Hazard analysis for rock-fall onto touristic beaches from overhanging cliffs in ophiolitic rock-mass

2014 ◽  
pp. 1153-1157
Author(s):  
M Coli ◽  
E Livi ◽  
I Erbetta
Keyword(s):  
Rock Mass ◽  
Hazard Analysis ◽  
Rock Fall ◽  
Ophiolitic Rock

scholarly journals Micro-seismic precursory cracks prior to rock-fall on coastal chalk cliffs: a case study at Mesnil-Val, Normandie, NW France

2009 ◽  
Vol 9 (5) ◽  
pp. 1625-1641 ◽  
Author(s):  
G. Senfaute ◽  
A. Duperret ◽  
J. A. Lawrence
Keyword(s):  
Rock Mass ◽  
Frequency Spectrum ◽  
Failure Mechanisms ◽  
Low Frequency ◽  
Rock Fall ◽  
Seismic Events ◽  
Initiation Mechanism ◽  
Frequency Components ◽  
Specific Frequency ◽  
Complete Detachment

Abstract. Erosion of rock cliffs has been considered to be relatively unpredictable. This perceived stochastic nature of the erosional processes often occurs through collapses along fractures in the rock-mass. The prediction of catastrophic cliff failures and collapses remains very difficult. For advancing in this field, it is important to understand the processes through which a crack is initiated, how it develops and propagates until the final failure. This paper examines the micro-seismic signals recorded 15 h prior to a rock-fall located at Mesnil-Val, France. The results lead to the hypothesis that several phases of failure mechanisms contribute to rock-fall occurrence. The most important phases were associated with micro-seismic event families identified by multiplet selection. Each event family contained one specific frequency spectrum showing a progressive decrease of the frequencies as the rock approached failure suggesting the following phases: 1) the micro-seismic events recorded 15 h before the rock-fall were characterised by the highest frequencies in a large spectrum-band, between ~100 and 1000 Hz (family 1), suggesting a crack initiation mechanism or the opening of existing fractures; 2) the micro-seismic events recorded several minutes before the rock-fall were associated with a clear decrease in the highest frequency components (family 2) suggesting that the mechanism was related to the growing and development (or coalesce) of existing micro-cracks into larger fractures; 3) micro-seismic events recorded just before the rock-fall were associated with a lower frequency spectrum than families 1 and 2, the highest frequency components were absent (family 3), the frequency emission source mechanism could be related to the shearing or opening of the existing large fractures permitting the complete detachment of the blocky rock-mass; 4) finally, micro-seismic events with a very low frequency spectrum (lower than 100 Hz) characterized the rock-fall impact on the ground. These encouraging results offer the possibility of using the micro-seismic system to monitor high risk sections of coastline and to advance understanding of cliff failure mechanisms.

scholarly journals Investigation of Critical Geotechnical, Petrological and Mineralogical Parameters for Landslides in Deeply Weathered Dunite Rock (Medellín, Colombia)

2021 ◽  
Vol 18 (21) ◽  
pp. 11141
Author(s):  
Tamara Breuninger ◽  
Bettina Menschik ◽  
Agnes Demharter ◽  
Moritz Gamperl ◽  
Kurosch Thuro
Keyword(s):  
Rock Mass ◽  
Early Warning ◽  
Hazard Analysis ◽  
Low Cost ◽  
Warning System ◽  
Field Studies ◽  
Early Warning Systems ◽  
Small Scale ◽  
Prone Area ◽  
Landslide Early Warning

The current study site of the project Inform@Risk is located at a landslide prone area at the eastern slopes of the city of Medellín, Colombia, which are composed of the deeply weathered Medellín Dunite, an ultramafic Triassic rock. The dunite rock mass can be characterized by small-scale changes, which influence the landslide exposition to a major extent. Due to the main aim of the project, to establish a low-cost landslide early warning system (EWS) in this area, detailed field studies, drillings, laboratory and mineralogical tests were conducted. The results suggest that the dunite rock mass shows a high degree of serpentinization and is heavily weathered up to 50 m depth. The rock is permeated by pseudokarst, which was already found in other regions of this unit. Within the actual project, a hypothesis has for the first time been established, explaining the generation of the pseudokarst features caused by weathering and dissolution processes. These parameters result in a highly inhomogeneous rock mass and nearly no direct correlation of weathering with depth. In addition, the theory of a secondary, weathering serpentinization was established, explaining the solution weathering creating the pseudokarst structures. This contribution aims to emphasize the role of detailed geological data evaluation in the context of hazard analysis as an indispensable data basis for landslide early warning systems.

scholarly journals The informativeness of roof tremor hazard analysis based on seismic measurements and analytical modelling

2019 ◽  
Vol 133 ◽  
pp. 01004
Author(s):  
Dariusz Chlebowski ◽  
Zbigniew Burtan
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Hazard Analysis ◽  
Analytical Techniques ◽  
Mining Area ◽  
Analytical Modelling ◽  
P Wave ◽  
Hard Coal ◽  
Deformable Bodies ◽  
Seismic Measurements

Rock bursts are a common hazard in Polish hard-coal mines. Their magnitude depends on the state of stress in the mining area, and on underground mining-induced seismicity. Both long-term and ongoing as-sessments of the capacity of the rock mass to generate tremors are based on geological and mining surveys, rock property measurements (in laborato-ries and in-situ) and observations involving signs of rock mass pressure, supported by available concepts applicable to geomechanical and geophys-ical measurements. These include seismic measurements, including profil-ing, scanning, passive/active geotomography and analytical techniques. This paper presents a comparative analysis involving exemplary results provided by both seismic and analytical methods for a selected panel in one of Upper Silesian Coal Basin (USCB) mines. For the purposes of our seismic measurements, we employed seismic tomography for the ge-otomographic reconstruction of velocity fields. Subsequently, we com-pared the results with the results of analytical modelling of rock stresses that relied on classical engineering solutions applicable to problems of me-chanics of deformable bodies. The tremor hazard analysis was based on observations of changes in P-wave velocity distributions in the coal seam environment relative to the evolution of the vertical stress concentration factor at the level of a potentially seismogenic roof layer.

scholarly journals Some Open Issues on Rockfall Hazard Analysis in Fractured Rock Mass: Problems and Prospects

2016 ◽  
Vol 49 (9) ◽  
pp. 3615-3629 ◽  
Author(s):  
Anna Maria Ferrero ◽  
Maria Rita Migliazza ◽  
Marina Pirulli ◽  
Gessica Umili
Keyword(s):  
Rock Mass ◽  
Hazard Analysis ◽  
Fractured Rock ◽  
Fractured Rock Mass ◽  
Rockfall Hazard ◽  
Open Issues ◽  
Mass Problems

scholarly journals LANDSLIDE RUNOUT DISTANCE PREDICTION BASED ON MECHANISM AND CAUSE OF SOIL OR ROCK MASS MOVEMENT

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Muhammad Qarinur
Keyword(s):  
Rock Mass ◽  
Linear Regression ◽  
Debris Flows ◽  
Empirical Equation ◽  
Mass Movement ◽  
Rock Fall ◽  
Hazard Evaluation ◽  
Linear Regression Method ◽  
Rock Falls ◽  
The Impact

Landslide often occurs in tropical hills area, such as Indonesia. Research on landslide hazard evaluation is necessary to decrease the impact in affected and surrounding areas. Empirical-statistical methods can be used to predict landslide run out distance in an effort to avoid the danger of landslide occurrences. This study aims to determine the correlation between landslide run out distance against high, slope, and volume based on mechanisms and causes of soil or rock mass movement. Data mainly from 106 landslides in Indonesia has been analyzed to search for possible correlations and empirical correlations, there are 34 rotational slides, 54 translational slides, 8 debris flows, and 10 rock falls. Analysis begins by studying the characteristics of the data (explanatory data analysis) and then analyzed by using empirical methods such as geomorphological assessment and geometrical approaches. Then the data is processed by simple linear regression and multiple linear regression method using the R software. The results obtained from the analysis of the general empirical equation form of the correlation between height (H) and run out distance (L) is 1.066H1.093, respectively. This results indicate the higher altitude slopes, the greater distance will happen. The results of the analysis correlation between height and run out distance for the type of mass movements for rotational is L=1.346+1.788 H, translational is L=-3.88+1.578H, debris flow is L=0.682H1.29, and rock fall is L=2.223H0.897. This result shows debris flows landslide run out distance is greater than rotational, translational and rock fall. The results of the analysis correlation between height and run out distance of the trigger due to the rain is L=1.267H1.027, and by an earthquake is L=0.574H1.38. This results show run out distance caused by an earthquake is larger than caused by rain. The correlation between the run out distance and volume (V) yields empirical equation which is V=0.772L2.108. This results indicate that greater run out distance is affected by the growing volume of mass movement. The results of the analysis correlation between height and slope (θ) to run out distance is L=1.448H1.062 tan θ-0,482. This results indicate that slope has a significant impact on the value of landslide run out distance.

scholarly journals Considerations on Swiss methodologies for rock fall hazard mapping based on trajectory modelling

2009 ◽  
Vol 9 (4) ◽  
pp. 1095-1109 ◽  
Author(s):  
J. M. Abbruzzese ◽  
C. Sauthier ◽  
V. Labiouse
Keyword(s):  
Hazard Analysis ◽  
Rock Fall ◽  
Hazard Mapping ◽  
Hazard Zoning ◽  
Mapping Process ◽  
A Site ◽  
Federal Guidelines ◽  
Frequency Diagram ◽  
Trajectory Modelling ◽  
Trajectory Simulations

Abstract. Rock fall hazard assessment and hazard mapping are essential for the risk management of vulnerable areas. This paper analyses some issues concerning fragmental rock fall hazard mapping methodologies. Two Swiss approaches based on rock fall trajectory simulations results are presented. An application to a site in Switzerland emphasises the differences in the results, uncertainties related to hazard zoning procedures and the influence of some factors on the mapping process. In particular, the influence of a change in the temporal rock fall frequency, of the longer propagation along the slope of only a few computed blocks (defined in this sense as "extreme blocks") and of the number of runs performed in trajectory modelling have been studied. Results are discussed with the purpose of achieving a more reliable and objective hazard analysis. The presented considerations are based on the Swiss Federal Guidelines, but many of them could be extended to other countries that evaluate rock fall hazard using an intensity-frequency diagram.

Sign in / Sign up

Export Citation Format

Share Document