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11.
The stability of the power law scaling of earthquake recurrence time distribution in a given space–time window is investigated,
taking into account the magnitude of completeness and the effective starting time of aftershock sequences in earthquake catalogs
from Southern California and Japan. A new method is introduced for sampling at different distances from a network of target
events. This method allows the recurrence times to be sampled many times on the same area. Two power laws with unknown exponents
are assumed to govern short- and long-recurrence-time ranges. This assumption is developed analytically and shown to imply
simple correlation between these power laws. In practice, the results show that this correlation structure is not satisfied
for short magnitude cutoffs (m
c
= 2.5, 3.5, 4.5), and hence the recurrence time distribution departs from the power law scaling. The scaling parameters obtained
from the stack of the distributions corresponding to different magnitude thresholds are quite different for different regions
of study. It is also found that significantly different scaling parameters adjust the distribution for different magnitude
thresholds. In particular, the power law exponents decrease when the magnitude cutoff increases, resulting in a slower decrease
of the recurrence time distribution, especially for short time ranges. For example, in the case of Japan, the exponent p2 of the power law scaling at large recurrence times follows roughly the relation: , where m
c
is the magnitude cutoff. In case of Southern California, it is shown that Weibull distribution provides a better alternative
fit to the data for moderate and large time scales. 相似文献
12.
Fouzi Bellalem Abdelhak Talbi Hamou Djellit Hayet Ymmel Mourad Mobarki 《Journal of Seismology》2018,22(4):897-908
The region of Blida is characterized by a relatively high seismic activity, pointed especially during the past two centuries. Indeed, it experienced a significant number of destructive earthquakes such as the earthquakes of March 2, 1825 and January 2, 1867, with intensity of X and IX, respectively. This study aims to investigate potential seismic hazard in Blida city and its surrounding regions. For this purpose, a typical seismic catalog was compiled using historical macroseismic events that occurred over a period of a few hundred years, and the recent instrumental seismicity dating back to 1900. The parametric-historic procedure introduced by Kijko and Graham (1998, 1999) was applied to assess seismic hazard in the study region. It is adapted to deal with incomplete catalogs and does not use any subjective delineation of active seismic zones. Because of the lack of recorded strong motion data, three ground prediction models have been considered, as they seem the most adapted to the seismicity of the study region. Results are presented as peak ground acceleration (PGA) seismic hazard maps, showing expected peak accelerations with 10% probability of exceedance in 50-year period. As the most significant result, hot spot regions with high PGA values are mapped. For example, a PGA of 0.44 g has been found in a small geographical area centered on Blida city. 相似文献
13.
Abdessalam Ouallali Habiba Aassoumi Mohamed Moukhchane Abdelhak Moumou Mhammad Houssni Velibor Spalevic 《水文科学杂志》2020,65(9):1568-1582
ABSTRACT Soil erosion is a serious ecological problem in Mediterranean areas. The IntErO model based on the erosion potential method (EPM) and the modified universal soil loss equation (MUSLE) have been used to assess soil erosion in several basins. This study aimed to assess and evaluate the effectiveness of these methods for evaluating sediment production and deposition rates in the Arbaa Ayacha basin, Morocco, in order to estimate sediment fluxes on a catchment scale. Our findings suggest that the basin is strongly exposed to erosion owing to geological formations, slope and land use, with average losses of about 28.4 t ha?1 year?1. Erosion processes were evaluated at the erosion production (Eocene marly formations) and sedimentation zones (Quaternary terraces). The results of these models may be useful to address soil and water management in this region and to assess the impact of a river dam that will be built in the basin. 相似文献
14.
Applied in Djebel Meni (Northwestern of Algeria), this research highlights the results obtained from the supervised classification using the Spectral Angle Mapper (SAM) algorithm, through introducing the spectral signatures of illite, kaolinite, and montmorillonite, via Jet Propulsion Laboratory (JPL) spectral library. These results were compared to the ones of the SAM classification, which use spectral signatures obtained by the Sequential Maximum Angle Convex Cone (SMACC) endmembers extraction algorithm. This implies the ability to detect and identify any object present on the Earth’s surface, whether its nature is mineral, vegetal, or human made, from hyperspectral imaging. By extracting the spectral signatures with the SMACC algorithm and matching them to the current signatures of JPL spectral library, comparing spectral signatures with another is not an easy task. Indeed, for a better comparison and a more appropriate interpretation in the use of the SAM classification, the results obtained were very relatively convincing because, regarding very strong similarities. It appears also that the signatures extracted with SMACC occupy the same areas as those of the JPL spectral library. This method of detection and identification of any present object on the Earth’s surface is rather conclusive. 相似文献
15.
Benali Amel Peresan Antonella Varini Elisa Talbi Abdelhak 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(6):775-791
Stochastic Environmental Research and Risk Assessment - An adequate characterization of the temporal features of background seismicity, namely after removal of temporally and spatially clustered... 相似文献
16.
Ahmed Abderrahmane Semchaoui Omar Kolli Abdelhak Boutaleb Tarek Zerrouki 《Arabian Journal of Geosciences》2016,9(16):679
The Draïssa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draïssa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting. 相似文献
17.
A mixed model is proposed to fit earthquake interevent time distribution. In this model, the whole distribution is constructed
by mixing the distribution of clustered seismicity, with a suitable distribution of background seismicity. Namely, the fit
is tested assuming a clustered seismicity component modeled by a non-homogeneous Poisson process and a background component
modeled using different hypothetical models (exponential, gamma and Weibull). For southern California, Japan, and Turkey,
the best fit is found when a Weibull distribution is implemented as a model for background seismicity. Our study uses earthquake
random sampling method we introduced recently. It is performed here to account for space–time clustering of earthquakes at
different distances from a given source and to increase the number of samples used to estimate earthquake interevent time
distribution and its power law scaling. For Japan, the contribution of clustered pairs of events to the whole distribution
is analyzed for different magnitude cutoffs, m
c, and different time periods. The results show that power laws are mainly produced by the dominance of correlated pairs at
small and long time ranges. In particular, both power laws, observed at short and long time ranges, can be attributed to time–space
clustering revealed by the standard Gardner and Knopoff’s declustering windows. 相似文献