Uppermost mantle (Pn) velocity model for the Afar region, Ethiopia: An insight into rifting processes

Geophysical Journal International

Volumn 193, Issue 1, 2013, Pages 321-328

  Stork, A L ^a,d   Stuart, G W ^a   Henderson, C M ^b,e   Keir, D ^c   Hammond, J O S ^d,f  

^a UNIVERSITY OF LEEDS   (United Kingdom)

^b VICTORIA UNIVERSITY OF WELLINGTON   (New Zealand)

^c UNIVERSITY OF SOUTHAMPTON   (United Kingdom)

^d UNIVERSITY OF BRISTOL   (United Kingdom)

^e GNS SCIENCE   (New Zealand)

^f IMPERIAL COLLEGE LONDON   (United Kingdom)

Author keywords

Continental margins; Divergent; Seismic tomography; Seismicity and tectonics

Indexed keywords

SEISMIC WAVES; SEISMOLOGY;

CONTINENTAL MARGIN; CONTINENTAL RIFTING; DIVERGENT; MANTLE UPWELLINGS; SEAFLOOR SPREADING; SEISMIC TOMOGRAPHY; SEISMICITY AND TECTONICS; TRAVEL TIME TOMOGRAPHY;

STRUCTURAL GEOLOGY;

CONTINENTAL MARGIN; IGNEOUS INTRUSION; MAGMA; P-WAVE; PARTIAL MELTING; RIFTING; SEAFLOOR SPREADING; SEISMIC TOMOGRAPHY; SEISMIC VELOCITY; SEISMICITY; TECTONICS; TRAVEL TIME; UPPER MANTLE;

AFAR; ETHIOPIA;

EID: 84876965983     PISSN: 0956540X     EISSN: 1365246X     Source Type: Journal    
DOI: 10.1093/gji/ggs106     Document Type: Article

References (54)

1. Bannister, S.C., Ruud, B.O. & Husebye, E.S., 1991. Tomographic estimates of sub-Moho seismic velocities in Fennoscandia and structural implications, Tectonophysics, 189, 37-53.
2. Bastow, I.D. & Keir, D., 2011. The protracted development of the continentocean transition in Afar, Nat. Geosci., 4, 248-250.
3. Bastow, I.D., Nyblade, A.A., Stuart, G.W., Rooney, T.O. & Benoit, M.H., 2008. Upper mantle seismic structure beneath the Ethiopian hot spot: rifting at the edge of the African low-velocity anomaly, Geochem. Geophys. Geosysts., 9, Q12022, doi:10.1029/2008GC002107.
4. Belachew, M., Ebinger, C., Cote, D., Keir, D., Rowland, J.V., Hammond, J.O.S. & Ayele, A., 2011. Comparison of dike intrusions in an incipient seafloor-spreading segment in Afar, Ethiopia: seismicity perspectives, J. geophys. Res., 116, B06405, doi:10.1029/2010JB007908.
5. Berckhemer, H. et al., 1975. Deep seismic soundings in the Afar region and on the highland ofEthiopia, in Afar depression of Ethiopia: Proceedings of the international symposium on the Afar region and related rift problems, held in Bad Bergzabern, FR Germany, 1-6 April, 1974, pp. 89-107, Schweizerbart, Stuttgart.
6. Buck, W.R. & Su, W., 1989. Focused mantle upwelling below mid-ocean ridges due to feedback between viscosity and melting, Geophys. Res. Lett., 16, 641-644.
7. Canales, J.P., Collins, J.A., Escartin, J. & Detrick, R.S., 2000. Seismic structure across the rift valley of the Mid-Atlantic Ridge at 23?20 (MARK area): implications for crustal accretion processes at slow spreading ridges, J. geophys. Res., 105, 28 411-28 425.
8. Christensen, N.I. & Mooney, W.D., 1995. Seismic velocity structure and composition of the continental crust: a global view, J. geophys. Res., 100, 9761-9788.
9. Detrick, R.S., Buhl, P., Vera, E., Mutter, J., Orcutt, J.,Madsen, J. & Brocher, T., 1987. Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise, Nature, 326, 35-41.
10. Dugda, M.T., Nyblade, A.A. & Jordi, J., 2007. Thin lithosphere beneath the Ethiopian plateau revealed by a joint inversion of Rayleigh wave group velocities and receiver functions, J. geophys. Res., 112, B08305, doi:10.1029/2006JB004918.
11. Dunn, R.A., Toomey, D.R., Detrick, R.S. &Wilcock,W.S.D., 2001. Continuous mantle melt supply beneath an overlapping spreading center on the East Pacific Rise, Science, 291, 1955-1958.
12. Dunn, R.A., Lekic, V., Detrick, R.S. & Toomey, D.R., 2005. Threedimensional seismic structure of theMid-Atlantic Ridge (35?N): evidence for focused melt supply and lower crustal dike injection, J. geophys. Res., 110, B09101, doi:10.1029/2004JB003473.
13. Engdahl, E.R., van der Hilst, R. & Buland, R., 1998. Global teleseismic earthquake relocationwith improved travel times and procedures for depth determination, Bull. seism. Soc. Am., 88, 722-743.
14. Field, L., Barnie,T.,Blundy, J.,Brooker,R.A.,Keir,D., Lewi, E.&Saunders, K., 2012. Integrated field, satellite and petrological observations of the November 2010 eruption of Erta Ale, Bull. Volcanol., 74, 2251-2271.
15. Grandin, R., Socquet, A., Doin, M.-P., Jacques, E., de Chabalier, J.B. & King, G.C.P., 2010a. Transient rift opening in response to multiple dike injections in the Manda Hararo rift (Afar, Ethiopia) imaged by timedependent elastic inversion of interferometric synthetic aperture radar data, J. geophys. Res., 115, B09403, doi:10.1029/2009JB006883.
16. Grandin, R., Socquet, A., Jacques, E., Mazzoni, N., De Chabalier, J.B. & King, G.C.P., 2010b. Sequence of rift- ing in Afar (Manda-Hararo rift, Ethiopia, 2005-2009): time-space evolution and interactions between dikes from InSAR and static stress change modeling, J. geophys. Res., 115, B10413, doi:10.1029/2009JB000815.
17. Guidarelli, M., Stuart, G., Hammond, J.O.S., Kendall, J.M., Ayele, A. & Belachew, M., 2011. Surface wave tomography across Afar, Ethiopia: crustal structure at a rift triple-junction zone, Geophys. Res. Lett., 38, L24313, doi:10.1029/2011GL046840.
18. Haines, A.J., 1979. Seismic-wave velocities in the uppermostmantle beneath New Zealand, N.Z. J. Geol. Geophys., 22, 242-257.
19. Hammond, J.O.S, Kendall, J.-M., Stuart, G.W., Keir, D., Ebinger, C., Ayele, A. & Belachew, M., 2011a. The nature of the crust beneath the Afar triple junction: evidence from receiver functions, Geochem. Geophys. Geosysts., 12, Q12004, doi:10.1029/2011GC003738.
20. Hammond, J.O.S. et al., 2011b. Seismically imaging the Afar plume, American Geophysical Union, Fall Meeting 2011, Abstract #DI13A-2155.
21. Hammond, W.C. & Humphreys, E.D., 2000. Upper mantle seismic wave velocity: effects of realistic partial melt geometries, J. geophys. Res., 105, 10 975-10 986.
22. Hayward, N.J. & Ebinger, C.J., 1996. Variations in the along-axis segmentation of the Afar Rift system, Tectonics, 15, 244-257.
23. Hearn, T.M., 1996. Anisotropic Pn tomography in the western United States, J. geophys. Res., 101, 8403-8414.
24. Hearn, T.M. & Ni, J.F., 1994. Pn velocities beneath continental collision zones-the Turkish-Iranian plateau, Geophys. J. Int., 117, 273-283.
25. Keir, D., Bastow, I.D., Whaler, K.A., Daly, E., Cornwell, D.G. & Hautot, S., 2009. Lower crustal earthquakes near the Ethiopian rift induced by magmatic processes, Geochem. Geophys. Geosysts., 10, Q0AB02, doi:10.1029/2009GC2382.
26. Keir, D., Belachew, M., Ebinger, C.J., Kendall, J.M., Hammond, J.O.S., Stuart, G.W., Ayele, A. & Rowland, J.V., 2011. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression, Nature Comms., 2, 285, doi:10.1038/ncomms1287.
27. Kendall, J.M., 2000. Seismic anisotropy in the boundary layers of the mantle, in Earth's Deep Interior: Mineral Physics and Tomography From the Atomic to the Global Scale, Vol. 117, pp. 133-159, eds Karato, S., Forte, A.M., Liebermann, R.C., Masters, G. & Stixrude, L., Geophysical Monograph, AGU, Washington DC.
28. Kendall, J.M., Stuart, G.W., Ebinger, C.J., Bastow, I.D. & Keir, D., 2005. Magma-assisted rifting in Ethiopia, Nature, 433, 146-148.
29. Kogan, L., Fisseha, S., Bendick, R., Reilinger, R., McClusky, S., King, R. & Solomon, T., 2012. Lithospheric strength and strain localization in continental extension from observations of the East African Rift, J. geophys. Res., 117, B03402, doi:10.1029/ 2011JB008516.
30. Lahitte, P., Gillot, P.-Y., Kidane, T., Courtillot, V. & Bekele, A., 2003. New age constraints on the timing of volcanism in central Afar, in the presence of propagating rifts, J. geophys. Res., 108(B2), 2123, doi:10.1029/2001JB001689.
31. Ligi, M. et al., 2012. Birth of an ocean in the Red Sea: initial pangs, Geochem. Geophys.Geosysts., 13, Q08009, doi:10.1029/2012GC004155.
32. Lin, J., Purdy, G.M., Schouten, H., Sempere, J.C. & Zervas, C., 1990. Evidence from gravity-data for focused magmatic accretion along the Mid-Atlantic Ridge, Nature, 6267, 627-632.
33. Macdonald, K.C. & Fox, P.J., 1988. The axial summit graben and crosssectional shape of the East Pacific Rise as indicators of axial magma chambers and recent volcanic eruptions, Earth planet. Sci. Lett., 88, 119-131.
34. Makris, J. & Ginzburg, A., 1987. The Afar depression-transition between continental rifting and sea-floor spreading, Tectonophysics, 141, 199-214.
35. McClusky, S. et al., 2010. Kinematics of the southern Red Sea-Afar Triple Junction and implications for plate dynamics, Geophys. Res. Lett., 37, L05301, doi:10.1029/2009GL041127.
36. McKenzie, D., 1978. Some remarks on the development of sedimentary basins, Earth planet. Sci. Lett., 40, 25-32.
37. McKenzie, D. & Bickle, M.J., 1988. The volume and composition of melt generated by extension of the lithosphere, J. Petrol., 29, 625-679.
38. Moritz, H., 1972. Advanced Least-Squares Methods, Dep. of Geod. Sci., Ohio State Univ., Ohio.
39. Pagli, C., Wright, T.J., Ebinger, C.J., Yun, S.-H., Cann, J.R., Barnie, T. & Ayele, A., 2012. Shallow axial magma chamber at the slow-spreading Erta Ale Ridge, Nat. Geosci., 5, 284-288.
40. Pei, S.P. et al., 2007. Upper mantle seismic velocities and anisotropy in China determined through Pn and Sn tomography, J. geophys. Res., 112, B05312, doi:10.1029/2006JB004409.
41. Perry, H.K.C., Jaupart, C., Mareschal, J.C. & Shapiro, N.M., 2006. Upper mantle velocity-temperature conversion and composition determined from seismic refraction and heat flow, J. geophys. Res., 111, B07301, doi:10.1029/2005JB003921.
42. Rawlinson, N., Houseman, G.A. & Collins, C.D.N., 2001. Inversion of seismic refraction and wide-angle reflection traveltimes for three-dimensional layered structure, Geophys. J. Int., 145, 381-400.
43. Rowland, J.V., Baker, E., Ebinger, C.J., Keir, D., Kidane, T., Biggs, J., Hayward, N. & Wright, T.J., 2007. Fault growth at a nascent slowspreading ridge: 2005 Dabbahu rifting episode, Afar, Geophys. J. Int., 171, doi:10.1111/j.1365-246X.2007.03584.x.
44. Rychert, C.A. et al., 2012. Volcanism in the Afar Rift sustained by decompression melting with minimal plume influence, Nat. Geosci., 5, 406-409.
45. Sato, H., Sacks, I.S., Murase, T. & Scarfe, C.M., 1988. Thermal structure of the low velocity zone derived from laboratory and seismic investigations, Geophys. Res. Lett., 15, 1227-1230.
46. Seward, A.M., Henderson, C.M.&Smith, E.G.C., 2009. Models of the upper mantle beneath the central North Island, New Zealand, from speeds and anisotropy of subhorizontal P waves (Pn), J. geophys. Res., 114, B0131, doi:10.1029/2008JB005805.
47. Stork, A.L., 2007. Optimisation and application of earthquake locationmethods, D.Phil. thesis, Univ. of Oxford, UK.
48. Tesfaye, S., Harding, D.J. & Kusky, T.M., 2003. Early continental breakup boundary and migration of the Afar triple junction, Ethiopia, Geol. Soc. Am. Bull., 115, 1053-1067.
49. Wang, Y., Forsyth, D.W. & Savage, B., 2009. Convective upwelling in the mantle beneath the Gulf of California, Nature, 462, 499-501.
50. Whaler, K.A. & Hautot, S., 2006. The electrical resistivity structure of the crust beneath the northern Main Ethiopian Rift, in The Afar Volcanic Province within the East African Rift System, Vol. 259, pp. 55-72, eds Yirgu, G., Ebinger, C.J. & Maguire, P.K.H., Geol. Soc. London Spec. Publ., doi:10.1144/GSL.SP.2006.259.01.22.
51. Whitehead, J.A., Dick, H.J.B. & Schouten, H., 1984. A mechanism for magmatic accretion under spreading centres, Nature, 312, 146-148.
52. Wolfenden, E., Ebinger, C., Yirgu, G., Renne, P.R. & Kelley, S.P., 2005. Evolution of a volcanic rifted margin: Southern Red Sea, Ethiopia, Geol. Soc. Am. Bull., 117, 846-864.
53. Wright, T.J., Ebinger, C., Biggs, J., Ayele, A., Yirgu, G., Keir, D. & Stork, A., 2006. Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode, Nature, 442, 291-294.
54. Wright, T.J. et al., 2012. Geophysical constraints on the dynamics of spreading centres from rifting episodes on land, Nat. Geosci., 5, 242-250.