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The Volcanological Service Support Project was established as a result of the destructive 1994 volcanic eruption ( AusAID Focus Vol. 15 no.3 [PDF 878KB ]) at Rabaul and was aimed at strengthening the Papua New Guinea volcanological service through RVO.

In an unpublished report Taylor (1955) suggested that both tectonic earthquakes and volcanic activity are related to prevailing conditions of regional stress. The diagnostic value of this relationship lies in the fact that abnormal stress conditions make their presence known first by tectonic earthquakes and later by volcanic eruption. This theory was developed as a result of intensive research following upon study of the new Hebrides volcanic arc and recent volcanism. Bougainville Island, with a deep trough (Planet Deep) situated west of and orientated parallel to its line of volcanoes, exhibits a similar structural pattern to the New Mebride4s Islands and it was considered by Taylor that the relationship between tectonic earthquakes and volcanic eruptions might also apply here. As a possible means of diagnosis an analysis of earthquakes and volcanic activity in the Bougainville area was undertaken to discover whether a positive relationship existed fro Mt. Bagana, and if so, whether there were indications of impending eruption of the Lake Loloru Crater.

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Recent field observations have identified the widespread occurrence of fluid seepage through the eastern Mediterranean Sea floor in association with mud volcanism or along deep faults. Gas hydrates and methane seeps are frequently found in cold seep areas and were anticipated targets of the MEDINAUT/MEDINETH initiatives. The study presented herein has utilized a multi-disciplinary approach incorporating observations and sampling of visually selected sites by the manned submersible Nautile and by ship-based sediment coring and geophysical surveys. The study focuses on the biogeochemical and ecological processes and conditions related to methane seepage, especially the anaerobic oxidation of methane (AOM), associated with ascending fluids on Kazan mud volcano in the eastern Mediterranean. Sampling of adjacent box cores for studies on the microbiology, biomarkers, pore water and solid phase geochemistry allowed us to integrate different biogeochemical data within a spatially highly heterogeneous system. Geophysical results clearly indicate the spatial heterogeneity of mud volcano environments. Results from pore water geochemistry and modeling efforts indicate that the rate of AOM is 6 mol m-2 year-1, which is lower than at active seep sites associated with conditions of focused flow, but greater than diffusion-dominated sites. Furthermore, under the non-focused flow conditions at Kazan mud volcano advective flow velocities are of the order of a few centimeters per year and gas hydrate formation is predicted to occur at a sediment depth of about 2 m and below. The methane flux through these sediments supports a large and diverse community of micro- and macrobiota, as demonstrated by carbon isotopic measurements on bulk organic matter, authigenic carbonates, specific biomarker compounds, and macrofaunal tissues...

Understanding the hydrology of cold seep environments is crucial to perform accurate estimates of fluid and chemical fluxes at sedimentary wedges. Shallow convection processes may affect fluid flux estimates and could favor the destabilization of gas hydrate accumulations, increasing the sediment-ocean methane flux. Evidence for the occurrence of convection at cold seeps, however, is still limited. We use the concentration of 14C (D14C) in carbonate crusts formed at cold seeps of the eastern Mediterranean Sea as a tracer for convective recirculation of seawater-derived fluids. A numerical model is applied to investigate the controls on 14C incorporation in cold seep carbonates. Our simulations show that increased amounts of CH4 in the expelled fluids result in elevated crust D14C, while high Ca2+ and HCO3 concentrations produce the opposite effect. Convection is the only transport process that can significantly increase crust D14C. Advection, bioirrigation, eddy diffusion and bioturbation instead, have little effect on, or produce a decrease of, crust D14C. In addition, the presence of old or modern carbon (MC) in host sediments prior to cementation and the 14C-decay associated to the time needed to form the crust contribute in defining the D14C of carbonate crusts. We then use the model to reproduce the 14C content of the eastern Mediterranean Sea crusts to constrain the chemical and hydrological conditions that led to their formation. Some crusts contain relatively low amounts of 14C (-945.0<D14C - <-930.2) which, assuming no ageing after crust formation, can be reproduced without considering convection. . Other crusts from two sites (the Amsterdam and Napoli mud volcanoes), instead, have a very high 14C-content (-899.0<D14C - <-838.4) which can only be reproduced by the model if convection mixes deep fluids with seawater.

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available