From 1 - 10 / 28
  • Categories  

    This dataset includes two cruises of data collected to investigate Arctic hydrate dissociation as a consequence of climate change and to determine vulnerable methane reservoir and gas escape mechanisms. Work during both JR269A and JR269B was focused on two separate geographical areas. The first of these was west of Prins Karls Forland, in water depths of between 150 and 1200 m. At its landward end, this survey area crosses a region at water depths up to 400 m where a dense concentration of methane escape bubble plumes occur. The second survey area straddles the summit of the Vestnesa Ridge, in water depths of 1180 to 1400 m, and is also the site of methane escape bubble plumes within the water column and of fluid escape chimneys and pockmarks previously imaged at and beneath the sea bed. This area lies approximately 100 km west of the mouth of Kongsfjorden. Data collection took place between August 2011 and July 2012. The research expedition used a deep-towed, very high resolution seismic system to image the small-scale structures that convey gas to the seabed and to detect the presence of gas in the sediments. This was done in conjunction with an electromagnetic exploration system that uses a deep-towed transmitter and receivers on the seabed to derive the variations in electrical resistivity in the sediments beneath the seabed. The observations carried out on the two cruises included; underway, meteorological observations and echo sounder data, multichannel seismic reflection profiling data, wide angle seismic survey data, and ocean bottom seismometer (OBS) data, ocean bottom electro-magnetometer data and controlled source electromagnetic surveys (CSEM). The overall objectives of the project were to determine the spatial distribution of gas and hydrate accumulations beneath the sea bed; to investigate and understand gas transport and escape mechanisms, their spatial distribution, and the controls on these; and to quantify gas and hydrate saturation values in situ within the pore spaces of the shallow sediment reservoirs. The research is focused on specific areas where significant accumulations of methane hydrate and active methane venting through the sea floor were observed and documented during the earlier JR211 cruise in 2008. This is a NERC funded project hosted by University of Southampton. The data held at BODC include multichannel seismic reflection, TOPAS sub-bottom profiler and 2D seismic reflection data in SEG-Y format. No further data are expected.

  • As part of as part of the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA2) a geophysical survey was carried out in three different quarters of the North Sea: Norfolk Coast (Area 1), Dogger Bank (Area 2) and Fladen Ground (Area 3) from Kommandor Jack SEA2 Survey Leg 1, 2001. Multibeam, sidescan sonar and chirp seismic data were collected. The survey was carried to identify potential offshore Special Areas of Conservation (SACs). It was necessary to acquire data on specific features identified in the EU Habitats Directive, such as sandbanks and pockmarks, some of which might subsequently be defined as SACs. The survey was carried out in two legs. Leg one included the geophysical surveys in three different quarters of the North Sea as well as the charting which was used to guide the sampling and photographic work on the second leg. The following data are available - 25 files of processed multibeam data. Screenshots of backscatter processing are also available. Side-scan mosaics. Images are available from 15 boxes. Processed seismic data. Cruise report

  • This report is a contribution to the Strategic Environmental Assessment (SEA4) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The report describes the field of mud diapirs in the northern part of the SEA4 area, known as the Pilot Whale Diapirs, which were mapped during a multibeam survey carried out in 2002. A diapir is a fold or dome caused by more plastic rocks at depth, such as salt or mud, intruding overlying denser rocks, generally driven by their own buoyancy. Sometimes a diapir breaks through to the seafloor. The diapir field extends over an area some 60 km across, creating a very variable seabed terrain. The largest diapirs have produced elevations at the seafloor of more than 120m. The largest diapirs in the group are thought to have intruded to the seafloor from 500m or more beneath it. The evidence suggests that the diapirism was initiated between 5 and 1 million years ago, but it does not appear to be continuing at the present time.

  • As part of the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA2), this report briefly describes the evidence for the origin of shallow gas in Outer Moray Firth open blocks 15/20c and 15/25d. Sea floor pockmarks are known to occur within these blocks, and they indicate the seepage of gas from shallow levels into the local water column. An environmental concern is that any industry activity in these blocks must not plumb into any component of the system that is sustaining the gas seepages at sea bed. The study area covers two part-blocks within the eastern part of the Witch Ground Graben within the UK Central North Sea. This study follows on from the DTI 2001 SEA research on pockmarks.

  • Categories  

    This dataset consists of optical and acoustic seabed profiles of near bed hydrodynamics, bed morphology and suspended material in the water. Fieldwork was carried out by a team of researchers over a two week period, 24 May to 04 June 2013, surveying an area near Hilbre Island in the Dee Estuary. Measurements were taken in the inter-tidal and sub-tidal zones. Measurements were collected at three sites within the sampling area. A SEDbed suite of acoustic and optical instruments were deployed at each station to collect data. These instruments included CTD, LISST, Acoustic Doppler Velocimeter, Bedform and suspended sediment imager, Multi-tier sediment trap and 3-D Acoustic Rippler Profiler. The data collection described formed the fieldwork component of the NERC-funded project “Realistic Sedimentary Bedform Prediction: Incorporating Physical and Biological Cohesion (COHBED)”. The project was undertaken with the aim to produce information about the growth, movement and stability of bedforms that consist of natural mixtures of sands and muds. The project was composed of Standard Grant reference NE/I027223/1 as the lead grant with child grants NE/I026863/1, NE/I024402/1, NE/I02478X/1. The lead grant runs from 05 January 2012 to 04 July 2015 and the child grants run from 15 December 2011 to 14 June 2015 (NE/I026863/1), 01 January 2012 to 30 June 2015 (NE/I024402/1), and 01 January 2012 to 31 October 2015 (NE/I02478X/1). Dr Jacobus Hugo Baas of Bangor University, School of Ocean Sciences was the principal investigator of the lead grant of this project. The child grants were led by Dr Sarah Bass of University of Plymouth, School of Engineering, Professor Daniel Roy Parsons of University of Hull, Geography, Environment and Earth Science, and Professor Daniel Paterson of University of St Andrews, Biology, respectively. The data described here have been received as raw files by BODC and will be processed using our in-house systems and made available online in the future.

  • This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report reviews published and newly-acquired seabed geological data in an area of 78,000 square kilometres extending from the coast to more than 200 m water depth to the east of the British Isles. While it can be argued that the modern environment is a product of past environmental conditions, the basis for the review is also that our understanding of the modern environment can be significantly improved if new techniques, data and ideas are applied to a revision of the existing research knowledge. The purpose of the review is to place the characteristics of the seabed features that were surveyed by the DTI in 2003, and the processes forming them, into an improved understanding of their historical, local and regional context. In the summer of 2003 the DTI carried out new surveys in order to collect environmental information in 6 project areas in SEA5 and 2 project areas in SEA4. The survey data included multi-beam bathymetry, sidescan sonar, seismic reflection profiles, sea-floor photographs and samples.

  • As part of the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA6) a geophysical survey was undertaken on SV Meridian SEA6 Survey B (or Leg 2) in the Irish Sea between Ireland and the Isle of Man and at the north of Wales. Multibeam, sidescan sonar and chirp seismic data were collected. 11 processed gridded multibeam files are available. Raw data are also available. 11 sidescan mosaic tif files available. Raw seismic data are also available. Cruise reports are available.

  • As part of the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA6) a geophysical survey was undertaken on SV Meridian SEA6 Survey A (or Leg 1) in the eastern Irish Sea mainly in the central region between the Isle of Man and Cumbrian coast. The aims of the data collection were to survey geographical areas where the regional BGS maps and other published data indicated knowledge gaps in the understanding of regional seabed sediment distribution patterns and processes; Create high resolution bathymetric, backscatter and superficial geological data suitable for mapping banks, deeps, transitions between seabed coarse and fine sediments and the mid-shelf and nearshore environments; Generate data suitable for calibration of previous interpretations of net bedload sediment transport directions. Multibeam, sidescan sonar and chirp seismic data were collected. 14 gridded processed multibeam files are available. Raw data are also available.14 mosaic sidescan tif files available. Raw seismic data also available. Cruise reports are available.

  • This report is a contribution to Strategic Environmental Assessment SEA2 conducted by the Department of Trade and Industry (now Department of Energy and Climate Change) and it reviews the distribution and character of pockmarks - shallow seabed depressions - which are common in the area of the North Sea to the north-east of Scotland known as the Fladen Ground. Pockmarks are believed to be produced by the escape of fluids (gas or water, but generally gas in the North Sea) from the seafloor and are found in areas where the seabed sediments are soft, silty clays. Processes of pockmark formation, their geometry, age and distribution, and the sources of gas in the underlying geological strata are discussed. While the great majority of pockmarks are inactive at the present time, a few are observed to be actively seeping gas. In order to provide a stronger basis upon which the significance of pockmarks within mature oil and gas provinces of the North Sea might be assessed, the Department of Trade and Industry commissioned the acquisition of new data directed towards increasing the scientific understanding of sandbanks and pockmarks as part of the SEA2 process. The survey vessel Kommandor Jack was chartered in April 2001 and, among other operations, conducted high-resolution geophysical surveys of pockmarks in the Fladen Ground. Preliminary results from that operation are included in this report.

  • As part of the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA6) a seabed sampling, video and geophysical survey was undertaken in the central Irish Sea with specific focus given to areas of Liverpool Bay and Tremadog Bay. The survey objectives were to conduct a strategic environmental study of locations where features of interest had been previously identified by organisations such as the Countryside Council for Wales and the School of Ocean Sciences. Survey operations were focused on the following features: Possible methane-derived carbonate reefs in Cardigan Bay; Gassy Sediments in Tremadog Bay, Biogenic Reefs - Horse mussel beds. 36 video files are available. 186 photographs are available. 52 samples were collected using a Day Grab. A cruise report is available Processed data mosaics are available