Ground fissures within the Main Ethiopian Rift: Tectonic, lithological and piping controls

Valenta, J.; Verner, K.; Martínek, K.; Hroch, T.; Buriánek, D.; Megerssa, L.A.; Boháč, J.; Kassa, M.; Legesse, F.; Yakob, M.; Kebede, B.; Málek, Jiří

doi:https://dx.doi.org/10.1002/esp.5227

Number of the records: 1

Ground fissures within the Main Ethiopian Rift: Tectonic, lithological and piping controls

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SYSNO ASEP	0551182
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Ground fissures within the Main Ethiopian Rift: Tectonic, lithological and piping controls
Author(s)	Valenta, J. (CZ) Verner, K. (CZ) Martínek, K. (CZ) Hroch, T. (CZ) Buriánek, D. (CZ) Megerssa, L.A. (CZ) Boháč, J. (CZ) Kassa, M. (ET) Legesse, F. (ET) Yakob, M. (ET) Kebede, B. (ET) Málek, Jiří (USMH-B)_{RID, ORCID, SAI}
Number of authors	12
Source Title	Earth Surface Processes and Landforms. - : Wiley - ISSN 0197-9337 Roč. 46, č. 15 (2021), s. 3158-3174
Number of pages	17 s.
Language	eng - English
Country	US - United States
Keywords	geomechanical properties ; pipe collapses ; pyroclastics ; seismic anisotropy ; soil ; subsurface erosion ; surface waves ; unconsolidated sediments
Subject RIV	DB - Geology ; Mineralogy
OECD category	Geology
Method of publishing	Limited access
Institutional support	USMH-B - RVO:67985891
UT WOS	000700628100001
EID SCOPUS	85115722867
DOI	10.1002/esp.5227
Annotation	Ground fissures, especially if they open due to a sudden collapse of the surface, is a serious risk for populated areas. Their common occurrence in unconsolidated sediments of the Main Ethiopian Rift was found to be mostly a result of piping. The fissures start by piping in linear sub-horizontal underground voids, which often propagate upwards resulting in ceiling collapse and formation of deep and long ground fissures with vertical walls. In the southern and central Main Ethiopian Rift the fissures pose a serious risk to infrastructure and settlements. The ground fissures are often linear (up to several kilometres long and often tens of metres deep) and accompanied by sinkholes (along the length). A detailed field mapping of the geological (rock composition, orientation and character of lithological boundaries, primary fabrics and brittle structures) and geomorphological features (especially a length, width and depth of fissures, sinkholes and gullies) followed by in situ seismic anisotropy measurements and a laboratory determination of the geomechanical properties of volcanoclastic deposits was carried out to investigate the ground fissures' origin. The conditions and factors leading to the formation of the ground fissures have been linked to: (a) the presence of regional normal faults and the associated extensional joints and (b) the alternation of lithological units with contrasting hydraulic permeability. The latter corresponds to a sequence of less permeable hard rocks (e.g., rhyolitic ignimbrites) overlain by heterogeneous, soft and permeable, unconsolidated volcaniclastic deposits with a low amount of clay (less than 10%). The ground fissures' occurrence has shown affiliation to areas which have a significantly high seismic anisotropy (more than 20% at the study sites), which can be used as a proxy to map out high risk areas prone to piping and ground fissure formation.
Workplace	Institute of Rock Structure and Mechanics
Contact	Iva Švihálková, svihalkova@irsm.cas.cz, Tel.: 266 009 216
Year of Publishing	2022
Electronic address	https://onlinelibrary.wiley.com/doi/10.1002/esp.5227

Number of the records: 1