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

Geothermal 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

Impact of draw velocity profile on footprint definition for primary rock

In block/panel caving mines the footprint geometry and the undercut level height are key planning elements that have a bearing on the project final value. Selection of these parameters obviously depends on the economic objective, but it is also strongly influenced by rock mass characteristics that define column extraction capacity from draw points. This paper presents a simple methodology that allows defining the footprint and the best height of draw (BHOD) based on column extraction velocities, which are defined with the aim of controlling mass rock dynamic response while caving is propagated. The proposed methodology can be used by industry because of the ease of application. A study case is presented for a block model which is evaluated by both the proposed methodology and nominal profit estimation.

New Approach for the Extraction Method of Landslide-Prone Slopes Using Geomorphological Analysis: Feasibility Study in the Shikoku Mountains, Japan

In recent years, airborne laser scanning has been used for terrain surveys of broad areas in Japan. This study attempted to extract the landslide-prone slope based on geomorphological and slope stability analyses using Digital Elevation Model obtained by airborne laser scanning. The study site is located in the mountainous region of the Shikoku Mountains, where landslides occur on the gentle slope deformed by mass rock creeps. Implementing slope stability analysis to incorporate “potential to increase pore water pressure” found that landslides occur in areas with low factor of safety. In the future, it is expected that the method developed in this study could contribute to the planning of basin-based disaster management.

Evaluation of tectonics and landscape evolution as predisposing factor for a Mass Rock Creep deforming slope in the Zagros Belt (Iran)

<p>In the hillslope landscapes of tectonically active regions, the steep topography represents the most evident result of rock uplift, valley incision and landslide erosion. In response to rock uplift, relief and hillslope dip increase linearly in time mainly due to fluvial erosion processes in landscapes affected by low to moderate tectonic forcing. Nonetheless, such a linear increase in relief and hillslope dip is limited by the reaching of threshold slope conditions associated with the hillslope material strength, until the latter is exceeded by gravitational stress giving rise to bedrock landslides. In this regard, Mass Rock Creep (MRC) process may become a primary factor for damaging rock masses so leading to slope failures that generate huge rock avalanches. MRC acts on large time-space scale through a continuous and non-linear variation of stress-strain conditions of entire portions of slopes and the coupled role of tectonics and landscape evolution represents a predisposing factor for Deep Seated Gravitational Slope Deformations (DSGSD).</p><p>This research focused on the Loumar DSGSD that affects the NE slope of the Palganeh anticline in the Lorestan region (Zagros Mts., Iran), almost 90 km northwest of the Seymareh landslide which is more famous as it represents the largest landslide on Earth surface. The Loumar DSGSD evolution is strictly related to the vertical and lateral growth of the fold and to the evolution of the Seymareh river drainage system that kinematically released the slope at the bottom likely causing the initiation of the deformational process. We combined an inverse modelling of the river profiles linked to the fold uplift history and the analysis of a plano-altimetric distribution of geomorphic markers, correlated to the detectable knickpoints along the river longitudinal profiles, which allowed to constrain the main morpho-evolutionary stages of the valley. These data will be used to constrain a Landscape Evolution Model (LEM) and a stress-strain numerical model, to be performed under time-dependent creep conditions, that will be calibrated by a back analysing the slope evolution from the LEM. The final goal will be to discuss the possible role of impulsive triggers (earthquakes) in anticipating the time-to-failure of the MRC deformational process.</p>