During its Regional Meeting at Addis-Abiba, Ethiopia, in February 2011, the Executive Committee of the IAG approved the creation of the Working Group "GEOMORPH-X - Extreme events in geomorphology". We invite all geomorphologists interested in the study of the significance of extreme events in the evolution of terrestrial landforms to join the Working Group and to participate to its activities.
The question of the linearity or non-linearity of the evolution of landforms has lain at the core of geomorphology since its beginnings as a scientific discipline. Following the seminal theory of W.M. Davis, relief creation started with a tectonic accident that gave "birth" to a volume of relief which normal erosion will shape afterwards. Then, the erosion cycle will progressively erase the relief towards the realization of the perfect peneplain – except if some "accidents" happened again. Following climatic geomorphology paradigms, landforms tend to be in equilibrium with regional climate, but sudden changes in thermal or precipitation regimes can lead to strong disequilibrium, enhancing or slowing erosion rates. In the 1960s, Wolman and Miller introduced the magnitude-frequency concept and recent epistemological advances enhance the non-linear dynamics of geomorphic systems (e.g. Phillips, 2006). High-magnitude events (X-events: extreme rains, mega-tsunamis, catastrophic landslides, etc.) are rare, sometimes never observed in historic times, and have long been regarded as somewhat ‘suspicious' by the scientific community. The first reason is that they do not fit well with gradualist ideas that dominate earth sciences; the second is that geologic arguments mobilized by the catastrophism theory (diluvianism) frequently anchored their roots in considerations more religious than scientific.
Sometimes, acceptance of extreme phenomena as providing possible explanations for particular landforms takes decades (such as the Missoula Lakes jökulhlaup proposed by Bretz in the 1920s for the formation of the Channeled Scabland was not accepted before the 1960s). New catastrophism, introduced in the early 1980s, opened a new way to study high-energy events and their impacts in the geological record. More and more studies reveal that extreme events might have played a role in the evolution of landforms in several regions of the world: sturzströme have been recognized in many places (Dawson et al., 1986; Schneider et al., 1999), catastrophic landslides are widespread in high mountain areas (Evans et al., 2006; Hewitt et al., 1988; Kojan & Hutchinson, 1978; Fort & Peulvast, 1995; etc.) and giant submarines slope failures have been discovered in recent years (Moore et al, 1989; Nisbet & Piper, 1998). Beyond these numerous examples, it is questionable how fundamental are extreme events in the evolution of landforms. Are they solely spectacular but local anomalies? How do they interfere with geomorphic system dynamics? Are they epiphenomena or driving forces?
It is time now for geomorphologists to start a common debate on the significance of these spectacular events and their resultant landforms in the geomorphic evolution of the Earth surface. The debate on the place of extreme events in the geomorphic continuum extends the major question of frequency/magnitude, stationarity, deterministic chaos, landform resilience, etc., developed in our community for decades. Some reflections on extreme events lie also within the sphere of natural hazards assessment, so this WG outputs will naturally feed the geomorphologic debate, and extend in a more theoretical view works by the WG IAGeomhaz. Some extreme events legacies are now popular scenery sites, so connections between this WG and Geomorphosites WG will be strong.
1 - Publication of a blog: http://geomorphx.blogspot.com
"X-site of the month": every month, one interesting/spectacular case will be presented. The text should be concise (maximum 1 page, references not included), illustrations demonstrative and, as far as possible, spectacular. This is not a short paper, but rather a spotlight on an original landform, a specific methodology, linked with an extreme phenomena. We invite you to submit any proposal.
- geomorphic markers
- event reconstruction
- local, regional or global impacts of the event on process dynamics
- study methodology
"List of papers published in peer journal, books published"
"List of upcoming conferences or sessions on extreme events in geosciences"
2 – News
New information (published papers, books, events, etc.) on extreme events will be highlighted on a regular basis on a social network: join us to get up-to-date news.
Look for user: Iag Geomorph-x on Facebook®.
3 - Information letter
Published on a quarterly basis, this information letter will gather the main information posted on the blog, and will be diffused to geomorphology distribution lists. This letter will be widely circulated and will increase the awareness amongst other scientists, stake-holders, planners, authorities and (hopefully) the general public about the importance of extreme geomorphic events.
To receive this information letter, send an email to the WG secretary, James Terry: firstname.lastname@example.org
Dr Samuel Etienne (University of French Polynesia, Tahiti, France, Chairman),
Dr James Terry (National University of Singapore, Singapore, Secretary),
Prof. John Clague (Simon Fraser University, Canada)
Prof. Jonathan Nott (James Cook University, Australia)
Dr Liz Safran (Lewis & Clark College, Portland, USA)
Dr Richard Chiverrell (University of Liverpool, UK).
Send any information to: email@example.com or firstname.lastname@example.org
Création d'un groupe de travail "GEOMORPH-X - Evènements extrêmes en géomorphologie"