Multi-modelling for a slope-scale deformation evolving from mass rock creep to rock avalanche

2016 ◽  
pp. 805-812
Author(s):  
M Della Seta ◽  
C Esposito ◽  
G Marmoni ◽  
S Martino ◽  
G Mugnozza ◽  
...  
Keyword(s):  
Rock Avalanche ◽  
Rock Creep ◽  
Mass Rock

Multi-modelling for a slope-scale deformation evolving from mass rock creep to rock avalanche

2018 ◽  
pp. 805-812
Author(s):  
M. Della Seta ◽  
C. Esposito ◽  
G.M. Marmoni ◽  
S. Martino ◽  
G. Scarascia Mugnozza ◽  
...  
Keyword(s):  
Rock Avalanche ◽  
Rock Creep ◽  
Mass Rock

scholarly journals Reconstruction of river valley evolution before and after the emplacement of the giant Seymareh rock avalanche (Zagros Mts., Iran)

2019 ◽  
Vol 7 (4) ◽  
pp. 929-947 ◽  
Author(s):  
Michele Delchiaro ◽  
Marta Della Seta ◽  
Salvatore Martino ◽  
Maryam Dehbozorgi ◽  
Reza Nozaem
Keyword(s):  
Slope Failure ◽  
Rock Avalanche ◽  
Evolutionary Model ◽  
River Valley ◽  
Time To Failure ◽  
Stress Release ◽  
Seismic Triggering ◽  
Rock Creep ◽  
Before And After

Abstract. The Seymareh landslide, detached ∼10 ka from the northeastern flank of the Kabir-kuh fold (Zagros Mts., Iran), is recognized worldwide as the largest rock slope failure (44 Gm3) ever recorded on the exposed Earth surface. Detailed studies have been performed that have described the landslide mechanism and different scenarios have been proposed for explaining the induced landscape changes. The purpose of this study is to provide still missing time constraints on the evolution of the Seymareh River valley, before and after the emplacement of the Seymareh landslide, to highlight the role of geomorphic processes both as predisposing factors and as response to the landslide debris emplacement. We used optically stimulated luminescence (OSL) to date lacustrine and fluvial terrace sediments, whose plano-altimetric distribution has been correlated to the detectable knickpoints along the Seymareh River longitudinal profile, allowing the reconstruction of the evolutionary model of the fluvial valley. We infer that the knickpoint migration along the main river and the erosion wave propagation upstream through the whole drainage network caused the stress release and the ultimate failure of the rock mass involved in the landslide. We estimated that the stress release activated a mass rock creep (MRC) process with gravity-driven deformation processes occurring over an elapsed time-to-failure value on the order of 102 kyr. We estimated also that the Seymareh damming lake persisted for ∼3500 years before starting to empty ∼6.6 ka due to lake overflow. A sedimentation rate of 10 mm yr−1 was estimated for the lacustrine deposits, which increased up to 17 mm yr−1 during the early stage of lake emptying due to the increased sediment yield from the lake tributaries. We calculated an erosion rate of 1.8 cm yr−1 since the initiation of dam breaching by the Seymareh River, which propagated through the drainage system up to the landslide source area. The evolutionary model of the Seymareh River valley can provide the necessary constraints for future stress–strain numerical modeling of the landslide slope to reproduce the MRC and demonstrate the possible role of seismic triggering in prematurely terminating the creep-controlled time-to-failure pathway for such an extremely large case study.

scholarly journals The 1998 Tatopani Landslide in the Kali Gandaki Valley of Western Nepal: cause and relation to mass rock creep

2000 ◽  
Vol 22 ◽  
Author(s):  
Hellmut R. Volk
Keyword(s):  
Slope Instability ◽  
Low Grade ◽  
Left Bank ◽  
Main Central Thrust ◽  
Slope Movements ◽  
Wedge Failure ◽  
Rock Avalanches ◽  
Rock Creep ◽  
Mass Rock ◽  
The Village

The village of Tatopani lies on a small gravel terrace in the middle reach of the Kali Gandaki River, along a narrow course of about 2 km in length. One kilometre south of the village, a major rockfall occurred recently in the region of the Lesser Himalaya, which is built up of low-grade metamorphic rocks of the Kuncha Group, consisting of a thick sequence of foliated phyllites and bedded quartzites as well as interlayering of both lithologies. The monoclinal structure of these metasedimentary rocks is clearly related to the general trend of the Nepal Himalaya near the Main Central Thrust (MCT): strike NW-SE 140- 150°, dip 25-45° NE. Besides a clear foliation in the phyllites (s1) parallel to the quartzite bedding (s0), four other discontinuities are also developed as steep joints (j1-j4). Two joint sets j1 and j2, both crossing each other and both acting in conjunction with the foliation (s1) as a shear plane, were responsible for the wedge failure of the Tatopani Landslide, which led to a rockfall and avalanche of about 400,000 cubic metres and dammed the river for about 72 hours. It is noteworthy that several other - strikingly similar but older - weathered wedge failure surfaces are exposed at various spots all over the same ridge, which is the spur-ridge dividing the Kali Gandaki River from the Gar Khela tributary. This visible slope instability evidenced by relatively small wedge failures is causally connected with a much larger mechanism, namely mass rock creep or "sagging"- a purely gravitational slope deformation. The repeatedly occurring wedge failures producing landslides (rockfalls and rock avalanches) are caused by extreme shear stress and deep-reaching joints and fissures during mass rock creep. Only the final trigger for landslides or rockfalls is provided by extreme and lengthy monsoon rainstorms, which reinforce the cleft-water pressure inside rock discontinuities and openings, especially along the impermeable interface of quartzites and phyllites (s0 =s1) at the base of the wedge failure. The right (western) bank above the village is morpho-dynamically active also through mass rock creep and “pushes” laterally against the river course. However, the kinematics of the rock slope is rather different because the foliation geometry is more important. The foliation dips obliquely towards the riverside and consequently has facilitated extremely slow large­ scale dip slope movements along quartzite-phyllite interfaces (s0) without any catastrophic danger. However, the creeping slope movements of thick quartzite: members caused a set of conjugate extension faults producing toppling at the distal slope margins. Rock avalanches from the spur-ridge on the eastern (left) bank of the Kali Gandaki River S of Tatopani will always remain a threat, especially when excessive seasonal rains increase the cleftwater pressure inside the invisibly slow creeping system of the steep bank in an extraordinary manner.

Thermal monitoring to infer possible interactions between shallow hydrothermal system and slope-scale gravitational deformation of Mt. Epomeo (Ischia Island, Italy)

2021 ◽  
pp. SP519-2020-131
Author(s):  
M. Della Seta ◽  
C. Esposito ◽  
M. Fiorucci ◽  
G. M. Marmoni ◽  
S. Martino ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Inverse Correlation ◽  
Local Stress ◽  
Slope Instability ◽  
Thermal Monitoring ◽  
Monthly Basis ◽  
Content Type ◽  
Rock Creep ◽  
Supplementary Material ◽  
Mass Rock

AbstractGeothermal and volcanic systems are prone to gravity-induced slope instability at different scales. Endogenous magmatic, hydrothermal, and seismic forcings can significantly modify mechanical properties and perturb the local stress field and gravitational equilibrium inducing shallow or slope-scale instabilities. The island of Ischia, which is part of the Phlegrean Volcanic District (Italy), is a remarkable example of this kind of complex interacting system. This study focuses on monitoring the hydrothermal system located beneath the ongoing slope-scale deformation, which involves Mt. Nuovo (the western part of Mt. Epomeo) and is a complementary effect of the resurgence of an ancient caldera. Debris and rock avalanches have affected the slopes of this volcanic island, in response to the renewal of volcanic activity and caldera resurgence. Large parts of the corresponding mass-wasting deposits overlay the most active areas of the Ischia hydrothermal system, where ongoing slope-scale gravity-driven deformation due to a mass rock creep (MRC) process is still evolving. To investigate possible relations between the perturbing shallow hydrothermal system and the MRC process, thermal monitoring of selected groups of fumarolic emissions located in several portions of the deforming sector has been carried out since 2008 on a monthly basis by means of direct (thermal probes) and remote sensing (IR-thermography) techniques. Thermal monitoring of specific fumaroles shows a peculiar seasonal trend characterised by a delayed inverse correlation with rainy periods and a short-term pulsating response to dry stages. The fumaroles also appear spatially correlated to the presence of MRC-related structures involving volcanic slopes. According to the measured thermal data, a conceptual model of the thermal interactions within the Mt. Nuovo slope is provided, framing the potential role of thermal actions in accelerating the deformation process. In this view, possible hazard scenarios, due to magmatic or hydrothermal renovation are depicted, delineating the interconnected multi-hazard worst scenario consisting of an accelerating evolution of the MRC process towards paroxysmal collapse.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5497819

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