scholarly journals Rockfall hazard and risk assessment: an example from a high promontory at the historical site of Monemvasia, Greece

2012 ◽  
Vol 12 (6) ◽  
pp. 1823-1836 ◽  
Author(s):  
H. Saroglou ◽  
V. Marinos ◽  
P. Marinos ◽  
G. Tsiambaos

Abstract. The paper presents the kinematics of rock instability of a high limestone promontory, where the Monemvasia historical site is situated, in Peloponnese in Southern Greece. The instability phenomena poses a significant threat to the town located at the base of the slope. Rockfall episodes occurred in the past due to the relaxation of the high cliff, whereas significant undermining of the castle frontiers has been observed at the slope crest. The predominant types of instability are of planar, wedge and toppling failure of medium to large blocks. In order to investigate the existing stability conditions and decide upon the protection measures, stability and rockfall analyses were carried out for numerous slope sections under different loading conditions and protection measures were suggested. A rock-fall risk rating system is proposed, which is based on morphological and structural criteria of the rock mass and on vulnerability and consequences. The rating system is applied for individual sections along the slope and a risk map was produced, which depicted areas having different degree of risk against rockfall occurrences.

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 158
Author(s):  
Didier Hantz ◽  
Jordi Corominas ◽  
Giovanni B. Crosta ◽  
Michel Jaboyedoff

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant.


Geografie ◽  
2011 ◽  
Vol 116 (2) ◽  
pp. 144-155 ◽  
Author(s):  
Jan Klimeš

Rockfall hazard is assessed using Rockfor.net, which is one dimensional tool for assessing the protective function of forests against rockfall. Three sites where chosen to test the tool with different morphological and forest conditions. For each site, it was evaluated how the boulder size and forest composition affects the probability of the rocks to surpass the forested slope. The Rockfor.net was also used for back calculations of past event, which happened during the floods in July 1997 in the village of Bystřička in the Vsetínské vrchy Hills. In this case, also a partial quantitative risk assessment with suggestions for risk management was performed.


2013 ◽  
Vol 47 (4) ◽  
pp. 1664 ◽  
Author(s):  
A. Andrianopoulos ◽  
H. Saroglou ◽  
G. Tsiambaos

This paper presents and compares the main methods of hazard and risk assessment for road slopes. Hazard assessment is achieved by rating several parameters such as the slope’s geometry, traffic conditions, the geology and the rockmass properties, weather conditions, historical rockfall data etc. A hazard assessment can also be executed using 2D or 3D trajectory models, by combining the frequency of a rockfall and the kinetic energy of a falling rock. Several methodologies have been developed for risk assessment, varying from simplistic approaches to comprehensive probabilistic or quantitative risk assessment methods. Finally, the most suitable methods were used in order to assess the level of hazard and risk as an example (the data from two sections of the national road at Tempi Gorge, Greece) where many rockfall events occurred in the past few years.


2021 ◽  
Vol 11 (19) ◽  
pp. 8946
Author(s):  
Ioakeim Konstantinidis ◽  
Vassilis Marinos ◽  
George Papathanassiou

Rockfall events consist one of the most hazardous geological phenomena in mountainous landscapes, with the potential to turn catastrophic if they occur near an anthropogenic environment. Rockfall hazard and risk assessments are recognized as some of the most challenging surveys among the geoengineering society, due to the urgent need for accurate foresight of likely rockfall areas, together with their magnitude and impact. In recent decades, with the introduction of remote sensing technologies, such as Unmanned Aerial Vehicles, the construction of qualitative and quantitative analyses for rockfall events became more precise. This study primarily aims to take advantage of the UAV’s capabilities, in order to produce a detailed hazard and risk assessment via the proposition of a new semi-quantitative rating system. The area of application is located in the cultural heritage area of Kipinas Monastery in Epirus, Greece, which is characterized by the absence of pre-existing data regarding previous rockfall events. As an outcome, it was shown that the suggested methodology, with the combination of innovative remote sensing technologies with traditional engineering geological field surveys, can lead to the extraction of all the necessary quantitative data input for the proposed rating system for any natural slope.


Author(s):  
Didier Hantz ◽  
Jordi Corominas ◽  
Giovanni B. Crosta ◽  
Michel Jaboyedoff

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests to use terms that appear to be the more logic and explicit as possible, and describes methods to derive some of the main hazard and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized hazards and diffused hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the propagation probability and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (reach frequency) can be derived. However, when the element at risk is not replaced or repaired, the probability that it is impacted by at least one rockfall must be considered.


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