Flowing, rolling, bouncing, sliding: Synopsis of basic mechanisms

Avalanche Dynamics

“…The essence of each of these hypotheses is to introduce some type of ftuidization mechanism to produce the high mobility of the large volume rockfalls. Those involve upward ftow of air (Kent, 1986), hovercraft action (Shreve, 1966(Shreve, , 1968, ftuidization by high pressure steam (Goguel, 1978), mechanical ftuidization aided by the presence of interstitial dust (Hsü, 1978), vibrational ftuidization by large earthquakes (McSaveney, 1978), lubrication by a thin layer of molten granular material (molten rock, Erismann, 1979Erismann, , 1986; molten snow at the bed of a ftow avalanche, Hutter, 1991), accoustic ftuidization (Melosh, 1986;Foda, 1994), and the presence of a thin layer of vigorously ftuctuating particles beneath a densely packed overburden (Dent, 1986). Many of these hypotheses can be ruled out: e.g., there is not enough air or water on the Moon and Mars, and earthquakes almost never trigger the motion of an avalanche or rockfall.…”

Numerical modelling of large landslides stability and runout

“…Methods include sliding friction and velocitydependent resistance models for point mass motion (Koerner, 1976(Koerner, , 1977Pariseau and Voight, 1979), point mass velocity-dependent resistance models coupled to digital elevation models (McEwen and Malin, 1989), sliding block models that include friction (Heim, 1932;Crosta, 1991;Erismann and Abele, 2001) and pore-water pressure parameters (Hutchinson, 1986;Sassa, 1988), modified flood prediction models (Jeyapalan et al, 1983;Fread, 1988;Sassa, 1988;O'Brien, 1993), two dimensional and pseudo three-dimensional (Chen and Lee, 2000) depth-averaged Lagrangian frictional models (Hutter and Savage, 1988) or using a wider range of rheological models for the basal highly sheared layer (Hungr, 1995, Amarù andCrosta, 2000), using a discrete element approach (Calvetti et al, 2000), and assuming Coulomb-like behaviour coupled with highly refined mathematical solutions to reach a three-dimensional flow description Denlinger and Iverson, 2001). These models are capable of simulating both runout and velocity distribution along the path under a broad spectrum of capabilities, limitations, and degrees of sophistication.…”

“…Rock and debris avalanches are, for example, a major hazard in mountainous areas and are characterized by an extreme mobility and extremely high velocities. They have been cause of extensive damages and casualties through the centuries as reported in the literature both for non volcanic (Heim, 1932;Abele, 1974;Eisbacher and Clague, 1984;Evans et al, 1987;Evans and Clague, 1988;Evans et al, 1994;Erismann and Abele, 2001), volcanic (Voight et al, 1981;Siebert, 1984;Voight and Sousa, 1994;Sousa and Voight, 1995;Glicken, 1998) and marine environments (Moore et al, 1989) as well as in waste mining dump materials (Kent and Hungr, 1995).…”

“…This difficulty is clearly represented by the large amount of theories and models that have been suggested in the literature (e.g. Heim, 1932;Shreve, 1968;Habib, 1975;Hsu, 1975;Melosh, 1979;Hutter and Savage, 1988;Sassa, 1988;Campbell, 1989;Kilburn and Soresen, 1998;Erismann, 1986;Erismann and Abele, 2001).…”

A laboratory-numerical approach for modelling scale effects in dry granular slides

“…Some of the main scale effects presently identified are the increased slide velocities and runout distances for extremely large events (Johnson et al 2016;Parez and Aharonov 2015). Many have attributed these to secondary factors such as fluidisation via airflow (Savage and Hutter 1989) or acoustics (Collins and Melosh 2003), shear-dependent frictional behaviour (Liu et al 2016), melt-induced self-lubrication (Erismann 1986), and fragmentation (Davies et al 1999;Lucas et al 2014). However, Parez and Aharonov (2015) refute this and state that this increased runout is mainly a product of the granular physics itself, particularly the spreading of mass from the release condition over time.…”