Events on Fans and Cones: Recurrence Interval and Magnitude

Debris flows, their volcanic counterparts lahars, and debris floods that may occur as part of a debris-flow event, are the mass movement events that result in most losses worldwide. Hundreds of deaths occur every year, while horrific multi-thousand death tolls are announced every decade or so. Debris-flow related economic and life losses are not limited to emerging and developing countries but regularly occur in the developed world as well. In the few month leading up to the writing of this chapter, debris flows in Madeira (Portugal), Italy and Brazil lead to well over 100 fatalities and created losses well over 100 Million USD. Consequently, debris flows have been the focus of intensive scientific investigation with hundreds of papers appearing annually on various aspects of debris-flow research. Several dedicated conferences have been held whose sole focus is debris flows. In 2005 a book on debris flows and related processes was published (Jakob and Hungr 2005) to offer a more systematic review of the state-of-the-art. The book was published in 2005 and thus reflects mostly knowledge up to 2003 or 2004. With that it is outdated in some fields. Furthermore, it only touched on various topics in chapter form while it is clear to the practitioner that some of the chapters in the Jakob and Hungr book would have deserved to be written up as individual volumes themselves.