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Yair Rinat Ari Matmon Maurice Arnold Georges Aumaître Didier Bourlès Karim Keddadouche Naomi Porat Efrat Morin Robert C. Finkel 《Quaternary Research》2014
Rockfall ages in tectonically active regions provide information regarding frequency and magnitude of earthquakes. In the hyper-arid environment of the Dead Sea fault (DSF), southern Israel, rockfalls are most probably triggered by earthquakes. We dated rockfalls along the western margin of the DSF using terrestrial cosmogenic nuclides (TCN). At each rockfall site, samples were collected from simultaneously exposed conjugate boulders and cliff surfaces. Such conjugate samples initially had identical pre-fall (“inherited”) TCN concentrations. After boulder detachment, these surfaces were dosed by different production rates due to differences in post-fall shielding and geometry. However, in our study area, pre-rockfall inheritance and post-rockfall production rates of TCN cannot be evaluated. Therefore, we developed a numerical approach and demonstrated a way to overcome the above-mentioned problems. This approach can be applied in other settings where rockfalls cannot be dated by simple exposure dating. Results suggest rockfall ages between 3.6 ± 0.8 and 4.7 ± 0.7 ka. OSL ages of sediment accumulated behind the boulders range between 0.6 ± 0.1 and 3.4 ± 1.4 ka and support the TCN results. Our ages agree with dated earthquakes determined in paleoseismic studies along the entire length of the DSF and support the observation of intensive earthquake activity around 4–5 ka. 相似文献
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B. H. Luckman 《地球表面变化过程与地形》1976,1(3):287-298
The major controls of rockfall activity are divided into two interacting groups. (a)Climatic factors which, through their control of temperatures and the availability and state of water, are primary controls of rockfall trigger mechanisms. (b) Geologic factors which, via cliff form (plan, profile, dissection etc.) and the character and availability of materials, influence the type, spatial distribution and intensity of rockfall activity. Detailed examination of these controls suggest that both seasonal and daily patterns of rockfall activity can vary markedly over a very small area. The implications of this variability for the design and interpretation of rockfall inventories are discussed using sample data from Surprise Valley, Jasper National Park, for the period from May-October 1969. On a seasonal basis rockfall activity showed a major spring peak with secondary maxima in the fall and associated with major summer storms. Two sites of differing aspect and morphology were studied in more detail revealing marked differences in the mean hourly frequency (0·94:0·20), mean hourly probability (0·40:0·16, hours with rockfall/hours observed) and daily pattern of rockfall activity. The west facing site showed equal hourly probability of rockfalls from 1000 to 2000 hr whereas the east facing slope had a greater hourly probability when it was in the sun (1100 1400hr) than in the shade (1400-1900hr). The differences in rockfall frequency and probabilities reflect the physical characteristics of the individual sites whereas the daily pattern of rockfalls is related to microclimate. These results suggest that if future inventory studies are to make a significant contribution, they must be carefully designed field experiments in which. (i) Data are restricted to the study or comparison of single continuously observed sites. (ii) Study sites and/or data periods are carefully selected to isolate and investigate specific controls e.g. the influence of cliff form, aspect, periods of rainfall etc. on rockfall patterns. (iii) Good on-site microclimate data are available. Also comparison of frequency measures based on the arithmetic mean should be avoided since the distribution of rockfalls per hour closely follows a Poisson distribution with occasional high values which unduly influence the value of the arithmetic mean. It is suggested that rockfall probabilities, based on the binary decision of whether or not a rockfall occurs in a given period, are a more useful measure for daily patterns of rockfall activity. 相似文献
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A rapid approach to estimate the rockfall energies and distances at the base of rock cliffs 总被引：1，自引：0，他引：1
Federica Ferrari Klaus Thoeni Anna Giacomini Cedric Lambert 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(3):179-199
This paper presents a new methodology for estimating the expected energies and first impact distances at the base of a rock cliff, subject to the geometry and properties of the cliff and the representative block being known. The method is based on a sensitivity analysis, conducted by means of kinematic simulations and carried out for a large range of input parameters and their combinations, taking into account the uncertainty associated with their estimate. The proposed approach is validated by comparing predictions to experimental data and shows great potential for a quick qualitative hazard assessment. 相似文献
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