More and more natural disasters are being reported worldwide, particularly with respect to landslides. They cause injuries and deaths and induce physical, environmental and economic damages that hamper the development of wealthy as well as poor countries and regions. It is therefore necessary to include consideration of landslide hazards in land use and emergency response planning for public safety and realization of safe engineering projects. It is essential for authorities to have appropriate maps describing hazardous areas at their disposal. It is also important that they are aware of the different steps within a coherent approach that lead to the identification of landslide areas, the evaluation of the corresponding hazards, and the assessment of the risks these assessments imply. A large number of distinctive methods for landslide hazard mapping have been tested and applied in different contexts for more than 30 years. Many of them have been presented in recent international conferences such as the International Symposium on Landslides (Rio de Janeiro, 2004), the International Conference on Landslide Risk Management (Vancouver, BC, 2005), or the International Forum on Landslide Disaster Management (Hong Kong, 2007), all of them organized under the auspices of the JTC-1, the joint ISSMGE, IAEG and ISRM Technical Committee on Landslides and Engineered Slopes. The JTC-1 recognizes that there is a need for unified terminology in susceptibility, hazard and risk zoning, so that zoning in any area could be compared on a similar basis with zoning of adjacent areas, and to insure that fundamental assessment steps are properly considered and applied in the management of landslide-prone areas. JTC-1 also recognizes that the time has now been reached when quantitative hazard and risk zoning is possible. With this in mind, JTC-1 appointed a Scientific Committee to undertake the development of guidelines for landslide susceptibility and hazard and risk zoning for land use planning with the requirement that the committee produce guidelines that are acceptable to the international community. A first draft in this complex process was developed by the Scientific Committee using as a starting point a document prepared by the Australian Geomechanics Society. This draft was discussed and its applicability was tested within an international group of 40 experts (listed at the end of the preface) most of whom met for a workshop in Barcelona from September 18 to 20, 2006. This very fruitful workshop proved to be a forum for vigorous debate, and many helpful suggestions arose on how to improve the guidelines. Many of these suggestions have been included in the Commentary appended to the Guidelines. There were numerous additional suggestions (which were not included in the interest of balance and because of space restrictions) and a large number of formal corrections that were important to improve the quality of the guidelines. A set of accompanying papers have been also included in this special issue of Engineering Geology. These papers are intended to clarify and develop some concepts and methods covered by the Guidelines in greater detail or describe well documented case histories that may be considered for methodological guidance. The guidelines are freely available in electronic form from the JTC-1 web page: http://www.geoforum.com/jtc1. The JTC-1 strongly encourages all persons who are undertaking landslide susceptibility, hazard and risk zoning to follow these guidelines. It also encourages those carrying out research in these areas to use the terminology presented here so that all will share a common language. The JTC-1 and the authors of this document are quite aware that such guidelines are never eternally valid and that it will be necessary to provide some amendments or clarifications in the next decade. Moreover, the applicability of these guidelines in specific economic and jurisdictional contexts will have to be tested, in order to assess to what extent they are dealing with local land use planning needs with sufficient refinement. It is through the repetitive application of the guidelines in different contexts that it will be possible to prove their pertinence. Finally, all comments to the Scientific Committee related to the use of the guidelines will be most welcome. It is also essential that the long-term impact of the application of these guidelines be quantitatively assessed, so as to prove that the proposed process really leads to a sustainable way to “live with risks”. Some indicators referring to other types of natural hazards have proved that an appropriate land use planning policy can lead to a decrease of disasters, even if the value and number of exposed elements shows an increasing trend. Let us hope that it will also be the case with landslides, if the present guidelines are appropriately used and considered in land use and disaster management worldwide.
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