1The second edition of the Encyclopedia of Volcanoes published by Haraldur Sigurdsson et al. (2015) makes an emphasis on the physical volcanology and on the characteristics of the eruption, but provides the reader with a fairly good overview of all the other issues related to volcanoes. The all span of the earth sciences, but also the social sciences have brought their own topics and methods and have widened the knowledge about the specificities of the volcanic environment. Thus, they have contributed to raise new approaches in order to appraise more sharply the volcanoes and the people living on their flanks: anthropology (Dove, 2007; Chester & Duncan, 2013a and b) or archaeology (Sheets, 2015) can be quoted among a much larger list, in which geography plays a major role. The study of the volcanic complex Rinjani-Salamas by Lavigne et al. (2013) has put forward an integrated approach to reconstruct the overall impact of an eruption. This work has shown all the different contributions of each scientific field from volcanology to climatology, from geography to history. Geography has indeed largely contributed to the knowledge of the volcanic landforms and societies. With their multi-scale approach, geographers are able to take into account the spatial and temporal variability of volcanic environments: this could be the aims of the “volcanography” (word created by Franck Lavigne and Frédéric Leone during the 10th Géorisques meeting in Montpellier in 2014).
2This special issue of Géomorphologie: relief, processus, environnement presents 4 approaches of the volcanic environments at different time and spatial scales. They share common issues on volcanic resources, which contribute to dwell people in potentially dangerous areas, and on the risk studies. The interactions and feedbacks between the anthropic activities and the volcanic environments are also described.
3The study presented by Christopher Gomez (University of Canterbury, New Zealand) and Patrick Wassmer (University of Strasbourg, Laboratory of Physical Geography, Meudon, France) concerning the landscapes of Unzen volcano (Kyushu, Japan) highlights such a feedback. Based on a method combining fieldwork and geomatics and photogrammetry, they have mapped the environmental changes due to the recent increase in anthropic infrastructures around the volcano. They consider the volcanic environment as a system which resilience may be weakened by anthropic causes. Volcanoes have indeed been populated and exploited areas over centuries. The article published by Anne-Kyria Robin (Paris 1 University, PhD candidate at the Laboratory of Physical Geography, Meudon, France) and her co-authors consider one important resource which has been exploited for a long time: the obsidian. The paper focuses on a geological and geomorphic approach of the volcanic environment of Nemrut volcano (Turkey), based on fieldwork and laboratory analyses. Anouk Ville (Paris 1 Panthéon-Sorbonne) et al. in the frame of the SEDIMER program (http://www.lgp.cnrs.fr/spip/spip.php?article111), however, have worked on a much smaller area and have documented more rapid processes at the scale of a quarry located in a lahar-prone valley at Merapi volcano (Indonesia). They have studied the impacts of the quarrying activity on the morphology of the valley, by associating photogrammetry with in-situ topographic measures, and show how rapidly the bottom of the valley is changing, mainly due to very intense anthropic causes. However, natural factors must not be forgotten, as the last paper, from Sandy Budi Wibowo (Gadjah Mada University, Indonesia, and PhD candidate at the Laboratory of Physical Geography, Meudon, France) et al., reminds us. They have monitored an upstream part of the valley studied by Ville et al. (this issue) in order to assess the behavior of lahars and their geomorphic consequences at a local scale. They have recorded a lahar in motion, and have associated the image with its seismic signal. This coupling between the video and the acoustic and seismic sensors has allowed them to characterise both the temporal and the spatial variations of the flow at a given location.
4These four studies provide some examples of the methods used to qualify and quantify the geomorphologic processes on active volcanoes, at different spatial scales and time scales. They are all based on different kinds of fieldworks, and they all show the large diversity of methods and data that the geographers (volcanographers) are able to produce, to analyse and to explain. If the following papers all focus on geomorphology, they all take into account the people living in volcanic areas as major actors of the environmental issues of volcanoes.
5We thank all the authors and their co-authors for their work, and the reviewers for their thorough comments and reports. Special thanks to Pierre-Salvador Gil who collected and edited the revised manuscripts.