Agostiny Marrios Lontsi

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Lontsi

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Agostiny Marrios

ORCID

0000-0002-7773-5510

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Publications1 - 10 of 23

Extracting Scholte and Love waves phase-velocity from small aperture Ocean Bottom Seismometer arrays in Lake Lucerne (Switzerland)
Lontsi, Agostiny Marrios; Shynkarenko, Anastasiia; Kremer, Katrina; et al. (2021)
Stability assessment of submerged lateral and deltaic slopes in Lake Lucerne
Shynkarenko, Anastasiia; Stegmann, Sylvia; Kremer, Katrina; et al. (2020)
EGUsphere
Numerous studies indicate that tsunamis do not only occur in oceans but also in lakes. Lake Tsunamis are mainly caused by sublacustrine and subaerial mass movements that can be triggered by seismic or aseismic processes (Schnellmann et al. 2002, Strasser et al. 2007, Kremer at al. 2012, Hilbe and Anselmetti 2015). Such tsunamis can have devastating effects on the surrounding population and infrastructure. To assess the tsunami hazard triggered by sublacustrine mass movements, the stability of the lake slopes needs to be examined. As a part of the SNSF funded SINERGIA project “Lake Tsunamis: Causes, Controls and Hazard”, we perform the slope stability analysis based on the comprehensive geotechnical in situ and laboratory dataset for the selected sites of Lake Lucerne, Central Switzerland. During 2018-2019 dense geotechnical investigations were carried out along slope-perpendicular profiles at 10 sites where the slopes have failed in the past or are susceptible to failure and included more than 130 in-situ free-fall cone penetration tests with pore pressure measurement (CPTu) and laboratory analysis of 30 short sediment cores. Already existing reflection seismic dataset complements these data and provides the thickness of different sediment layers. 1D undrained, infinite slope stability analysis following Morgenstern and Price (1965) is used to define the Factor of Safety and critical conditions for deltaic and lateral slopes, where different triggers can be responsible for the failure. Based on the conducted analysis, static and dynamic stability together with critical failure conditions for different slopes in Lake Lucerne can be compared.
Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland)
Shynkarenko, Anastasiia; Kremer, Katrina; Stegmann, Sylvia; et al. (2022)
Natural Hazards
Tsunamis occur not only in marine settings but also in lacustrine environments. Most of the lacustrine tsunamis are caused by seismically- or aseismically-triggered mass movements. Therefore, an assessment of the stability of subaqueous slopes is crucial for tsunami hazard assessment in a lake. We selected Lake Lucerne (Switzerland) as a natural laboratory to perform an in-depth geotechnical characterization of its subaqueous slopes. This lake experienced documented tsunamis in 1601 and 1687. Some of its slopes still bear sediment volumes with a potential for tsunamigenic failure. To identify such slopes, we interpreted available reflection seismic data and analyzed the bathymetric map. Then, we performed 152 dynamic Cone Penetration Tests with pore pressure measurement (CPTu) and retrieved 49 sediment cores at different locations in the lake. These data were used to characterize the failure-prone sediments and to evaluate the present-day static stability of subaqueous slopes. Obtained results allowed the definition of three classes of slopes in terms of static stability: unstable slopes, stable slopes close to the unstable state, and stable areas. Non-deltaic slopes with thicker unconsolidated fine-grained sediment drape and moderate-to-high slope gradients (>5-10 degrees) have the lowest Factor of Safety. In agreement with previous studies, the failure plane for the non-deltaic slopes is embedded within the fine-grained glaciolacustrine sediments. Deltaic slopes with prevailing coarse-grained sediments mostly appear statically stable. Finally, we generalized the measured undrained shear strength profiles s(u)(z) into the depth-dependent power-law models. These models define the s(u) of Lake Lucerne's sediments and can be applied to other lakes with similar sedimentation history.
Full microtremor horizontal-to-vertical spectral ratio inversion for the characterization of Swiss borehole and OBS sedimentary sites
Lontsi, Agostiny Marrios; Shynkarenko, Anastasiia; Hobiger, Manuel; et al. (2021)
Abstract Volume 19th Swiss Geoscience Meeting
Revealing the structure of submerged slopes in Lake Lucerne using ambient vibration techniques
Shynkarenko, Anastasiia; Lontsi, Agostiny Marrios; Kremer, Katrina; et al. (2020)
Abstract Volume 18th Swiss Geoscience Meeting
S-Wave Velocity Profiles from Full Microtremor Horizontal-to-Vertical (H/V) Spectral Ratios Inversion Onshore and Offshore
Lontsi, Agostiny Marrios; Shynkarenko, Anastasiia; Hobiger, Manuel; et al. (2021)
6th IASPEI / IAEE International Symposium: Effects of Surface Geology on Seismic Motion - ESG6 Extended Abstracts
Recent theoretical developments in horizontal-to-vertical (H/V) spectral ratio modeling are used to invert the microtremor H/V spectral ratio curves for the shear wave velocity profile at one onshore and one offshore sedimentary site in Switzerland. The H/V forward model uses the seismic interferometry principles under the diffuse field assumption to estimate the imaginary part of the Green’s function for collocated source and receiver. At the onshore site at Buochs, the H/V curves are obtained from a strong motion borehole station with three sensors located at surface, 26, and 100 m depth. At Lake Lucerne (offshore Weggis), the H/V curve is estimated from an ocean bottom seismometer station located on the lake floor at 38.1 m water depth. The inversion of real offshore H/V curves is preceded by a synthetic modeling and inversion where a water layer is considered on top of the best model candidate from H/V inversion at Buochs.
In-situ and laboratory geotechnical investigations (CPTu, sediment coring) performed in Lake Lucerne (Switzerland) in 2018–2020
Shynkarenko, Anastasiia; Kremer, Katrina; Stegmann, Sylvia; et al. (2022)
In the framework of an SNSF-funded SINERGIA project “Lake Tsunamis: Causes, Controls and Hazard” we performed dense geotechnical investigations along the slope-perpendicular profiles at 11 sites in Lake Lucerne, central Switzerland, where the slopes have failed in the past or might be susceptible to future failures. In total, 152 in-situ free-fall cone penetration tests with pore pressure measurement (CPTu) and laboratory analysis of 49 sediment cores were performed. In this report, we present all conducted field investigations, data processing steps, laboratory experiments and results obtained. Based on the acquired data and results of data processing, we produced a comprehensive dataset with geotechnical (e.g. undrained shear strength) and sediment-physical information (e.g. density, compression wave velocity) regarding the different types of sediments and lithologies found on the failure-prone slopes of Lake Lucerne. The derived parameters are important inputs for the analysis of the stability of sublacustrine slopes and the tsunami hazard assessment for Lake Lucerne.
First steps to create a comprehensive geophysical and geotechnical model of submerged slopes in Lake Lucerne
Shynkarenko, Anastasiia; Lontsi, Agostiny Marrios; Kremer, Katrina; et al. (2019)
Abstract Volume 17th Swiss Geoscience Meeting
A seismological survey on Lake Lucerne (Switzerland)
Lontsi, Agostiny Marrios; Shynkarenko, Anastasiia; Kremer, Katrina; et al. (2020)
Abstract Volume 18th Swiss Geoscience Meeting
Geotechnical investigations and slope stability analysis in Lake Lucerne
Shynkarenko, Anastasiia; Kremer, Katrina; Stegmann, Sylvia; et al. (2021)
Abstract Volume 19th Swiss Geoscience Meeting

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Agostiny Marrios Lontsi

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