Rock slope failure and landscape evolution in the Caledonian Mountains, as exemplified in the Abisko area, northern Sweden     

David Jarman 《Geografiska Annaler: Series A, Physical Geography》2002,84(3&4):213-224

Paraglacial rock slope failure (RSF) is here studied as a locally major contributor to mountain landscape evolution in the Caledonian ranges. Dense RSF clusters exist in Scotland and Norway, but overall RSF distribution in Scandinavia is poorly known. In the Abisko area, air photo scrutiny confirms the reported incidence of sparse but significant RSF. In the Kärkevagge complex, the Rissa RSF is one of the largest in northern Europe, with a scar volume of 42 Mm3. The well–known Giant Boulder Deposit (GBD) is a rock avalanche emanating from the Rissa RSF scar, the interpretation of wholesale valley wall retreat at deglaciation being discounted. In the adjacent valley of Vassivagge, a major RSF on Vuoitasrita has a similar area and morpholocation, but lacks a GBD. It has consumed 5–10% of the relict preglacial mountain surface. Both RSFs are near incipient watershed breaches in valleys which may have undergone vigorous enlargement during the last stadial. Glaciation history may explain spatial incidence as well as neotectonic and other triggers. The localised geomorphic impact of RSF in the Abisko mountains is high by comparison with contemporary slope processes. The cumulative impact of paraglacial RSF over the Quaternary may have been considerable, and RSF may be an indicator of concentrated late–stage glacial erosion.  相似文献   

Rock slope failure and landscape evolution in the Caledonian Mountains, as exemplified in the Abisko area, northern Sweden     

David Jarman 《Geografiska Annaler: Series A, Physical Geography》2002,84(3-4):213-224

Paraglacial rock slope failure (RSF) is here studied as a locally major contributor to mountain landscape evolution in the Caledonian ranges. Dense RSF clusters exist in Scotland and Norway, but overall RSF distribution in Scandinavia is poorly known. In the Abisko area, air photo scrutiny confirms the reported incidence of sparse but significant RSF. In the Kärkevagge complex, the Rissa RSF is one of the largest in northern Europe, with a scar volume of 42 Mm3. The well–known Giant Boulder Deposit (GBD) is a rock avalanche emanating from the Rissa RSF scar, the interpretation of wholesale valley wall retreat at deglaciation being discounted. In the adjacent valley of Vassivagge, a major RSF on Vuoitasrita has a similar area and morpholocation, but lacks a GBD. It has consumed 5–10% of the relict preglacial mountain surface. Both RSFs are near incipient watershed breaches in valleys which may have undergone vigorous enlargement during the last stadial. Glaciation history may explain spatial incidence as well as neotectonic and other triggers. The localised geomorphic impact of RSF in the Abisko mountains is high by comparison with contemporary slope processes. The cumulative impact of paraglacial RSF over the Quaternary may have been considerable, and RSF may be an indicator of concentrated late–stage glacial erosion.  相似文献   

The Elements of Applied Avalanche Forecasting,Part II: The Physical Issues and the Rules of Applied Avalanche Forecasting     

McClung  D. M. 《Natural Hazards》2002,26(2):131-146

This paper (Part II) constitutes the second of a two part series todefine the seven elements of avalanche forecasting. Part I contains the first four elements which are neededto present the human issues. This paper contains the last three elements which deal mostly with thephysical issues and their use in the decision-making process. Some basic rules of applied avalancheforecasting are included here, for the first time, to illustrate physically based principleswhich are used in applied avalanche forecasting and their link to data analysis and decisions.Since the seven elements of applied avalanche forecasting are strongly connected, the reader should consultPart I (this journal issue) as a prelude to the present paper. Part II contains sections about dataand information, scale issues in time and space, decision making and errors and physical rules ofapplied forecasting. Since all seven elements of applied avalanche forecasting are connected, Part II does not stand alone.  相似文献   

Snow Avalanche Hazards and Management in Canada: Challenges and Progress   总被引：2，自引：1，他引：2  

Jamieson  Bruce  Stethem  Chris 《Natural Hazards》2002,26(1):35-53

Avalanche impacts in Canada, including fatalities, are summarized for residential and public areas, as well as roads, ski areas, backcountry recreation, and resource industries. Methods for managing avalanche hazard, which include defence structures, zoning, forecasting and explosive control, are outlined. Problems with current avalanche hazard management are identified and progress at solving these problems is identified with an emphasis on residential areas, backcountry recreation and resource industries.  相似文献   

Small fast-moving flow-like landslides in volcanic deposits: The 2001 Las Colinas Landslide (El Salvador)   总被引：4，自引：0，他引：4  

G.B. Crosta  S. Imposimato  D. Roddeman  S. Chiesa  F. Moia 《Engineering Geology》2005,79(3-4):185-214

Fast-moving landslides are one of the most significant dangers deriving from slope instabilities. Landslides involving large volumes can develop in rock or debris avalanches with extreme mobility and enormous destructiveness. Nevertheless, a relevant number of casualties and damages derive from small, fast-moving landslides with flow-like behaviour.

The Las Colinas landslide occurred at Santa Tecla (El Salvador, Central America) during a strong earthquake. It slid off the northern flank of the Bálsamo ridge, and resulted in almost 500 casualties and can be considered one of the most destructive landslides ever known. Earthquake shaking was amplified by the rock mass and the steep ridge topography.

We collected original geological, geomorphological and geophysical data in the Cordillera del Bálsamo area. The involved materials, ranging from lapilli to tuff layers of different strength, have been mapped and characterized.

Slope stability analyses have been performed both under static and dynamic conditions through limit equilibrium and finite element methods.

Hazard zonation for this type of landslides requires the forecast of the movement velocity and final deposition area. We used a fully two-dimensional FEM model to simulate landslide spreading downslope. The developed code allows the use of different constitutive models and yield rules with the possibility to model and study internal deformation of the landslide mass, as well material entrainment and deposition.  相似文献   

Geomorphological evidence of the influence of pre-volcanic basement structure on emplacement and deformation of volcanic edifices at the Cofre de Perote–Pico de Orizaba chain and implications for avalanche generation     

Aline Concha-Dimas  Mariano Cerca  Sergio R. Rodríguez  Robert J. Watters   《Geomorphology》2005,72(1-4):19-39

Pre-volcanic structure of the basement influences volcanism distribution and avalanche generation in volcanic edifices. Therefore, systematic studies of basement structure below volcanic chains are necessary to understand the deformation effects observed in the surface and vice versa. Based on a compilation of pre-existing data, interpretation of aerial photographs and satellite images, and a collection of structural data we analyzed morphological and structural features of the Cofre de Perote–Pico de Orizaba (CP–PO) volcanic chain and its basement. We have identified three sets of regional lineaments that are related to basement trends. (1) NW 55° SE fractures are parallel to anticline folds observed in Cretaceous rocks that originated during Laramide shortening. These folds present an abrupt morphology observed only in the eastern flank but that is likely to continue below the volcanic chain. (2) NE 55° SW fractures are parallel to normal faults at the basement. We infer that these basement faults confine the CP–PO chain within a stepped graben with a total normal displacement of about 400 m. These faults have been active through time since they have affected volcanic deposits and induced the emplacement of monogenetic vents. Notably, lineaments of monogenetic vents concentrate where the basement is relatively shallow. (3) Another set of faults, oriented N–S, has been observed affecting the scarce basement outcrops at the western flank of the chain covered by lacustrine deposits. Lineaments measured in the volcanic edifice of Pico de Orizaba correlate with the regional trends.In particular, the NE 55° SW alignment of monogenetic vents and fractures at Pico de Orizaba suggest that the same dike trend exists within the volcanic edifice. A normal fault with similar orientation was documented at the NE continuation of an alignment crossing the volcanic edifice along the Jamapa canyon. In the absence of magmatic activity related to collapses, the displacement of NE 55° SW faults represents a potential triggering mechanism for generating avalanches at Pico de Orizaba volcano. Instability is enhanced by the presence of N–S trending fractures crossing the entire volcanic edifice and E–W fractures affecting only the present day cone. We conclude that mechanical instability of the volcanic chain is influenced by the basement structure heterogeneity, but further detailed studies are necessary at individual volcanoes to evaluate their effects on volcano deformation.  相似文献   

Seismic Signals Induced by Snow Avalanche Flow     

Kishimura  K.  Izumi  K. 《Natural Hazards》1997,15(1):89-100

In this paper some observations and their analysis are presented dealing with the link between seismic signals and avalanche flow. The measurements during the passage of avalanches showed a specific spindle pattern which was quite different from the one of natural earthquakes. The general trend strongly depended on the topographic features of the avalanche path, and as a result we could estimate avalanche velocity. The running power spectrum showed a meaningful shift of the dominant peak from the front to the rear part of the flow.  相似文献   

Measurements of powder snow avalanche- nature -     

K. Nishimura  F. Sandersen  K. Kristensen  K. Lied 《Surveys in Geophysics》1995,16(5-6):649-660

Snow cloud growth rates of powder snow avalanche were obtained with analysing the pictures recorded in Ryggfonn, Norway. Although results showed wide scattering, as far as the data obtained in runout zone are concerned, they roughly agreed with the water tank experiments by Beghin and Olagne (1991).Air movement in snow avalanche cloud was measured with an ultra-sonic anemometer in Kurobe Canyon, Japan. It showed rising current existed near the front and downward at the trail. Comparing with drifting snow threshold and particle suspension criterion, entrainment, suspension and deposition of snow particles in the snow cloud were discussed.  相似文献   

Late-holocene snow-avalanche activity in southern norway: Interpreting lichen size–frequency distributions using an alternative to simulation modelling     

Danny McCarroll  John A. Matthews  Richard A. Shakesby 《地球表面变化过程与地形》1995,20(5):465-471

Recent work by McCarroll (1993, 1994) suggests that a new approach to lichenometry can be used to date diachronous surfaces. Size–frequency distributions of largest lichens obtained from the diachronous surfaces of avalanche boulder ramparts comprise two elements: an equilibrium population growing on boulders deposited throughout the Holocene, and overlapping populations growing on groups of boulders deposited by events during the last 300 years. In this study, almost 10000 lichens were measured on two groups of closely similar ramparts. The number of very large lichens is used to predict the form of the equilibrium distribution, which is then removed, leaving a corrected distribution which reflects the age-frequency of surface boulders deposited during the ‘Little Ice Age’. The results confirm that maximum avalanche activity occurred during the 19th century, but a minor peak at one site suggests that avalanche activity was enhanced during the mid-18th century.  相似文献   

天山山系的雪崩危险区分布     

胡汝骥 Blag.  VP 《干旱区地理》1995,18(4):33-40

根据山地生态特征，地形切割深度及河谷横剖面形成和雪崩重视率等，将天山山系雪崩危险区分为：１）低山草原或半荒漠雪崩危险区；２）中山森林－草原雪崩危险区；３）中山草地雪崩危险区；４）高山冰缘带（石质）雪崩危险区；５）高山；极高山冰川带雪崩危险区。  相似文献