Swath sonar bathymetry data used for that dataset was recorded during RV Heincke during cruise He525 using the onboard Kongsberg EM 710 multibeam echosounder. The cruise took place between 2019-03-05 and 2019-03-08 in the German North Sea. Data were recorded on 3 days between 2019-03-05 and 2019-03-07. The approximate average depth of the entire dataset is around 20 m.
To enhance MBES data accuracy, one sound velocity profile casts were conducted in the vicinity of the working area prior to the survey using sound velocity profiler MIDAS SVP 3000. After processing, these data were directly imported into the MBES Acquisition software Kongsberg SIS Seafloor Information System. Raw data were converted to MB-System format. Data were automaticallay and manually edited for false measurements. No further artificial sound velocity profiles were used during further processing. The data were corrected for tidal changes using data provided by the OSU Tidal Prediction Software OTPS that is retrievable through MB-System. The vertical datum of the data is now matched to mean sea level (MSL). Raster were calculated and stored in as GRD-files (Float-32, netCDF, EPSG 4326).
Multibeam bathymetry raw data using the ship's own Kongsberg EM 710 multibeam echosounder was not continuously recorded during RV Heincke cruise He525. Data were recorded on 3 days between 2019-03-05 and 2019-03-07 in the German North Sea and data acquisition was continuously monitored during the survey. The survey was targeted to cover occurences of boulders in the North of Helgoland.
Before data acquisition, sound velocity measurements using a sound velocity profil (SVP) probe were applied on the data for data calibration and are part of this dataset publication (He525_SVP_20190305.txt). Data are unprocessed and therefore may contain incorrect depth measurements without further processing. Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2017).
The understanding of the dynamics and scales of glacially induced faulting greatly benefits from an analyis using multiple geophysical datasets. By using a combination of high-resolution 2D seismic reflection data in combination with diffraction imaging, sediment echosounder data and shallow wells, we investigate a fault and graben system offshore Langeland Island in the Baltic Sea, which we term the Langeland Fault System. This approach allows to unravel the spatial character of the Langeland Fault System along an elevated basement block of the Ringkoebing-Fyn High. Our analysis shows the continuation of deep-rooted faults up to the seafloor. Imaging the shallowmost strata reveals Quaternary fault reactivation during glacial or postglacial times. This combination of imaging techniques is rarley realized in the onshore hinterland, thus, representing a unique analysis of Quaternary fault reactivation by combining onshore and offshore data and methods. Seismic data was acquired in September 2020 during a student field exercise cruise onboard R/V Alkor. The survey was organized by the University of Hamburg (Cruise AL545). Seismic data acquisition was carried out using a Mini-GI gun (true GI-mode with a 15 in³ generator and 30 in³ injector volume) and a 48-channel streamer with 4 m group spacing. The data have a dominant frequency of 250 Hz. Signal penetration is up to 1 s two-way travel time (TWT). The seismic processing routine included frequency filtering, amplitude recovery, noise reduction, surface-related multiple attenuation (SRME), Kirchhoff time migration. Innomars SES 2000 parametric sub-bottom profiler, which is hull-mounted on R/V Alkor, was used for the acquistion of the sediment echosounder data (Primary frequencies of about 100 kHz, secondary parametric frequency: 8 kHz). The diffraction imaging is based on separating the dominant reflected wavefield through a coherent summation scheme guided by a dip-based wavefront filter. In a next step, the reflection-only data is subtracted from the input data. The diffraction-only data is then focused using FD migration. By calculating the squared envelope of the focused diffractions, the diffraction energy stacks are obtained. The mapping procedure includes gridding using all available profiles in order to create time-structure maps by minimum curvature spline interpolation. Isochron maps (vertical thickness in two-way time) for the Triassic to Quaternary units were calculated by subtracting the top and bottom horizons of the specific units.
Ultra high resolution multi channel seismic data has been collected during the expedition He525 with R/V Heincke between 2019-03-05 and 2019-03-08 in the German North Sea to conduct a feasibility study on boulder detection in the shallow sub-seafloor with beamforming on ultra-high resolution seismic data. The campaign took place in the north of Helgoland where boulders on the seafloor have been identified. A digital solid-state streamer system (HTI) in a planar array set-up with 48 channels in a 8x3 m tow frame as well as a ultra high resolution seismic source (Applied Acoustics Dura-Spark 400 with a CSP-N 2400 Negative Discharge, 1750 J) were employed to acquire the profile GeoB19-112. The acquisition set-up is optimized for diffraction imaging but conventional seismic reflection imaging quality is limited. The data archived has been processed for diffraction imaging and thus boulder detection in a small area of interest (60x60 m). The archived Kingdom Porject required SQL 2012 (forward compatible, may require project updates).