Instability of the surface of a granular medium behind sliding shock and detonation waves

Борисов, А. А.; Lyubimov, Alexander V.; Kogarko, S. M.; Kozenko, V. P.

doi:10.1007/bf00741621

Cited by 10 publications

(4 citation statements)

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“…Similarly as for the Tower Hill maar, these structures can be the record of shock waves that destabilized the uppermost deposits and transferred them a tilt. Here again, the vortex-like entrainment evidenced in shock experiments supports the interpretation (Borisov et al, 1967;Wayne et al, 2013), and the proximity from the vent make shock wave influence probable. The passage of a shock wave is likely asedimentary (not associated with deposition), and the conformity of overlying fall beds supports a trigger mechanism without sedimentation, the signature being uniquely present as deformation.…”

Section: Deformation Driven By Shock Wavessupporting

confidence: 74%

Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Douillet¹,

Taisne²,

Tsang-Hin-Sun³

et al. 2014

Preprint

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Abstract. Soft-sediment deformation produces intriguing sedimentary structures and can occur in diverse environments and from a variety of triggers. From the observation of such structures and their interpretation in terms of trigger mechanisms, valuable information can be extracted about former conditions. Here we document examples of syn-eruptive deformation in dilute pyroclastic density current deposits. Outcrops from 6 different volcanoes have been compiled in order to provide a broad perspective on the variety of structures: Ubehebe craters (USA), Tungurahua (Ecuador), Soufrière Hills (Montserrat), Laacher See (Germany), Tower Hill and Purrumbete lake (both Australia). Isolated slumps as well as sinking pseudonodules are driven by their excess weight and occur after deposition but penecontemporaneous to the eruption. Isolated, cm-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin–Helmholtz instabilities. Their recognition can be a diagnostic for flows with a granular basal boundary layer. The occurrence of degassing pipes together with basal intrusive dikes suggest fluidization during flow stages, and can facilitate the development of Kelvin–Helmholtz structures. The occurrence at the base of flow units of injection dikes in some outcrops compared with suction-driven local uplifts in others indicates the role of dynamic pore pressure. Variations of the latter are possibly related to local changes between depletive and accumulative dynamics of flows. Ballistic impacts can trigger unconventional sags producing local displacement or liquefaction. Based on the deformation depth, these can yield precise insights into depositional unit boundaries. Such impact structures may also be at the origin of some of the steep truncation planes visible at the base of the so-called "chute and pool" structures. Finally, the passage of shock waves emanating from the vent may be preserved in the form of trains of isolated, fine-grained overturned beds which may disturb the surface bedding without occurrence of a sedimentation phase in the vicinity of a vent. Dilute pyroclastic density currents occur contemporaneously with seismogenic volcanic explosions. They are often deposited on steep slopes and can incorporate large amounts of water and gas in the sediment. They can experience extremely high sedimentation rates and may flow at the border between traction, granular and fluid-escape boundary zones. These are just some of the many possible triggers acting in a single environment, and reveal the potential for insights into the eruptive mechanisms of dilute pyroclastic density currents.

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Section: Deformation Driven By Shock Wavessupporting

confidence: 74%

Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Douillet¹,

Taisne²,

Tsang-Hin-Sun³

et al. 2014

Preprint

View full text Add to dashboard Cite

show abstract

“…Similarly as for the Tower Hill maar, these structures can be the record of shock waves that destabilized the uppermost deposits and conferred them a tilt. Here again, the vortex-like entrainment evidenced in shock experiments supports the interpretation (Borisov et al, 1967;Wayne et al, 2013), and the proximity to the vent make shock wave influence probable. The (d) show the envisaged scenario if destabilization of a and c permitted complete remobilization.…”

Section: Deformation Driven By Shock Wavessupporting

confidence: 74%

“…Valentine et al (1989) suggested shock waves as a possible trigger for overturned flame-like structures. They noted that "when a shock passes over a granular deposit, bed particles experience a lift force due to the change in velocity across the shock" and "the bed immediately behind the shock has been observed in experiments to take on a wavelike configuration" citing the convincing experiments by Borisov et al (1967). Recent shock experiments by Wayne et al (2013) developed recumbent vortex-like shapes on dust beds and further support the interpretation (see also Fedorov, 2004).…”

Section: Deformation Driven By Shock Wavesmentioning

confidence: 93%

Syn-eruptive, soft-sediment deformation of deposits from dilute pyroclastic density current: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Douillet¹,

Taisne

Tsang-Hin-Sun

et al. 2015

Solid Earth

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“…It should be noted here that the large vortex, which is seen in Figs. 3 and 4, resembles the surface instabilities which were photographed by Borisov et al (1967). Kuhl's (1990Kuhl's ( , 1992 calculations show many vortices of similar shape.…”

Section: Introductionmentioning

confidence: 93%

Dust entrainment by means of a planar shock induced vortex over loose dust layers

Ben‐Dor

1995

Shock Waves

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Instability of the surface of a granular medium behind sliding shock and detonation waves

Cited by 10 publications

References 0 publications

Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Syn-eruptive, soft-sediment deformation of deposits from dilute pyroclastic density current: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

Dust entrainment by means of a planar shock induced vortex over loose dust layers

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