Astenosphere : The weak section of soft rock in the upper mantle just below the lithosphere. It is involved in plate movement. Depth is 70 to 100 km below the surface
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}