A global Earth Magnetic Anomaly Grid (EMAG2) was compiled from satellite, ship and airborne magnetic measurements. (Maus et al., 2009) Over the continents and the Arctic we made use of exisiting magnetic anomaly grids, whereas original ship and airborne trackline data were processed over the rest of the oceans, wherever available. CHAMP satellite magnetic measurements provided the magnetic field at wavelengths above 330 km. The EMAG2 grid is available at http://geomag.org and http://ngdc.noaa.gov. Directional gridding Due to the sparsity of magnetic field measurements in the southern oceans, it is necessary to interpolate the magnetic field between tracklines. Our interpolation algorithm takes the direction of the magnetic lineations into account. Tje lineations are parallel to the isochrons, which are perpendicular to the gradient of the age of teh oceanic crust. We use the age grid of Müller et al. (2008). The magnetic field ad a given grid point is computet by Least Squares Collocation from the surrounding measurements. If the point is on land, we use an isotropic correlation function with Rc = 14 km correlation length. Over the oceans we use Rc = 56 km parallel to the isochrons and Rc = 14 km in the spreading direction. Measurements seperated from the grid point by an age discontinuity or a topographic feature are excluded from the collation.

During the cruise with S.V. EXPLORA within the Ross Sea on the second marine-geophysical expedition of the Federal Institute for Geosciences and Natural Resources (BGR) to Antarctica, in total 6,745 km of magnetic, gravity and digital reflection seismic lines and additionally 1,400 km gravity lines were acquired in the period from January 10th to March 2nd 1980. On 43 stations sonobuoy refraction measurements have been carried out. The main results are: (1) In the eastern part of the Ross Sea Shelf two striking discontinuities have been identified in the reflection seismics representing gaps in the sediments at the turn-over of the Upper Miocene to the Pliocene (ca. 7 mio years B.P.) and between the Middle and Upper Miocene (ca. 11.5 mio. years B.P.) according to results of DSDP boreholes. (2) In the southern part of the Ross Sea Shelf the basement is uncovered at depths over 700m due to a thrust of the shelf ice recently. (3) A structural unit extends alongside the meridian of 180° separating the Ross Sea into two different geologic regions. This unit is characterised by two basement highs with seismic velocities exceeding 5 km/sec. (4) In relation with the GANOVEX expedition two profiles have been measured off northern Victoria Land which indicate two large faults with a faulting amount of 2 km. Another area is characterised by intrusive and volcanic bodies.

Within the frame of the comprehensive SPOC project (Subduction Processes off Chile) the SONNE cruises SO161 Leg 2 and 3 have been conducted between October 16th and November 29th, 2001, off central Chile between 28° and 44° S. In that period some 5,300 km were surveyed with multichannel seismic (MCS) reflection, magnetic, gravity, high-resolution bathymetric and echographic methods. In addition, approximately 3,900 km were surveyed with the same spectrum of methods but without MCS. The total number of 2D profiles was 48. Target was the variation of the subduction properties between the convergent oceanic Nazca and continental Southamerica plates and the different conditions that might influence the subduction process as there are: (1) age of the oceanic crust, (2) its structure and composition, (3) its sedimentary cover, (4) its thermal state, (5) the subduction angle and obliquity, and (6) the terrigenous sediment afflux from the continent. Furthermore, special focus was given to the subduction front, the subduction interface, the structure of the slope as well as to the forearc basin structure and history, and the general distribution of gas hydrate indicating bottom simulating reflectors (BSR's). The results are to be compared with previous studies of the Chilean active margin, e.g. CONDOR (SO 101 and 103) and CINCA (SO 104). The SPOC target area was subdivided into three sub-areas A,B and C. One area was chosen for a detailed survey by aid of a narrowly spaced grid and for a close link with a lot of partners. This area is characterized by a distinctly different margin type south of it is assumed. Moreover, the subducting portion of the aseismic Juan Fernandez Ridge is located in that area representing another important target of the survey. Advantageous conditions enabled the survey of an east-west profile south of Chiloé Island, providing a section through the submerged coastal Cordillera into the flooded longitudinal valley. Some results of Leg 2 and 3 are: In all areas A, B and C no subduction bulge (outer high) in the oceanic crust was visible perhaps due to the shortness of the profiles. The sedimentary cover of the oceanic crust is exceptionally thin, and the crustal thickness is generally quite "normal" with around 7 km derived from relatively weak Moho reflections. In area B a so far magnetically unmapped region was filled providing reliable ages of the oceanic crust, and suggesting that the Challenger Fracture Zone abruptly terminates west of the area of investigation. The survey in area C yielded valuable information on the trench morphology. The so far unique MCS profile south of Chiloé island shows a very wide trench and allows to extrapolate the general conditions encountered an area A southward to approximately 44° S. It can be stated that the situation is in sharp contrast to the basin structures detected by industry profiles further north in the Golfo de Corcovado.

The cruise leg MSM09/3 was conducted as a cooperative project between the Alfred Wegener Institute for Polar and Marine Research (AWI), the Federal Institute for Geosciences and Resources (BGR), the Geological Survey of Denmark and Greenland (GEUS) and Dalhousie University. The data format is Society of Exploration Geophysicists SEG Y. A geophysical survey covered areas of Baffin Bay and Davis Strait between Greenland and the Canadian Baffin Island. A component of the IPY 2007/08 Lead Project Plate Tectonics and Polar Gateways in the Earth System (PLATES & GATES), this project DAVIS GATE is aimed to develop a tectonic and sedimentary reconstruction of the opening process of this oceanic gateway. Baffin Bay and Davis Strait play an important role in the shallow water exchange from the Arctic to the Atlantic Ocean. The plate-tectonic evolution as well as the magmatic history of this region has been sparsely known and required a careful geophysical investigation in order to construct a set of gridded detailed paleotopographic maps for a complete geodynamic reconstruction of this gateway. With a set of three seismic refraction/wide-angle reflection profiles, using ocean-bottom seismometers on 62 stations, as well as multi-channel reflection seismic recordings with a 3000-m long streamer, data were acquired from the sedimentary cover to the deep crust and even from parts of the uppermost mantle. Additional seismic data supplement these profiles and provide insights into the structures of the basement and dominant fault zones such as the Ungava fault system. A parallel running magnetic survey aimed to resolve the temporal evolution of the oceanic crust of Baffin Bay. The extension and subsidence of the continental and transitional crust in the Davis Strait and the evolution of oceanic crust in the Labrador Sea and Baffin Bay could be investigated with dataset to which continuously recorded gravity anomaly data and sub-bottom profiler data also contribute. This dataset provides the basis of geometrical and physical properties of the crust required for a realistic geodynamic model which will describe the break-up and the ocean basin evolution between Greenland and Canada in terms of detailed paleo-topography.

The CINCA marine geoscience investigations on the convergent continental margin of Chile between 19°S and 33°30'S were accomplished during three legs of RV SONNE cruise SO-104, from 22. July to 15. October 1995. The objectives of the first leg are to contribute to an understanding of the geological architecture and of the tectonic mechanism in the area of the Chile convergent zone through a geophysical assessment of the tectonic structures of the Chile continental margin and the adjacent oceanic Nazca plate. During the first leg from 22. July to 24. August 1995 multichannel seismic reflection data with BGR's new digital streamer were collected along a systematic grid with a total traverse length of 4,494 km simultaneously with the acquisition of magnetic, gravimetric, Hydrosweep and Parasound data over a total traverse length of 7,012 km. GFZ's mobile land array of 12 seismic stations recorded the air gun shots fired by RV SONNE within the CINCA area. Three seismic lines were surveyed between 32°30'S and 33°30'S in the area of the CONDOR project. Here, the surface of the downbending oceanic crust is smooth. The 5,000 m to 6,000 m deep trench floor is underlain by sediments, in excess 2,500 m thick. The inner trench slope consists of a landward thickening accretionary wedge which terminates against a body forming the base of a fore arc basin near Valparaiso. The principal area of the CINCA project extends between 19°S and 26°S and comprises the convergent continental margin, the Peru-Chile trench and the seaward adjacent part of the Nazca plate up to approximately 75°W longitude. The tectonic regime of these units of the CINCA area is very different from the tectonic system of the respective units of the CONDOR area. The Eocene-aged and sediment-starved oceanic crust of the Nazca plate becomes blockfaulted when approaching the outer trench slope break. The 50 km to 70 km wide outer trench slope is characterized by a complex system of horst and graben structures in the CINCA area probably resulting from the strong downbending. Steep fault scarps forming the flanks of the horsts reach vertical offsets varying between few hundreds of metres to 1,000 m, and locally even more. The 7,000 m to 8,l00 m deep trench is very narrow and mostly sediment-starved in the CINCA area. Morphology and architecture of the continental margin of the CINCA area are controlled by planar and listric faulting and tilted blocks of inferred continental nature, which apparently slid down into the trench. The inferred continental blocks, overlying a reflective mass, are covered by sediments of presumably turbiditic nature. An accretionary wedge is difficult to define on the seismic single channel records from the CINCA area. However, processed seismic data show a deep reflective mass underlying the downfaulted blocks of inferred continental nature. This deep reflective mass is interpreted to consist of a tectonically eroded and underplated continental crust-basalt melange forming the transition between the downfaulted continental upper plate and the subducting oceanic lower plate. Complex structural highs of still unknown origin and nature have been observed on the upper continental slope at 20°S, 24°S and 25°S. The northernmost structural high represents the seaward termination of the Iquique fore arc basin. The accuracy of the acquired gravity and bathymetric data is very good, i.e. better than 1 mGal and less than 10 m. The Chile trench is associated with strong negative gravity anomalies, and the continental margin is characterized by several positive and negative gravity anomalies of varying size and amount. The first results of magnetic modeling show, that the intensive blockfaulting of the oceanic crust across the outer trench slope causes no loss of the magnetization of the oceanic crust. The air gun shots fired by RV SONNE in 50 m intervals along 17 seismic traverses were recorded by GFZ's mobile land array in the coastal area of Chile. Good quality data were obtained out to about 100 km distance and in some cases even out to about 150 km.

During the German-Canadian Nares Strait Expedition in 2001, an aeromagnetic survey was carried out across the northern part of the Nares Strait including the Hall Basin, Judge Daly Promontory and in Robeson Channel in cooperation with the Canadian GSC. The aim of the research was to detect and localize the Wegener Fault, a transform fault between Ellesmere Island and NW Greenland, which is closely linked to the opening of the North Atlantic and the Arctic Ocean. The helicopter-borne magnetic survey NARES I (Robeson Channel) was carried out with a flight line spacing of 2 km, and control profiles were flown every 10 km. During the expedition, 5470 km of line data were collected. The aeromagnetic data were recorded by a magnetometer, which was towed approx. 25 m beneath the helicopter and recorded at a constant altitude of 305 m (1000 ft) above ground.

The Sonne Cruise SO122 was carried out by the Federal Institute for Geosciences and Natural Resources (BGR, Hannover) from 3rd August to 9th September 1997, in cooperation with GEOMAR (Kiel), the National Institute of Oceanography (NIO, Karachi) and the Hydrocarbon Development Institute of Pakistan (HDIP). During the joint project with R/V SONNE the Makran accretionary wedge off Pakistan should have been investigated in detail with multi-channel reflection seismics, magnetics and gravimetry. Intense fishery offshore Pakistan forced a change of the area of investigation to the south with the following objectives: investigation of the crustal structure and occurrence of the bottom simulating reflector (BSR) in the Makran accretionary wedge; investigation of the structure of the Murray Ridge System in order to reconstruct the geodynamic evolution of the eastern Indian Plate margin; determination of the origin of the crust underlying the Indus Fan and reconnaissance of the sedimentary history of the Indus Fan in order to reveal the uplift and erosion history of the Himalayas.

A geophysical reconnaissance survey was carried out in the Labrador Sea and Davis Strait between July and September 1977 by BGR. The data format is Society of Exploration Geophysicists SEG Y. The survey was executed on the research vessel MS Explora. The seismic, magnetic and gravity data from 5931 line-kilometers on 21 lines were recorded on magnetic tape. A 24-fold coverage technique was used with 48 seismic channels (traces), with a 2400m streamer cable, and 23.45 l airgun array. A full integrated computerized satellite navigation system (INDAS III) served as positioning system. Based on a preliminary interpretation of the seismograms, the Labrador Sea was devided into an eastern (Greenland) and western (Canadian) area, seperated by the Mid Labrador Ridge. Within the eastern part of the Labrador Sea the Pre-Cenozoic sediments show three distinct layers, traceable over the entire Greenland area of the sea. In the Cenozoic layer olisthostromes occur. The highest apparent velocity determined from sonobuoy data was 9.26 km/sec. The calculated refractor lies at a depth of approximately 13 km. The seismic section from the sediments on the Canadian side of the Labrador Sea show a uniform series of thick sediments below the Cenozoic cover. The highly disturbed basement is often masked by the multiple reflections from the seafloor. Statements about the nature and structure of the basement can only be made after processing data.