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Zekkos, Dimitrios (University of California, Berkeley)
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Science
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- Creator:
- Medwedeff, William, G (University of Michigan Earth & Environmental Science), Clark, Marin, K (University of Michigan Earth & Environmental Science), and Zekkos, Dimitrios (University of California, Berkeley)
- Description:
- The matlab code, digital elevation data, and landslide volume data here support the findings of Medwedeff et al. (2024) in JGR: Earth Surface. In this article, we study past landslides to understand how the strength of rocks and soil vary across the landscape and below the ground. We develop a matlab-based model that uses the length, width, slope angle, and thickness of landslides that have occurred in the past to estimate how strong the rock or soil was before it gave way. We improve upon previous studies by using elevation data from before and after landslides occurred to measure how thick the sliding mass was for each landslide. The thickness measurements help us understand how the strength of the ground changes as a function of depth below the surface, like for example, when rocks get weaker near the surface due to increased weathering. We apply our model to landslides that occurred during earthquakes in Greece and Nepal, and we compare the results to rock strength field data. In addition to our model code, we include in this data repository the landslide volume and elevation data for Nepal and Greece that we used to run our model for this study.
- Keyword:
- landslide, inversion, rock strength, and slope stability
- Citation to related publication:
- Medwedeff, W.G., Clark, M.K., Zekkos, D. (in review 2024) Regional Back-Analysis of Earthquake Triggered Landslide Inventories: a 2D Method for Estimating Rock Strength from Remote Sensing Data. In review in JGR Earth Surface.
- Discipline:
- Science
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Geotechnical observations of weathered rock across a tectonic and climatic gradient in Central Nepal
- Creator:
- Medwedeff, William, G (University of Michigan Earth & Environmental Science), Clark, Marin, K (University of Michigan Earth & Environmental Science), Zekkos, Dimitrios (University of California, Berkeley), West, A., Joshua (University of Southern California), and Chamlagain, Deepak (Tribhuvan University, Kathmandu Nepal)
- Description:
- These datasets support the findings of Medwedeff et al. (2021) in JGR: Earth Surface. In this article, we present seismic and geotechnical characterizations of the shallow subsurface across a 200 km by 50 km swath of the central Himalayan Range, in Nepal. By pairing widely-distributed 1D shear wave velocity surveys and engineering outcrop descriptions per the Geological Strength Index classification system, we evaluate landscape-scale patterns in near-surface mechanical characteristics and their relation to environmental factors known to affect rock strength. We find that near-surface strength is more dependent on the degree of weathering, rather than the mineral and textural differences between the metamorphic lithologies found in the central Himalaya. Furthermore, weathering varies systematically with topography. Bedrock ridge top sites are highly weathered and have S-wave seismic velocities and shear strength characteristics that are more typical of engineering soils, whereas sites near the bedrock channel bottom tend to be less weathered and characterized by high S-wave velocities and shear strength estimates typical of hard rock. Weathering of bedrock on hillslopes is significantly more variable, resulting in S-wave velocities that range between the ridge and channel endmembers. We hypothesize variability in the hillslope environment may be partly explained by the stochastic nature of mass wasting, which clears away weathered material where landslide scars are recent. These results underscore the mechanical heterogeneity in the shallow subsurface and highlight the need to account for bedrock weathering when estimating strength parameters for regional landslide hazard analysis.
- Keyword:
- rock strength, critical zone, shallow seismic, and chemical weathering
- Discipline:
- Science