{"id":10651,"date":"2021-04-13T09:40:20","date_gmt":"2021-04-13T08:40:20","guid":{"rendered":"https:\/\/www.innovationnewsnetwork.com\/?p=10651"},"modified":"2021-04-13T15:48:11","modified_gmt":"2021-04-13T14:48:11","slug":"understanding-complexity-creeping-landslides-initiation","status":"publish","type":"post","link":"https:\/\/www.innovationnewsnetwork.com\/understanding-complexity-creeping-landslides-initiation\/10651\/","title":{"rendered":"Understanding the complexity of creeping landslides initiation and beyond"},"content":{"rendered":"

Dr Andre Baldermann, Senior Scientist at TU Graz, explains how creeping landslides are initiated and presents a customised engineered solution to help prevent them.<\/h2>\n

Our dynamic Earth is in steady motion, spanning from sub-atomic scale processes to global events. An important side effect of the complex interactions between the different \u2018spheres\u2019 of the Earth, including the atmosphere, anthroposphere, hydrosphere, biosphere, and lithosphere, is the appearance of natural disasters, which can severely impact human beings and our daily lives. While gigantic natural events, like earthquakes, tsunamis, and volcanic eruptions are in the spotlight of current and past scientific investigations, the factors causing the initiation and progression of more local natural phenomena, like continental to submarine landslides, are clearly underexplored.<\/p>\n

Landslides are a common form of ground movements on Earth, which are often triggered by local tectonics, surface erosion, chemical and physical weathering of rocks, sediments or soil masses, and gravitational influences, and they are modulated by case-specific hydrological, mineralogical, biological, and geotechnical factors.1-3<\/sup> The destabilisation of the slide masses through a reduction of shear strength of the formerly stable (under)ground is typically driven by a range of geogenic factors, like heavy rainfalls, groundwater fluctuations, changes in pore (water) pressures and earth eruptions. However various anthropogenic (man-made) factors also frequently result in underground failure and sliding activities, like deforestation, traffic and transportation actions, earthworks, and urbanisation, or a combination of all these potential triggers.<\/p>\n

The results are manifold natural disasters, which may express as rock falls, mudflows, debris flows, hillslope deformation and soil liquefaction that may, in all cases, damage critical infrastructure or, in severe cases, cost human life. The economic damage arising from landslides and hillslope debris flows around the world cost billions of euro every year.4<\/sup><\/p>\n

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Fig. 1: Digital elevation model of a landslide area, which affected the state route and adjacent areas for more than five decades (super-elevation: two-times; modified after Reference 1)<\/figcaption><\/figure>\n

An overlooked hotspot<\/h3>\n

Advanced knowledge of how the diverse physical, hydrological, anthropogenic, and biochemically-coupled factors initiate landslides is a prerequisite for the development of site-specific conceptual process models and, more importantly, for the realisation of adequate prevention strategies. Unfortunately, more recent concepts are limited to regions possessing a high geohazard potential, like deep-seated gravitational slope deformations or nuclear waste disposal sites, and only a few concepts are focused on urban areas and\/or local infrastructure.5<\/sup> Landslides occurring near highway roads or state roads are an example of such critical but currently overlooked hotspots. In severe cases, episodic deformations taking place in mostly fine-grained sediments require cost-intensive route repair measures, whilst their success is not always guaranteed, if the total system\u2019s behaviour remains partly unknown (see Fig. 1).<\/p>\n

Total system assessment<\/h3>\n

The identification of the interaction mechanisms between geogenic and anthropological factors is the key to understanding our dynamic Earth and, in particular, landslides. Without detailed knowledge provided by engineers, geologists, ecologists, and other Earth Science disciplines, a total system assessment may be difficult to achieve. However, the \u2018toolbox\u2019 of Earth scientists is enormous and has continued to rise in recent decades,6 <\/sup>which allows us to make use of multi-methodological approaches that combine, for example, field work to establish terrain models, core logging to define soil-mechanical parameters, analysis of waters and solid matter to understand how weathering and alteration reactions destabilise the underground through the development of sliding horizons over millions of years, and experimental approaches to assess how anthropogenic factors (use of de-icing salts and agricultural fertilisers) can seasonally modify the slide masses.1<\/sup><\/p>\n

In fine-grained sediments, the type and distribution of clay minerals are of fundamental importance to landslides, as they are highly sensitive to variations of the ambient climatic and environmental conditions; a fact that is too often ignored.7<\/sup> In light of increasing negative effects arising from global warming, like the expected increase in rainstorm intensity,8,9<\/sup> the site-specific triggering factors causing landslide initiation and progression, as well as the reactivation of dormant mass movements, must be identified to develop customised, engineered solutions for proactive environmental protection (see Fig. 2).<\/p>\n

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Fig. 2: Cartoon showing the complexity of the potential triggers for landslides (modified after Reference 1)<\/figcaption><\/figure>\n

Site-specific solutions and beyond<\/h3>\n

Very often, small adaptions to the construction of road infrastructure can greatly improve the total system\u2019s behaviour, with the most critical aspect being the design of the de-watering system: the choice of using longitudinal-drainage elements vs cross-drainage elements, for example, controlling the dynamics of the water discharge which subsequently impacts:<\/p>\n