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1.
The main objective of the research work isthe homogenisation of the two recentAlgerian earthquake catalogues for thecommon covered period of time, from 1900 to1990, for the region under considerationlimited by [33°N–38°N,4°E-9.5°E] and the updatingof the catalogue for the twentieth century(1900–2000). To mitigate the deficiencyof the incompleteness of catalogue, aneffort was made to establish a correlationbetween surface-wave magnitude Ms andbody-wave magnitude mb in the form ofMs = a + b (mb). A complete, exact andhomogeneous earthquake catalogue as much aspossible, comprising 870 seismic events,has been compiled. Seismicity analysis ofthe region shows a strong concentration ofseismicity along a band of no more than400 km width oriented mainly in theeast-west direction parallel to the coast.Moreover, earthquakes in this zone arerather associated to strike-slip mechanism.The focal mechanism show a regional stressregime that corresponds to horizontalcompression in NW-SE to N-S direction. As aresult of the review of the seismicity ofnorth-eastern Algeria from the compilationof checked and corrected data and itscorrelation with other geologic andgeophysical investigations based ondocumentary sources, it was possible toconstruct a most complete seismotectonicmap. It leads also to delineate fourseismogenic zones in the Tellian Atlas, aless important zone in the Saharan Atlas, asixth zone at the boundary of both Atlasand finally, a seventh one along thecoastal zone. The seismicity-active faultscorrelation of some of these defined zonesis examined in details with a specialattention to the Saharan Atlas zone, theHodna and Biban zone as well as Soummam andBabor zone where further research workallowed to find some neotectonic featuresconsidered as a significant sign of recenttectonic activity. 相似文献
2.
Faisal Rehman Sherif M. El-Hady Ali H. Atef Hussein M. Harbi 《Arabian Journal of Geosciences》2016,9(8):519
The present study deals with the seismic site classification of Bahrah area, Wadi Fatima, to characterize the local site conditions. The dynamic behavior of sediments was studied by the application of surface wave inversion. The multichannel analysis of surface waves (MASW) shallow geophysical technique was utilized for site classification. MASW survey was carried out at 66 sites along with 13 seismic refraction profiles at suitable localities. MASW and seismic refraction profiles were processed and compared with the available borehole data. The integration of MASW techniques with seismic refraction and borehole data progressively enhanced the subsurface visualization and reliability of the shear wave velocity estimation in the subsurface in the study area. The subsurface shear-wave velocity model was achieved by the solution of an inverse problem-based dispersion of surface waves and propagation in a vertically heterogeneous medium. The 2D genetic algorithm was employed for the inversion of dispersion curves to obtain velocity and thickness of subsurface layers. The depth to engineering bedrock and velocity of shear waves in the first 30 m was deciphered and mapped. The depth of bedrock in study area varies from 4 to 30 m, and V S 30 ranges from 320 to 800 m/s. The most of study area falls in B and C class categories in addition to few sites of D class according to the NEHRP guidelines. 相似文献
3.
Seismicity, seismic input and site effects in the Sahel—Algiers region (North Algeria) 总被引：2，自引：0，他引：2
A. Harbi S. Maouche F. Vaccari A. Aoudia F. Oussadou G.F. Panza D. Benouar 《Soil Dynamics and Earthquake Engineering》2007,27(5):427-447
Algiers city is located in a seismogenic zone. To reduce the impact of seismic risk in this Capital city, a realistic modelling of the seismic ground motion (SGM) is conducted by using the hybrid method that combines the finite differences method and the modal summation. For this purpose, a complete database of geological, geophysical and earthquake data is constructed. A critical re-appraisal of the seismicity of the zone [2.25°E–3.50°E, 36.50°N–37.00°N] is performed and an earthquake list, for the period 1359–2002, is compiled. The analysis of existing and newly retrieved macroseismic information allowed the definition of earthquake parameters of macroseismic events for which a degree of reliability is assigned. Geological cross sections have been built up to model the SGM in the city, caused by the 1989 Mont-Chenoua and the 1924 Douéra earthquakes. Synthetic seismograms and response spectral ratio is produced for Algiers, and they show that the soft sediments in Algiers centre are responsible of the noticed amplification of the SGM. 相似文献
4.
五大连池近代火山老黑山火烧山火山喷发过程的考察研究 总被引：4，自引：0，他引：4
作者在已有工作的基础上,以当代火山学的研究思路和观点,为恢复五大连池两个近代火山,老黑山火烧山的喷发历史过程进行了野外考察研究工作。老黑山火山锥是由三套不同的碎屑堆积物组成。在锥体的南侧、东侧和西侧以及北测和北西侧有５个熔岩溢出口,按它们形成先后关系,认为有早、中、晚三期熔岩流。本文还对老黑山火山锥上的寄生火山、结壳熔岩与渣状熔岩的分布、流动特点及形成的控制因素进行了分析讨论。最后得出结论：老黑山火山是经多期次喷发活动形成的。火烧山火山锥是一碎屑化泡沫化程度很低的浮岩块和熔岩碎块组成,同老黑山有明显区别。 相似文献
5.
Neo-deterministic seismic hazard assessment in North Africa 总被引：2，自引：2，他引：0
T. Mourabit K. M. Abou Elenean A. Ayadi D. Benouar A. Ben Suleman M. Bezzeghoud A. Cheddadi M. Chourak M. N. ElGabry A. Harbi M. Hfaiedh H. M. Hussein J. Kacem A. Ksentini N. Jabour A. Magrin S. Maouche M. Meghraoui F. Ousadou G. F. Panza A. Peresan N. Romdhane F. Vaccari E. Zuccolo 《Journal of Seismology》2014,18(2):301-318
North Africa is one of the most earthquake-prone areas of the Mediterranean. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss of life and considerable economic damage to the region. In order to mitigate the destructive impact of the earthquakes, the regional seismic hazard in North Africa is assessed using the neo-deterministic, multi-scenario methodology (NDSHA) based on the computation of synthetic seismograms, using the modal summation technique, at a regular grid of 0.2?×?0.2°. This is the first study aimed at producing NDSHA maps of North Africa including five countries: Morocco, Algeria, Tunisia, Libya, and Egypt. The key input data for the NDSHA algorithm are earthquake sources, seismotectonic zonation, and structural models. In the preparation of the input data, it has been really important to go beyond the national borders and to adopt a coherent strategy all over the area. Thanks to the collaborative efforts of the teams involved, it has been possible to properly merge the earthquake catalogues available for each country to define with homogeneous criteria the seismogenic zones, the characteristic focal mechanism associated with each of them, and the structural models used to model wave propagation from the sources to the sites. As a result, reliable seismic hazard maps are produced in terms of maximum displacement (D max), maximum velocity (V max), and design ground acceleration. 相似文献
6.
The seismicity of Algeria since the nineteenth century is relatively well documented. However, compared with the numerous damaging earthquakes that are documented since 1850, fewer than a dozen reports of earthquakes are listed for the pre-1850 ad period, suggesting that the historical record is missing a substantial number of earthquakes. This paper examines the use of literary and epigraphic sources relevant to the investigation of seismicity in Algeria during Roman times. We provide examples where the meager written literary record may be supplemented with appropriate archaeological and epigraphic data describing damage to ancient Roman sites. The examples show that collaboration between earth scientists and archeologists is of utility in improving the seismic record and highlights the need for further study of data sources and repositories located both inside and outside of Algeria. 相似文献
7.
New historical data from primary sources, allow us to revisit the Djidjelli earthquakes of 21 and 22 August 1856 (I0 VIII, IX respectively). These two large seismic events are among the most significant events that have affected the North
African coast. They have caused extensive damage and generated a tsunami that propagated at several harbours of the western
Mediterranean Sea. The effects of each earthquake are analysed from all documentary source materials, emphasising the confrontation
of observations and data for an accurate reconstruction of the macroseismic field of both events. The method used provides
a more precise way to determine the characteristics of the Djidjelli earthquakes. 相似文献
8.
Hesham M. Harbi Abdelmonem A. Eldougdoug M. S. El-Shahawi 《Arabian Journal of Geosciences》2011,4(3-4):353-363
A technological sample (50 kg) from Wadi Khamal Nelsonite ore was subjected to magnetic and flotation concentration techniques. Excellent recovery percentages of 72.95% and 71.22% were achieved by the dry/wet magnetic and flotation concentration techniques, respectively. The weight of the apatite concentrate reached a reasonable percentage of approximately 23.5% with an overall 40.23% P2O5 total content. Analytical data of the apatite concentrate after digestion in concentrated sulfuric acid revealed that the total content of the rare earth elements (REE) constitutes about 0.2% of the total apatite content. The REE content (0.2%) was partitioned between phosphoric acid liquor (65%) and gypsum precipitate (36%). The extraction of the REEs from the phosphoric acid liquor using oxalic acid and sodium carbonate–bicarbonate mixture (1:10?w/w) yielded the RE oxide cake which constitute about 1.2% (w/w). The produced rare earth oxide cake contains traces of various metal oxides, e.g., SrO, Na2O, etc. in addition to rare earth oxides. Attempts to determine quantitatively the constituents of the cake will be considered in future work. 相似文献
9.
Assia Benchouk Mounir Derfouf Nabil Abou-Bekr Said Taibi 《Arabian Journal of Geosciences》2013,6(12):4565-4573
This paper presents an experimental study carried out on some clayey soils of Tlemcen region situated in the North West of Algeria. The characterization of the volumetric behavior under the effect of suction is studied on drying–wetting paths which highlight the correspondence between void ratio, degree of saturation, and water content versus suction. The initial conditions of studied material are in slurry form and compacted at different initial water contents. For the slurry form, correlations are derived to predict parameters characterizing the drying path. 相似文献
10.
Information about space distribution is collected for selected classes of evolving stars in the globular cluster M13. After a rigorous elimination of field stars, three samples are examined, corresponding to the red giant stage (G), the blue (B) and the yellow (YG) parts of the horizontal branch. It is shown that results are easy to understand in terms of:
- A substantial mass loss in the H-shell burning stage;
- Evolution along the horizontal branch from the blue side to the red one;
- A mixing in the observed giant branch of two populations with sensible differences in masses.