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
  • 1
    facet.materialart.
    Unknown
    Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults (2005)
    In:  Nature, New York, August, vol. 434, no. 7032, pp. 457-461, pp. 1610, (ISSN: 1340-4202)
    Details
    Publication Date: 2005
    Keywords: Earthquake precursor: prediction research ; Earthquake precursor: statistical anal. of seismicity ; Fore-shocks ; Fault zone ; Plate tectonics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    BIBLIOGRAPHY SEISMOLOGY
  • 2
    facet.materialart.
    Unknown
    Variations in earthquake rupture properties along the Gofar transform fault, East Pacific Rise (2012)
    Springer Nature
    Details
    Publication Date: 2012-05-01
    Description: Variations in earthquake rupture properties along the Gofar transform fault, East Pacific Rise Nature Geoscience 5, 336 (2012). doi:10.1038/ngeo1454 Authors: Jeffrey J. McGuire, John A. Collins, Pierre Gouédard, Emily Roland, Dan Lizarralde, Margaret S. Boettcher, Mark D. Behn & Robert D. van der Hilst On a global scale, seismicity on oceanic transform faults that link mid-ocean ridge segments is thermally controlled. However, temperature cannot be the only control because the largest earthquakes on oceanic transform faults rupture only a small fraction of the area that thermal models predict to be capable of rupture. Instead, most slip occurs without producing large earthquakes. When large earthquakes do occur, they often repeat quasiperiodically. Moreover, oceanic transform faults produce an order of magnitude more foreshocks than continental strike-slip faults. Here we analyse a swarm of about 20,000 foreshocks, recorded on an array of ocean-bottom seismometers, which occurred before a magnitude 6.0 earthquake on the Gofar transform fault, East Pacific Rise. We find that the week-long foreshock sequence was confined to a 10-km-long region that subsequently acted as a barrier to rupture during the mainshock. The foreshock zone is associated with a high porosity and undergoes a 3% decrease in average shear-wave speed during the week preceding the mainshock. We conclude that the material properties of fault segments capable of rupturing in large earthquakes differ from those of barrier regions, possibly as a result of enhanced fluid circulation within the latter. We suggest that along-strike variations in fault zone material properties can help explain the abundance of foreshocks and the relative lack of large earthquakes that occur on mid-ocean ridge transform faults.
    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
  • 3
    facet.materialart.
    Unknown
    Nano- and picoseismicity rate changes from static stress triggering caused by a MW2.2 earthquake in Mponeng gold mine, South Africa (2014)
    Wiley
    Details
    Publication Date: 2014-12-21
    Description: Static stress changes following large earthquakes are known to affect the rate and distribution of aftershocks, yet this process has not been thoroughly investigated for nano and pico seismicity at centimeter length scales. Here we utilize a unique dataset of M ≥ −3.4 earthquakes following a M W 2.2 earthquake in Mponeng gold mine, South Africa that was recorded during a quiet interval in the mine to investigate if rate and state based modeling is valid for shallow, mining-induced seismicity. We use Dieterich's [1994] rate and state dependent formulation for earthquake productivity, which requires estimation of four parameters: (1) Coulomb stress changes due to the mainshock, (2) the reference seismicity rate, (3) frictional resistance parameter, and (4) the duration of aftershock relaxation time. Comparisons of the modeled spatio-temporal patterns of seismicity based on two different source models with the observed distribution show that while the spatial patterns match well, the rate of modeled aftershocks is lower than the observed rate. To test our model, we used three metrics of the goodness-of-fit evaluation. The null hypothesis, of no significant difference between modeled and observed seismicity rates, was only rejected in the depth interval containing the mainshock. Results show that mining-induced earthquakes may be followed by a stress relaxation expressed through aftershocks located on the rupture plane and in regions of positive Coulomb stress change. Furthermore, we demonstrate that the main features of the temporal and spatial distribution of very small, mining-induced earthquakes can be successfully determined using rate- and state-based stress modeling.
    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
  • 4
    facet.materialart.
    Unknown
    The relationship between seismicity and fault structure on the Discovery transform fault, East Pacific Rise (2014)
    Wiley
    Details
    Publication Date: 2014-08-22
    Description: There is a global seismic moment deficit on mid-ocean ridge transform faults, and the largest earthquakes on these faults do not rupture the full fault area. We explore the influence of physical fault structure, including step-overs in the fault trace, on the seismic behavior of the Discovery transform fault, 4S on the East Pacific Rise. One year of microseismicity recorded during a 2008 ocean bottom seismograph deployment (24,377 0 ≤ M L ≤ 4.6 earthquakes) and 24 years of Mw ≥ 5.4 earthquakes obtained from the Global Centroid Moment Tensor catalog, are correlated with surface fault structure delineated from high-resolution multibeam bathymetry. Each of the 15 5.4 ≤ Mw ≤ 6.0 earthquakes that occurred on Discovery between January 1, 1990 - April 1, 2014 was relocated into one of five distinct rupture patches using a teleseismic surface wave cross-correlation technique. Microseismicity was relocated using the HypoDD relocation algorithm. The western fault segment of Discovery (DW) is composed of three zones of varying structure and seismic behavior: a zone with no large events and abundant microseismicity, a fully coupled zone with large earthquakes, and a complex zone with multiple fault strands and abundant seismicity. In general, microseismicity is reduced within the patches defined by the large, repeating earthquakes. While the extent of the large rupture patches on DW correlates with physical features in the bathymetry, step-overs in the primary fault trace are not observed at patch boundaries, suggesting along-strike heterogeneity in fault zone properties controls the size and location of the large events.
    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
  • 5
    facet.materialart.
    Unknown
    Thermal segmentation of mid-ocean ridge transform faults (2017)
    Wiley
    Details
    Publication Date: 2017-08-13
    Description: 3D finite element simulations are used to calculate thermal structures and mantle flow fields underlying mid-ocean ridge transform faults (RTFs) composed of two fault segments separated by an orthogonal step-over. Using fault lengths and slip rates, we derive an empirical scaling relation for the critical step-over length ( ), which marks the transition from predominantly horizontal to predominantly vertical mantle flow at the base of the lithosphere under a step-over. Using the ratio of step-over length ( L S ) to , we define 3 degrees of segmentation: first-degree, corresponding to type I step-overs (  ≥ 3); second-degree, corresponding to type II step-overs (1 ≤   〈 3); and third-degree, corresponding to type III step-overs ( 〈1). In first-degree segmentation, thermal structures and mantle upwelling patterns under a step-over are similar to those of mature ridges, where normal mid-ocean ridge basalts (MORBs) form. The seismogenic area under first-degree segmentation is characteristic of two, isolated faults. Second-degree segmentation creates pull-apart basins with subdued melt generation, and intra-transform spreading centers with enriched MORBs. The seismogenic area of RTFs under second-degree segmentation is greater than that of two isolated faults, but less than that of an unsegmented RTF. Under third-degree segmentation, mantle flow is predominantly horizontal, resulting in little lithospheric thinning and little to no melt generation. The total seismogenic area under third-degree segmentation approaches that of an unsegmented RTF. Our scaling relations characterize the degree of segmentation due to step-overs along transform faults, and provide insight into RTF frictional processes, seismogenic behavior, and melt transport.
    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
  • 6
    Electronic Resource
    Electronic Resource
    Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults (2005)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 434 (2005), S. 457-461 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] East Pacific Rise transform faults are characterized by high slip rates (more than ten centimetres a year), predominately aseismic slip and maximum earthquake magnitudes of about 6.5. Using recordings from a hydroacoustic array deployed by the National Oceanic and Atmospheric Administration, we ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature03377
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    facet.materialart.
    Unknown
    Non-linear glacier response to calving events, Jakobshavn Isbræ, Greenland (2018)
    Cambridge University Press
    Details
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉〈p〉Jakobshavn Isbræ, a tidewater glacier that produces some of Greenland's largest icebergs and highest speeds, reached record-high flow rates in 2012 (Joughin and others, 2014). We use terrestrial radar interferometric observations from August 2012 to characterize the events that led to record-high flow. We find that the highest speeds occurred in response to a small calving retreat, while several larger calving events produced negligible changes in glacier speed. This non-linear response to calving events suggests the terminus was close to flotation and therefore highly sensitive to terminus position. Our observations indicate that a glacier's response to calving is a consequence of two competing feedbacks: (1) an increase in strain rates that leads to dynamic thinning and faster flow, thereby promoting destabilization, and (2) an increase in flow rates that advects thick ice toward the terminus and promotes restabilization. The competition between these feedbacks depends on temporal and spatial variations in the glacier's proximity to flotation. This study highlights the importance of dynamic thinning and advective processes on tidewater glacier stability, and further suggests the latter may be limiting the current retreat due to the thick ice that occupies Jakobshavn Isbræ’s retrograde bed.〈/p〉〈/div〉
    Print ISSN: 0022-1430
    Electronic ISSN: 1727-5652
    Topics: Geography , Geosciences
    Published by Cambridge University Press on behalf of The International Glaciological Society (IGS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Call for Models—A Test Case for the Source Inversion Validation: The 2014ML 5.5 Orkney, South Africa, Earthquake (2017)
    Seismological Society of America
    Details
    Publication Date: 2017-07-05
    Print ISSN: 0895-0695
    Electronic ISSN: 1938-2057
    Topics: Geosciences
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults (2005)
    Springer Nature
    Details
    Publication Date: 2005-03-24
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Spatial and Temporal Variations in Earthquake Stress Drop on Gofar Transform Fault, East Pacific Rise: Implications for Fault Strength (2018)
    American Geophysical Union
    Details
    Publication Date: 2018-09-01
    Description: On Gofar Transform Fault on the East Pacific Rise, the largest earthquakes (6.0 ≤ MW ≤ 6.2) have repeatedly ruptured the same portion of the fault, while intervening fault segments host swarms of microearthquakes. These long-term patterns in earthquake occurrence suggest that heterogeneous fault zone properties control earthquake behavior. Using waveforms from ocean bottom seismometers that recorded seismicity before and after an anticipated 2008 MW 6.0 mainshock, we investigate the role that differences in material properties have on earthquake rupture at Gofar. We determine stress drop for 138 earthquakes (2.3 ≤ MW ≤ 4.0) that occurred within and between the rupture areas of large earthquakes. Stress drops are calculated from corner frequencies derived using an empirical Green's function spectral ratio method, and seismic moments are obtained by fitting the omega-square source model to the low frequency amplitude of the displacement spectrum. Our analysis yields stress drops from 0.04 to 3.2 MPa with statistically significant spatial variation, including ~2 times higher average stress drop in fault segments where large earthquakes also occur compared to fault segments that host earthquake swarms. We find an inverse correlation between stress drop and P wave velocity reduction, which we interpret as the effect of fault zone damage on the ability of the fault to store strain energy that leads to our spatial variations in stress drop. Additionally, we observe lower stress drops following the MW 6.0 mainshock, consistent with increased damage and decreased fault strength after a large earthquake. ©2018. American Geophysical Union. All Rights Reserved.
    Print ISSN: 2169-9313
    Electronic ISSN: 2169-9356
    Topics: Geosciences , Physics
    Published by American Geophysical Union
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...