Cliff collapse and rock avalanches (sturzstroms) in the Mackenzie Mountains, northwestern Canada: Reply

1980 ◽  
Vol 17 (1) ◽  
pp. 151-152
Author(s):  
G. H. Eisbacher
Keyword(s):  
Rock Avalanches ◽  
Mackenzie Mountains

A reassessment of transport mechanisms of some rock avalanches in the Mackenzie Mountains, Yukon and Northwest Territories, Canada

1990 ◽  
Vol 27 (1) ◽  
pp. 129-144 ◽  
Author(s):  
P. K. Kaiser ◽  
J. V. Simmons
Keyword(s):  
Debris Flow ◽  
Northwest Territories ◽  
Valley Bottom ◽  
Flow Simulations ◽  
Rock Avalanches ◽  
Field Evidence ◽  
Debris Transport ◽  
Glacier Ice ◽  
Mackenzie Mountains ◽  
New Hypothesis

The transport mechanism of some rock avalanches of the Mackenzie Mountains in the Yukon and Northwest Territories of Canada is reassessed on the basis of evidence collected during fieldwork and by comparison with results from numerical simulations of the debris flow mechanism. A new hypothesis of glaciation-related transport is advanced as an alternate explanation of apparently very mobile rock avalanches with anomalous travel distances. By the example of the Avalanche Lake slide, it is demonstrated that the debris was most likely not deposited on the current topography but on valley glacier ice at an elevation of about 400–500 m above the valley bottom. This conclusion is supported by field evidence, an empirical runup relationship, and the results from numerical flow simulations. A qualitative interpretation of other debris deposits suggests that several events in the Mackenzie Mountains can be interpreted in the same manner. Key words: rock avalanches, rock slides, debris transport, debris flow modelling, Mackenzie Mountains, Northwest Territories.

Cliff collapse and rock avalanches (sturzstroms) in the Mackenzie Mountains, northwestern Canada

1979 ◽  
Vol 16 (2) ◽  
pp. 309-334 ◽  
Author(s):  
G. H. Eisbacher
Keyword(s):  
Roller Bearing ◽  
Maximum Level ◽  
Static Friction ◽  
Bedding Plane ◽  
Mechanical Analysis ◽  
Fault Scarp ◽  
Earthquake Activity ◽  
Seismic Zone ◽  
Rock Avalanches ◽  
Mackenzie Mountains

Cliff collapse and resulting rock avalanches or sturzstroms have occurred widely in carbonate formations of the Mackenzie Mountains, northwestern Canada. Some of the rock slides are close to a Holocene fault scarp and may be due to past earthquake activity. The Mackenzies are located within an intraplate seismic zone; presently monitored seismic activity may not indicate the maximum level of ground motion that caused failure of large rock slopes during the last 10 000 years. At several localities at least two generations of slide material can be recognized. All major sturzstroms originated by failure above inclined bedding plane surfaces, ranging in dip from 13–40°.The mechanical analysis of dry sturzstroms has to consider two stages: failure and streaming. Failure can occur by either 'sliding' (static friction of about tan 30°) or 'roller bearing' and internal collapse (kinetic friction as low as tan 13°). Streaming is initiated by momentum transfer from the back of a collapsing cliff to its frontal disintegrating portion and facilitated by dispersion of large blocks in finer interstitial material. Prediction of reach or excessive travel distance of dry sturzstroms is not a simple matter and one has to consider the effect of slide mass, fall height, topographic constraints, and lithology. The best method of predicting reach in a potential sturzstrom situation is comparison with documented sturzstroms in similar geologic, climatic, and topographic settings.

scholarly journals Stress level effect on mobility of dry granular flows of angular rock fragments

Landslides ◽  
2021 ◽  
Author(s):  
B. Cagnoli
Keyword(s):  
Stress Level ◽  
Granular Flow ◽  
High Stress ◽  
Granular Flows ◽  
Flow Dynamics ◽  
Small Scale ◽  
Flow Volume ◽  
Rock Fragments ◽  
Rock Avalanches ◽  
Flow Mobility

AbstractGranular flows of angular rock fragments such as rock avalanches and dense pyroclastic flows are simulated numerically by means of the discrete element method. Since large-scale flows generate stresses that are larger than those generated by small-scale flows, the purpose of these simulations is to understand the effect that the stress level has on flow mobility. The results show that granular flows that slide en mass have a flow mobility that is not influenced by the stress level. On the contrary, the stress level governs flow mobility when granular flow dynamics is affected by clast agitation and collisions. This second case occurs on a relatively rougher subsurface where an increase of the stress level causes an increase of flow mobility. The results show also that as the stress level increases, the effect that an increase of flow volume has on flow mobility switches sign from causing a decrease of mobility at low stress level to causing an increase of mobility at high stress level. This latter volume effect corresponds to the famous Heim’s mobility increase with the increase of the volume of large rock avalanches detected so far only in the field and for this reason considered inexplicable without resorting to extraordinary mechanisms. Granular flow dynamics is described in terms of dimensionless scaling parameters in three different granular flow regimes. This paper illustrates for each regime the functional relationship of flow mobility with stress level, flow volume, grain size, channel width, and basal friction.

Potassium–argon ages of intrusion and scheelite mineralization, Cantung, Tungsten, Northwest Territories

1978 ◽  
Vol 15 (7) ◽  
pp. 1205-1207 ◽  
Author(s):  
Douglas A. Archibald ◽  
Alan H. Clark ◽  
Edward Farrar ◽  
U Khin Zaw
Keyword(s):  
Northwest Territories ◽  
Late Stage ◽  
Upper Cretaceous ◽  
Quartz Monzonite ◽  
Mackenzie Mountains ◽  
Tungsten Mineralization

K–Ar dating of magmatic biotite, and of hydrothermal biotite and muscovite, demonstrates that quartz monzonite intrusion and exoskarn scheelite mineralization at Cantung, N.W.T., took place over a brief interval in the Upper Cretaceous (ca. 91 Ma). The regional age relationships of magmatic and ore-forming activity in the Logan–Mackenzie Mountains are poorly defined, but it is tentatively inferred that tungsten mineralization may have been related to a late stage in the plutonic development of the area.

Application of a New Rheological Model to Rock Avalanches: An SPH Approach

2016 ◽  
Vol 49 (6) ◽  
pp. 2353-2372 ◽  
Author(s):  
D. Manzanal ◽  
V. Drempetic ◽  
B. Haddad ◽  
M. Pastor ◽  
M. Martin Stickle ◽  
...  
Keyword(s):  
Rheological Model ◽  
Rock Avalanches

Discrete modelling of rock avalanches: sensitivity to block and slope geometries

2015 ◽  
Vol 17 (5) ◽  
pp. 645-666 ◽  
Author(s):  
Guilhem Mollon ◽  
Vincent Richefeu ◽  
Pascal Villard ◽  
Dominique Daudon
Keyword(s):  
Rock Avalanches ◽  
Discrete Modelling

Recurrent rock avalanches progressively dismantle mountain ridges in the Longmen Shan, China, most recently in the 2008 Wenchuan earthquake

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Slope Failure ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Ground Vibration ◽  
Source Area ◽  
Slope Failures ◽  
Rock Avalanches ◽  
Beichuan County

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>

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