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Introduction
Published in Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan, Blue Economy of the Indian Ocean, 2020
Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan
The Southeast Indian Ridge, on the other hand, separates the Indo-Australian Plate from the Antarctic Plate. The Indo-Australian Plate, in fact, comprises three plates: Indian Plate, Capricorn Plate, and Australian Plate. All these three meet to form a diffuse plate boundary south of Sri Lanka. The enormous African Plate has been divided since 20 Ma by the East African Rift into the Nubian and Somali Plates (Chatterjee et al., 2013).
Distribution of rocks at and below the surface
Published in A.C. McLean, C. D. Gribble, Geology for Civil Engineers, 2017
More important changes may occur because parts of the rigid outer shell of the Earth (the lithosphere) move on top of the asthenosphere. The study of the movement of these rigid shell parts (or plates) is known as plate tectonics. The essential concept of plate tectonics is that the entire surface of the Earth is composed of a series of rigid, undeformable, thin (<150 km thick) plates, and seven major plates cover most of the Earth’s surface (Fig. 4.30a), namely the Pacific Plate, the African Plate, the Indian Plate, the Eurasian Plate, the Antarctic Plate, the North and South American Plate, and the Nazca Plate. Many smaller plates exist in addition to these, such as the Caribbean Plate, which is sited at the Caribbean Sea. The plates are continuously in motion, both in relation to each other and to the Earth’s axis of rotation.
Probabilistic seismic hazard assessment for West Africa region
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2022
Stephen A. Irinyemi, Domenico Lombardi, Syed M. Ahmad
West Africa is located within the African plate, the third largest tectonic plate, which extends for approximately 60 million km2 (Schulte and Mooney 2005; Meghraoui et al. 2016). The nearest active plate boundaries are the Mid-Atlantic Ridge to the west and the North African margins to the north. The African plate consists of three major Archean cratons, i.e. West African, Congo and Kalahari Cratons, and smaller cratonic fragments. The main structural units were established in the Late Neoproterozoic-Early Paleozoic Pan-African orogeny (Begg et al. 2009; Celli et al. 2020). Although the African plate has moved relatively slowly for the past 150Ma, its continental interior has experienced rifting, folding and variations in sedimentary basin subsidence, even in areas thousands of kilometres away from its boundaries (Gaina et al. 2013). Intra-continental crustal deformation has been related to local and regional tectonic events (Cloetingh and Burov 2011), mantle–lithosphere interaction (Heine et al. 2008), and propagation of far-field stresses related to changes in plate boundaries (Xie and Heller 2009). Freeth (1978) studied the plate tectonic forces within West Africa, suggesting that the northward movement of the African plate has been responsible for the limited seismicity of the region.