Advertisement

Journal of Seismology

, Volume 17, Issue 2, pp 361–384 | Cite as

Complex deep seismic anisotropy below the Scandinavian Mountains

  • Corinna Roy
  • Joachim R. R. Ritter
Original Article

Abstract

Several seismological projects focused on the deep structure of the Scandinavian Mountains, in Norway and neighbouring Sweden. We use these recordings to study seismic anisotropy by analysing the birefringence of SKS and SKKS phases. These phases, which should be polarised radially, are split into an additional transverse component if they propagate through an anisotropic medium. Our results are directions Φ of the apparent fast shear wave polarisation and delay times δt between the split phases. For station KONO in Southern Norway, we find frequency-dependent Φ and δt values, indicating a depth-dependent anisotropy. Additionally, Φ and δt values vary with epicentre backazimuths in Norway, indicating a complex anisotropic structure in the crust and upper mantle. Stacking of the SKS/SKKS waveforms improves the signal-to-noise ratio along one station line and allows us to better determine the splitting parameters. A unique and complete model of the complex anisotropy cannot be obtained due to the limited observed backazimuth range. Near-surface tectonic structures correlate with the splitting pattern and thus the crust is one anisotropic layer in the region. Partly preferred orientations in the rock fabric at the surface can be correlated with Φ. Below one or more anisotropic layers must exist to explain the backazimuth- and frequency-dependent observations, as well as the long δt values (>2 s) which cannot be explained with crustal anisotropy alone. The spatial distribution of the splitting results indicates that different tectonics units, e.g. the Sveconorwegian, the Central and Northern Svecofennian and the Caledonian nappes, are each characterised by specific anisotropic signatures.

Keywords

Scandinavia SKS splitting Anisotropy Lithosphere 

Notes

Acknowledgments

We thank especially Dr. Richard England, Dr. Johannes Schweitzer, and Dipl.-Geophys. Britta Wawerzinek for providing SCANLIPS, NORSAR, and MAGNUS waveforms, respectively. Two anonymous reviewers provided helpful and critical comments. MAGNUS waveforms were recorded with the mobile KArlsruhe BroadBand Array of the Universität Karlsruhe (TH) (now KIT), Germany, as well as with permanent stations of the NORSAR array and the Norwegian National Seismological Network. Financial support for the MAGNUS experiment was provided by the University of Aarhus, University of Copenhagen, University of Karlsruhe, and University of Oslo as well as NORSAR. SCANLIPS was conducted using seismic stations from the NERC Geophysical Equipment Facility (SEIS-UK) and NERC funding. This work has been done in association with the partners of the ESF EUROCORES TOPO-EUROPE Programme 07-TOPO-EUROPE-FP-014 “The Scandinavian mountain chain: deep processes (TopoScandiaDeep)”. It was supported by the Deutsche Forschungsgemeinschaft through grant RI1133/8-1. SeismicHandler (Stammler 1993) was used for seismic waveform processing and GMT software (Wessel and Smith 1998) was used for plotting maps.

References

  1. Andersen TB (1998) Extensional tectonics in the Caledonides of southern Norway, an overview. Tectonophysics 285:333–351CrossRefGoogle Scholar
  2. Anell I, Thybo H, Artemieva IM (2009) Cenozoic uplift and subsidence in the North Atlantic region: geological evidence revisited. Tectonophysics 474:78–105CrossRefGoogle Scholar
  3. Babuska V, Cara M (1991) Seismic anisotropy in the Earth. Kluwer Academic, DordrechtCrossRefGoogle Scholar
  4. Barruol G, Mainprice D (1993) A quantitative evaluation of the contribution of crustal rocks to the shear-wave splitting of teleseismic SKS waves. Phys Earth Planet Inter 78:281–300CrossRefGoogle Scholar
  5. Bastow ID, Owens TJ, Helffrich G, Knapp JH (2007) Spatial and temporal constraints on sources of seismic anisotropy: evidence from the Scottish highlands. Geophys Res Lett 34:L05305CrossRefGoogle Scholar
  6. Bijwaard H, Spakman W (2000) Nonlinear global P-wave tomography by iterated linearized inversion. Geophys J Int 141:71–82CrossRefGoogle Scholar
  7. Bungum H, Husebye ES, Ringdal F (1971) The NORSAR array and preliminary results of data analysis. Geophys J R astr Soc 25:115–126CrossRefGoogle Scholar
  8. Eken T, Plomerová J, Roberts R, Vecsey L, Babuška V, Shomali H, Bodvarsson R (2010) Seismic anisotropy of the mantle lithosphere beneath the Swedish National Seismological Network (SNSN). Tectonophysics 480:241–258Google Scholar
  9. England RW, Ebbing J (2008) SCANLIPS—a seismological study of epeirogenic uplift of Scandinavia. Geophys Res Abstr 10:EGU2008-A-02842Google Scholar
  10. England RW, Ebbing J (2012) Crustal structure of central Norway and Sweden from integrated modelling of teleseismic receiver functions and the gravity anomaly. Geophys J Int, in pressGoogle Scholar
  11. Evans MS, Kendall J, Willemann RJ (2003) Development of automated SKS splitting measurement—an additional parameter to be provided by the ISC. Eos Trans Am Geophys Union 84(46) Fall Meet Suppl Abstract S32C-03Google Scholar
  12. Gabrielsen RH, Faleide JI, Pascal C, Braathen A, Nystuen JP, Etzelmuller B, O’Donnell S (2010) Reply to discussion of Gabrielsen et al. (2010) by Nielsen et al. (this volume): latest Caledonian to present tectonomorphological development of southern Norway. Marine Petroleum Geol 27:1290–1295CrossRefGoogle Scholar
  13. Gilotti JA, Hull JM (1993) Kinematic stratification in the hinterland of the central Scandinavian Caledonides. J Struc Geol 15:629–646CrossRefGoogle Scholar
  14. Gledhill K, Gubbins D (1996) SKS splitting and the seismic anisotropy of the mantle beneath the Hikurangi subduction zone, New Zealand. Phys Earth Planet Inter 95:227–236CrossRefGoogle Scholar
  15. Grechka VY, McMechan GA (1995) Anisotropy and non-linear polarization of body waves in exponentially heterogeneous media. Geophys J Int 123:959–965CrossRefGoogle Scholar
  16. Högdahl K, Sjöström H, Bergman S (2009) Ductile shear zones related to crustal shortening and domain boundary evolution in the central Fennoscandian Shield. Tectonics 28:TC1003Google Scholar
  17. Japsen R, Chalmers JA (2000) Neogene uplift and tectonics around the North Atlantic: overview. Global Planet Chang 24:165–173CrossRefGoogle Scholar
  18. Karato S, Jung H, Katayama I, Skemer P (2008) Geodynamic significance of seismic anisotropy of the upper mantle: new insights from laboratory studies. Annu Rev Earth Planet Sci 36:59–95CrossRefGoogle Scholar
  19. Kaviani A, Rümpker G, Weber M, Asch G (2011) Short-scale variations of shear-wave splitting across the Dead Sea basin: evidence for the effects of sedimentary fill. Geophys Res Lett 38:L04308CrossRefGoogle Scholar
  20. Kennett BLN, Engdahl ER (1991) Traveltimes for global earthquake location and phase identification. Geophys J Int 105:429–465CrossRefGoogle Scholar
  21. Köhler A, Weidle C, Maupin V (2011) Directionality analysis and Rayleigh wave tomography of ambient seismic noise in southern Norway. Geophys J Int 184:287–300CrossRefGoogle Scholar
  22. Lidmar-Bergström K, Bonow JM (2009) Hypotheses and observations on the origin of the landscape of southern Norway—a comment regarding the isostasy–climate–erosion hypothesis by Nielsen et al. 2008. J Geodynamics 48:95–100CrossRefGoogle Scholar
  23. Long ML (2010) Frequency-dependent shear wave splitting and heterogeneous anisotropic structure beneath the Gulf of California region. Phys Earth Planet Inter 182:59–72CrossRefGoogle Scholar
  24. Long ML, van der Hilst RD (2005) Estimating shear-wave splitting parameters from broadband recordings in Japan: a comparison of three methods. Bull Seism Soc Am 95:1346–1358CrossRefGoogle Scholar
  25. Marson-Pidgeon K, Savage MK (1997) Frequency-dependent anisotropy in Wellington, New Zealand. Geophys Res Lett 24:3297–3300CrossRefGoogle Scholar
  26. Maupin V (2011) Upper-mantle structure in southern Norway from beamforming of Rayleigh wave data presenting multipathing. Geophys J Int 185:985–1002CrossRefGoogle Scholar
  27. Maupin V, Park J (2007) Theory and observations: wave propagation in anisotropic media. In: Romanowicz B, Dziewonski A (eds) Treatise on geophysics, vol 1, Seismology and structure of the earth. Elsevier, Amsterdam, pp 289–321CrossRefGoogle Scholar
  28. Medhus AB, Balling N, Jacobsen BH, Weidle C, Voss P, England RW, Kind R, Thybo H (2012) Upper mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone revealed by P-wave travel time tomography. Geophys J Int 189:1315–1334Google Scholar
  29. Neumann ER, Olsen KH, Baldridge WS (1995) The Oslo rift. In: Olsen KH (ed) Continental rifts: evolution, structure, tectonics. Elsevier, Amsterdam, pp 345–373Google Scholar
  30. Nicolas A (1993) Why fast polarization directions of SKS seismic waves are parallel to mountain belts. Phys Earth Planet Interiors 78:337–342CrossRefGoogle Scholar
  31. Nielsen SB et al (2009) The evolution of western Scandinavian topography: a review of Neogene uplift versus the ICE (isostacy–climate–erosion) hypothesis. J Geodynamics 47:72–95CrossRefGoogle Scholar
  32. Niu F, Perez AM (2004) Seismic anisotropy in the lower mantle: a comparison of waveform splitting of SKS and SKKS. Geophys Res Lett 31:L24612. doi: 10.1029/2004GL021196 CrossRefGoogle Scholar
  33. Olsen E, Gabrielsen RH, Braathen A, Redfield TF (2007) Fault systems marginal to the Møre–Trøndelag fault complex, Osen–Vikna area, Central Norway. Norwegian J Geol 87:59–73Google Scholar
  34. Pascal C, Olesen O (2009) Are the Norwegian mountains compensated by a mantle thermal anomaly at depth? Tectonophysics 475:160–168CrossRefGoogle Scholar
  35. Plomerová J, Frederiksen AW, Park J (2008) Preface: seismic anisotropy and geodynamics of the lithosphere–asthenosphere system. Tectonophysics 462:1–6CrossRefGoogle Scholar
  36. Ramberg IB, Bryhni I, Nøttvedt A, Rangnes K (2008) The making of a land. Geology of Norway. The Norwegian Geological Association, OsloGoogle Scholar
  37. Redfield TF, Braathen A, Gabrielsen RH, Osmundsen PT, Torsvik TH, Andriessen PAM (2005) Late Mesozoic to Early Cenozoic components of vertical separation across the Møre–Trøndelag fault complex, Norway. Tectonophysics 395:233–249CrossRefGoogle Scholar
  38. Rohrman M, van der Beek P, Andriessen P, Cloetingh S (1995) Meso-Cenozoic morphotectonic evolution of southern Norway: Neogene domal uplift inferred from apatite fission track thermochronology. Tectonics 14:704–718CrossRefGoogle Scholar
  39. Rost S, Thorne MS, Garnero EJ (2006) Imaging global seismic phase arrivals by stacking array processed short-period data. Seis Res Lett 77:697–707. doi: 10.1785/gssrl.77.6.697 CrossRefGoogle Scholar
  40. Roy C (2010) SKS-Doppelbrechung und Anisotropie unter dem Skandinavischen Gebirge. Diploma thesis, KIT, Geophysical Institute (in German)Google Scholar
  41. Rümpker G, Silver PG (1998) Apparent shear-wave splitting parameters in the presence of vertically varying anisotropy. Geophys J Int 135:790–800CrossRefGoogle Scholar
  42. Rümpker G, Tommasi A, Kendall J-M (1999) Numerical simulations of depth-dependent anisotropy and frequency-dependent wave propagation effects. J Geophys Res 104:23141–23153CrossRefGoogle Scholar
  43. Savage MK (1999) Seismic anisotropy and mantle deformation: what have we learned from shear wave splitting? Rev Geophys 37:65–106CrossRefGoogle Scholar
  44. Sieminski A, Paulssen H, Trampert J, Tromp J (2008) Finite-frequency SKS splitting: measurement and sensitivity kernels. Bull Seism Soc Am 98:1797–1810CrossRefGoogle Scholar
  45. Silver PG (1996) Seismic anisotropy beneath the continents: probing the depth of geology. Annu Rev Earth Planet Sci 24:385–432CrossRefGoogle Scholar
  46. Silver PG, Chan WW (1991) Shear wave splitting and subcontinental mantle deformation. J Geophys Res 96:16429–16454CrossRefGoogle Scholar
  47. Silver PG, Savage MK (1994) The interpretation of shear-wave splitting parameters in the presence of two anisotropic layers. Geophys J Int 119:949–963CrossRefGoogle Scholar
  48. Smelror M, Dehls J, Ebbing J, Larsen E, Lundin ER, Nordgulen O, Osmundsen PT, Olesen O, Ottesen D, Pascal C, Redfield TF, Rise L (2007) Towards a 4D topographic view of the Norwegian sea margin. Global Planet Chang 58:382–410CrossRefGoogle Scholar
  49. Stammler K (1993) SeismicHandler—programmable multichannel data handler for interactive and automatic processing of seismological analyses. Comp Geosci 19:135–140CrossRefGoogle Scholar
  50. Stratford W, Thybo H (2011) Seismic structure and composition of the crust beneath the southern Scandes, Norway. Tectonophysics 502:364–382CrossRefGoogle Scholar
  51. Stratford W, Thybo H, Faleide JI, Olesen O, Tryggvason A (2009) New Moho map for onshore southern Norway. Geophys J Int 178:1755–1765CrossRefGoogle Scholar
  52. Svenningsen L, Balling N, Jacobsen BH, Kind R, Wylegalla K, Schweitzer J (2007) Crustal root beneath the highlands of southern Norway resolved by teleseismic receiver functions. Geophys J Int 170:1129–1138CrossRefGoogle Scholar
  53. Tommasi A (1998) Forward modeling of the development of seismic anisotropy in the upper mantle. Earth Planet Sci Lett 160:1–13CrossRefGoogle Scholar
  54. Torsvik TH, Cocks LRM (2005) Norway in space and time: a centennial cavalcade. Norwegian J Geol 85:73–86Google Scholar
  55. Vecsey L, Plomerová J, Babuŝka V (2008) Shear-wave splitting measurements—problems and solutions. Tectonophysics 462:178–196CrossRefGoogle Scholar
  56. Weidle C, Maupin V (2008) An upper-mantle S-wave velocity model for Northern Europe from Love and Rayleigh group velocities. Geophys J Int 175:1154–1168CrossRefGoogle Scholar
  57. Weidle C, Maupin V, Ritter J, Kværna T, Schweitzer J, Balling N, Thybo H, Faleide JI, Wenzel F (2010) MAGNUS—a seismological broadband experiment to resolve crustal and upper mantle structure beneath the southern Scandes mountains in Norway. Seism Res Lett 81:76–84. doi: 10.1785/gssrl.811.76 CrossRefGoogle Scholar
  58. Wessel P, Smith WHF (1998) New, improved version of generic mapping tools released. Eos Trans Am Geophys Union 79:579CrossRefGoogle Scholar
  59. Wirth E, Long MD (2010) Frequency-dependent shear wave splitting beneath the Japan and Izu-Bonin subduction zones. Phys Earth Planet Inter 181:141–154CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Geophysical InstituteKarlsruhe Institute of TechnologyKarlsruheGermany

Personalised recommendations