Seismic Hazard Evaluation Using Markov Chains: Application to the Japan Area     

F. Alejandro Nava  Claudia Herrera  José Frez  Ewa Glowacka 《Pure and Applied Geophysics》2005,162(6-7):1347-1366

Seismogenic regions within some geographic area are interrelated through tectonics and seismic history, although this relation is usually complex, so that seismicity in a given region cannot be predicted in a straightforward manner from the activity in other region(s). We present a new statistical method for seismic hazard evaluation based on modeling the transition probabilities of seismicity patterns in the regions of a geographic area during a time interval, as a Markov chain. Application of the method to the Japan area renders good results, considering the occurrence of a high probability transition as a successful forecast. For magnitudes M5.5 and time intervals t=0.10 year, the method yields a 78% aftcast (forecast of data already used to evaluate the hazard) success rate for the entire catalog, and an indicative 80% forecast success rate for the last 10 transitions in the catalog. A byproduct of the method, regional occurrence probabilities determined from the transition probabilities, also provides good results; aftcasts of regional activity have a 98% success rate, and those of activity in the highest probability region about 80.5% success rate. All results are superior to those from the null hypotheses (a memory-less Poissonian, fixed-rate, or uniform system) and have vanishingly small probabilities of resulting from purely random guessing.  相似文献   

Impact of forecasted land use changes on flood risk in the Polish Carpathians     

Marcin Szwagrzyk  Dominik Kaim  Bronwyn Price  Agnieszka Wypych  Ewa Grabska  Jacek Kozak 《Natural Hazards》2018,94(1):227-240

Flooding is a major environmental hazard in Poland with risks that are likely to increase in the future. Land use and land cover (LULC) have a strong influencing on flood risk. In the Polish Carpathians, the two main projected land use change processes are forest expansion and urbanization. These processes have a contradictory impact on flood risk, which makes the future impact of LULC changes on flooding in the Carpathians hard to estimate. In this paper, we investigate the impact of the projected LULC changes on future flood risk in the Polish Carpathians for the test area of Ropa river basin. We used three models of spatially explicit future LULC scenarios for the year 2060. We conduct hydrological simulations for the current state and for the three projected land use scenarios (trend extrapolation, ‘liberalization’ and ‘self-sufficiency’). In addition, we calculated the amount of flood-related monetary losses, based on the current flood plain area and both actual and projected land use maps under each of the three scenarios. The results show that in the Ropa river, depending on scenario, either peak discharge decreases due to the forest expansion or the peak discharge remains constant—the impact of LULC changes on the hydrology of such mountainous basins is relatively low. However, the peak discharges are very diverse across sub-catchments within the modeling area. Despite the overall decrease of peak discharge, there are areas of flow increase and there is a substantial projected increase in flood-related monetary losses within the already flood-prone areas, related to the projected degree of urbanization.  相似文献   

Effects of sample disturbance and heterogeneity on the triaxial behaviour of a Canadian oil sand at ambient and high temperatures     

Ewa Piotrowska  Morteza Mohamadi  Richard Wan 《Acta Geotechnica》2018,13(2):457-471

The present paper investigates the mechanical behaviour of oil sand specimens in triaxial compression tests at both ambient and elevated temperatures. The emphasis is particularly on core sample disturbance and on the multiphase/strongly heterogeneous nature of the material that introduces difficulties in achieving an objective characterization of its shear behaviour. First, the effect of sample disturbance on the behaviour of the oil sand is studied. Tests are performed on both disturbed and recompressed specimens. Recompression to large stress prior to shearing improves evaluation of the initial stiffness and associated volumetric changes of the oil sand, strongly affected by sample disturbance. A method for the correction of test results obtained from disturbed specimens is also proposed. The corrected results are in good agreement with those pertaining to recompressed specimens. Furthermore, a general classification of the tested oil sands into lean and rich in bitumen, where the former shows much softer and weaker behaviour, is considered to help in addressing the variability in sample composition. As for thermal aspects, the experimental results indicate that both strength and stiffness exhibit a limited temperature dependency. The temperature does not affect lean oil sand specimens, whereas heating considerably increases deformability of rich specimens.  相似文献   

Assessing medicinal qualities of groundwater from the Busko-Zdrój area (Poland) using the probabilistic method     

Katarzyna Wątor  Ewa Kmiecik  Barbara Tomaszewska 《Environmental Earth Sciences》2016,75(9):804

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