25 November 2008

World Landslide Forum Report

Posted by Dave Petley

Readers will probably be aware that last week the First World Landslide Forum was held at the United Nations University in Tokyo. This was apparently “a global cooperation platform for all types of organizations from academia, United Nations, governments, private sectors, and individuals which are willing to contribute for landslide and other related earth system risk reduction.”
Unfortunately I wasn’t able to attend, but two of my colleagues (Nick Rosser and Mike Lim) were there and have kindly written the following conference report. Thanks very much to them for doing this.

The First World Landslide Forum was held last week at the United Nations University, Tokyo, Japan. The initiative for this meeting has been driven by the International Programme on Landslides (IPL) under the remit of strengthening research and learning on Earth system risk analysis and sustainable disaster management. The meeting was attended by 450 delegates from 49 countries. Although attracting participants from beyond the normal geo-science conference circuit, there were also notable absences.

Continuing the focus on management issues raised in the preceding Sendai satellite conference, the need to marry scientific knowledge with practical site-specific implementation was stressed in opening addresses by representatives of the many organisations officiating. Konrad Osterwalder gave an eloquent address on behalf of the host United Nations University. He suggested that the crippling costs of landslides, driven by a lack of preparedness, can only be mitigated through a concerted effort towards resilience where the connectivity between the human and natural environments is fully appreciated; a theme which the following sessions attempted to follow. The welcome was concluded with a short play recounting the experiences a group of children who survived the 2006 Leyte landslide disaster. The play was a poignant reminder of the human cost of landslide disasters. Although not as punctual as the Shinkansen, the five parallel sessions of papers covered a range of topics from landslide mapping and early warning to social impacts and interesting country case studies, most with time for discussion.

Amongst the highlights were some interesting contributions from Jon Godt (USGS), Ken Hewitt (Canada), Janus Wasowski (Italy), Masahiro Chigira (Japan), and Sandre Catane (Phillipines). Jon Godt presented recent developments of the USGS near-real-time earthquake induced landslide prediction models, developed upon the PAGER platform. Based on the 1994 Mw=6.7 Northridge earthquake in California, the model uses a combination of modelled peak ground acceleration from tele-seismic monitoring combined with SRTM derived topography, coarse resolution geological mapping and material properties to predict the potential locations of failures. Jon presented an application of the technique to the 2008 Wenchuan earthquake, showing that the results demonstrated a basic similarity with the initial post-earthquake mapping, which was later presented in several papers in this session. Of these the presentation by Masahiro Chigira gave a comprehensive overview with landslide locations mapped primarily from ALOS PRISM data. Professor Chigira demonstrated the concentration of the failures along the fault rupture, with a tendency of failures to follow both topographic ridges, in addition to appearing to follow the main river valleys. A tendency for landslides to be oriented NW – SW was highlighted, most probably reflecting the fault controlled topographic alignment, in addition to some interesting observations of ruptures on calcium carbonate surfaces.

The all encompassing ‘catastrophic slides and avalanches’ session began with an engaging presentation from Professor Ken Hewitt, on his work identifying massive rock avalanches in the Nanga Parbat-Haramosh massif in Northern Pakistan. Ken gave a compelling overview of the changing interpretation of Himalaya landforms, suggesting that the frequency of large rockslides may actually be significantly greater than we believe. Without adequate dating of these now numerous identified failures, their temporal spacing and frequency remains a mystery, but they may hold significant information on mountain chain evolution given their impact and persistence. This is clearly an important subject for further research.

The ‘view from space’ session saw a range of papers, many applying the PSInSAR technique for landslide monitoring. Of note was a critical overview by Janus Wasowski of some of the challenges that remain when applying this technique. Janus demonstrated the apparent mismatch of displacement measurement identified by ascending and descending orbit imagery over a relatively short distance, and noted the problem of scatterer distribution across the area of interest. The other presenters on this subject gave impressive results, though questions remain with regards the ability to compare these results to more conventional techniques and to extract true landslide movement data. A need for presentation of the assumptions and the limitations of the technique alongside the impressive levels of precision is clear. A second predictably impressive paper in this session was given by Fausto Guzzetti, in which he presented the MORFEO project. Here a range of remote sensing imagery is employed to automatically derive landsli
de susceptibility maps. This work builds upon previous research to use data such as ASTER to characterise the spectral response of landslide scars at the regional scale. Again a promising area for future research.

In the country case studies session, Sandra Catane presented an extremely balanced appraisal of the current progress in landslide risk-reduction in the Philippines. She recounted the increasing awareness of land instability resulting from both climate change and population pressures and highlighted the problems faced by authorities in preventing settlements developing on hazardous areas. A conscious shift has been made by the government away from reactive damage limitation to proactive mitigation measures with the generation of a national coverage of 1:50,000 landslide susceptibility maps. Despite the progress made from the National Geohazards Mapping Program the Leyte and Albay landslide disasters of 2006 demonstrated the need to further improve the hazard management strategies. Sandra concluded by calling for a more formalised links between government agencies, industry and academia in order to develop more effective policies aimed at reducing risk from landslide hazards. The challenge of implementing national strategies successfully at the local scale was a recurrent theme throughout the conference.

The final day of the meeting focussed upon future directions. Overall a useful meeting that brought together a group of scientists and policy makers, with a perhaps notable absence of practitioners. Clearly evident was the disparity between the extreme and the everyday, and the esoteric versus the chronic landslide hazards that ultimately have the greatest cumulative impact. Many researchers are following parallel paths; let’s hope that meetings such as this enable these paths to cross. Clear issues remain including the motivation to study landslide risk (both hazard and vulnerability) in the everyday, and the appropriate transfer of both understanding and technology to those communities most impacted upon by landslides. We hope that the follow-up meeting in Rome 2011 will show progress in these areas.