RRS James Clark Ross Cruise 269B, 07-24 Jul 2012, Reykjavik – Reykjavik. Arctic hydrate dissociation as a consequence of climate change: determining the vulnerable methane reservoir and gas escape mechanisms

Cruise JR269B was the second part of a two-leg geophysical programme led by a science party from the School of Ocean and Earth Science, University of Southampton, and carried out on the western margin of the Svalbard archipelago. The overall objective was to investigate gas transport and escape mechanisms and quantify gas and hydrate saturation values, in shallow sediments along the margin in areas where both significant accumulations of methane hydrate and active methane venting through the sea floor are known to occur. During the first leg, JR269A, which was completed in August-September 2011, the main objective had been to acquire high resolution seismic reflection and wide-angle survey data, working in collaboration with IFREMER’s ‘SYSIF’ team. In contrast, the primary objective of this second (2012) leg, JR269B, was the acquisition of controlled source electromagnetic (CSEM) survey data, to complement the pre-existing seismic data and to provide better constraints on the gas and hydrate saturation values within pore spaces. Secondary objectives during both legs included acquiring additional sub-bottom profiler, water column physical properties, and swath bathymetry data. A key objective of the analysis of data from both legs will be the joint inversion of co-located seismic and CSEM data, in order to optimise in situ estimates of concentrations of methane in free gas and hydrate forms within the subsurface.