Hazardous volcanic activity continue to occur because of rising populations, development pressures and expanding national and international air traffic over volcanic regions. Moreover, rapid globalisation makes U.S. businesses, financial markets, and government interests vulnerable to volcano hazards throughout the world. This book addresses these concerns and addresses the question of whether volcanic activity has been increasing over the past decades. The world's highest volcanoes, their locations and their effects on the local populations are also examined. Additionally, volcanoes have many different types of eruptions. The duration of the eruptions, how often they occur, and the magma supply system and preparatory processes for these eruptions are reviewed. Finally, this book reviews the effects of mud volcanoes, occurring in different geologic settings around the world.