Aspects of Rift Valley faulting and volcanicity in North Tanzania: report of a Geologists’ Association Field Meeting in 2008     

J. Barry Dawson 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(3):342-34

The African Rift Valleys results from Neogene-Recent breakup up the African Plate due to continental extension. Compared with the western sector, in the eastern or Gregory Rift Valley the fracturing is accompanied by a large amount of volcanic activity and, in northern Tanzania, the volcanic rocks are relatively young compared with those in Ethiopia and Kenya where the products of the earliest stages of mantle melting are buried beneath older, more-extensive volcanic formations. The volcanic rocks vary from Pliocene and early Pleistocene intraplate basalts and trachytes to late Pleistocene/Holocene nephelinites and carbonatites.  相似文献   

A numerical approach to study the properties of solutions of the diffusive wave approximation of the shallow water equations     

Mauricio Santillana  Clint Dawson 《Computational Geosciences》2010,14(1):31-53

In this paper, we study the properties of approximate solutions to a doubly nonlinear and degenerate diffusion equation, known in the literature as the diffusive wave approximation of the shallow water equations (DSW), using a numerical approach based on the Galerkin finite element method. This equation arises in shallow water flow models when special assumptions are used to simplify the shallow water equations and contains as particular cases the porous medium equation and the p-Laplacian. Diverse numerical schemes have been implemented to approximately solve the DSW equation and have been successfully applied as suitable models to simulate overland flow and water flow in vegetated areas such as wetlands; yet, no formal mathematical analysis has been carried out in order to study the properties of approximate solutions. In this study, we propose a numerical approach as a means to understand some properties of solutions to the DSW equation and, thus, to provide conditions for which the use of the DSW equation may be inappropriate from both the physical and the mathematical points of view, within the context of shallow water modeling. For analysis purposes, we propose a numerical method based on the Galerkin method and we obtain a priori error estimates between the approximate solutions and weak solutions to the DSW equation under physically consistent assumptions. We also present some numerical experiments that provide relevant information about the accuracy of the proposed numerical method to solve the DSW equation and the applicability of the DSW equation as a model to simulate observed quantities in an experimental setting.  相似文献   

C. L. SARAZIN: X-ray emission from clusters of galaxies. Cambridge University Press,Cambridge/New York/New Rochelle/Melbourne/Sydney, 1988, Preis: £ 32.50. ISBN 0 521 32957 4     

TH. Boller 《Astronomische Nachrichten》1989,310(5):362-362

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