SeaCause cruise SO186-2, aboard the RV Sonne, was carried out off northern Sumatra between 21st January and 24th February 2006, with mobilisation and demobilisation in Singapore and Penang, Malaysia, respectively. The geophysical survey acquired multichannel seismic data (MCS) using a 240 channel, 3 km Sercel streamer, and a tuned airgun array comprising 16 airguns with a total capacity of 50.8 litres. Bathymetry data, using the 12 kHz Simrad swath system, subseabed data using the hull mounted high resolution Parasound profiler together with gravity and magnetic data were also acquired. The main scientific objective of the survey was to investigate the southern part of the rupture zone of the 26th December 2004 9.3 magnitude earthquake, that caused the catastrophic tsunami of that date, and the rupture zone of the 8.7 magnitude earthquake of March 28th 2005. Specifically, to identify the segment boundary between the two earthquakes, as recognised by the distribution of their aftershocks. This was to be achieved by mapping the structure of the subduction zone including the dip angle of the subducted plate, the architecture of the accretionary prism and the structure of the forearc basins, particularly their strike-slip fault systems. Also to be investigated was whether there was a contribution to the 2004 tsunami from major submarine failures. During the survey a total of 5358 line kilometres of MCS data were acquired, mainly on lines oriented orthogonal to the subduction zone and extending from the ocean basin across the trench and accretionary prism to the forearc basins offshore Sumatra. The orthogonal survey lines were located on average approximately 40 km apart. The survey was planned using the bathymetry from the HMS Scott, RV Natsushima and RV Sonne cruises carried out in 2004. The morphology of the trench and sediment thickness varies from north to south. In the north the trench is poorly defined with shallow seabed dip but with sediment thickness of ~3.5 secs (TWT). The seafloor dips increase southwards, but sediment thickness decreases to ~2.5 secs (TWT) off Nias. Both the ocean basin and trench sediments are dissected by numerous normal faults, oriented subparallel to the plate boundary, with many that penetrate the oceanic crust. In the south Fracture Zones were identified. The structure of the deformation front on the seaward margin of the accretionary prism is highly variable. While the younges main thrust are predominantly landward vergent there are examples for seaward verging thrusts. The frontal fold develops in some cases already in the french while in most cases the frontal fold is at the beginning of the accretionary wedge. At some locations there are large sediment slumps on the frontal thrusts, the slope angle of the prism varies between 6 to 15 degrees, an angle that explains the large scale slumping. The width of the accretionary prism is widest in the north of the area at 140 km and narrows southwards until in the vicinity of the islands it is 40 km. In the north and central parts of the survey area the passage from the deformation front landwards into the older prism is rapid and the seabed gradients steep. The dip of the oceanic crust remains low and there is an obvious twofold increase (6-7 seconds TWT) in the sediment thickness. The basal decollement of the thrusts at the deformation front is in the lower sediment layer overlying oceanic basement. This is traced northeastward. A possible explanation for the increase in thickness of the prism is therefore considered to be the formation of a thrust duplex. Perhaps this is due to the subducted sediment thickness. In this region the prism forms a plateau and the internal pattern of the uppermost sediments shows striking similarities to the trench fill. Offshore of Simeulue Island the prism structure changes and it forms the more usually seen taper. The offscraped sediment forms a thinner section, the thrusts are more steeply dipping. The dip of the subducted plate here is greater than in the north. Three forearc basins were surveyed. In the north the western margin of the Aceh Basin lies along the West Andaman Fault. Within the main basin the sediments are internally undeformed. Farther south in the Simeulue Basin the northern and central parts there are numerous, active steeply dipping faults. In southern part of the basin there is a transpressional fault similarly to the Mentawi Fault off southern Sumatra. There are notable ‘bright spots’ in the upper section that may indicate the presence of hydrocarbon gas. There are also widespread Bottom Simulating Reflectors indication the presence of gashydrates and there may be also one double BSR. At the southern end of the surveyed area the Nias Basin may be subdivided along its length into two parts by a northnorthwest to southsoutheast trending carbonate platform development. The basin has had a varying subsidence history, in the south the subsidence was completed before the northern part started.

In the period from September 25th to October 19th 1979 5,260 km of magnetic, gravity and bathymetric lines and 3,567 km of reflection seismic lines were recovered on the first leg of the VALDIVIA Westafrica-cruise 1979 with the research objective to study similarities and differences in the geological development of physiographically different Northwest African continental margin segments. Test measurements have been carried out during this cruise with an “implosive" seismic sound source. The software for acquisition, calculation and presentation of gravity, magnetic and bathymetric data has been developed so that onboard presentation of free-air anomalies, Bouguer anomalies, anomalies of the earth's magnetic field and of the bathymetry could be achieved. Differences within the regional geological development of the Northwest African continental margin has been confirmed. Parts of the Moroccan continental margin are modified by a Cretaceous epirogenic uplift associated with block—faulting and halokinesis. Tertiary folding of the Western High Atlas extends into the shelf of the Tafelney Plateau segment.

During the period from 1974 to 2018 various cruises from BGR acquired seismic lines worldwide. The aim of these marine expeditions was a detailed survey of the geological structure.

The METEOR cruise M20/3 from 4th February to 13th March 1992 had two scientific objectives: One research topic was to study the variability of the Mesozoic oceanic crust along two flow-line profiles located north of the Kane and Hayes Fracture Zones. The other research topic was the investigation of the weak magnetic anomalies in the Jurassic magnetic quiet zone north of the Canary Islands. Seismic data with a coverage of 2,400 % were acquired together with magnetic, gravimetric and hydroacoustic data along the two flow-line profiles with a total length of 1,595 km. Magnetic, gravimetric and hydroacoustic measurements were carried out on 31 profiles with a total length of 6,069 km in the Jurassic quiet zone north of the Canary Islands. On 10 of these lines multichannel seismic reflection data (2,138 km) have been acquired.

The MSM67 SEGMENT research cruise was carried out between August 31st and October 4th 2017 aboard the research vessel MARIA S. MERIAN. Survey MSM67 SEGMENT it is intended to study the architecture of the rifted continental margin off East Greenland around the Jan Mayen fracture zone. Key issues to be addressed are margin segmentation and the location of the continent-ocean transition (COT). Both subjects are highly debated. Symmetric segmentation of conjugate margins has significant implications on our general understanding of continental rifting processes, and a margin-parallel COT off East Greenland would indicate an N-S opening in the Norwegian/Greenland Sea. The latter challenging most publications on the early evolution of the North Atlantic. A major open question is also the timing, duration and distribution of magmatism that resulted in the formation of the North Atlantic large igneous province. Previous suggestions of very short (~3 Myr) periods of intense magmatism have been challenged and a much longer duration and/or a post-breakup origin are under discussion. Here, we want to establish the amount of post-breakup magmatism as evident in high-velocity lower crust and test the dependence of magmatism with distance from the proposed hot-spot under Iceland and the influence of major fracture zones on volcanism.

On the MS Explora (1st September, 1976 - 29th September, 1976) multichannel seismic measurements were carried out on 44 lines The area covered was the Barentssea. The data format is Society of Exploration Geophysicists SEG Y.

The BGR Antarctic cruise 1996 from 29th December 1995 to 6th February 1996 with M.S. AKADEMIK NEMCHINOV was designed to acquire new marine geophysical data for a better understanding of the geological processes, timing, occurrence and location of rifts of the initial break-up of southern Gondwanaland. A total of 3,836 km of multichannel seismic reflection data have been collected in the areas of the Cosmonaut Sea, the Astrid Ridge, the Lazarev Sea and the southern Agulhas Plateau in parallel with magnetic and gravity measurements. In addition magnetic and gravity measurements were carried out on transit. Major new observations of the collected MCS data include: (1) Volcanic rocks play a major part in the construction of the Astrid Ridge and also of the Agulhas Plateau. (2) The early opening of the Lazarev Sea was associated with excessive volcanism resulting in the emplacement of a voluminous volcanic body characterized by an internally divergent pattern of seaward-dipping reflectors. (3) The Astrid Fracture Zone continues in form of a sediment-filled basement depression flanked by distinct basement highs into the Lazarev Sea, and apparently swings to the west parallel to the coast of Queen Maud Land. (4) The thickness of sediments in the Cosmonaut Sea overlying oceanic crust of inferred Early Cretaceous age is in excess of 4s (twt), i.e. about 6,000 m. Three regional seismic markers of inferred Cretaceous, Late Eocene-Oligocene and Middle Miocene ages subdivide the sedimentary column.

The cruise AL278 started on May, 10th 2006 in Kiel and ended in Kiel on May, 19th 2006. The previous BGR-cruises with RV AURELIA in 2003 and 2004 were designed to collect a grid of seismic MCS-data which should enable us to get a high-resolution overview over the upper 1 s TWT of the sediments of the German North Sea sector. During October/November 2005 a subsequent cruises with RV HEINCKE and FK SENCKENBERG was designed to tackle several special aims: - The detailed mapping of glacio-tectonic features North of Heligoland. - The shallow seismic mapping of the Holocene/Pleistocene-Boundary and topography of the Pleistocene sub-glacial valley system offshore of the East Friesian Islands. - High-resolution surveying of two areas designated for offshore wind farms in the southwestern German sector. - Detailed mapping of a wide and deep sub-glacial valley. One additional aim was to acquire a dense grid of seismic line in the area North of Weisse Bank where on several from previous cruises indications for shallow gas accumulations (e.g. “bright spots”) were found. Unfortunately, due to very bad weather conditions this aim could not be reached. Therefore this short cruise with RV ALKOR was used to acquire twelve MCS lines over this area. During the cruise a total ca. 1400 km of high quality MCS lines were surveyed and simultaneously measured by a sediment echosounder system that enabled additional profiles during transits with speeds 5 kn. Together with the previously acquired data these new data should help to extend our knowledge of the Late Tertiary and Quaternary evolution of the German North Sea Sector. The BGR high-resolution multichannel seismic reflection system consisting of a GI-Gun (0.8 l) and a 300 m streamer with 24 channels and a sediment echosounder type SES 2000 standard by Innomar, Rostock. While the BGR-seismic system was used to observe the shallow subsurface down to 2 s TWT penetration depth, the sediment echosounder with a penetration depth of several meters was primarily intended to identify sampling positions for the deployment of the BGR vibration corer during the succeeding Leg 2. Additionally, the echosounder system enables the relationship to the highest-resolution multichannel seismic measurements of the group of the University of Bremen on FK SENCKENBERG. All seismic records were processed onboard for the quality control and for a first interpretation.

During RV SONNE cruise 137 from 21st November to 28th December 1998 Geoscientific Investigations on the active Convergence Zone between the east Eurasian and Indo-Australian Plate (GINCO I) were carried out along the Sunda Arc, off Sumatra, Java and the Sunda Strait. The studies were headed by the BGR in close cooperation with German and Indonesian research institutions. A total amount of 5,500 km of magnetic, gravity and swath bathymetric profiles were recorded of which multi-channel seismic data exceeded 4,100 km. The scientific objectives were: (1) investigation of the structure and age of the accretionary wedges, outer arc highs and fore-arc basins off Sumatra and Java with special emphasis on the evolution of the Sunda Strait and the Krakatau area (2) differences in tectonic deformation between oblique (Sumatra) versus frontal (Java) subduction (3) search for oceanic crustal splinters in the accretionary wedges (4) definition of seismic sequences, thicknesses and ages of the fore-arc basin sediments as a pre-requisite for later on hydrocarbon assessments (5) identification and regional occurrence of bottom simulating reflectors (BSR) indicating gas hydrates. From the GINCO I project there is evidence for the existence of two accretionary wedges along the Sunda Arc: wedge I is of assumed Paleogene age and wedge II of Neogene to Recent age. The first inner wedge I is composed of tectonic flakes which are correlated from SE Sumatra across the southern Sunda Strait to NW Java. This implies a very similar plate tectonic regime at the time of the flake development during the Upper Oligocene to Lower Miocene and without marked differences in plate convergence direction from Java to Sumatra. Wedge I shows backthrusting along the northern transition toward the fore-arc basin. Today, wedge I forms the outer arc high and the backstop for the younger, outer wedge II. Magnetic, gravity and seismic results show, that within both wedges, there are no indications for an oceanic crustal splinter as hitherto postulated. Both wedges are underlain by oceanic crust of the subducting Indo-Australian slab which could be correlated from the trench off Sumatra up to 135 km to the northeast and up to 65 km from the trench off Java. Since the top of the oceanic crust differs considerably in reflectivity and surface relief we distinguished two types in the seismic records. One type is characterized by strong top reflections and a smooth surface and underlies accretionary wedge II and the southwest part of the wedge I (outer arc high) off Sumatra and Java. The second type has a low reflectivity and a rougher relief and underlies the tectonic flakes of accretionary wedge I (outer arc high) between the southwestern tip of Sumatra, the SundaStrait and NW Java. The missing outer arc high off the southern entrance of the Sunda Strait is explained by Neogene transtension in combination with arc-parallel strike-slip movements. The NW-SE running, transpressional Mentawai strike-slip fault zone (MFZ) was correlated from the SE Sumatra fore-arc basin to the NW Java fore-arc basin. Off the Sunda Strait northward bending branches of the MFZ are connected with the Sumatra Fault zone (SFZ). It is speculated that the SFZ originally was attached to the Cimandiri-Pelabuhan-Ratu strike-slip faults and shifted from the volcanic arc position into the fore-arc basin area due to clockwise rotation of Sumatra with respect to Java as well as due to increasingly oblique plate convergence since the late Lower Miocene. We explain the transtension of the western Sunda Strait (Semangka graben) and the transpression with inversion of the eastern Sunda Strait, along the newly detected Krakatau Basin, by this rotation. Seismostratigraphic interpretation revealed 5 main sequences (A - E), tentatively dated as Paleogene to Recent in age. The oldest seismic sequence A of assumed Eocene to Oligocene age is bounded at the top by a major erosional unconformity that was identified on all GINCO seismic profiles. The seaward diverging seismic pattern of sequence A is interpreted as a correlative sequence to the prograding Paleogene deltaic sediments encountered by wells offshore central and northern Sumatra. This is opposed to previous interpretation which assumed seaward dipping reflector sequences of basaltic origin erupted along the former Mesozoic passive margin of Sumatra. According to constructed time structure maps, the main NW-SE running depocentres of the post-Paleogene sediments are arc-parallel off Sumatra and Java with thicknesses of 3 s (TWT) and 5 s (TWT), respectively. The main depocentres of the Semangka graben and of the Krakatau Basin of the Sunda Strait strike north-south and have infills of 2 s - 5 s (TWT). Bottom simulating reflectors (BSR) occur within the upper sequences C - D along the flanks of the fore-arc basins and along doming structures but could not be detected in basin centres. Empiric relations of heat flow values and depths of BSR were determined indicating that with increasing waterdepth and decreasing heat flow the depths of the BSR increase.

In the period from February 13th to March 2nd 1980 4,037 km of magnetic, gravity and bathymetric lines and 1,195 km of digital reflection seismic lines were recovered on the 2nd leg of METEOR cruise no. 53. Heat flow measurements have been performed on 13 stations; on two stations sonobuoy refraction measurements and dredging have been carried out. From a preliminary interpretation of the seismic monitor records the Mazagan Plateau is part of the Moroccan Meseta. Seawards of this stable swell lies the 75 km wide, downfaulted rift graben characterized by salt diapirs. A submarine body, 150 square kilometres large, lying at the foot of the Mazagan Escarpment in water depths of 3000 m - 3800 m beneath sea level, from which western flank few granitic fragments were retrieved, is interpreted as a subsided and tilted block of the Mazagan Plateau. The north-trending magnetic anomalies, discovered during METEOR cruise no. 46 within the Essaouira continental margin segment have also been recognized within the Tafelney Plateau segment, situated between latitudes 30°45'N and 31°30'N off Morocco. Two neo-volcanic zones were found west of the Conception Bank and west of the Betancuria Massif/Fuerteventura Is. The Mesozoic and Tertiary depositional sequences are highly deformed by small piercement structures interpreted as dykes within these zones.