ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
Publisher
Years
  • 1
    Publication Date: 2017-12-07
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2019-01-09
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2019-01-14
    Description: The Earth’s ocean floor deforms continuously under the influence of plate tectonic processes. In recent years, the development of deep-sea instruments using acoustic direct-path ranging allows observations of ocean floor deformation with unprecedented spatial and temporal resolution. Due to rapid technological progress, acoustic ranging emerged as a central research field to monitor seafloor deformation. Here we review recent developments and the progress of direct-path ranging applications. We discuss the methodology and examine the effects of the oceanographic environment on the measurement precision. Comparing the resolution of previous deployments, we find that the baseline uncertainty increases linearly with baseline length, at least for distances up to 3 km, but with different linear relations for each deployment. Measurements of displacement at millimeter-level precision across normal, thrust or strike-slip faults are discussed to evaluate the influence of dedicated network designs appropriate for the discrete fault geometries. Furthermore, tectonically quiet areas, such as flanks of coastal or ocean island volcanoes and passive continental margins pose substantial hazards that often lack in-situ monitoring and are therefore a significant target for the application of seafloor geodetic techniques.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2016-12-01
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2017-05-11
    Description: The Ionian Sea between Sicily and Calabria is known for its complex geological setting, as it is located at the convergence zone of the African and Eurasian plates. The seismogenic potential in this region is manifested by several high magnitude and disastrous earthquakes like the 1908 Messina Earthquake. Furthermore, the area is affected by intense volcanism like the Aeolian Island volcanos in the Tyrrhenian Sea and Europe’s largest active volcano, Mt Etna, sitting directly at the eastern coast of Sicily. During the last years, the possible presence of Subduction Tear Edge Propagator faults (STEP-faults) has been heavily debated. The main candidates for these faults are the Ionian Fault in the Northeast and the Alfeo-Etna Fault in the Southwest of the working area between Sicily and Calabria. Nevertheless, only little is known about near seafloor deformation zones and sedimentary processes in the Ionian Sea directly south of the Messina Strait. In order to obtain a better understanding of the sedimentary processes and the role of tectonics in the region, a new high-resolution 2D reflection seismic dataset was acquired during POS496 cruise during March – April 2016. In combination with existing additional seismic and bathymetric data, we mapped the area in terms of sedimentary and tectonic systems between Sicily and Calabria south of Messina Strait. The overall aim is to understand the relationship between tectonics and sedimentary processes in this complex geological area. The entire working area shows a variety of submarine channels, evolving from the central Messina Strait Canyon. In addition, large syn-tectonic south-north trending half grabens and sedimentary basins are imaged. The basins are filled by turbiditic- and contouritic deposits. Furthermore, several anticlines and negative flower structures were identified. We interpret these tectonic lineaments as the surface expression of deeply rooted transpressiveand transtensional fault systems. These fault systems with large strike-slip components could be near surface indicators for the proposed STEP Faults in the region. Not all morphological features like canyons/channels and structural heights follow significant tectonic lineaments. This indicates that some sedimentary features are decoupled from tectonics and are rather the expression of long lasting sedimentary processes like turbidity currents, mass transport events and bottom current activity.
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    facet.materialart.
    In:  [Talk] In: MarFluid Symposium 2017, 16.10.-19.10.2017, Brest, France .
    Publication Date: 2017-09-15
    Description: The seafloor stores crucial information on sub-seafloor processes, including stress, elastic strain, and earthquakes. This information may be extracted through the nascent scientific field of seafloor geodesy. The GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array uses acoustic signals for direct-path ranging and relative positioning at mm-scale resolution for a period of up to 3.5 years. The transponders also include high-precision pressure sensors to monitor vertical movements and dual-axis inclinometers in order to measure their altitude as well as subsidence or uplift of submarine fault zones. A further component of the network is GeoSURF, a self-steering autonomous surface vehicle (Wave Glider), which monitors system health and is able to download the seafloor geodetic data to the sea surface and to transfer it via satellite. At present, the geodetic seafloor transponders are monitoring: The southern dextral strike-slip fault of the eastern flank of Mt Etna in Sicily, where a recent slow slip event indicates the instability of the offshore volcanic flank. The North Anatolian Fault in the Sea of Marmara offshore Istanbul to measure the strain build-up along the Main Marmara fault. The North Chilean subduction zone system, where three transponder arrays are deployed on the marine forearc and outer rise. This segment of the Nazca-South American plate boundary has last ruptured in an earthquake in 1877 and was identified as a seismic gap prior to the 2014 Iquique earthquake (Mw 8.1). The southern portion of the segment remains unbroken by a recent earthquake. The first 12 month of all geodetic installations were analyzed and we discuss baselines and baseline changes with precision less 5 mm for ranges up to 2000 m of distance.
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2019-02-01
    Description: Receiver functions (RF) have been used for several decades to study structures beneath seismic stations. Although most available stations are deployed on-shore, the number of ocean bottom station (OBS) experiments has increased in recent years. Almost all OBSs have to deal with higher noise levels and a limited deployment time (∼1 year), resulting in a small number of usable records of teleseismic earthquakes. Here, we use OBSs deployed as mid-aperture array in the deep ocean (4.5-5.5 km water depth) of the eastern mid-Atlantic. We use evaluation criteria for OBS data and beam forming to enhance the quality of the RFs. Although some stations show reverberations caused by sedimentary cover, we are able to identify the Moho signal, indicating a normal thickness (5-8 km) of oceanic crust. Observations at single stations with thin sediments (300-400 m) indicate that a probable sharp lithosphere-asthenosphere boundary (LAB) might exist at a depth of ∼70-80 km which is in line with LAB depth estimates for similar lithospheric ages in the Pacific. The mantle discontinuities at ∼410 km and ∼660 km are clearly identifiable. Their delay times are in agreement with PREM. Overall the usage of beam formed earthquake recordings for OBS RF analysis is an excellent way to increase the signal quality and the number of usable events.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    facet.materialart.
    In:  [Poster] In: EGU General Assembly 2018, 08.-13.04.2018, Vienna, Austria .
    Publication Date: 2018-04-13
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    facet.materialart.
    facet.materialart.
    In:  [Poster] In: EGU General Assembly 2018, 08.-13.04.2018, Vienna, Austria .
    Publication Date: 2019-01-09
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    facet.materialart.
    Wiley
    In:  Geophysical Journal International, 207 . pp. 1796-1817.
    Publication Date: 2019-02-01
    Description: Our knowledge of the absolute S wave velocities of the oceanic lithosphere is mainly based on global surface wave tomography, local active seismic or compliance measurements using oceanic infragravity waves. The results of tomography give a rather smooth picture of the actual S wave velocity structure and local measurements have limitations regarding the range of elastic parameters or the geometry of the measurement. Here, we use the P wave polarization (apparent P wave incidence angle) of teleseismic events to investigate the S wave velocity structure of the oceanic crust and the upper tens of kilometres of the mantle beneath single stations. In this study, we present an up to our knowledge new relation of the apparent P wave incidence angle at the ocean bottom dependent on the half space S wave velocity. We analyse the angle in different period ranges at ocean bottom stations (OBS) to derive apparent S wave velocity profiles. These profiles are dependent on the S wave velocity as well as on the thickness of the layers in the subsurface. Consequently, their interpretation results in a set of equally valid models. We analyse the apparent P wave incidence angles of an OBS data set which was collected in the Eastern Mid Atlantic. We are able to determine reasonable S wave velocity-depth models by a three step quantitative modelling after a manual data quality control, although layer resonance sometimes influences the estimated apparent S wave velocities. The apparent S wave velocity profiles are well explained by an oceanic PREM model in which the upper part is replaced by four layers consisting of a water column, a sediment, a crust and a layer representing the uppermost mantle. The obtained sediment has a thickness between 0.3 km and 0.9 km with S wave velocities between 0.7 km s−1 and 1.4 km s−1. The estimated total crustal thickness varies between 4 km and 10 km with S wave velocities between 3.5 km s−1 and 4.3 km s−1. We find a slight increase of the total crustal thickness from ∼5 km to ∼8 km towards the South in the direction of a major plate boundary, the Gloria Fault. The observed crustal thickening can be related with the known dominant compression in the vicinity of the fault. Furthermore, the resulting mantle S wave velocities decrease from values around 5.5 km s−1 to 4.5 km s−1 towards the fault. This decrease is probably caused by serpentinization and indicates that the oceanic transform fault affects a broad region in the uppermost mantle. Conclusively, the presented method is useful for the estimation of the local S wave velocity structure beneath ocean bottom seismic stations. It is easy to implement and consists of two main steps: (1) measurement of apparent P wave incidence angles in different period ranges for real and synthetic data, and (2) comparison of the determined apparent S wave velocities for real and synthetic data to estimate S wave velocity-depth models.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...