Eos, Vol. 91, No. 30, 27 July 2010
MEETINGS Coping With Lake Kivu, East Africa Workshop on Tropical Rift Lake Systems: Integrated Volcanogenic, Tectonic, Biogeochemical, and Geohazard Assessment of Lake Kivu; Gisenyi, Rwanda, 13–15 January 2010 PAGE 264 Situated in the volcanic highlands of the East African Rift Valley’s western branch, Lake Kivu contains one of the most unusual and fascinating aquatic ecosystems on the planet. Bottom waters in the 480-meter- deep lake are warmer and saltier than its surface waters. The concentrations of dissolved carbon dioxide and methane are so high in the deep water that catastrophic overturn, an abrupt upwelling of deep water and gas driven by the buoyancy of expanding gas bubbles as they rise from the depths, could well happen in the coming century. Were this to occur, human fatalities would likely number in the hundreds of thousands—a disaster similar to what occurred when Lake Nyos (Cameroon) in 1986 emitted a large amount of carbon dioxide, causing hundreds of local residents to suffocate— but with orders- of-magnitude more gas release. Given the danger that Lake Kivu poses for the roughly 3 million people who live along its shore, a U.S. National Science Foundation (NSF) funded workshop was organized by Anthony Vodacek of the Rochester Institute of Technology, Robert Hecky of the University of Minnesota Duluth, and Cynthia
Ebinger of the University of Rochester to consider the dynamic components of the Lake Kivu system. The objective was to generate a plan for future investigations that address the most pressing issues of safety, ecological preservation, fisheries, and energy production. Fifty- seven scientists from North America, Europe, and Africa, representing many disciplines, attended the workshop. After introductory presentations by representatives from the Rwandan Ministries of Education, Infrastructure, and Agriculture and the Rwanda Environment Management Authority, scientific results were presented in sessions organized around the themes of tectonics, volcanology, limnology, fisheries, and hazard assessment. Presentations addressed how Kivu was formed by a combination of rifting and volcanic damming processes. Deadly earthquakes along faults bounding the lake and the recent eruptions of Nyamuragira and Nyiragongo volcanoes, just to the north of the shoreline city of Goma, warrant close scrutiny for potential impacts, including landslides, on the lake’s water column. Participants learned of sediment cores recovered in the mid-1970s that indicate that
Complexity and Extreme Events: Interdisciplinary Science of Natural Hazards Chapman Conference on Complexity and Extreme Events in Geosciences; Hyderabad, India, 15–19 February 2010 PAGE 265 Extreme events are key themes in geosciences research because of their devastating effects on society and their scientific complexities. The ever increasing economic and human losses from natural hazards underscore the urgency for improving understanding of extreme events to develop effective strategies to reduce their impact. Recent advances in nonlinear geophysics such as the role of long-term correlations and clustering, predictability of complex dynamical systems, and new approaches to nonequilibium phenomena have led to a new framework for understanding extreme events. The Chapman Conference on Complexity and Extreme Events in Geosciences was held to explore this emerging interdisciplinary
science, consolidate the recent understanding, and define new research directions. The conference brought together scientists engaged in research in extreme events (earthquakes, floods, hurricanes, marine storms, space storms, tsunamis, and other geophysical phenomena), as well as end users of research, including risk analysis and reinsurance industries. The interdisciplinary nature of the research and the need to assimilate across disciplines was highlighted in many presentations. The challenges of interdisciplinary research and the need for better communication across the boundaries were the focus of many discussions. Discussions of the recent advances in the science underlying extreme events were the highlights of the conference. Predictability
catastrophic gas overturn events occurred repeatedly, perhaps as many as five times in just the past 5500 years. Recent studies confirm that the lake’s unusual chemistry and stratification is derived from hydrothermal springs, which inject warm, saline, carbon dioxide–charged water into the deep basins. The number of major springs in the lake, their locations, and their behavior through time are not known, but their combined input currently amounts to about one third of the lake’s water supply. The methane concentration in the deep waters is a commercially viable source of energy for the region. A pilot plant was described that is presently harvesting enough methane to generate 2 megawatts of electricity on site, and a 50-megawatt system is under development. In addition, several presentations reviewed the lake’s biology. The population of haplochromine cichlid fish in Lake Kivu is represented by only 15 species, markedly less than nearby Lake Victoria, which harbors some 500 species of these fish. The low biodiversity of Kivu is likely a reflection of its environmental instability, yet paradoxically, mitochondrial DNA analyses indicate that the diverse cichlid populations of lakes Victoria and Edward evolved from Kivu ancestors. The participants subsequently met in thematic groups to recommend future research initiatives and to consider joint lake management by both riparian governments. A meeting white paper is available at http://dirs.cis .rit.edu/node/270. —THOMAS C. JOHNSON, Large Lakes Observatory and Department of Geological Sciences, University of Minnesota Duluth; E-mail:
[email protected]; and CHRISTOPHER A. SCHOLZ, Department of Earth Sciences, Syracuse University, Syracuse, N. Y.
of natural systems was a recurring theme, and its dual role as a measure of scientists’ understanding and as the basis for forecasting was emphasized in different settings. Recent advances in the understanding of the magnetosphere, triggered earthquakes, river runoffs, and other natural phenomena led to the emerging recognition that a better understanding of the driving mechanisms is essential for improved predictability. Society has an increasing need for improved forecasts, and complexity science is critical for developing new forecasting capabilities. The techniques to detect and characterize long-term correlations and trends in data have been successful in modeling extreme events and quantifying long-term trends, for instance, in climate change. Participants noted that better understanding of the nature of distribution functions, multifractality, nonequilibrium behavior, and other nonlinear phenomena are essential in developing comprehensive models of extreme events. An important outcome of the conference was the strong endorsement of sharing the knowledge gained from research among scientists, policy makers, and the
