORUP
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
have destabilized the rock slope above. The 1998 and 2009
landslides were large (>10
6
m
3
) debris flows; the former, like
the much larger 2010 landslide, blocked Meager Creek and
impounded a short-lived lake (Bovis and Jakob, 2000).
Many of the landslides in the watershed, including those in
Capricorn Creek, have occurred on slopes that were buttressed
by glacier ice during the Little Ice Age (Holm et al., 2004).
Glaciers on Mount Meager have downwasted and retreated over
the past century, removing lateral support from slopes that since
have failed. Records of mean annual temperatures of climate sta-
tions in the region (Whistler, 650 m a.s.l.) show a warming of
2.3C over the past three decades (Figure 5). Based on relations
between rock and air temperature in the Alps and New Zealand
(Gruber et al., 2004b; Allen et al., 2009), we suggest that warm
permafrost (0 to 2C) existed in the upper detachment zone of
Mount Meager. Permafrost degradation due to strong decadal
warming is likely and may have reduced the shear strength of
the rock and facilitating accumulation of water in cracks, with
concomitant local elevation of pore pressures.
It is furthermore interesting to note that all large historic
landslides in the Meager Creek watershed occurred during or
following spells of warm weather in summer. During the weeks
prior to the August 6, 2010 landslide, air temperatures reached
as high as about 20C at the top of the south-facing failure zone
(Figure 6). Snow and ice melt caused hydrostatic pressure and
stress changes, and rapid thaw may have occurred along rock
joints; both may have played a role in triggering the landslide.
A more integrative perspective, however, needs to consider
decadal to millennium-scale glacier retreat, poor volcanic rock
strength, recent permafrost degradation, and brief warm events
as factors reducing the stability of slopes at Mount Meager.
Discussion and Conclusions
Research into the detection of changes in landslide activity
over the past several decades of observed atmospheric warm-
ing and identification of factors that control climate-driven
changes in landslide magnitude and frequency is still limited.
There is still no unambiguous evidence that the frequency or
the magnitude of landslides has changed over this period. Even
in Switzerland, which has a relatively complete database of
mass movements, no statistically significant trend is evident in
the occurrence of all types of landslides or their damage (Hilker
et al., 2009). However, for large rock slope failures (>10
5
m
3
)
in the Swiss Alps and neighboring areas, the frequency is higher
during the past two decades than earlier during the twentieth
century (Fischer et al., 2010). The same trend has been found
for small to medium rock falls in the Mont Blanc area (Ravanel
and Deline, 2011).
Rather than seeking evidence of changes in landslide
magnitude and frequency, some researchers have examined
changes in impacts of landslides. For example, Petley (2010)
concludes that in south, east, and southeast Asia both summer
monsoon and tropical cyclones are important climatic triggers
of landslides, although population growth is driving increases in
damaging and fatal landslides. He argues that future socio-
economic development will have a more important effect
on landslide-related losses than climate change. These find-
ings support a larger body of research in other fields of nat-
ural hazards that attributes the increasing losses due to
floods, hurricanes, cyclones, and windstorms primarily to
societal change and economic development (Pielke et al.,
2008). Most of this research uses a normalization approach
to adjust for economic and societal change in order to iden-
tify a possible climatic signal (Bouwer et al., 2007; Barredo,
2009, 2010).
In the case of landslides, more instructive evidence comes from
case studies and field observations, which is the approach we took
in this paper, with a summary, put into context of additional recent
events, provided in Table I. It is striking that in recent years several
events have occurred in the central Alps without historical prece-
dence, for example the Ritzlihorn and Rotlaui debris flows in
Guttannen and the slope failures at Monte Rosa. Recent changes
in the source slopes related to glacier thinning and retreat, and
also likely to permafrost degradation, may have caused these
events. The frequent large landslides at Mount Meager during
the twentieth and twenty-first centuries are also likely related to
effects of glacier retreat and permafrost degradation.
Another important aspect of emerging instability events is the
complex interplay among different landslide processes, and
among landslide and river processes. Massive loss of glacier
ice on the Monte Rosa east face over the past several decades
and attendant changes in permafrost destabilized large parts
of the mountain face and initiated a cascade of slope failures
in the 1990s and 2000s. The 2010 landslide at Mount Meager
strongly affected Meager Creek and Lillooet River through dam-
ming the two streams and introducing large amounts of sedi-
ment that are being transported downstream into populated
areas, possibly increasing flood hazards. The Kolka-Karmadon
icerock avalanche obliterated fluvial processes through long-
term river damming and changes in sediment supply. Recent
changes in the northeast flank of Ritzlihorn induced rock fall ac-
tivity that triggered previously unrecorded debris flow activity on
Figure 12. Failure zone of the Mount Meager landslide a few days after the event. The limit of the landslide scar is marked with a thick black line,
which extends down to the surface of Capricorn Glacier (left image). A close-up of the failure zone (corresponding to the square in the left image) is
shown on the right. Note that water is surfacing at several bedrock fractures.
87CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
the fan at the base of the slope. Historically unprecedented land-
slide activity, however, may not necessarily be an indicator of cli-
matically induced changes in slope stability; it could relate to
natural variability. This possibility must be considered, given that
the observation period is short compared to the return period of
large landslides. For instance, the slope morphology at Mount
Steele hints at a recurrence of slope failures in rock and ice, al-
though the remoteness of the area precludes a reliable historical
record. Static fatigue in the underlying bedrock, with stress
changes caused by periodic loading by accumulating firn and
ice, may exert an important control on slope instability, but we
cannot exclude the possibility that strong decadal warming and
related effects contributed to the 2007 avalanche. In this context,
it should be noted that topography and geology, including rock
mass strength (Moore et al., 2009) or structural characteristics
(Reid et al., 2000; Wyllie and Mah, 2004) remain key controls
on slope failures.
The case studies presented here raise the question of whether
there are tipping points in geomorphic systems related to climatic
change. Some researchers in climate science have argued that
warming above certain thresholds can trigger a sudden shift to a
contrasting dynamical regime. Examples include disruption of
thermohaline circulation, complete melting of the Greenland
ice sheet, or dieback of the Amazon rainforest (Schneider et al.,
2007; Kriegler et al., 2009). Recent research on tipping points
and reasons for concern that have been published since release
of the IPCC Forth Assessment Report in 2007 and that are partly
based on new evidence from paleo-climatic records have low-
ered the threshold of critical temperature increase (Füssel, 2009;
Kriegler et al., 2009; Smith et al., 2009).
Non-linear threshold behavior has been observed in a num-
ber of geomorphic processes, including sediment entrainment
and deposition (Phillips, 2003). Exceedance of such erosion
thresholds may be recorded in the case of the extraordinary
debris flow at Rotlaui-Guttannen in 2005, which was erosive
enough to entrain large amounts of sediment on the Holocene
debris fan (Huggel et al., 2011).
However, sediments exposed by recent glacier retreat may
remain in place for several decades or more before being
mobilized by landslides or debris flows (Figure 2). This important
lag effect has been observed in many events in high mountains in
recent times (Rickenmann and Zimmermann, 1993; Chiarle
et al., 2007; Keiler et al., 2010).
In summary, we identify the following mechanisms by which
climate change can affect landslide activity in high mountains:
(1) positive feedbacks acting on mass movement processes that
can be reinforced after a climatic stimulus independently of
climate change (Monte Rosa, Kolka, Ritzlihorn-Guttannen,
Lower Grindelwald Glacier); (2) threshold behavior and tipping
points in geomorphic systems (Ritzlihorn-Guttannen, Rotlaui-
Guttannen); (3) storage of sediment and ice involving important
lag-time effects (Salcantay, Rotlaui-Guttannen, Mount Meager,
Mount Steele).
AcknowledgmentsThis work benefited from discussions and colla-
borations with Stephan Gruber, Luzia Fischer, Wilfried Haeberli,
Andreas Kääb, Jeannette Noetzli, Andreas Hasler, Demian Schneider,
Patrick Städelin, Daniel Tobler, Brian McArdell, Thomas Scheuner,
John Reynolds, and several other colleagues. We much appreciate the
support of Marlene Scheel and Mario Rohrer for TRMM data and Panya
Lipovsky, Andy Heald, Luzia Fischer and Jürg Alean for photographs.
The authors are also grateful for support provided by Fichtner, GmbH
& Co. KG, EGEMSA S.A, and the Swiss Agency for Development and
Cooperation. Climate data from Environment Canada, US National
Oceanic and Atmospheric Administration (NOAA), the Peruvian Na-
tional Meteorological and Hydrological Service (SENAMHI), and the
Swiss Federal Office of Meterology and Climatology (MeteoSwiss) are
also acknowledged. Finally the authors would like to thank two
anonymous reviewers and the editors for their very constructive and
useful comments that helped to improve the manuscript.
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91CLIMATE CHANGE AND LANDSLIDES IN HIGH MOUNTAINS
Copyright © 2011 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms, Vol. 37,7791 (2012)
... Among the climatically driven processes responsible for landslide initiation are permafrost degradation (Schneider et al., 2014;Coe et al., 2018), mountain glacier recession and thinning (Kos et al., 2016;Dussaillant et al., 2019;Emmer et al., 2020a), as well as effects of stress redistribution within the slopes due to the repeated cycle of loading and unloading (e.g., Hugenholtz et al., 2008;McColl, 2012). A complex interplay between passive settings (e.g., morphological, geological and structural) and climatically driven glacier development (Holm et al., 2004;Klimeš et al., 2021) has been described to result in a non-linear relationship between slope and climate-glacier systems (Holm et al., 2004;Huggel et al., 2012). ...
... The above described warming trends (including predictions of increasing number of heat waves) and altitudinal increase of the 0 °C isotherm will most likely result in warmer conditions enhancing permafrost degradation and resulting in increased number of landslides initiated from the high glaciated ridges. Such a trend has been observed in alpine environments around the world (Fischer et al., 2012;Huggel et al., 2012) and the 2010 rock-ice fall from Mt. Hualcán (with the source area at approximately 5400 m a.s.l.; Carey et al., 2012; represents a type of landslide which may occur more frequently in the future. At the same time, it is necessary to consider snow and ice melt from retreating glaciers in the upper parts of mountain ridges as sources of water recharge for the lower portions of the slopes. ...
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Landslides are among the major landscape forming processes in mountain regions like the Cordillera Blanca in the Ancash region, Peru. They include a wide variety of types with specific movement dynamics ranging from slow-moving landslides to debris flows and extremely rapid ice-rock avalanches. They are commonly triggered by extreme precipitation and temperature driven processes. Climatological analyses in the Cordillera Blanca suggest a warming trend in the 20 th and early 21 st centuries, resulting in accelerated glacier ice loss that alters the slope stability conditions. Regardless of the scenario considered, climate predictions agree on the continuation of warming, which may be especially profound in the highest altitudes (> 5000 m a.s.l.). Besides the climate-driven landslides, historical earthquakes triggered a large number of landslides, ranking among the most frequent landslide trigger in the region. In addition, the seismic effects on rocks may set more favorable preconditions for future landslides. However, the predictability of a strong earthquake occurrence is limited. Under such complex natural conditions and landslide hazard drivers, it is important to keep in mind that future landslide risk could also be managed by lowering exposure and vulnerability of possibly affected communities. Mitigation of these risk components entirely depends on our (i.e., human) decisions. Therefore, our contemporary decisions will largely determine future landslide risk, which underlines our responsibility for future landslide disaster occurrence.
... This is because the marine glaciers (snow) facing south rapidly melt due to stronger solar radiation, resulting in frequent landslide occurrences in Nyingchi. The result is consistent with the literature [55]. With the slope increasing, the frequency ratio increased, reaching a maximum value of 2.67 in the class 38-50 • . ...
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Landslides are common geological hazards worldwide, posing significant threats to both the environment and human lives. The preparation of a landslides susceptibility map is a major method to address the challenge related to sustainability. The study area, Nyingchi, is located in the southeastern region of the Qinghai-Tibet plateau, characterized by diverse terrain and complex geological formations. In this study, CNN was used to extract high-order features from the influencing factors, while BiLSTM was utilized to mine the historical data. Additionally, the attention mechanism was added to adjust the model weights dynamically. We constructed a hybrid CNN–BiLSTM-AM model to assess landslide susceptibility. A spatial database of 949 landslides was established using remote sensing images and field surveys. The effects of various feature selection methods were analyzed, and model performance was compared to that of six advanced models. The results show that the proposed model achieved a high prediction accuracy of 90.12% and exhibits strong generalization capabilities over large areas. It should be noted, however, that the influence of feature selection methods on model performance remains uncertain under complex conditions and is affected by multiple mechanisms.
... Although these landslides are visible in optical images, there has been relatively limited research on them. Through in-depth analysis of these large and giant landslides, we can gain a more comprehensive understanding of the impact of geological processes, climate change, and other factors on landscape evolution (Huggel et al., 2012;Korup et al., 2010). The landslide inventory provided in this study serves as foundational data for researchers, facilitating further investigation into landslide studies in the Qinling Mountains and providing a scientific basis for exploration in related fields. ...
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The Qinling Mountains in China frequently experience geological disasters, with large‐scale landslides being particularly prominent, causing severe economic losses to the local area. To gain a comprehensive understanding of the geological disaters distribution in the region, we conducted extensive research on the entire Qinling Mountains, covering an area of approximately 380,000 km². By employing methods such as literature review, data collection, and interpretation of remote sensing images, we have successfully created a database of landslides. The inventory of landslides includes a total of 169,888 large‐scale landslides, covering a combined area of approximately 1575 km². The average size of these landslides is approximately 92,734 m². The scale of these landslides varies widely, with the smallest individual landslide covering an area of 166.25 m² and the largest reaching 12.9 km². Upon examining areas with frequent landslides, it was observed that landslides are usually densely distributed along riverbanks or within valleys. Landslide development is also dense in areas prone to frequent historical earthquakes. This comprehensive database provides essential data to support the analysis of spatial distribution patterns of large‐scale landslides in the Qinling Mountains. It also facilitates landslide assessments and serves as a reference for the prevention and control of landslide disasters in the area.
... The climatic patterns in Asia are the main drivers of landslide occurrence in the region, particularly along the Himalayan arc and in countries such as China, the Philippines, and Indonesia (Petley 2012). While temperature-induced landslides affect many parts of the world, it is widely acknowledged that precipitation has the most pronounced influence on landslides compared to other climate change factors (Dhakal and Sidle 2004;Huggel et al. 2012;Jones et al. 2021;Lewkowicz and Way 2015). ...
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Climate warming is constantly causing hydro-meteorological perturbations, especially in high-altitude mountainous regions, which lead to the occurrences of landslides. The impact of climatic variables (i.e., precipitation and temperature) on the distribution of landslides in the eastern regions of the Himalayas is poorly understood. To address this, the current study analyzes the relationship between the spatial distribution of landslide characteristics and climatic variables from 2013 to 2021. Google Earth Engine (GEE) was employed to make landslide inventories using satellite data. The results show that 2163, 6927, and 9601 landslides were heterogeneously distributed across the study area in 2013, 2017, and 2021, respectively. The maximum annual temperature was positively correlated with the distribution of landslides, whereas precipitation was found to have a non-significant impact on the landslide distribution. Spatially, most of the landslides occurred in areas with maximum annual precipitation ranging from 800 to 1600 mm and maximum annual temperature above 15°C. However, in certain regions, earthquake disruptions marginally affected the occurrence of landslides. Landslides were highly distributed in areas with elevations ranging between 3000 and 5000 m above sea level, and many landslides occurred near the lower permafrost limit and close to glaciers. The latter indicates that temperature change-induced freeze-thaw action influences landslides in the region. Temperature changes have shown a positive correlation with the number of landslides within elevations, indicating that temperature affects their spatial distribution. Various climate projections suggest that the region will experience further warming, which will increase the likelihood of landslides in the future. Thus, it is crucial to enhance ground observation capabilities and climate datasets to effectively monitor and mitigate landslide risks.
... news the same day, the November 27, 2022 landslide around the Damas neighborhood in Yaoundé , the October 29, 2019 landslide of Gouatchié in Bafoussam, the October 20, 2007 landslide in Kekem and the August 24, 2004 landslide in the Abangoh neighborhood in Bamenda, the Kolka event in the Russian Caucasus killed 125 people and the Brenva landslide killed two skiers, the Conchita landslide in California mobilized previous landslide deposits due to intense rainfall, causing 10 deaths and damaging around 30 houses. [1,12,14,15,23]. ...
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This study focuses on the influence of climatic, geological and hydrodynamic factors on slope stability of Kekem located in the Western Highlands of Cameroon. The methodological approach was based on the analysis of three factors: hydrological, geological and assessment of the hydrodynamic parameters influencing the stability of slopes. The hydrological factors indicate an average annual rainfall of 1,763.04 mm, generating 248.59 mm of runoff and around 402.61 mm of infiltrated water. Geologically, the soils have a high angle of friction at all three elevations, from 25.8° at the bottom of the slope to 27.2° at mid-slope and 26.2° at the top. On the other hand, the cohesion of these soils remains low, varying from 0.325 bar at the bottom of the slope to 0.265 bar at the top and 0.225 bar at mid-slope. Permeability analysis yielded values ranging from 1 x 10-9 to 1 x 10-11 m/s, with an overall porosity of around 55%. These conditions, combined with the morphology of the environment, are the main causes of slope instability in the Kekem district.
... Landslides are natural hazards in alpine regions around the world [1][2][3]. Climate change has increased the frequency and amplitude of landslides [4][5][6], endangering mountain people's property and lives and impeding social development [7][8][9]. The task of landslide susceptibility mapping (LSM) is typically assigned to regional landslide risk management and land use planning [10,11]. ...
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Climate change has recently increased the frequency of landslides in alpine areas. Susceptibility mapping is crucial for anticipating and assessing landslide risk. However, traditional methods focus on static environmental variables to emphasize the spatial distribution of landslides, ignoring temporal dynamics in landslide development in the context of climate change. In this work, we focused on static and dynamic environment factors and utilized the certainty factor-logistic regression (CF-LR) model to assess and predict landslide susceptibility in Taxkorgan County, located in the Karakorum. The assessment and prediction were based on a catalog of climate change-related landslides over the past 20 years, the causative factors, and predicted climatic variables for the Shared Socioeconomic Pathways (SSP1-2.6) scenario. The results indicated that elevation, slope, groundwater, slope length gradient (LS) factor, Topographic Wetness Index (TWI), valley depth, and maximum precipitation were the key causes of slides below the snow line. The key factors causing debris flow above the snow line were elevation, slope, topographic relief, aspect, LS factor, distance to the river, and maximum temperature. The accuracy of slide and debris flow susceptibility was 0.92 and 0.89, respectively. The area of slides with medium, high, and very high susceptibility is 25.5% of the Taxkorgan. In addition, 82.6% of the slides happened in this region, and 49.5% of the entire area is covered by debris flows with medium, high, and very high susceptibility. Moreover, this area accounts for 91.8% of all debris flows. Until 2060, the region's climate is anticipated to become warmer and wetter. Slides below the snow line will gradually decrease and shift eastward, and debris flows above the snow line will expand. Our findings will contribute to the management of landslide risks at the regional scale.
... It gains more and more importance and has already become an indispensable part of risk prevention in the Alps and other mountainous regions. Due to climate change and the accompanying more extreme weather conditions, the number of gravitational mass movements like landslides and rockfalls in the Alpine region has increased [1]. In com-bination with growing urbanisation in the mountains, this raises the risk of disastrous events for local communities and infrastructures. ...
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In this paper we propose a monitoring method that allows the inclusion of point clouds into a geodetic monitoring network. Consequently, network adjustment and a rigorous deformation analysis can be performed allowing consistent error propagation and trustful significance calculation. We introduce a supervised pipeline based on ICP-matching of small-scale laser scan patches. It is specially designed for geo-monitoring applications and allows to improve the spatial resolution as well as the network geometry of monitoring networks in inaccessible hazardous areas in the mountains, where the installation of a sufficient number of targets is difficult. We apply our method to two datasets. The first is a monitoring setup in the laboratory, where we establish the parameters for the supervised patch selection and demonstrate how the network geometry is improved. Second is the real case study of Mt. Hochvogel, where the proposed method helps to clearly improve the spatial resolution of deformation vectors.
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Debris-flow activity in the Alps is anticipated to undergo pronounced changes in response to a warming climate. Yet, a fundamental challenge in comprehensively assessing changes in process activity is the systematic lack of long-term observational debris-flow records. Here, we reconstruct the longest, continuous time series (1626-2020) of debris flows at Multetta, a supply-limited torrential system in the Eastern Swiss Alps. Relying on growth-ring records of trees that were damaged by debris flows, we do not detect significant changes in the frequency or magnitude over time. This seeming absence of a direct climatic influence on debris-flow initiation aligns with the regular distribution of repose time patterns, indicating a dependence of local process activity on sediment discharge and recharge. This stark difference in process behavior between our supply-limited site and transport-limited catchments has implications for assessing torrential hazard and risk mitigation in a context of global warming.
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Data on temperature and accumulation of high altitude firn in the Alps are compiled and discussed. Firn temperature varies with incoming radiation (slope aspect) at a given altitude. The altitudinal gradient of temperature in highly permeable firn bodies appears to be about twice as high as the mean lapse rate of air temperature. “Cold infiltration” takes place above about 3500 m a.s.l. Firn temperatures on the highest peaks are around -15°C. Accumulation (net balance) also decreases with increasing altitude from about 3m H2O at 3500 m a.s.1. to around 0.5 m H2O at wind exposed sites between 4300 and 4800 m a.s.l. Probably this is strongly due to wind erosion and topographical effects. However, temperature and accumulation not only appear to be interrelated, but also seem to be positively correlated to the heat applied to the surface. Assuming the observed altitudinal gradients have remained constant in time, it can be estimated that high altitude firn bodies have become considerably warmer since the last century. CO2-induced atmospheric warming could lead to a drastic change in (he mass turnover and flow activity of high glaciers, in wind-exposed places where wind erosion of the snowpack becomes a controlling factor of accumulation.
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Assessing risks from potential glacier hazards in relation to safety considerations for settlements and other fixed installations in high mountain areas requires the application of experience gained from previous events, combined with simple rules derived from basic glaciological theory. The general characteristics of steep, and usually unmeasured, glaciers can be estimated on the basis of a rough parameterization scheme. Variations in glacier length, ice avalanches, and glacier floods then have to be considered for time periods ranging from a few years up to a few decades. As a result of such systematic assessments, maps of potentially dangerous zones can be prepared. Although the inhabitants of many Alpine villages have always lived with the risk of glacier hazards, it now appears that modern construction work, especially that connected with the development of tourism, has started to infiltrate previously avoided high-risk zones more and more. In order to plan reasonable safety measures, risks from glacier hazards have to be compared with those from other natural hazards in mountain areas, such as snow avalanches, landslides, rock falls! or storm-induced floods. Decisions about the acceptable level of risk are difficult and subjective; they are also often influenced by political and economical considerations rather than by scientific reasoning.
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In high mountain areas, permafrost is important because it influences natural hazards and construction practices, and because it is an indicator of climate change. The modeling of its distribution and evolution over time is complicated by steep and complex topography, highly variable conditions at and below the surface, and varying climatic conditions. This paper presents a systematic investigation of effects of climate variability and topography that are important for subsurface temperatures in Alpine permafrost areas. The effects of both past and projected future ground surface temperature variations on the thermal state of Alpine permafrost are studied based on numerical experimentation with simplified mountain topography. For this purpose, we use a surface energy balance model together with a subsurface heat conduction scheme. The past climate variations that essentially influence the present-day permafrost temperatures at depth are the last glacial period and the major fluctuations in the past millennium. The influence of projected future warming was assessed to cause even larger transient effects in the subsurface thermal field because warming occurs on shorter time scales. Results further demonstrate the accelerating influence of multi-lateral warming in Alpine topography for a temperature signal entering the subsurface. The effects of thermal properties, porosity, and freezing characteristics were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over shorter time periods (i.e., decades to centuries). Finally, as an example of a real and complex topography, the modeled transient three-dimensional temperature distribution in the Matterhorn (Switzerland) is given for today and in 200 years.
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Climate time series are of major importance for base line studies for climate change impact and adaptation projects. However, in mountain regions and in developing countries there exist significant gaps in ground based climate records in space and time. Specifically, in the Peruvian Andes spatially and temporally coherent precipitation information is a prerequisite for ongoing climate change adaptation projects in the fields of water resources, disasters and food security. The present work aims at evaluating the ability of Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) to estimate precipitation rates at daily 0.25° × 0.25° scale in the Central Andes and the dependency of the estimate performance on changing spatial and temporal resolution. Comparison of the TMPA product with gauge measurements in the regions of Cuzco, Peru and La Paz, Bolivia were carried out and analysed statistically. Large biases are identified in both investigation areas in the estimation of daily precipitation amounts. The occurrence of strong precipitation events was well assessed, but their intensities were underestimated. TMPA estimates for La Paz show high false alarm ratio. The dependency of the TMPA estimate quality with changing resolution was analysed by comparisons of 1-, 7-, 15- and 30-day sums for Cuzco, Peru. The correlation of TMPA estimates with ground data increases strongly and almost linearly with temporal aggregation. The spatial aggregation to 0.5°, 0.75° and 1° grid box averaged precipitation and its comparison to gauge data of the same areas revealed no significant change in correlation coefficients and estimate performance. In order to profit from the TMPA combination product on a daily basis, a procedure to blend it with daily precipitation gauge measurements is proposed. Different sources of errors and uncertainties introduced by the sensors, sensor-specific algorithm aspects and the TMPA processing scheme are discussed. This study reveals the possibilities and restrictions of the use of TMPA estimates in the Central Andes and should assist other researchers in the choice of the best resolution-accuracy relationship according to requirements of their applications.
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Direct shear box tests have revealed that the stiffness and strength of an ice-filled joint are a function of both normal stress and temperature. Comparison of these data with the results of similar experiments conducted on unfrozen joints indicates that at low temperatures and normal stresses the strength of an ice-filled joint can be significantly higher than that of an unfrozen joint. However, in the absence of sufficient closure pressure, the strength of an ice-filled joint can be significantly less than that of an unfrozen joint. This implies that if the stability of a slope is maintained by ice-filled joints, its factor of safety will reduce with temperature rise. This hypothesis suggests that a jointed rock slope that is stable when there is no ice in the joints and is also stable when ice in the joints is at low temperatures will become unstable as the ice warms. Results from the model tests have confirmed this hypothesis. Copyright (C) 2001 John Wiley St Sons, Ltd.
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Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 18. Landslides are a constant in shaping our landscape. Whether by large episodic, or smaller chronic, mass movements, our mountains, hills, valleys, rivers, and streams bear evidence of change from landslides. Combined with anthropogenic factors, especially the development and settlement of unstable terrain, landslides (as natural processes) have become natural disasters. This book charts our understanding of landslide processes, prediction methods, and related land use issues. How and where do landslides initiate? What are the human and economic consequences? What hazard assessment and prediction methods are available, and how well do they work? How does land use, from timber harvesting and road building to urban and industrial development, affect landslide distribution in time and space? And what is the effect of land use and climate change on landslides? This book responds to such questions with: Synopses of how various land uses and management activities influence landslide behavior Analyses of earth surface processes that affect landslide frequency and extent Examples of prediction techniques and methods of landslide hazard assessment, including scales of application Discussion of landslide types and related costs and damages Those who study landslides, and those who deal with landslides, from onset to after-effects-including researchers, engineers, land managers, educators, students, and policy makers-will find this work a benchmark reference, now and for years to come.
Article
Since 2009 several extremely erosive debris flows have occurred in the Spreitgraben near Guttannen (central Switzerland). They were initially triggered by rockfall events and started with small and harm less flows. Within three years they have increased to become destructive events with an enormous hazard potential. Strong erosion along the debris flow channel caused considerable depositions in the receiving stream. A total of 650,000 m3 bedload has been deposited to date. Due to the scale of the erosion and deposition processes, no constructive protection measure can be implemented to stop the process evolution. Important infrastructures are increasingly affected; the major gas pipeline between Germany and Italy had to be relocated and two houses had to be abandoned. The main passroad is endangered in different places and has already been locally destroyed. The only reasonable solution to confront these natural hazard processes is land use planning, in order to avoid any human activity in this increasingly dangerous area. As a matter of urgency a vast, sophisticated early warning system has been established. A profound knowledge of the ongoing processes is the precon dition for reliable hazard and risk management. Scenario-based debris flows have been simulated for the near future in order to estimate the deposit progress of depositions and to define areas at risk. These simulations form the basis for the safety and monitoring concept. A project handbook defines the role, tasks, responsibilities and cooperation among all affected infrastructure owners and public authorities. The article focuses on the hazard management in a highly endangered area with enormous vulnerabil ity. The devastating debris flows are forcing the authorities to adapt yearly to new situations. Due to the high event-frequency in the Spreitgraben, the established system has already been approved after only three years - a unique case in Switzer land.