What kind of volcanite the rock-hewn churches of the Lalibela UNESCO's world heritage site are made of?

Renzulli, Alberto; Antonelli, Fabrizio; Margottini, Claudio; Fratini, Fabio

doi:10.1016/j.culher.2010.11.003

Cited by 12 publications

(6 citation statements)

References 14 publications

(31 reference statements)

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“…The presence of montmorillonite and analcite are reported by other workers (Delmonaco et al, 2009;Renzullia et al, 2011) as the sources of the progressive deterioration of the geomechanical properties of the rocks in Lalibela. In the present study, we bring attention to the presence of kaolinite, gypsum and whewellite/weddellite not identified before on the rock hewn churches of Lalibela, besides the presence of montmorillonite in depth of bulk samples.…”

Section: Resultsmentioning

confidence: 53%

Fourier transform infrared spectroscopic characterization of clay minerals from rocks of Lalibela churches, Ethiopia

Kiros¹,

Gholap²,

Gigante³

2013

Int. J. Phys. Sci.

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This study demonstrates the Fourier transform infrared (FTIR), Raman spectroscopy and scanning electron microscope -energy dispersive X-ray spectrometer (SEM-EDS) techniques which has been applied to characterize decay products and processes occurring at the surface of rock-hewn churches at the UNESCO's World Heritage site of Lalibela, Northern Ethiopia. Spectroscopic analyses comparing the observed frequencies with the available literature, minerals were identified. A special emphasis is devoted to the presence of whewellite/weddellite and kaolinite minerals, never pointed out before this study in the rock hewn churches of Lalibela, and their possible roles on rock decay. The identification of montmorillonite as a weathering product up to 20 mm from the rock/atmosphere interface beyond the level at which kaolinite, whewellite and gypsum are found, suggests that montmorillonite may penetrate even deeper into the rock substrate causing major rock decay. Results indicate that biological attack by green algae and lichens is currently responsible for severe stone surface, physical and chemical weathering leading to considerable weakening of the churches walls. A prompt and careful removal of the biological and other deposits with the non-destructive method (laser cleaning) treatment is therefore recommended.

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Section: Resultsmentioning

confidence: 53%

Fourier transform infrared spectroscopic characterization of clay minerals from rocks of Lalibela churches, Ethiopia

Kiros¹,

Gholap²,

Gigante³

2013

Int. J. Phys. Sci.

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“…None of them is directly inscribed under criterion (viii), but Simien National Park was partially enlisted for its natural beauty under criterion (vii) (Mauerhofer et al 2017). Several cultural designations also have an associated geoheritage importance such as the paleontological values for hominids of the Lower Valley of Awash and the Lower Valley of Omo, or the heritage stone significance of the Rock-hewn churches of Lalibela or Aksum (Renzulli et al 2011;Hagos et al 2017;Megerssa et al 2019). An overview of Ethiopian geodiversity has been given by Williams (2016) and Asrat (2018), but no national level geoconservation project or geosite inventorying project has been implemented as yet.…”

Section: The Global and Ethiopian Context Of Geoheritage And Geohazarmentioning

confidence: 99%

Geoheritage and Resilience of Dallol and the Northern Danakil Depression in Ethiopia

et al. 2020

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The Danakil Depression, located in the northern segment of the Afar rift, is a world-class example of active rifting and the birth of a new ocean. The unique, yet only partially interpreted geothermal system of Dallol in northern Danakil is currently receiving renewed attention by researchers and visitors despite its extreme climate since the recent improvements of infrastructure and the stabilisation of Ethio-Eritrean political relations. Previous studies focused on the general geological description, the economic exploitation of potash reserves and interpretation of the complex hydrothermal processes. Continuing monitoring of geothermal activity has not yet been carried out, and the valorisation of local geoheritage has not accompanied the increased interest of tourists. Here, we present a three-step study in order to demonstrate the unique geological environment and international geoheritage significance of Dallol and Danakil. A three-year-long remote sensing campaign has been done to provide information on improving the resilience of visitors through interpreted, monthly hazard maps, and on following up the changes of geothermal activity. Over the same time, the first geoheritage assessment of the region for 13 geosites was carried out along with a comparative analysis of three quantitative methods (to evaluate the scientific importance and the geotouristic development potential of the area). Finally, with the input of the assessment, a preliminary geoheritage management plan was created for practical consideration by stakeholders toward a geoconservation and geotourism development, as well as a resilience system of this peculiar area.

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“…These instabilities are frequently due to the different mechanical behavior of superimposed lithologies and their intrinsic weakness. Other examples of cultural heritage in tuffs and ignimbrites include some of the Buddha statues in Japan (e.g., Heiwa-Kannon statue, Oguchi and Yuasa 2010), the Moai statue in the Easter Islands (Gioncada et al 2010), the Macusani rock art site in Peru (Hostnig 2008), the underground cities of Vardzia in Georgia (Tutberidze and Tsutsunava 2015;Margottini et al 2015) and Kandovan in Iran (Kaljahi and Birami 2015), and the rock-hewn churches of Lalibela in Ethiopia (Delmonaco et al 2005;Renzulli et al 2011). In Turkey, apart a few exceptions (Binal and Ercanoglu 2010;Topal et al 2007Topal et al , 2012, the majority of engineering geological studies on instabilities at the heritage sites are concentrated in Cappadocia (Doyuran 1976;Aydan et al 2007;Ulusay et al 2006;Tunusluoglu and Zorlu 2009;Tuncay 2009;Zorlu et al 2011;Kaşmer et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Rockfall at the heritage site of the Tatlarin Underground City (Cappadocia, Turkey)

et al. 2016

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Cappadocia is one of the most important natural, historical and cultural heritages of Turkey. The region is seriously threatened by different instability problems, and several locations were accordingly closed to visit, mainly because of rockfalls. The aim of current study is to investigate the rockfall hazard potential near the Tatlarin Underground City. For this purpose, an extensive engineering geological investigation was performed and complemented with a set of rockfall simulations performed by means of the 3D numerical model HY-STONE. The investigation included: (1) mapping of the lithological units (tuffs and overlying basalts, talus deposits) and of unstable blocks along the cliff; (2) rock mass geomechanics and kinematic analysis of block stability; and (3) laboratory testing of tuff and basalt. These allowed to show that the instabilities are mainly controlled by different durability of tuffs and basalts. The weakness of tuffs facilitates a progressive undercutting of the basalt layer, the opening of subvertical joints and the consequent movement of large basaltic blocks. Two future potential rockfall scenarios have been produced by 3D rockfall modelling for hazard zonation and for suggesting risk management strategies. Model parameters were calibrated by back-analysis of both historical events and field tests. Different sets of parameters have been calibrated for different release volumes to consider different degrees of interaction with slope material of different size. The effect of roughness of the topography was investigated in terms of trajectories and lateral dispersion of blocks and its consequences on hazard zonation and risk management actions.

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What kind of volcanite the rock-hewn churches of the Lalibela UNESCO's world heritage site are made of?

Cited by 12 publications

References 14 publications

Fourier transform infrared spectroscopic characterization of clay minerals from rocks of Lalibela churches, Ethiopia

Fourier transform infrared spectroscopic characterization of clay minerals from rocks of Lalibela churches, Ethiopia

Geoheritage and Resilience of Dallol and the Northern Danakil Depression in Ethiopia

Rockfall at the heritage site of the Tatlarin Underground City (Cappadocia, Turkey)

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