Reply to comment by Iverson on “The reduction of friction in long runout landslides as an emergent phenomenon”

Johnson, Brandon C.; Campbell, Charles S.; Melosh, H. J.

doi:10.1002/2016jf004093

Cited by 5 publications

(2 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent studies of debris avalanches have indicated the necessity of the normal stress reduction in debris avalanches (Pudasaini & Miller, 2013), which is also supported by experimental (R H Iverson, 1997;R M. Iverson & Vallance, 2001) and numerical (Gueugneau et al, 2017;Iverson et al, 2015;Lucas et al, 2014) studies. Nevertheless, this is currently the source of active debate (Davies & McSaveney, 2016;Iverson, 2016;Johnson et al, 2016aJohnson et al, , 2016bJohnson et al, , 2016c.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Mobility in Concentrated Pyroclastic Density Currents: An Examination of a Self‐Fluidization Mechanism

Bréard

Dufek

Lube

2018

Geophysical Research Letters

View full text Add to dashboard Cite

Pyroclastic density currents (PDCs) are a significant volcanic hazard. However, their dominant transport mechanisms remain poorly understood, in part because of the large variability of PDC types and deposits. Here we combine field data with experimental and numerical simulations to illuminate the twofold fate of particles settling from an ash cloud to form the dense PDC basal flow. At solid fractions >1 vol %, heterogeneous drag leads to formation of mesoscale particle clusters that favor rapid particle settling and result in a mobile dense layer with significant bed weight support. Conversely, at lower concentrations the absence of particle clusters typically leads to formation of poorly mobile dense beds that deposit massive layers. Based on this transport dichotomy, we present a numerical dense‐dilute parameter that allows a PDC's dominant transport mechanism to be determined directly from the deposit geometry and grainsize characteristics.

show abstract

Section: Discussionmentioning

confidence: 99%

Enhanced Mobility in Concentrated Pyroclastic Density Currents: An Examination of a Self‐Fluidization Mechanism

Bréard

Dufek

Lube

2018

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Water plays an important role for the amount and rate of entrainment and erosion (Iverson and Ouyang, 2015). Especially for rock avalanches traveling on ice (Huggel et al, 2008;Deline et al, 2015;Bessette-Kirton et al, 2018;Walter et al, 2020) or wet, soft sediments (e.g., lake sediments, Figure 2E), the increased pore pressure enhances the scour of the bed, reduces basal friction and causes velocity, mass and momentum to increase (Iverson et al, 2011;Iverson, 2016;Johnson et al, 2016). Pure ice has a basal friction which is about 75% lower than that of pure rock.…”

Section: Erosion/entrainment/role Of Watermentioning

confidence: 99%

Conceptual Framework of Energy Dissipation During Disintegration in Rock Avalanches

Knapp

Krautblatter

2020

Front. Earth Sci.

View full text Add to dashboard Cite

Rock avalanches usually progress through three consecutive phases: Detachment (Phase 1), Disintegration (Phase 2), and Flow (Phase 3). While significant advances have been achieved in modeling Rock Avalanche Phase 1 (Detachment) and Phase 3 (Flow), the crucial link between both during Phase 2 (Disintegration) is still poorly understood. Disintegration of the detached rock mass is often initiated as soon as sliding starts, and in situ measurements are impossible due to the excessive energy release equivalent to multiple nuclear explosions. Better understanding the energy dissipation during Phase 2, and the resulting residual kinetic energy that propels the rock avalanche in Phase 3, is one of the keys to defining the mechanical properties of the avalanche in the runout zone and thus also the resisting force within the avalanche. This paper is a review of our knowledge of energy dissipation in rock avalanches with a focus on processes like friction, collision, fragmentation, comminution, entrainment and explosion during the phase of disintegration. We distinguish between energy sources and sinks and consider not only physical processes, but also chemical alterations that might occur at high temperatures. With that, we make a contribution to improve our understanding of Phase 2 "Disintegration," which is needed for accurately modeling rock avalanches and assessing their hazard potential.

show abstract

Granular avalanches on the Moon: Mass‐wasting conditions, processes, and features

et al. 2017

View full text Add to dashboard Cite

Seven lunar crater sites of granular avalanches are studied utilizing high‐resolution images (0.42–1.3 m/pixel) from the Lunar Reconnaissance Orbiter Camera; one, in Kepler crater, is examined in detail. All the sites are slopes of debris extensively aggraded by frictional freezing at their dynamic angle of repose, four in craters formed in basaltic mare and three in the anorthositic highlands. Diverse styles of mass wasting occur, and three types of dry‐debris flow deposit are recognized: (1) multiple channel‐and‐lobe type, with coarse‐grained levees and lobate terminations that impound finer debris, (2) single‐surge polylobate type, with subparallel arrays of lobes and fingers with segregated coarse‐grained margins, and (3) multiple‐ribbon type, with tracks reflecting reworked substrate, minor levees, and no coarse terminations. The latter type results from propagation of granular erosion‐deposition waves down slopes dominantly of fine regolith, and it is the first recognized natural example. Dimensions, architectures, and granular segregation styles of the two coarse‐grained deposit types are like those formed in natural and experimental avalanches on Earth, although the timescale of motion differs due to the reduced gravity. Influences of reduced gravity and fine‐grained regolith on dynamics of granular flow and deposition appear slight, but we distinguish, for the first time, extensive remobilization of coarse talus by inundation with finer debris. The (few) sites show no clear difference attributable to the contrasting mare basalt and highland megaregolith host rocks and their fragmentation. This lunar study offers a benchmarking of deposit types that can be attributed to formation without influence of liquid or gas.

show abstract

Reply to comment by Iverson on “The reduction of friction in long runout landslides as an emergent phenomenon”

Cited by 5 publications

References 23 publications

Enhanced Mobility in Concentrated Pyroclastic Density Currents: An Examination of a Self‐Fluidization Mechanism

Enhanced Mobility in Concentrated Pyroclastic Density Currents: An Examination of a Self‐Fluidization Mechanism

Conceptual Framework of Energy Dissipation During Disintegration in Rock Avalanches

Granular avalanches on the Moon: Mass‐wasting conditions, processes, and features

Contact Info

Product

Resources

About