Correlations between SO2 flux, seismicity, and outgassing activity at the open vent of Villarrica volcano, Chile

The characteristics of the open vent activity of Villarrica volcano, Chile, were studied in detail by integrating visual observations of the lava lake, analysis of the seismic tremor, and measurements of SO2 flux. The outgassing activity comprises a persistent gas plume emission from the bottom of the crater as well as frequent explosive events. Three main styles of bubble bursting were identified at the surface of the active lava lake: seething magma, small short-lived lava fountains, and Strombolian explosions. Seething magma consists of continual burst of relatively small bubbles (a few meters in diameter) with varying strength over the entire surface of the lava lake. Small lava fountains, seen as a vigorous extension of seething magma, commonly have durations of 20–120 s and reach 10–40 m high above the lava lake. Correlations between seismicity and visual observations indicate that the seismic tremor is mostly caused by the explosive outgassing activity. Furthermore, for different periods between 2000 and 2006, during which the activity remained comparable, the real-time seismic amplitude measurement system (RSAM) and SO2 emission rates show a very good correlation. Higher SO2 emissions appeared to be related to higher levels of the lava lake, stronger bubble bursting activity, and changes in the morphology and texture of the crater floor. Background (low) levels of activity correspond to a lava lake located >80 m below the crater rim, small and/or blocky morphology of the roof, seismic amplitude (RSAM) lower than 25 units, few volcano-tectonic earthquakes, and daily averages of SO2 emissions lower than 600 Mg/d

Dynamic political contexts and power asymmetries: the cases of the Blue Nile and the Yarmouk Rivers

This paper explores the evolving patterns of hydropolitical relations in the dynamic contexts of Yarmouk and Blue Nile Rivers in comparison. The analysis aims at shedding light over the complex implications that recent political and social changes have aroused for the water disputes between Jordan and Syria on the one hand, and Ethiopia and Egypt on the other. In both basins, cooperative efforts toward the integrated management of transboundary waters have been only partially effective and largely undermined by the perpetuation of unilateral actions by riparian states. In the case studies, the lack of a basin-wide vision over the control and use of shared waters has resulted in disputes among the basin states and ultimately in an unsustainable, unfair, and unwise utilization of the resources. This paper argues that a substantive and effective integration of national water policies is unlikely to occur, unless power asymmetries are properly addressed in order to overcome the likelihood of hegemonic regimes

Malaria Vectors in Lake Victoria and Adjacent Habitats in Western Kenya

The prevalence of malaria among the residents of the Lake Victoria basin remains high. The environment associated with the lake may maintain a high number of malaria vectors. Lake habitats including water hyacinths have been suspected to be the source of vectors. This study investigated whether malaria vectors breed in the lake habitats and adjacent backwater pools. Anopheline larvae were collected within the littoral zone of the lake and adjacent pools located along approximately 24.3 km of the lakeshore in western Kenya, and their breeding sites characterized. Three primary vector species, Anopheles arabiensis, Anopheles gambiae s.s. and Anopheles funestus s.s., and three potential vectors, were found in the lake habitats. Unexpectedly, An. arabiensis was the most dominant vector species in the lake sampling sites. Its habitats were uncovered or covered with short grass. A potential secondary malaria vector, Anopheles rivulorum, dominated the water hyacinths in the lake. Most breeding sites in the lake were limited to areas that were surrounded by tall emergent plants, including trees, and those not exposed to waves. Nearly half of adjacent habitats were lagoons that were separated from the lake by sand bars. Lagoons contained a variety of microhabitats. Anopheles arabiensis dominated open habitats, whereas An. funestus s.s. was found mainly in vegetated habitats in lagoons. The current study confirmed that several breeding sites are associated with Lake Victoria. Given that Lake Victoria is the second largest lake in the world, the lake related habitats must be extensive; therefore, making targeted vector control difficult. Further exploration is necessary to estimate the effects of lake associated habitats on malaria transmission so as to inform a rational decision-making process for vector control

Intermittent Preventive Treatment for Malaria in Papua New Guinean Infants Exposed to Plasmodium falciparum and P. vivax: A Randomized Controlled Trial

A three-arm randomized trial conducted among infants in Papua New Guinea estimates the preventive effect against malaria episodes of intermittent preventive treatment, in an area where children are exposed to both falciparum and vivax malaria

Managing Environmental Risk in Presence of Climate Change: The Role of Adaptation in the Nile Basin of Ethiopia

This study investigates the impact of climate change adaptation on farm households' downside risk exposure in the Nile Basin of Ethiopia. The analysis relies on a moment-based specification of the stochastic production function. We use an empirical strategy that accounts for the heterogeneity in the decision on whether to adapt or not, and for unobservable characteristics of farmers and their farm. We find that past adaptation to climate change (i) reduces current downside risk exposure, and so the risk of crop failure; (ii) would have been more beneficial to the non-adapters if they adapted, in terms of reduction in downside risk exposure; and (iii) is a successful risk management strategy that makes the adapters more resilient to climatic conditions