Between 07.10.2007 and 28.10.2007, bathymetric data was acquired in the Makran region during the R/V METEOR cruise M74/2. The subduction of the Eurasian plate beneath the Arab plate in the Makran region is associated with continuous sediment input, active mud volcanism and fluid venting. The expedition was dedicated to the investigation of known seeps and the location of new venting sites. Furthermore, the scientists focused on the influence of extreme sediment thickness on the nature of vents and the relationship between local tectonics and spatial distribution of seeps. The multibeam echosounders (MBES) KONGSBERG SIMRAD EM120 and EM710 were utilized for large-scale mapping of vent-related structures on the seafloor. In order to visualize vent-related structures in the shallow subsurface, a deep-tow sidescan sonar, sediment echosounder, and high-resolution multichannel equipment were utilized. These acoustic methods were supplemented by video observations and gravity corer and multicorer samples, which yielded detailed information at many locations.
CI Citation: Paul Wintersteller (email@example.com) as responsible party for bathymetry raw data ingest and approval.
Description of the data source:
During the M74/2 cruise, the hull-mounted multibeam ecosounder (MBES) KONGSBERG SIMRAD EM710 was utilized to perform bathymetric mapping. The system is optimised to survey with high resolution in water depths of maximum 1,000 m depth and uses a frequency range from 70 to 100 kHz. 256 beams with an acoustical 1°(TX)/1°(RX) footprint are formed for each ping. Combining phase and amplitude bottom detection algorithms allows achieving best possible accuracy. For further information, consult: https://epic.awi.de/id/eprint/26726/1/Kon2007b.pdf.
The position and depth of the water column is estimated for each beam by using the detected two-way-travel time and the beam angle known for each beam and taking ray bending due to refraction in the water column by sound speed into account. As most of the working area during M74/2 was deeper than 1,000m water depths, the EM 710 was used sporadically as an addition to the EM120.
Systematically biased outer beams produced problems in areas with large overlap of parallel profiles. The applied sound velocity profile and a roll bias were tested as possible error sources, but no significant error was found. As the effect seems to be strongest on steep slopes, it might be a problem in yaw, which was not corrected for so far.
Responsible person during this cruise / PI: Markus Brüning
Chief Scientist: Volkhard Spiess (firstname.lastname@example.org)
Bohrmann, Gerhard; Lahajnar, Niko; Gaye, Birgit; Spieß, Volkhard; Betzler, Christian (2010): Nitrogen Cycle, Cold Seeps, Carbonate Platform Development in the Northwestern Indian Ocean, Cruise No.74, August 31 - December 22, 2007. METEOR-Berichte, Leitstelle Meteor, Institut für Meereskunde der Universität Hamburg, 10-3, 212, https://doi.org/10.2312/cr_m74
Latitude: 25.178300 * Longitude: 56.373900
Date/Time Start: 2007-10-07T00:00:00 * Date/Time End: 2007-10-28T00:00:00
M74/2-track * Latitude Start: 25.178300 * Longitude Start: 56.373900 * Latitude End: 25.178300 * Longitude End: 56.373900 * Date/Time Start: 2007-10-07T00:00:00 * Date/Time End: 2007-10-28T00:00:00 * Location: northwestern Indian Ocean * Campaign: M74/2 * Basis: Meteor (1986) * Device: Underway cruise track measurements (CT) * Comment: Fujayrah Harbor - Fujayrah Harbor
784 data points