Addressing one of the major challenges in modern volcanology, "Active Lavas" looks at the practical aspects of monitoring uncontrolled streams of molten rock and how field data can be applied for theoretical modelling and forecasting the growth of lava flows. It describes the basic features of common subaerial lava flows and domes - both on Earth and on other bodies in the Solar System - before discussing the logistics of measuring lava properties during eruption and how these measurements are used to develop simple theoretical models for forecasting flow behaviour. The topics covered include flow morphology and hazard, direct and remote-sensing measuring techniques, lava rheology and heat-transfer mechanisms, surface crusting, and the potential of cellular automata for computer simulations. To link field and theoretical studies, a background chapter reviews the physical principles of fluid mechanics. A special chapter is also devoted to the responsibilities of volcanologists during volcanic emergencies. Drawing together the best of current research and field reports, "Active Lavas" offers an introduction to lava flows in addition to its usefulness as a handbook for lava monitoring during eruptions. It should serve as reading for not only researchers and field scientists involved in volcanology but also for the many other Earth scientists with an interest in mineralogy and petrology in their most dramatic manifestation. This book is intended for research students and scientists in volcanology, petrology, mineralogy and studies of natural hazards, plus libraries serving this community.