ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Publisher
Language
Years
  • 1
    facet.materialart.
    Unknown
    Crustal structure of the Kermadec arc from MANGO seismic refraction profiles (2016)
    Wiley
    Details
    Publication Date: 2016-08-27
    Description: Three active-source seismic refraction profiles are integrated with morphological and potential field data to place the first regional constraints on the structure of the Kermadec subduction zone. These observations are used to test contrasting tectonic models for an along-strike transition in margin structure previously known as the 32°S boundary. We use residual bathymetry to constrain the geometry of this boundary and propose the name Central Kermadec Discontinuity (CKD). North of the CKD, the buried Tonga Ridge occupies the forearc with V P 6.5–7.3 km s -1 and residual free-air gravity anomalies constrain its latitudinal extent (north of 30.5°S), width (110 ± 20 km) and strike (~005° south of 25°S). South of the CKD the forearc is structurally homogeneous down-dip with V P 5.7–7.3 km s -1 . In the Havre Trough backarc, crustal thickness south of the CKD is 8-9 km, which is up-to 4 km thinner than the northern Havre Trough and at least 1 km thinner than the southern Havre Trough. We suggest that the Eocene arc did not extend along the current length of the Tonga-Kermadec trench. The Eocene arc was originally connected to the Three Kings Ridge and the CKD was likely formed during separation and easterly translation of an Eocene arc substrate during the early Oligocene. We suggest that the first-order crustal thickness variations along the Kermadec arc were inherited from before the Neogene and reflect Mesozoic crustal structure, the Cenozoic evolution of the Tonga-Kermadec-Hikurangi margin and along-strike variations in the duration of arc volcanism.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    3-D active source tomography around Simeulue Island offshore Sumatra: Thick crustal zone responsible for earthquake segment boundary (2013)
    Wiley
    Details
    Publication Date: 2013-01-16
    Description: [1]  We present a detailed 3-D P -wave velocity model obtained by first-arrival travel-time tomography with seismic refraction data in the segment boundary of the Sumatra subduction zone across Simeulue Island, and an image of the top of the subducted oceanic crust extracted from depth-migrated multi-channel seismic reflection profiles. We have picked P -wave first arrivals of the air-gun source seismic data recorded by local networks of ocean-bottom seismometers, and inverted the travel-times for a 3-D velocity model of the subduction zone. This velocity model shows an anomalous zone of intermediate velocities between those of oceanic crust and mantle that is associated with raised topography on the top of the oceanic crust. We interpret this feature as a thickened crustal zone in the subducting plate with compositional and topographic variations, providing a primary control on the upper plate structure and on the segmentation of the 2004 and 2005 earthquake ruptures.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Magnetotelluric image of the fluid cycle in the Costa Rican subduction zone (2011)
    Springer Nature
    Details
    Publication Date: 2011-02-01
    Description: Magnetotelluric image of the fluid cycle in the Costa Rican subduction zone Nature Geoscience 4, 108 (2011). doi:10.1038/ngeo1041 Authors: Tamara Worzewski, Marion Jegen, Heidrun Kopp, Heinrich Brasse & Waldo Taylor Castillo Fluids entering the subduction zone play a key role in the subduction process. They cause changes in the dynamics and thermal structure of the subduction zone, and trigger earthquakes when released from the subducting plate during metamorphism. Fluids are delivered to the subduction zone by the oceanic crust and also enter the oceanic plate as it bends downwards at the plate boundary. However, the amount of fluids entering subduction zones is not matched by that leaving through volcanic emissions or transfer to the deep mantle, implying possible storage of fluids in the crust. Here we use magnetotelluric data to map the entire hydration and dehydration cycle of the Costa Rican subduction zone to 120 km depth. Along the incoming plate bend, we detect a conductivity anomaly that we interpret as sea water penetrating down extensional faults and cracks into the upper mantle. Along the subducting plate interface we document the dehydration of sediments, the crust and mantle. We identify an accumulation of fluids at ∼20–30 km depth at a distance of 30 km seaward from the volcanic arc. Comparison with other subduction zones indicates that such fluid accumulation is a global phenomenon. Although we are unable to test whether these fluid reservoirs grow with time, we suggest that they can account for some of the missing outflow of fluid at subduction zones.
    Print ISSN: 1752-0894
    Electronic ISSN: 1752-0908
    Topics: Geosciences
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Finding a realistic velocity distribution based on iterating forward modelling and tomographic inversion (2011)
    Oxford University Press
    Details
    Publication Date: 2011-05-12
    Description: SUMMARY Tomography is like a photograph that was taken by a camera with blurred and defective lenses that deform the shapes and colours of objects. Reporting quantitative parameters derived from tomographic inversion is not always adequate because tomographic results are often strongly biased. To quantify the results of tomographic inversion, we propose a forward modelling and tomographic inversion (FM&TI) approach that aims to find a more realistic solution than conventional tomographic inversion. The FM&TI scheme is based on the assumption that if two tomograms derived from the inversion of observed and synthetic data are identical, the synthetic structure may appear to be closer to the real unknown structure in the ground than the inversion result. However, the manual design of the synthetic velocity distribution is usually time-consuming and ambiguous. In this study, we propose an approach that automatically searches for a probabilistic model. In this approach, a synthetic model is iteratively updated while taking into account the bias of the model in previous stages of the FM&TI performance. Here, we present an example of synthetic modelling and real data processing for an active source refraction data set corresponding to a marine profile across the subduction zone in Chile at about 32°S latitude. A key feature of the model is a low-velocity channel above the subducted oceanic crust, which was defined in the synthetic model and expected in the real case. The conventional first arrival traveltime tomography was barely able to resolve this channel. However, after several iterations of the FM&TI modelling, we succeeded in reconstructing this channel clearly. In the paper, we briefly discuss the nature of this low-velocity subduction channel, and we compare the results with other studies.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Seismic structure of the north-central Chile convergent margin: Subduction erosion of a paleomagmatic arc (2014)
    Wiley
    Details
    Publication Date: 2014-02-19
    Description: [1]  We study the erosive convergent margin of north-central Chile (at ~31°S) by using high-resolution bathymetric, wide-angle refraction, and multichannel seismic reflection data to derive a detailed tomographic 2D velocity-depth model. In the overriding plate, our velocity model shows that lowermost crustal velocities beneath the upper continental slope are 6.0-6.5 km/s, which are interpreted as the continental basement composed by characteristic metamorphic and igneous rocks of the Coastal Cordillera. Beneath the lower and middle continental slope, however, the presence of a zone of reduced velocities (3.5–5.0 km/s) is interpreted as the outermost forearc composed of volcanic rocks hydrofractured as result of frontal and basal erosion. At the landward edge of the outermost forearc, the bathymetric and seismic data provide evidence for the presence of a prominent trenchward-dipping normal scarp (~1 km offset), which overlies a strong lateral velocity contrast from ~5.0 to ~6.0 km/s. This pronounced velocity contrast propagates deep into the continental crust, and it resembles a major normal listric fault. We interpret this seismic discontinuity as the volcanic-continental basement contact of the submerged Coastal Cordillera characterized by a gravitational collapse of the outermost forearc. Subduction erosion has, most likely, caused large scale crustal thinning and long term subsidence of the outermost forearc.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Crustal structure of the Ionian basin and eastern Sicily margin: results from a wide-angle seismic survey. (2018)
    Wiley
    Details
    Publication Date: 2018-02-20
    Description: In the Ionian Sea (Central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreat toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian Basin. A major lateral slab tear fault is required to accommodate the slab roll-back. This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial. This study focuses on the deep crustal structure of the Eastern-Sicily margin and the Malta Escarpment. We present two two-dimensional P-wave velocity models obtained from forward modeling of wide-angle seismic data acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. The interpretation of the velocity models suggests that the tear fault is located east of the Malta Escarpment, along the Alfeo fault system (AFS).
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Dehydration of subducting slow-spread oceanic lithosphere in the Lesser Antilles (2017)
    Springer Nature
    Details
    Publication Date: 2017-07-11
    Description: Dehydration of subducting slow-spread oceanic lithosphere in the Lesser Antilles Nature Communications, Published online: 10 July 2017; doi:10.1038/ncomms15980 During subduction water is transported into the mantle, but constraining its release remains challenging. Here, using seismic tomography of the Lesser Antilles arc, the authors track the multistage dehydration of the slab and its lateral variations associated with heterogeneous slab composition.
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Geometry of the deep Calabrian subduction (Central Mediterranean Sea) from wide‐angle seismic data and 3‐D gravity modeling (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract The Calabrian subduction zone is one of the narrowest arcs on Earth and a key area to understand the geodynamic evolution of the Mediterranean and other marginal seas. Here in the Ionian Sea, the African plate subducts beneath Eurasia. Imaging the boundary between the downgoing slab and the upper plate along the Calabrian subduction zone is important for assessing the potential of the subduction zone to generate mega‐thrust earthquakes and was the main objective of this study. Here we present and analyze the results from a 380 km long, wide‐angle seismic profile spanning the complete subduction zone, from the deep Ionian Basin and the accretionary wedge to NE Sicily, with additional constraints offered by 3‐D Gravity modeling and the analysis of earthquake hypocenters. The velocity model for the wide‐angle seismic profile images thin oceanic crust throughout the basin. The Calabrian backstop extends underneath the accretionary wedge to about 100 km SE of the coast. The seismic model was extended in depth using earthquake hypocenters. The combined results indicate that the slab dip increases abruptly from 2‐3° to 60‐70° over a distance of ≤50 km underneath the Calabrian backstop. This abrupt steepening is likely related to the roll‐back geodynamic evolution of the narrow Calabrian slab which shows great similarity to the shallow and deep geometry of the Gibraltar slab.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Land seismic data of the ALPHA amphibious controlled source experiment - Datasets (2017)
    GFZ Data Services
    Details
    Publication Date: 2022-05-13
    Description: Abstract
    Description: Raw-, SEG-Y and other supplementary data of the landside deployment from the amphibious wide-angle seismic experiment ALPHA are presented. The aim of this project was to reveal the crustal and lithospheric structure of the subducting Adriatic plate and the external accretionary wedge in the southern Dinarides. Airgun shots from the RV Meteor were recorded along two profiles across Montenegro and northern Albania.
    Keywords: Seismology ; Adriatic Plate ; Montenegro ; Albania
    Language: English
    Type: Dataset , controlled source data
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA GFZ
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...