Rockslide-debris avalanche of May 18, 1980, Mount St. Helens Volcano, Washington

Glicken, Harry

doi:10.3133/ofr96677

Cited by 158 publications

(84 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(a) Sketch of the initial dome and edifice geometry characterizing the 18 May 1980 blast at Mount St. Helens [ Esposti Ongaro et al , 2011a; modified after Glicken , 1996]. The surface of slide block I is indicated by dotted line.…”

Section: Multiphase Flow Modelmentioning

confidence: 99%

“…The granulometric spectrum of juvenile particles [ Hoblitt et al , 1981; Druitt , 1992; Glicken , 1996] was approximated by adopting three particle classes with equivalent hydraulic diameters [ Burgisser and Gardner , 2006] of 3,250 μ m (35 wt.%), 150 μ m (37 wt.%) and 13 μ m (28 wt.%), and densities of 1,900, 2,300 and 2,500 kg/m 3 , respectively. For the eroded substrate and fragmented country rocks we adopted one particle class, with 500 μ m diameter and 2,500 kg/m 3 density (Table 1 and Appendix B).…”

Section: Multiphase Flow Modelmentioning

confidence: 99%

See 1 more Smart Citation

Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens

Ongaro¹,

Clarke²,

Voight³

et al. 2012

J. Geophys. Res.

View full text Add to dashboard Cite

[1] The dynamics of the May 18, 1980 lateral blast at Mount St. Helens, Washington (USA), were studied by means of a three-dimensional multiphase flow model. Numerical simulations describe the blast flow as a high-velocity pyroclastic density current generated by a rapid expansion (burst phase, lasting less than 20 s) of a pressurized polydisperse mixture of gas and particles and its subsequent gravitational collapse and propagation over a rugged topography. Model results show good agreement with the observed large-scale behavior of the blast and, in particular, reproduce reasonably well the front advancement velocity and the extent of the inundated area. Detailed analysis of modeled transient and local flow properties supports the view of a blast flow led by a high-speed front (with velocities between 100 and 170 m/s), with a turbulent head relatively depleted in fine particles, and a trailing, sedimenting body. In valleys and topographic lows, pyroclasts accumulate progressively at the base of the current body after the passage of the head, forming a dense basal flow depleted in fines (less than 5 wt.%) with total particle volume fraction exceeding 10 À1 in most of the sampled locations. Blocking and diversion of this basal flow by topographic ridges provides the mechanism for progressive current unloading. On ridges, sedimentation occurs in the flow body just behind the current head, but the sedimenting, basal flow is progressively more dilute and enriched in fine particles (up to 40 wt.% in most of the sampled locations). In the regions of intense sedimentation, topographic blocking triggers the elutriation of fine particles through the rise of convective instabilities. Although the model formulation and the numerical vertical accuracy do not allow the direct simulation of the actual deposit compaction, present results provide a consistent, quantitative model able to interpret the observed stratigraphic sequence.

show abstract

Section: Multiphase Flow Modelmentioning

confidence: 99%

Section: Multiphase Flow Modelmentioning

confidence: 99%

Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens

Ongaro¹,

Clarke²,

Voight³

et al. 2012

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…By contrast, in natural conditions the volume of rock is initially roughly cohesive before failing: it is only during the flow that rocks experience multiple fragmentations. As a consequence, the deposit of a rockslide usually consists of a very wide range of fragment sizes (from nanometers to meters): the subsurface material in long runout rock avalanches has been observed in diverse geological conditions to be composed of highly fragmented parent material [ Cruden and Hungr , ; Ui et al , ; Fauque and Strecker , ; Glicken , ; Schneider and Fisher , ]. This wide size distribution results in particle segregation by size: the largest particles usually accumulate at the front and at the surface of the deposit, laying on top of a basal layer of finer particles [ Cruden and Hungr , ; Hewitt , ; Yarnold , ; Davies et al , ; Bernard et al , ].…”

Section: Introductionmentioning

confidence: 99%

Collapse of a two‐dimensional brittle granular column: Implications for understanding dynamic rock fragmentation in a landslide

2015

View full text Add to dashboard Cite

International audienceWe investigate numerically the failure, collapse, and flow of a two-dimensional brittlegranular column over a horizontal surface. In our discrete element simulations, we consider a verticalmonolayer of spherical particles that are initially held together by tensile bonds, which can be irreversiblybroken during the collapse. This leads to dynamic fragmentation within the material during the flow.Compared to what happens in the case of a noncohesive granular column, the deposit is much rougher,and the internal stratigraphic structure of the column is not preserved during the collapse. As has beenobserved in natural rockslides, we find that the deposit consists of large blocks laying on a lower layer offine fragments. The influence of the aspect ratio of the column on the runout distance is the same as inthe noncohesive case. Finally, we show that for a given aspect ratio of the column, the runout distance ishigher when the deposit is highly fragmented, which confirms previous hypotheses proposed by Davieset al. (1999)

show abstract

“…Sector collapses create debris avalanche deposits, which are often hummocky in their upper reaches due to large intact blocks from the source area, and have natural levees at their margins [ Ui , 1983; Siebert , 1984; Glicken , 1996; Ui et al , 2000]. This is also true at volcanic islands where most of the slide deposits are underwater [ Moore et al , 1989; Holcomb and Searle , 1991; Mitchell et al , 2002; Oehler et al , 2004].…”

Section: Discussionmentioning

confidence: 99%

Cyclic eruptions and sector collapses at Monowai submarine volcano, Kermadec arc: 1998–2007

Chadwick

Wright

Schwarz-Schampera

et al. 2008

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Repeated multibeam bathymetric surveys at Monowai Cone, a shallow submarine basaltic volcano and part of the Monowai Volcanic Center in the northern Kermadec arc, were conducted in 1998, 2004, and 2007. These surveys document dramatic depth changes at the volcano including negative changes up to −176 m from two sector collapses and positive changes up to +138 m from volcanic reconstruction near the summit and debris avalanche deposits downslope of the slide scars. One sector collapse occurred on the SE slope between 1998 and 2004 with a volume of ∼0.09 km3, and another occurred on the SW slope between 2004 and 2007 with a volume of ∼0.04 km3. The volume of positive depth change due to addition of volcanic material by eruption is of the same order: ∼0.05 km3 between 1998 and 2004 and ∼0.06 km3 between 2004 and 2007. During these time intervals, monitoring by the Polynesian Seismic Network detected frequent T wave swarms at Monowai, indicative of explosive eruptive activity every few months. An unusual T wave swarm on 24 May 2002 was previously interpreted as the collapse event between the 1998 and 2004 surveys, but no similarly anomalous T waves were detected between 2004 and 2007, probably because the Polynesian Seismic Network stations were acoustically shadowed from the second slide event. We interpret that the sector collapses on Monowai are caused by the unstable loading of fragmental erupted material on the summit and steep upper slopes of the volcano (>20°). Moreover, there appears to be a cyclic pattern in which recurrent eruptions oversteepen the cone and periodically lead to collapse events that transport volcaniclastic material downslope to the lower apron of the volcano. Volumetric rate calculations suggest that these two processes may be more or less in equilibrium. The repeated collapses at Monowai are relatively modest in volume (involving only 0.1–0.5% of the edifice volume), have occurred much more frequently than is estimated for larger debris avalanches at subaerial volcanoes, and may be characteristic of how persistently active shallow submarine arc volcanoes grow.

show abstract

Rockslide-debris avalanche of May 18, 1980, Mount St. Helens Volcano, Washington

Cited by 158 publications

References 72 publications

Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens

Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens

Collapse of a two‐dimensional brittle granular column: Implications for understanding dynamic rock fragmentation in a landslide

Cyclic eruptions and sector collapses at Monowai submarine volcano, Kermadec arc: 1998–2007

Contact Info

Product

Resources

About