This approach is thus easier to use and computationally cheaper than models simulating the dynamics of each solid or fluid particle, and allows to model the dynamics and the geometry of the flows more finely than purely empirical models.Three research issues are considered in this work. We test the SHALTOP numerical model with an empirical rheology described only one or two parameters, in order to facilitate its operational use. Thin-layer equations model the propagation of a flow on a topography and give its thickness, and its depth-averaged velocity. In this work, we assess the possibility to use empirical thin-layer models to enhance propagation hazard estimation for gravitational flows. We estimate that between 3.5 × 10^6 m3 and 8.3 × 10^6 m3 could still be mobilized by future destabilizations in the coming decades. Our analysis suggests that the destabilizations occurring on the cliff may be associated to the re opening of a paleo-valley filled by pyroclastic materials. We use the Samperre cliff in Martinique (Lesser Antilles, French West Indies) as a study site, where recurrent destabilizations since at least 1988 have produced debris flows that threaten populations and infrastructures. We use ortho-photographs, aerial views and topographic surveys to (i) describe the different geological units of the cliff, (ii) identify stable and unstable units, (iii) infer the paleo-morphology of the site and (iv) estimate potential unstable volumes. In this work, we show how remote observations can be used to estimate the surface envelope of an unstable mass on a volcanic cliff. Geometry characterization is all the more complex when unstable masses are located in steep and hardly accessible landscapes, which limits data acquisition. Indeed, it results in complex layering geometries where the interfaces between geological layers may be neither parallel nor planar. This characterization can be particularly difficult in volcanic context due to the succession of deposition and erosion phases. For hazard assessment, it is of prior importance to estimate the geometry and volume of potential unstable masses. Gravitational instabilities can be significant threats to populations and infrastructures. The topics bear on understandin hazardous edifice and dome failures, and the measures to anticipate such failures. Case examples discusse include edifice instability at Mt St Helens, USA, and Soufriere Hills volcano, Montserrat, the stability of lava spines a Mont Pelee, Martinique, and Lamington, Papua New Guinea, and lavadome stability at Soufriere Hills. Some aspect of material property evaluation, analysis procedures, and implications on monitoring are also discussed. The primary focus of the presentatio is on mechanisms and factors associated with collapse, the geometric factors, augmented loading by magma, localized strengt reduction by physical and chemical changes (the latter commonly associated with hydrothermal processes), strain weakening pore-fluid (water or gas) pressure enhancement, retrogressive failure, time-dependent failure, and seismic shaking. This paper examines some aspects of current understanding of edifice and lavadome instability. Collapses of growing lava domes are more frequent, are similar in many ways, to edifice collapse, and can directly generate devastating pyroclastic currents. Hazards derive from the debris avalanches themselves from associated explosive activity that ranges from vertical eruptions (often accompanied by pyroclastic currents) to devastatin directed blasts, from associated lahars, and from tsunamis. More than 20 major slope failures have occurred worldwid over the past 500 years, a rate exceeding that of caldera collapse. NB.Slope failures resulting from structural instability of andesitic volcanic edifices can generate mobile debris avalanche that travel long distances down or beyond the flanks of volcanoes. Please remember that you can jump across all league classes, but DO need to only jump within classes eligible for Bronze League Points if you wish to aim for the Bronze League Championships. Information on the how Bronze League Points are allocated for classes run between 85cm – 1.10m and on the Bronze League Championships can be found within your National Member Handbook which can also be found online here.Ĭlick here for a class guide to the Bronze League and for a guide on how to qualify for the Bronze League Championships. There are eight Regional Bronze Horse/Rider Combination Leagues and the league that you will accrue points in is determined by your postcode. If you are unsure of the region you reside in, please log in to your account via Membership Online where it will be displayed within ‘Member Details’. The following is only relevant to those Members who wish to contest the Bronze League Championships.
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