Microearthquake characteristics and crustal VP/VS structure at the Mid-Atlantic Ridge, 35°N

Journal of Geophysical Research: Solid Earth

Volumn 106, Issue B2, 2001, Pages 2017-2034

  Barclay, Andrew H ^a,c   Toomey, Douglas R ^a   Solomon, Sean C ^b  

^a UNIVERSITY OF OREGON   (United States)

^b GEOPHYSICAL LABORATORY   (United States)

^c WOODS HOLE OCEANOGRAPHIC INSTITUTION   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CRUSTAL STRUCTURE; MID-OCEAN RIDGE; OCEANIC CRUST; SEISMICITY;

ATLANTIC OCEAN; MID-ATLANTIC RIDGE;

EID: 0035071530     PISSN: 21699313     EISSN: 21699356     Source Type: Journal    
DOI: 10.1029/2000jb900371     Document Type: Article

References (61)

1. Au, D., and R. M. Clowes, Shear-wave velocity structure of the oceanic lithosphere from ocean bottom seismometer studies, Geophys. J. R. Astron. Soc., 77, 105-123, 1984.
2. S structure beneath the axial high of a slow spreading ridge segment (abstract), Eos Trans. AGU, 76 (46), Fall Meet. Suppl., F609, 1995.
3. Barclay, A. H., D. R. Toomey, and S. C. Solomon, Seismic structure and crustal magmatism at the Mid-Atlantic Ridge, 35°N, J. Geophys. Res., 103, 17,827-17,844, 1998.
4. Bideau, D., R. Hekinian, C. Bollinger, M. Constantin, E. Gracia, C. Guivel, B. Sichler, R. Apprioul, and R. Le Gall, Submersible investigation of highly contrasted magmatic activities recorded on two segments of the Mid-Atlantic Ridge near 34°52′N and 33°55′N, InterRidge News, 5, 9-14, 1996.
5. Brune, J. N., Tectonic stress and the spectra of seismic shear waves from earthquakes, J. Geophys. Res., 75, 4997-5009, 1970. (Correction, J. Geophys. Res., 76, 5002, 1971.)
6. Chen, Y., and W. J. Morgan, Rift valley/no rift valley transition at mid-ocean ridges, J. Geophys. Res., 95, 17,571-17,581, 1990.
7. Christensen, N. I., Poisson's ratio and crustal seismology, J. Geophys. Res., 101, 3139-3156, 1996.
8. Christeson, G. L., P. R. Shaw, and J. D. Garmany, Shear and compressional wave structure of the East Pacific Rise, J. Geophys. Res., 102, 7821-7835, 1997.
9. Collier, J. S., and S. C. Singh, Poisson's ratio structure of young oceanic crust, J. Geophys. Res., 103, 20,981-20,996, 1998.
10. Detrick, R. S., H. D. Needham, and V. Renard, Gravity anomalies and crustal thickness variations along the Mid-Atlantic Ridge between 33°N and 40°N, J. Geophys. Res., 100, 3767-3787, 1995.
11. Escartín, J., and J. Lin, Ridge offsets, normal faulting, and gravity anomalies of slow spreading ridges, J. Geophys. Res., 100, 6163-6177, 1995.
12. Francis, T. J. G., The ratio of compressional to shear velocity and rock porosity on the axis of the Mid-Atlantic Ridge, J. Geophys. Res., 81, 4361-4364, 1976.
13. Gephart, J. W., and D. W. Forsyth, An improved method for determining the regional stress tensor using earthquake focal mechanism data: Application to the San Fernando earthquake sequence, J. Geophys. Res., 89, 9305-9320, 1984.
14. Hanks, T. C., and M. Wyss, The use of body-wave spectra in the determination of seismic-source parameters, Bull. Seismol. Soc. Am., 62, 561-589, 1972.
15. Herrmann, R. B., A student's guide to the use of P and S wave data for focal mechanisms determination, Earthquake Notes, 46, 29-39, 1975.
16. Hirth, G., J. Escartín, and J. Lin, The rheology of the lower oceanic crust: Implications for lithospheric deformation at mid-ocean ridges, in Faulting and Magmatism at Mid-Ocean Ridges, Geophys. Monogr. Ser., vol. 106, edited by W. R. Buck, P. T. Delaney, J. A. Karson, and Y. Lagabrielle, pp. 291-304, AGU, Washington, D.C., 1998.
17. Hooft, E. E. E., R. S. Detrick, D. R. Toomey, J. A. Collins, and J. Lin, Crustal thickness and structure along three contrasting spreading segments of the Mid-Atlantic Ridge, 33.5°-35°N, J. Geophys. Res., 105, 8205-8226, 2000.
18. Hussenoeder, S. A., Seismic and magnetic constraints on the structure of upper oceanic crust at fast and slow spreading ridges, Ph. D. thesis, Woods Hole Oceanogr. Inst./Mass. Inst. of Technol. Joint Program, Woods Hole, 1998.
19. Hyndman, R. D., Poisson's ratio in the oceanic crust - A review, Tectonophysics, 59, 321-333, 1979.
20. Johnston, J. E., and N. I. Christensen, Seismic properties of layer 2 basalts, Geophys. J. Int., 128, 285-300, 1997.
21. Klein, F. W., Hypocenter location program HYPOINVERSE, 1, User's guide to versions 1, 2, 3, 4, U.S. Geol. Surv. Open File Rep., 78-694, 103 pp., 1978.
22. Kong, L. S. L., S. C. Solomon, and G. M. Purdy, Microearthquake characteristics of a mid-ocean ridge along-axis high, J. Geophys. Res., 97, 1659-1685, 1992.
23. Lin, J., and J. Phipps Morgan, The spreading rate dependence of three-dimensional mid-ocean ridge gravity structure, Geophys. Res. Lett., 19, 13-16, 1992.
24. Lin, J., G. M. Purdy, H. Schouten, J.-C. Sempere, and C. Zervas, Evidence from gravity data for focused magmatic accretion along the Mid-Atlantic Ridge, Nature, 344, 627-632, 1990.
25. Magde, L. S., A. H. Barclay, D. R. Toomey, R. S. Detrick, and J. A. Collins, Crustal magma plumbing within a segment of the Mid-Atlantic Ridge, 35°N, Earth Planet. Sci. Lett., 175, 55-67, 2000.
26. Meissner, R., and J. Strehlau, Limits of stresses in continental crusts and their relation to the depth-frequency distribution of shallow earthquakes, Tectonics, 1, 73-89, 1982.
27. S anomalies in traveltime tomography, Geophys. J. Int., 114, 405-410, 1993.
28. Miller, A. D., G. R. Foulger, and B. R. Julian, Non-double-couple earthquakes; 2, Observations, Rev. Geophys., 36, 551-568. 1998.
29. Morris, E., and R. S. Detrick, Three-dimensional analysis of gravity anomalies in the MARK area, Mid-Atlantic Ridee 23°N, J. Geophys. Res., 96, 4355-4366, 1991.
30. Moser, T. J., Shortest path calculation of seismic rays, Geophysics, 56, 59-67, 1991.
31. Nur, A., and G. Simmons, The origin of small cracks in igneous rocks, Int. J. Rock Mech. Min. Sci., 7, 307-314, 1970.
32. Phipps Morgan, J., E. M. Parmentier, and J. Lin, Mechanisms for the origin of mid-ocean ridge axial topography: Implications for the thermal and mechanical structure of accreting plate boundaries, J. Geophys. Res., 92, 12,823-12,836, 1987.
33. Poliakov, A. N. B., and W. R. Buck, Mechanics of stretching elastic-plastic-viscous layers: Applications to slow-spreading mid-ocean ridges, in Faulting and Magmatism at Mid-Ocean Ridges, Geophys. Monogr. Ser., vol. 106, edited by W. R. Buck, P. T. Delaney, J. A. Karson, and Y. Lagabrielle, pp. 291-304, AGU, Washington, D.C., 1998.
34. Purdy, G. M., and R. S. Detrick, Crustal structure of the Mid-Atlantic Ridge at 23°N from seismic refraction studies, J. Geophys. Res., 91, 3739-3762, 1986.
35. Rowlett, H., and D. W. Forsyth, Recent faulting and microearthquakes at the intersection of the Vema Fracture Zone and the Mid-Atlantic Ridse, J. Geophys. Res., 89, 6079-6094, 1984.
36. Scholz, C. H., The brittle-plastic transition and the depth of seismic faulting, Geol. Rundsch., 77, 319-328, 1988.
37. Scholz, C. H., The Mechanics of Earthquakes and Faulting, 439 pp., Cambridge Univ. Press, New York, 1990.
38. Shaw, P. R., Ridge segmentation, faulting and crustal thickness in the Atlantic Ocean, Nature, 358, 490-493, 1992.
39. Shaw, P. R., Age variations of oceanic crust Poisson's ratio: Inversion and a porosity evolution model, J. Geophys. Res., 99, 3057-3066, 1994.
40. Shaw, W. J., and J. Lin, Models of ocean ridge lithospheric deformation: Dependence on crustal thickness, spreading rate, and segmentation, J. Geophys. Res., 101, 17,977-17,993, 1996.
41. Shearer, P. M., Cracked media, Poisson's ratio and the structure of the upper oceanic crust, Geophys. J., 92, 357-362, 1988.
42. Shen, Y., D. W. Forsyth, J. Conder, and L. M. Dorman, Investigation of microearthquake activity following an intraplate teleseismic swarm on the west flank of the southern East Pacific Rise, J. Geophys. Res., 102, 459-475, 1997.
43. Sibson, R. H., Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the United States, Bull. Seismol. Soc. Am., 72, 151-163, 1982.
44. Sibson, R. H., Roughness at the base of the seismogenic zone: Contributing factors, J. Geophys. Res., 89, 5791-5799, 1984.
45. Sleep, N. H., and B. R. Rosendahl, Topography and tectonics of mid-oceanic ridge axes, J. Geophys. Res., 84, 6831-6839, 1979.
46. Sohn, R. A., J. A. Hildebrand, and S. C. Webb, Postrifting seismicity and a model for the 1993 diking event on the CoAxial segment, Juan de Fuca Ridge, J. Geophys. Res., 103, 9867-9877, 1998.
47. Spudich, P., and J. Orcutt, Petrology and porosity of an oceanic crustal site: Results from wave form modeling of seismic refraction data, J. Geophys. Res., 85, 1409-1433, 1980.
48. Takanami, T., and G. Kitagawa, A new efficient procedure for the estimation of onset times of seismic waves, J. Phys. Earth, 36, 267-290, 1988.
49. Tapponnier, P., and J. Francheteau, Necking of the lithosphere and the mechanics of slowly accreting plate boundaries, J. Geophys. Res., 83, 3955-3970, 1978.
50. Thatcher, W., and D. P. Hill, A simple model for the fault-generated morphology of slow-spreading mid-oceanic ridges, J. Geophys. Res., 100, 561-570, 1995.
51. Tolstoy, M. A., A. J. Harding, and J. A. Orcutt, Crustal thickness on the Mid-Atlantic Ridge: Bull's eye gravity anomalies and focused accretion, Science, 262, 726-729, 1993.
52. Toomey, D. R., S. C. Solomon, G. M. Purdy, and M. H. Murray, Microearthquakes beneath the median valley of the Mid-Atlantic Ridge near 23°N: Hypocenters and focal mechanisms, J. Geophys. Res., 90, 5443-5458, 1985.
53. Toomey, D. R., S. C. Solomon, and G. M. Purdy, Microearthquakes beneath the median valley of the Mid-Atlantic Ridge near 23°N: Tomography and tectonics, J. Geophys. Res., 93, 9093-9112, 1988.
54. Toomey, D. R., S. C. Solomon, and G. M. Purdy, Tomographic imaging of the shallow crustal structure of the East Pacific Rise at 9°30′N, J. Geophys. Res., 99, 24,135-24,157, 1994.
55. Tse, S. T., and J. R. Rice, Crustal earthquake instability in relation to the depth variation of frictional slip properties, J. Geophys. Res., 91, 9452-9472, 1986.
56. Tucholke, B. E., and J. Lin, A geological model for the structure of ridge segments in slow spreading crust, J. Geophys. Res., 99, 11,937-11,958, 1994.
57. Tucholke, B. E., J. Lin, M. C. Kleinrock, M. A. Tivey, T. B. Reed, J. Goff, and G. E. Jaroslow, Segmentation and crustal structure of the western Mid-Atlantic Ridge flank, 25°25′-27°10′N and 0-29 m.y., J. Geophys. Res., 102, 10,203-10,223, 1997.
58. Wilcock, W. S. D., and D. R. Toomey, Estimating hypocentral uncertainties for marine microearthquake surveys: A comparison of the generalized inverse and grid search methods, Mar. Geophys. Res., 13, 161-171, 1991.
59. Wilkens, R. H., G. J. Fryer, and J. Karsten, Evolution of porosity and seismic structure of upper oceanic crust: Importance of aspect ratios, J. Geophys. Res., 96, 17,981-17,995, 1991.
60. Wolfe, C. J., G. M. Purdy, D. R. Toomey, and S. C. Solomon, Microearthquake characteristics and crustal velocity structure at 29°N on the Mid-Atlantic Ridge: The architecture of a slow spreading segment, J. Geophys. Res., 100, 24,449-24,472, 1995.
61. Wyss, M., K. Shimazaki, and S. Wiemer, Mapping active magma chambers by b values beneath the off-Ito volcano, Japan, J. Geophys. Res., 102, 20,413-20,422, 1997.