The 2007 Fox Creek landslide,Peace River Lowland,Alberta, Canada

Fox Creek is a small tributary of the Saddle River, a tributary of the Peace River in northwestern Alberta. It has several dormant landslides with degraded scarps and grabens. A new, reactivated landslide on the north bank of the Fox Creek occurred on 5 May 2007. The landslide formed two major sliding blocks. A rapid translational block slide, it mobilized 47 Mm³ of displaced materials, blocked the creek, and made a natural dam with a maximum height of 19 m at the tips of the displaced blocks. The rupture surfaces of the 2007 landslide were within the advance phase glaciolacustrine sediments. The residual friction angles are about 10° similar to those of the previous landslides in the Peace River Lowland. Precipitation and snow melt prior to the landslide are likely triggers of the 2007 Fox Creek landslide. The farmlands on the crest of the river valley and timber resources were impacted. The current landslide dam in Fox Creek does not have any evidence of seepage downstream; it may last for many years. Eventually, the creek will overtop and erode the dam. The same cycle of actions, landsliding, damming, and erosion will continue in the foreseeable future.     

A 36Cl age determination for Mystery Creek rock avalanche and its implications in the context of hazard assessment, British Columbia, Canada

The Sea to Sky Corridor has experienced hundreds of historic and prehistoric landslides. The most common types of historical landslides are rock falls and debris flows, which are relatively small in volume but can be damaging. These types of failures are more common in the southern part of the corridor, between Horseshoe Bay and Porteau, where infrastructure has been built in close proximity to steep slopes. Farther north, fewer landslides have been reported historically, but those that have been recorded are usually large and date to prehistoric time (e.g., Cheekye fan and Mystery Creek rock avalanche). As part of a Geological Survey of Canada surficial geology and landslide inventory mapping study, Mystery Creek rock avalanche, near Whistler, British Columbia, was sampled for ³⁶Cl dating. Samples were collected from three large flat boulders of quartz diorite in the rock avalanche deposit to test a correlation with the previously reported radiocarbon age of 800 ± 100 years BP on charcoal. One sample revealed a mean age of 2,400 years and the other two, 4,300 and 4,800 years, respectively. These new results point to four possible interpretations: (1) Mystery Creek landslide is about 800 years old; (2) Based on the overlapping 2σ uncertainties, the rock avalanche took place between 2,200 and 3,600 years ago; (3) The rock avalanche deposit is 2,400 years old and the other two blocks are too old; and (4) The rock avalanche is between 4,300 and 4,800 years old. Although there is strength in numbers and it is likely that the age varies between 4,300 and 4,800 years, we favor the second interpretation where the age range is broader and statistically significant for all three samples. Moreover, at this time, we favor discounting the radiocarbon age based on a greater number of samples analyzed for ³⁶Cl analysis and lack of detailed information on the charcoal sampling. The causes and triggers of the Mystery Creek rock avalanche remain unknown, but direct glacial debuttressing can be ruled out. Some of the causes are likely a combination of the regional tectonic setting which produced preferential planes of weakness reflected in the trend of major faults, headscarp, and reverse scarps. Yearly cycles of freezing and thawing are considered a plausible cause based on present-day climate records. Finally, a large earthquake still remains a possible trigger because of the active tectonic setting and the presence of potentially contemporaneous landslides in the same area. Mystery Creek rock avalanche and other historic and pre-historic landslides contributed to validation of a heuristic rock fall/rock slide/rock avalanche susceptibility mapping study, in which their headscarps correlated well with medium-high to high susceptibility zones. In terms of hazard assessment, Mystery Creek rock avalanche, although pre-historic in age, occurred in present-day climatic and geological conditions. This poses a threat to infrastructure such as the Sea to Sky Highway, railway, and power line.     

Glacial advances constrained by Be exposure dating of bedrock landslides, Kyrgyz Tien Shan

Numerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains unresolved due to the lack of "absolute" age constraints. Here we present the first ¹⁰Be exposure ages for three prominent (> 10⁷ m³) bedrock landslides that blocked major rivers and formed lakes, two of which subsequently breached, in the northern Kyrgyz Tien Shan. Three ¹⁰Be ages reveal that one landslide in the Alamyedin River occurred at 11–15 ka, which is consistent with two ¹⁴C ages of gastropod shells from reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in semi-arid continental interiors, with a ¹⁰Be age of 63–67 ka. The Ukok River landslide deposit(s) yielded variable ¹⁰Be ages, which may result from multiple landslides, and inheritance of ¹⁰Be. Two ¹⁰Be ages of 8.2 and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial erosion, hence their locations and ¹⁰Be ages mark maximum extents and minimum ages of glacial advances, respectively. Using toe-to-headwall altitude ratios of 0.4–0.5, we reconstruct minimum equilibrium-line altitudes that exceed previous estimates by as much as 400 m along the moister northern fringe of the Tien Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for glacial advances in landscapes where moraines and glacial deposits have low preservation potential.     

Rock avalanching into a landslide-dammed lake causing multiple dam failure in Las Conchas valley (NW Argentina) — evidence from surface exposure dating and stratigraphic analyses

Generally landslide dams which exist for several hundreds to thousands of years are considered as stable. We show with an example from the Argentine Andes that such dams can exist for several thousands of years but still may fail catastrophically. Multiple rock avalanches impounded two lakes with surface areas of ~8 km² and ~600 km², respectively, in Las Conchas valley, NW Argentina. Surface exposure dating (SED) by ¹⁰Be of the rock-avalanche deposits or landslide scars indicates that these landslides occurred at 15,300±2,000 yr and 13,550±900 yr. The dams were stable during a strong earthquake, as suggested by seismites within related lake sediments and by multiple coeval landslides in this region, which occurred at ~7.5 kyr. However, when a further rock-avalanche fell into the lower, smaller lake at 4,800±500 yr the dam downriver was destroyed, presumably by the resulting tsunami wave. The resulting flood also destroyed an additional rock-fall dam which had formed at ~5,630 yr ¹⁴C cal BP 30 km downriver. The new dam formed by the second rock avalanche was eroded prior to 3,630 yr ¹⁴C cal BP. This dam erosion coincides with an important climatic shift towards more humid conditions in the Central Andes. Our results show that instead of direct effects of strong seismicity on landslide dams, (1) landsliding into a landslide-dammed lake, (2) abrupt hydrological changes, and (3) climate change towards conditions related to enhanced run-off are processes which can produce failures of quasi-stable natural dams.     

Using an airborne laser scanner for the identification of shallow landslides and susceptibility assessment in an area of ignimbrite overlain by permeable pyroclastics

An airborne laser scanner can identify shallow landslides even when they are only several meters in diameter and are hidden by vegetation, if the vegetation is coniferous or deciduous trees in a season with fewer leaves. We used an airborne laser scanner to survey an area of the 1998 Fukushima disaster, during which more than 1,000 shallow landslides occurred on slopes of vapor-phase crystallized ignimbrite overlain by permeable pyroclastics. We identified landslides that have occurred at the 1998 event and also previous landslides that were hidden by vegetation. The landslide density of slopes steeper than 20° was 117 landslides/km² before the 1998 disaster. This event increased the density by 233 landslides/km² indicating that this area is highly susceptible to shallow landsliding.     

Radiocarbon Dating of the Dynamics of Landslides in the Upper Reaches of the Mzymta River Basin (Western Caucasus)

The article contains materials on the study of landslide deposits in the upper reaches of the Mzymta river basin. The results of ¹⁴C analysis showed that the youngest landslides are common on the southern slope of the Psekhako Ridge and date back to less than 200 and 390 ± 90, 400 ± 70 cal. years BP and more than 770 ± 150 cal. years BP. The most ancient landslide-collapse on the northern slope of the Aibga Ridge and dates back to 1110 ± 90 cal. years BP.     

A geotechnical investigation of the retrogressive Yaka Landslide and the debris flow threatening the town of Yaka (Isparta,SW Turkey)

In this study the factors affecting the retrogressive Yaka Landslide, its mechanism and the hazard of debris flow on the town of Yaka are investigated. In the landslide area, the first landslide was small and occurred in March 2006 on the lower part of the Alaard?ç Slope near the Gelendost District town of Yaka (Isparta, SW Turkey). The second, the Yaka Landslide, was large and occurred on 19 February 2007 in the soil-like marl on the central part of Alaard?ç Slope. The geometry of the failure surface was circular and the depth of the failure surface was about 3 m. Following the landslide, a 85,800 m³ of displaced material transformed to a debris flow. Then, the debris flow moved down the Eglence Valley, traveling a total distance of about 750 m. The town of Yaka is located 1,600 m downstream of Eglence Creek and hence poses a considerable risk of debris flow, should the creek be temporarily dammed as a result of further mass movement. Material from the debris accumulation has been deposited on the base of Eglence Valley and has formed a debris-dam lake behind a debris dam. Trees, agricultural areas, and weirs in the Eglence Creek have seen serious damage resulting from the debris flow. The slope angle, slope aspect and elevation of the area in this study were generated using a GIS-based digital elevation model (DEM). The stability of the Alaard?ç Slope was assessed using limit equilibrium analysis with undrained peak and residual shear strength parameters. In the stability analyses, laboratory test results performed on the soil-like marls were used. It was determined that the Alaard?ç Slope is found to be stable under dry conditions and unstable under completely saturated conditions. The Alaard?ç Slope and its vicinity is a paleolandslide area, and there the factor of safety for sliding was found to be about 1.0 under saturated conditions. The Alaard?ç Slope and the deposited earthen materials in Eglence Creek could easily be triggered into movement by any factors or combination of factors, such as prolonged or heavy rainfall, snowmelt or an earthquake. It was established that the depth of the debris flow initiated on the Yaka Landslide reached up to 8 m in Eglence Creek at the point it is 20 m wide. If this deposited material in Eglence Creek is set into motion, the canal that passes through Yaka, with its respective width and depth of 7 and 1.45 m, could not possibly discharge the flow. The destruction or spillover of this canal in Yaka could bring catastrophic loss to residents which are located within 3–5 m of the bank of the canal. Furthermore, if material present in the landslide source area slides and this displaced material puts pressure on the unstable deposited material in Eglence Creek, even more catastrophic loss would occur to the town of Yaka. In this study, it was determined that debris flows are still a major hazard to Yaka and its population of 3,000. The results provided in this study could help citizens, planners, and engineers to reduce losses caused by existing and future landslides and debris flow in rainfall and snowmelt conditions by means of prevention and mitigation.     

The Todagin Creek landslide of October 3, 2006, Northwest British Columbia, Canada

The Todagin Creek landslide is located at 57.61° N 129.98° W in Northwest British Columbia. A seismic station 90 km north of the landslide recorded the event at 1643 hours coordinated universal time (UTC; 0943 hours Pacific daylight time (PDT)) on October 3, 2006. The signal verifies the discovery and relative time bounds provided by a hunting party in the valley. The landslide initiated as a translational rock slide on sedimentary rock dipping down slope at 34° and striking parallel to the valley. The landslide transformed into a debris avalanche and had a total volume estimated at 4 Mm³. An elevation drop of 771 m along a planar length of 1,885 m resulted in a travel angle (fahrb?schung) of 21.3°. The narrowest part of the landslide through the transport zone is 345 m. The widest part of the divergent toe of the landslide reaches a width of 1,010 m. Landslide debris impounded a lake of approximately 32 ha and destroyed an additional 67 ha of forest. The impoundment took 7 to 10 days to fill, with muddied waters observed downstream on October 13. No clear linkage exists with precipitation and temperature records preceding the landslide, but strong diurnal temperature cycles occurred in the days prior to the event. The Todagin Creek area appears to have an affinity for large landslides with the deposits of three other landslides >5 Mm³ observed in the valley.     

Landslide susceptibility mapping of vicinity of Yaka Landslide (Gelendost,Turkey) using conditional probability approach in GIS

On 19 February 2007, a landslide occurred on the Alaard?ç Slope, located 1.6 km south of the town of Yaka (Gelendost, Turkey.) Subsequently, the displaced materials transformed into a mud flow in E?lence Creek and continued 750 m downstream towards the town of Yaka. The mass poised for motion in the Yaka Landslide source area and its vicinity, which would be triggered to a kinetic state by trigger factors such as heavy or sustained rainfall and/or snowmelt, poise a danger in the form of loss of life and property to Yaka with its population of 3,000. This study was undertaken to construct a susceptibility mapping of the vicinity of the Yaka Landslide’s source area and to relate it to movement of the landslide mass with the goal of prevention or mitigation of loss of life and property. The landslide susceptibility map was formulated by designating the relationship of the effecting factors that cause landslides such as lithology, gradient, slope aspect, elevation, topographical moisture index, and stream power index to the landslide map, as determined by analysis of the terrain, through the implementation of the conditional probability method. It was determined that the surface area of the Goksogut formation, which has attained lithological characteristics of clayey limestone with a broken and separated base and where area landslides occur, possesses an elevation of 1,100–1,300 m, a slope gradient of 15 °–35 ° and a slope aspect between 0 °–67.5 ° and 157 °–247 °. Loss of life and property may be avoided by the construction of structures to check the debris mass in E?lence Creek, the cleaning of the canal which passes through Yaka, the broadening of the canal’s base area, elevating the protective edges along the canal and the establishment of a protective zone at least 10-m wide on each side of the canal to deter against damage from probable landslide occurrence and mud flow.     

Optically Stimulated Luminescence (OSL) Chronology of the Dehenglong Landslide from Longyang Gorge to Liujia Gorge along Upper Yellow River, China

Giant landslides are common along the upper Yellow River from Longyang Gorge to Liujia Gorge, and some of them even blocked and dammed the upper Yellow River. Chronology is inevitable in studying the mechanism of giant landslides. Controversy exists about the chronology of those giant landslides, and some have not yet dated. The Dehenglong landslide is the largest one among them. In this study, OSL samples were collected from lacustrine silty sediments and loess directly overlying the landslide sediments, as well as fault sediments related to the landslide. This landslide yielded an age of 89 ± 8 ka, which is identical with the fault age of 73 ± 5 ka at two sigma errors. The agreement of a topographic analysis and the absolute age of landslides imply that the formation of the Dehenglong landslide is strongly correlated with the tectonic activity.     

Mapping of landslide hazard zonation using GIS at Golestan watershed, northeast of Iran

Landslide hazard zonation is essential for planning future developmental activities. At the present study, after the preparation of a landslide inventory of the study area, nine factors as well as sub-data layers of factor class weights were tested for an integrated analysis of landslide hazard in the region. The produced factor maps were weighted with the analytic hierarchy process method and then classified into four classes—negligible, low, moderate, and high. The final produced map for landslide hazard zonation in Golestan watershed revealed that: (1) about 53.85 % of the basin is prone to moderate and high threats of landslides. (2) Landslide events at the Golestan watershed were strongly correlated to the slope angle of the basin. It was observed that the active landslide zones, including moderate to high landslide hazard classes, have a high correlation to slope classes over 30° (R ²?=?0.769). (3) The regions most susceptible to landslide hazard are those located south and southwest of the watershed, which included rock topples, falls, and debris landslides.     

Distribution of landslides in southwest New Zealand

This study examines the size distribution of a regional medium-scale inventory of 778 landslides in the mountainous southwest of New Zealand. The spatial density of mapped landslides per unit area can be expressed as a negative power–law function of Landslide area A_L spanning three orders of magnitude (10^–2–10¹ km²). Although observed in other studies on landslide inventories, this relationship is surprising, given the lack of absolute ages, and thus uncertainty about the temporal observation window encompassed by the data. Large slope failures (arbitrarily defined here as having a total affected area A_L>1 km²) constitute 83% of the total affected landslide area A_LT. This dominance by area affects slope morphology, where large-scale landsliding reduces slope angles below the regional modal value of hillslopes, _mod39°. More numerous smaller and shallower failures tend to be superimposed on the pre-existing relief. Empirical scaling relationships show that large landslides involve >10⁶ m³ of material. The volumes V_L of individual preserved and presumably prehistoric (i.e. pre-1840) landslide deposits equate to 10⁰–10² years of total sediment production from shallow landsliding in the respective catchments, and up to 10³ years of contemporary regional sediment yield from the mountain ranges. Their presence in an erosional landscape indicates the geomorphic importance of landslides as temporary local sediment storage.     

Description of dynamics of the Tuzla Landslide and its implications for further landslides in the northern slope and shelf of the Cinarcik Basin (Marmara Sea, Turkey)

Seismic and multi-beam bathymetric data from the northern shelf and slope of the Cinarcik Basin, which is generated by the North Anatolian Fault Zone (NAFZ) located in the easternmost basin in the Marmara Sea, were re-interpreted to better understand the future sub-marine landslide susceptibility. Seismic data indicate that upper surface of the sub-marine extension of the Paleozoic rocks has an NNE–SSW oriented basin and a ridge type morphology controlled by the secondary faults of the NAFZ. Basins are fulfilled by Plio-Quaternary sediments, which are cut by strike-slip faults on the shelf and slope. The thickness of basin deposits reaches up to 130 m toward the linear northern slope of the Cinarcik Basin. A relatively recent sub-marine landslide, the Tuzla Landslide, cuts the slope of the Cinarcik Basin. The detailed morphological investigation indicates that the Tuzla Landslide is a deep-seated rotational landslide, which was likely triggered by activity of the NAFZ. Morphological analyses also indicate that the thick Plio-Quaternary deposits on the Paleozoic basement slid during the Tuzla Landslide event. This landslide is considered as a key event to understand the dynamics of the potential landslides on the northern shelf and slope of the Cinarcik Basin. Two areas locating on the eastern and the western sides of the Tuzla Landslide are considered as the potential areas for future sliding due to similarities of geological and geomorphological features with the Tuzla Landslide such as similar thick Plio-Quaternary deposits, similar slope morphology, and similar fault activity cutting the sediments. Considering this information, the purposes of the present study are to determine the dynamics of the possible landslide areas and to discuss their effects on the sub-marine morphology. In the light of the interpretations, the amounts of possible displaced material are obtained. Three different landslide scenarios due to possible slide surfaces for future landslides are developed and assessed. The first scenario is sliding of the sediments at the shelf break. The third scenario is a mass movement of almost whole basin deposits on the Paleozoic rocks. The latter one is evaluated as less important because of the volume of the displaced material, and the latter one is accepted as lowest possible event. Among the scenarios, the second scenario is accepted as the most critical and possible because of the amount of the slipped material and existence of faults rupture, which is considered as further sliding surfaces. These landslides will result in important changes in shelf, slope and basin floor in the study area.     

Landslides triggered by slipping-fault-generated earthquake on a plateau: an example of the 14 April 2010, Ms 7.1, Yushu, China earthquake

On 14 April 2010 at 07:49 (Beijing time), a catastrophic earthquake with Ms 7.1 struck Yushu County, Qinghai Province, China. A total of 2,036 landslides were interpreted from aerial photographs and satellite images, verified by selected field checking. These landslides cover about a total area of 1.194 km². The characteristics and failure mechanisms of these landslides are presented in this paper. The spatial distribution of the landslides is evidently strongly controlled by the locations of the main co-seismic surface fault ruptures. The landslides commonly occurred close together. Most of the landslides are small; there were only 275 individual landslide (13.5 % of the total number) surface areas larger than 1,000 m². The landslides are of various types. They are mainly shallow, disrupted landslides, but also include rock falls, deep-seated landslides, liquefaction-induced landslides, and compound landslides. Four types of factors are identified as contributing to failure along with the strong ground shaking: natural excavation of the toes of slopes, which mean erosion of the base of the slope, surface water infiltration into slopes, co-seismic fault slipping at landslide sites, and delayed occurrence of landslides due to snow melt or rainfall infiltration at sites where slopes were weakened by the co-seismic ground shaking. To analyze the spatial distribution of the landslides, the landslide area percentage (LAP) and landslide number density (LND) were compared with peak ground acceleration (PGA), distance from co-seismic main surface fault ruptures, elevation, slope gradient, slope aspect, and lithology. The results show landslide occurrence is strongly controlled by proximity to the main surface fault ruptures, with most landslides occurring within 2.5 km of such ruptures. There is no evident correlation between landslide occurrences and PGA. Both LAP and LND have strongly positive correlations with slope gradient, and additionally, sites at elevations between 3,800 and 4,000 m are relatively susceptible to landslide occurrence; as are slopes with northeast, east, and southeast slope aspects. Q₄ al-pl, N, and T₃ kn ¹ have more concentrated landslide activity than others. This paper provides a detailed inventory map of landslides triggered by the 2010 Yushu earthquake for future seismic landslide hazard analysis and also provides a study case of characteristics, failure mechanisms, and spatial distribution of landslides triggered by slipping-fault generated earthquake on a plateau.     

Interpretation of landslide distribution triggered by the 2005 Northern Pakistan earthquake using SPOT 5 imagery

The 2005 northern Pakistan earthquake (magnitude 7.6) of 8 October 2005 occurred in the northwestern part of the Himalayas. We interpreted landslides triggered by the earthquake using black-and-white 2.5-m-resolution System Pour l’Observation de la Terre 5 (SPOT 5) stereo images. As a result, the counts of 2,424 landslides were identified in the study area of 55 by 51 km. About 79% or 1,925 of the landslides were small (less than 0.5 ha in area), whereas 207 of the landslides (about 9%) were large (1 ha and more in area). Judging from our field survey, most of the small landslides are shallow rock falls and slides. However, the resolution and whitish image in the photos prevented interpreting the movement type and geomorphologic features of the landslide sites in detail. It is known that this earthquake took place along preexisting active reverse faults. The landslide distribution was mapped and superimposed on the crustal deformation detected by the environmental satellite/synthetic aperture radar (SAR) data, active faults map, geological map, and shuttle radar topography mission data. The landslide distribution showed the following characteristics: (1) Most of the landslides occurred on the hanging-wall side of the Balakot–Garhi fault; (2) greater than one third of the landslides occurred within 1 km from the active fault; (3) the greatest number of landslides (1,147 counts), landslide density (3.2 counts/km²), and landslide area ratio (2.3 ha/km²) was found within Miocene sandstone and siltstone, Precambrian schist and quartzite, and Eocene and Paleocene limestone and shale, respectively; (4) there was a slight trend that large landslides occurred on vertically convex slopes rather than on concave slopes; furthermore, large landslides occurred on steeper (30° and more) slopes than on gentler slopes; (5) many large landslides occurred on slopes facing S and SW directions, which is consistent with SAR-detected horizontal dominant direction of crustal deformation on the hanging wall.     

Geology,palynology, and climatic significance of two pre-Pinedale Lake sediment sequences in and near Yellowstone National Park

Pollen analysis of a section of lake sediments at Grassy Lake Reservoir indicates a vegetational sequence changing from tundra, to spruce-fir-pine forest, to pine forest, to tundra at the top. Pollen analysis of a section of lake sediments on Beaverdam Creek indicates a tundra vegetation at the base, followed by a brief episode of spruce-fir forest and a return to a tundra vegetation at the top. The analyses of both sections suggest a cold to cool to cold climatic sequence, interpreted as interstadial in character. However, differences suggest that they represent separate interstadials. Pinedale Till disconformably overlies the lake deposits at Grassy Lake Reservoir. The upper sediments contain wood ¹⁴C dated at >42,000 yr; the lowermost interfinger with till shown to be more than about 70,000 yr old. The deposits at Beaverdam Creek grade upward into proglacial Pinedale deposits, contain an ash that is probably about 70,000 yr old near their base, and rest comformably on gravel that grades down into lake sediments containing wood debris suggestive of an older climatic amelioration. We conclude that the warmest part of the interstadial at Grassy Lake Reservoir is probably more than 70,000 yr old, and that the warmest part of the interstadial analyzed at Beaverdam Creek is slightly younger than 70,000 yr old.     

Large-scale landslides in Toyama Prefecture,central Japan,and their probable relationship with earthquakes

Large-scale landslides along the Kubusu and Besso rivers in Toyama Prefecture are developed in the Miocene Iwaine Formation, which is composed of andesitic lava, tuff, and tuff breccia. In the middle member of this formation, the tuff is easily altered to montmorillonite-bearing rock, and subsequently plays an important role in the development of landslides events, which tend to be large-scale events, as the massive lava of the upper member forms a cap rock over the tuff. The Kiritani and Koinami basins, which are flat intermontane basins located along the Kubusu and Besso rivers, respectively, are interpreted as landslide-dammed lakes, later filled with sediment. Accelerator mass spectrometry ¹⁴C ages show that the landslides forming each dam occurred simultaneously, at approximately 2500 BP. These ages were measured from wood fragments embedded in the landslide material of Kiritani, and from an in situ stump drowned during the impoundment of Koinami. If the trigger of these landslides was an earthquake, it is most likely to have been the penultimate event along the Atotsugawa fault zone.     

Preliminary investigation of some large landslides triggered by the 2008 Wenchuan earthquake, Sichuan Province, China

The M _s 8.0 Wenchuan earthquake or “Great Sichuan Earthquake” occurred at 14:28 p.m. local time on 12 May 2008 in Sichuan Province, China. Damage by earthquake-induced landslides was an important part of the total earthquake damage. This report presents preliminary observations on the Hongyan Resort slide located southwest of the main epicenter, shallow mountain surface failures in Xuankou village of Yingxiu Town, the Jiufengchun slide near Longmenshan Town, the Hongsong Hydro-power Station slide near Hongbai Town, the Xiaojiaqiao slide in Chaping Town, two landslides in Beichuan County-town which destroyed a large part of the town, and the Donghekou and Shibangou slides in Qingchuan County which formed the second biggest landslide lake formed in this earthquake. The influences of seismic, topographic, geologic, and hydro-geologic conditions are discussed.     

Stratigraphy of Pleistocene glaciations in the St Elias Mountains,southwest Yukon,Canada

At least five Middle to Late Pleistocene advances of the northern Cordilleran Ice Sheet are preserved at Silver Creek, on the northeastern edge of the St Elias Mountains in southwest Yukon, Canada. Silver Creek is located 100 km up‐ice of the Marine Isotope Stage (MIS) 2 McConnell glacial limit of the St Elias lobe. This site contains ~3 km of nearly continuous lateral exposure of glacial and non‐glacial sediments, including multiple tills separated by thick gravel, loess and tilted lake beds. Infrared‐stimulated luminescence (IRSL) and AMS radiocarbon dating constrain the glacial deposits to MIS 2, 4, either MIS 6 or mid‐MIS 7, and two older Middle Pleistocene advances. This chronology and the tilt of the lake beds suggest Pleistocene uplift rates of up to 1.9 mm a^?1 along the Denali Fault since MIS 7. The non‐glacial sediment consists of sand, gravel, loess and organic beds from MIS 7, MIS 3 and the early Holocene. The MIS 3 deposits date to between 30–36 ¹⁴C ka BP, making Silver Creek one of the few well‐constrained MIS 3‐aged sites in Yukon. This confirms that ice receded close to modern limits in MIS 3. Pollen and macrofossil analyses show that a meadow‐tundra to steppe‐tundra mosaic with abundant herbs and forbs and few shrubs or trees, dominated the environment at this time. The stratigraphy at Silver Creek provides a palaeoclimatic record since at least MIS 8 and comprises the oldest direct record of Pleistocene glaciation in southwest Yukon.