Section 2.2: Geophysical Deep Sounding

Current Projects

The DFG-Priority Programme "4D-MB - Mountain Building Processes in 4-Dimensions" (SPP 2017) forms an integral part of the international AlpArray mission to image the structure of the European Alps from their surface down to several hundred kilometers depth in the mantle.

Submarine permafrost layers represent the seaward extension of the arctic permafrost layers at the continental margins in Northern America and Eurasia. By recording ocean bottom seismic noise at a larger number of locations and analysing the data by the H/V method we will be able to map the spatial extend and temporal changes of the IBP.

DESERVE explores an environmentally unique region on Earth - the Dead Sea region - addressing three grand challenges: environmental risk, water availability, and climate change by combining long-term monitoring of geophysical parameters (stations are identical to IPOC), studies of coupled processes in the atmosphere, hydrosphere, pedosphere, and lithosphere as well as models for prediction and remediation strategies of geogenic risks.

The THICNES (The Highland-Vijayan Contact zone experiment in Sri Lanka) is a mid to long-term program focussing to reveal the properties of crust and upper mantle of Sri Lanka and to model and quantify the underlying geodynamic processes. In 2016 and 2017 a temporary broadband seismic network was installed in the island to observe local, regional and teleseismic earthquakes.

The great Sumatra fault (SF) is one of the most prominent examples for large strike-slip fault systems developing along subduction zones. A passive seismological experiment is carried out in northern Sumatra, close to the city of Banda Aceh. Our temporary seismological network is covering an interesting segment of the SF, which is also characterized by increased surrounding volcanic activity.

The project West Makran seismic transect aims to better determine the plate geometry of the western part of the Makran subduction zone (Iran), the crustal structure and hence the seismogenic and tsunamogenic potential of this region. Within this project 3 NS-running crustal-scale refraction seismic line (each 200km long) have been recorded.

The project SIOLA (SeIsmicity and neOtectonics of the LAptev sea region) will study the recent geodynamics and reconstruct Cenozoic rift evolution. Within this study we deployed 25 short-period seismic stations between Summer 2016 and Summer 2018 in the Lena delta and the region around Tiksi (Sibiria).

RomUkrSeis - This project involves seismic wide-angle reflection / refraction (WARR) measurements along a 675 km long profile extending from the Carpathian mountains in Romania across the Trans European Suture Zone (TESZ) to the East European Craton and the Ukrainian Shield.

In the past many groups have studied end-members of plate tectonic systems like a) Subduction, b) Collision and plateau building and c) large Transforms.

All these processes are active now simultaneously at the Anatolian Plate. In a new step forward to understand the geodynamics of our planet we want to integrate and understand how these processes work together and how they actively influence each other at this medium sized plate.

The main aim of the Longmenshan project is to study the structure and seismicity in the vicinity of the Longmenshan fault, which forms part of the eastern border of the Tibet plateau in China.

The South Atlantic and its conjugate rifted margins is a key site to study the whole spectrum of phenomena related to continental breakup and passive margin formation. It is an ideal natural laboratory on which to focus research. The newly funded SPP 1375 will establish a coordinated research program on passive margin processes by the German geoscience community. While focused on the South Atlantic research within the SPP will be process-oriented and the programme wlll maintain a global perspective through comparative studies and exchange with other key regions, most notably the Central and North Atlantic.

TIPAGE - TIEN SHAN - PAMIR GEODYNAMIC PROGRAM
In a series of geophysical experiment we study deep structures and geodynamic processes in the Tien Shan and Pamir collision zones, central Asia.

ANCORP 96 - ANdean COntinental Research Project
The aim of the project was to yield an image of the subduction process of the Nazca plate underneath South America. To obtain information about the velocity too, a combined near-vertical, wide-angle reflection/refraction seismic investigation was carried out. The profile stretched W-E at 21°S for 370 km from the coast of the Pacific ocean (Chile) until the Altiplano in Bolivia.

BASE - BAza Seismic Experiment
Controlled source seismic measurements shall be used to investigate the subsurface of the Baza Basin (Southern Spain). The aim of the study is 1) to study the structure of the sedimentary basin and of the fault system bounding the basin, and 2) to provide structural information for a planned scientific drilling project in the context of the International Continental Drilling Program (ICDP). The seismic project, funded by the German Science Foundation (DFG), is conducted by a German-Spanish group.

The interpretation of seismic refraction/wide-angle reflection data from the 1995 Crustal Investigations off- and on-shore Nazca/Central Andes (CINCA95) project has resulted in the derivation of nine E-W two-dimensional (2-D) velocity cross sections for the region between the Peru-Chile trench and the coast between 19.5°S and 25°S, with three of the cross sections extending a farther 100-200 km inland. These sections define the major lithospheric structures of the upper South American plate and the lower Nazca plate down to uppermost mantle depths of 30-60 km beneath this part of the present-day forearc region. In addition to showing the Nazca plate subducting at an increasing angle of 9-25° down to 30-50 km depth near the coast, these cross sections show a portion of the Moho dipping eastward from 43-50 km near the coast to 55-64 km up to about 240 km inland.

COBO - Cape Verdes Origin from Broadband Observations
The goal of this project is to image the Cape Verde mantle plume with seismological methods and to determine the physical properties of the plume.

The Dabie Shan marks the collision zone between the Sino-korean and the Yangtze craton with exposed ultra-high pressure metamorphic complexes. This region was considered as a possible drill site in the framework of the ICDP project. In spring 1997 a joint Chinese-German seismic project was carried out to investigate this region. The main objective of this project was to reveal the structure of the Earth's crust down to the Moho to understand the processes which are connected with the process of the triassic collision.

DEKORP - Deutsches Kontinentales Reflexionsseismisches Programm

DESERT - DEad SEa Rift Transect
A multi-national and interdisciplinary project to study the crustal structure and geodynamics of the Dead Sea Transform.

DESIRE - DEad Sea Integrated REsearch Project
GEO-DESIRE aims at studying the corner-stone of the geo-dynamics of the region, the pull-apart basin – the Dead Sea Basin. DESIRE will build on the knowledge from previous geoscientific/geophysical experiments like DESERT and the existing GPS and seismological networks in the Middle East.

Main aim of the experiment is the investigation of the local seismicity (distribution and kinematics) within the Fergana basin and the Southern Tien Shan in Southern Kirgistan. This will be achieved by installing a temporary local seismic network in 2009 and 2010.

Records of densely spaced shots along the Sino-US reflection line INDEPTH II at offsets between 70 and 130 km parallel to the main profile provide an image of the crust straddling the Indus-Yarlung suture. The major features are prominent reflections at about 20 km depth beneath and extending out to about 20-30 km north and south of the surface exposure of the suture, and north-dipping reflectors north of the suture. Despite the fact that several geological interpretations for the reflections are possible, the seismic mapping points to the importance of post-collisional (Oligocene-Miocene) tectonics, which reshaped the suture.

In the summer of 1998 as part of the INDEPTH III project, wide-angle seismic data were recorded from large shots along a 400 km long NNE-SSW profile crossing the Banggong-Nujiang suture (BNS) at about 89.5°E in central Tibet. Analysis of these data suggests that i) crustal thickness in the vicinity of the Banggong-Nujiang suture is 65+/-5 km and there is no evidence at 89.5°E for a step of 20 km in the Moho at the BNS and ii) a 25-30 km thick high velocity (6.5-7.2 km/s) lower crustal layer exists. In addition the present P-wave model contains no crustal low velocity layer.

The goal of the project GRANU 95 was an seismic investigation of the Saxothutingian zone of the Variscian foldbelt. A special focus was the saxonian Granulitgebirge and the question of its origin. Another adressed problem was the SW extension of the Saxothuringian zone and its relationship to the Muenchberger Gneissmasse.

The project aims to investigate the possibility of monitoring microseismicity due to fluid injection in sedimentary rocks. The drill hole which is used for the frac-experiment is situated in Gross Schoenebeck, 45 km north of Berlin.

Hawaii is certainly one of the best known examples of regions associated to hotspot-volcanism. The Hawaii-Emperor chain was formed by hot material ascending from the earth's deep interior. While the position of the plume conduit is approximately fixed the Pacific plate slowly passes over it, leaving behind a chain of volcanic islands.

In a previous study Li et al. (2000) investigated broadband data from station KIP (Oahu) and a temporary array (HIBSN) on the Big Island. The basic findings are an updoming area of the 660 km discontinuity SW of Big Island and a low velocity zone (LVZ) in about 140 km depth beneath the SW of Big Island.

The project I-GET is aimed at developing an innovative geothermal exploration approach based on advanced geophysical methods. The objective is to improve the detection, prior to drilling, of fluid bearing zones in naturally and/or artificially fractured geothermal reservoirs. This new approach will be tested in four European geothermal systems with different geological and thermodynamic reservoir characteristics.

INDEPTH - INternational DEep Profiling of Tibet and the Himalaya, Phase IV
The overall goal of the INDEPTH IV project is to develop a better understanding of the structure and evolution of the northeast margin of the Tibet plateau. This region is thought by many to represent the focus of active growth of the plateau into the Asian continent. INDEPTH IV and other closely linked projects will use active and passive seismic imaging, magnetotelluric profiling and geological surface investigations to achieve the above mentioned goal. The instruments from the GIPP will be used in the wide-angle profiling of the active seismic component and the receiver function profiling of the passive seismic component of the project.

A joint German-Indonesian research programme is focussing on technology and capacity building to support the geothermal energy development in Indonesia. The exploration research team investigates the exemplary geothermal region of Sipoholon (northern Sumatra). A wide range of methods such as structural geology, seismology, magnetotellurics and near-surface seismics is applied in an integrated approach to explore the geothermal potential and to derive a conceptual model of the target region.

The project seeks to establish the causes (mantle dynamics, continental structure, plate boundary forces), and some of the consequences (sedimentation style, opening of oceanic gateways, post-rift magmatism, oceanic plateaux formation) of continental breakup. From this a model for the break-up of central Gondwana, and effectively the birth of the African continent sensu stricto, will be established. This can serve as model for the break-up of supercontinents in general.

Determination of crustal velocity structure around Lake Toba (incl. Sumatra Fault) and possibly between Nias Island and the coast using British air-gun sources (Pg and Pn phases). Using local volcano-related events to study Lake Toba caldera and its relation to Sumatra Fault.

SIMBA - Seismic Investigations in the Messum and Brandberg Area
Continental breakup at the Namibia passive margin was accompanied by emplacement of a large number of subvolcanic ring-type intrusive complexes in northern Namibia (the Damaraland complexes). The seismic experiment SIMBA is focussed on the detailed crustal structure around one of the largest intrusive complexes, Messum. It furthermore aims to complement the northernmost profile of the MAMBA'95 experiment. The two projects are part of the interdisciplinary GFZ Namibia project.

The project aims to investigate details of the crustal structure crossing the Waterberg fault zone south of the Erongo Mountains in central Namibia. The special aim of our project is a combined near-incidence and wide-angle seismic reflection survey using 35 mobile six-component stations of GFZ Potsdam, each supplied with 6 vertical geophones (180 seismic channels) along two 18 km long lines across the Waterberg fault zone.

The aim of this project is to investigate the transition zone between the SE Atlantic and the African continent to reveal the history and mechanisms of the break-up and its relation to the driving magmatic processes. To achieve this goal GFZ (Potsdam), BGR(Hannover) and the CGS (Cape Town) will conduct together a seismic onshore-offshore wideangle experiment between about 30° and 32° S latitude.

SAFOD is the San Andreas Fault Observatory at Depth. The goal of SAFOD is to provide direct observational data on the composition, physical state and mechanical behavior of a major active fault zone at depth to test hypotheses pertaining to faulting and earthquake generation.

The Seychelles Plateau is believed to be continental material isolated during the separation of Africa from India some 60 million years ago. A 10 month deployment of broad-band and short-period 3-component seismometers started February 2003 with the aim of studying the heterogeneity and anisotropy of the upper-mantle beneath the Seychelles. Questions to be addressed are the role of the Seychelles during breakup, evidence of subsequent plume activity and the extent to which the plateau is continental in nature.

SPOC - Subduction Processes Off-shore Chile
In November 2001 a network of reflection profiles utilizing airgun sources was shot using the RV Sonne across the continental margin of southern Chile, in the vicinity of the source region of the 1960 earthquake (Mw = 9.5). Utilizing onshore recordings of the airgun sources and additional onshore and offshore sources, a combined onshore-offshore, active-passive seismic project between 36°S and 39°S was realized. This project comprised i) a pilot near-vertical incidence reflection (NVR) seismic experiment covering the onshore-offshore transition along an E-W line at 38°15´S, ii) three consecutive E-W wide-angle reflection / refraction (WRR) lines at 36°20´S, 37°15´S and 38°15´S, iii) an array of 30 stations for recording both active and passive sources and iv) six broadband stations along a profile at 39°S.

TANGO 98 - Feasibility study for Trans-America New Geophysical Observations 1998
In December 1998 the BGR recorded a network of combined reflection/refraction lines offshore Argentinia using streamer and OBHs. In order to close the gap between land and marine survey and to test the general propagation of signals for later projects in this area, additional receivers on land have been deployed, recording the airgun signals from the WE-trending OBH refraction line BGR98-REF1 also onshore. It turned out, that the airgun signals could be recorded with remarkable quality from the eastern end of the marine refraction line (500 km offshore) to the western end of the land stations (150 km onshore), i.e. up to distances of 650 km.

TICOSECT - Trans Isthmus COsta Rica Scientific Exploration of a Crustal Transect
The TICOSECT program aims to investigate the crustal structure of the active continental margin of Costa Rica and to understand the geodynamic processes within the subduction system. With the help of a comprehensive wide-angle seismic data set, composed of an onshore/offshore experiment as well as refraction measurements on land in northern Costa Rica, the lithospheric structure from the Middle America Trench (MAT) to the Caribbean lowland have been modelled.

TIPTEQ - From The Incoming Plate To mega Thrust Earth Quake Processes
The vision of this integrated study is a quantitative understanding of megathrust earthquake seismicity in subduction zones and its relation to processes at depth and at the surface.

TIPTIMON - Tien-Shan-Pamir Monitoring Program
TIPTIMON is a cross-disciplinary project that comprises long-term monitoring of geodynamics and climate in the Central Asian

URSEIS 95 - Urals Reflection Seismic Experiment and Integrated Studies
Within the project URSEIS 95 a 400 km long traverse crossing the Southern Urals was recorded by application of both, near-vertical and wide-angle seismic methods. High-resolution images of the near-vertical sections as well as P- and S-wave modelling of the wide-angle data demonstrate the presence of a 15-18 km thick crustal root beneath the central part of the Urals orogen. The high velocities and densities in the crustal root can be most easily explained by mafic rocks or a mix of mafic and ultramafic rocks belonging to the Russian plate which was being subducted beneath the Siberian plate during the Uralian orogeny.