Alistair Harding

Researcher

Room: Munk Lab 328

Institute of Geophysics and Planetary Physics,
Scripps Institution of Oceanography,
University of California San Diego,
La Jolla, CA 92093-0225, USA.

Telephone: (858) 534-4301

Email: aharding@ucsd.edu

Research Summary for 2006: Download PDF (11.597MB)

Research Interests:

• Three-D tomographic study of the Clipperton Transform
• Oceanic Crustal structure
• Ridge Crest Processes
• Rifting of continental lithosphere
• Modeling and evolution of Moho at oceanic ridges
• Reflection seismic processing

Courses Taught:

• ERTH180 (Geophysics/Natural Resources)
• ERTH182 (Field Geophysics)
• ERTH182A (Applied Geophysics)
• SIO182A (Envr & Exploration Geophys A)
• SIO182B (Envr & Exploration Geophys B)
• SIO232 (Environmental Geophysics)
• SIO299 (Research)

Recent publications: ^†

• Wilson, D. S., E. Hallenborg, , A. J. Harding, and G. M. Kent, “Data Report: Site Survey Results from Cruise EW9903, Proceedings of the Ocean Drilling Program, Initial Reports, 206, (04) 1-49, 2003.
• Vera, E.E., Mutter J. C., Buhl P., Orcutt J. A., Harding A. J., Kappus, M. E., Detrick R. S., & Brocher T. M., The structure of 0- to 0.2 m.y. old oceanic crust at 9°N on the East Pacific Rise from expanded spread profiles, J. Geophys. Res., 95, 15,529-15,556 1990.
• van Avendonk, H., A. J. Harding, J. A. Orcutt, and J. S. McClain, A two-dimensional tomographic inversion of the Clipperton Transform Fault, J. Geophys. Res., 103, 17885-17899, 1998.
• Van Avendonk, H. J. A.; Harding, A. J.; Orcutt, J. A.; McClain, J. S., Contrast in crustal structure across the Clipperton transform fault from travel time tomography. J. Geophys. Res., 106, 10961-10981, 2001.
• Van Avendonk, H. J. A., A. J. Harding, J. A. Orcutt, and W. S. Holbrook, Hybrid method for traveltime and raypath calculations, Geophysics, 66, 648-653, 2001.
• Van Ark, E. M., R. S. Detrick, J. P. Canales, A. J. Harding, G. M. Kent, M. R. Nedimovic, W. S. D. Wilcock, J. B. Diebold and J. M. Babcock, Seismic structure of the Endeavour Segment, Juan de Fuca Ridge: Correlations with seismicity and hydrothermal activity, J. Geophys. Res., 112, B02401 (1-22 pp.), doi:10.1029/2005JB004210, 2007.
• Tong, C. H., P. J. Barton, R. S. White, M. C. Sinha, S. C. Singh, J. W. Pye, R. W. Hobbs, S. Bazin, A. J. Harding, G. M. Kent and J. A. Orcutt, Influence of enhanced melt supply on upper crustal structure at a mid-ocean ridge discontinuity: A three-dimensional seismic tomographic study of 9°N East Pacific Rise, J. Geophys Res., 108, EPM(2) 1-14, 2003.
• Tong, C. H., J.W. Pye, P.J. Barton, R.S. White, M.C. Sinha, S.C. Singh, R.W. Hobbs, S. Bazin, A.J. Harding, G.M. Kent, and J.A. Orcutt, Asymmetric melt sills and upper crustal construction beneath overlapping ridge segments: Implications for the development of melt sills and ridge crests, Geology, 30, 83-86, 2002.
• Tolstoy. M., 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.
• Tolstoy M., A. J. Harding, J. A. Orcutt and the TERA group, Deepening of the axial magma chamber on the Southern East Pacific Rise toward the Garrett Fracture Zone, J. Geophys. Res., 102, .3097-3108, 1997.
• Stephen, R. A., & Harding A. J., Travel time analysis of borehole seismic data. Journal. Geophys. Res., 88, 8289-8298, 1983.
• Singh, S. C., M. C. Sinha, A. J. Harding, G. M. Kent, P. J. Barton, J. A. Orcutt, R. S. White, and R. W. Hobbs, Preliminary results are in from mid-ocean ridge three-dimensional seismic reflection survey, Eos, Trans. AGU, 80, 181 & 185, 1999.
• Singh, S. C., G. M. Kent, J. S. Collier, A. J. Harding and J. A. Orcutt, Melt to mush variations in crustal magma properties along the ridge crest at the southern East Pacific Rise, Nature, 394, 874-878, 1998.
• Singh, S C, J. S. Collier, A. J. Harding, G. M. Kent, and J. A. Orcutt, Seismic evidence for a hydrothermal layer above the solid roof of the axial magma chamber at the southernEast Pacific Rise,Geology, 27,219-222, 1999.
• S. M. Carbotte, R. S. Detrick, A. Harding, J. P. Canales, J. Babcock, G. Kent, E. Van Ark, M. Nedimovic, J. Diebold, Rift topography linked to magmatism at the intermediate spreading Juan de Fuca Ridge, Geology, 34, 209-212, 2005.
• S. C. Singh, A. J. Harding, G. M. Kent, M. C. Sinha, V. Combier, S. Bazin, C. H. Tong, J. W. Pye, P. J. Barton, R. W. Hobbs, R. S. White and J. A. Orcutt, Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise, Nature, 442, 287-290, 2006.
• Phipps Morgan, J., A. J. Harding, G. M. Kent, J. A. Orcutt, and Y. J. Chen, An observational and theoretical synthesis of magma chamber geometry and crustal genesis along a mid-ocean ridge spreading center, in Magmatic Systems, ed. M. P. Ryan, pp139-178, Academic Press, New York, 1994.
• Nedimovic, M. R., S. M. Carbotte, J. B Diebold, A. J. Harding, J. P. Canales, and G. M. Kent, Upper crustal evolution across the Juan de Fuca ridge flanks, Geochem. Geophys. Geosyst., 9, Q09006, doi:10.1029/2008GC002085, 2008.
• Mutter, J. C., S. M. Carbotte, W. Su, L. Xu, P. Buhl, R. S. Detrick, G. M. Kent, J. A. Orcutt and A. J. Harding, Seismic images of active magma systems beneath the East Pacific Rise between 17° 05' and 17° 35' S, Science, 374, 391-395, 1995.
• Mutter, J. C., Barth G. A., Buhl P., Detrick R. S., Orcutt J. A., & Harding A. J., Magma distribution across ridge axis discontinuities on the East Pacific Rise (8°40' to 9°50' North) from multichannel seismic images, Nature, 336, 156-158, 1988.
• M. R. Nedimovic, Suzanne M. Carbotte, A. J. Harding, R. S. Detrick, J. P. Canales, J. B. Diebold, G. M. Kent, M. Tischer and J. M. Babcock, Frozen magma lenses below the oceanic crust, Nature 436, 1149-1152, 2005.
• Lizarralde, D., G. J. Axen, J. M. Fletcher, A. Gonzalez-Fernandez, G. M. Kent, A. J. Harding, W. S. Holbrook, and P. J. Umhoefer, A Seismic and Geologic Study of Gulf of California Rifting and Magmatism, Margins Newsletter, 7, 1-5, 2001.
• Lizarralde, D., G. J. Axen, H. E. Brown, J. M. Fletcher, A. Gonzalez-Fernadez, A. J. Harding, W. S. Holbrook, G. M. Kent, P. Paramo, F. Sutherland and P. J. Umhoefer, Variations in styles of rifting in the Gulf of California, Nature, 466-469, doi:10.1038/nature06035, 2007.
• Kent, G.M., S.C. Singh, A.J. Harding, M.C. Sinha, J.A. Orcutt, P.J. Barton, R.S. White, S. Bazin, R.W. Hobbs, C.H. Tong, and J.W. Pye, Evidence from three-dimensional seismic reflectivity images for enhanced melt supply beneath mid-ocean-ridge discontinuities. Nature, 406, 614-618, 2000.
• Kent, G. M., I. I. Kim, A. J. Harding, R. S. Detrick, and J. A. Orcutt, Suppression of sea-floor-scattered energy using a dip-moveout approach; Application to the mid-ocean ridge environment, Geophysics, 61, 821-834, 1996.
• Kent, G. M., Harding A. J., & Orcutt J. A, Evidence for a smaller magma chamber beneath the East Pacific Rise at 9°30’N, Nature, 344, 650-653, 1990.
• Kent, G. M., A. J. Harding, J. A. Orcutt, R. S. Detrick, J. C. Mutter, and P. Buhl, Uniform accretion of oceanic crust south of the Garrett transform at 14° 15’S on the East Pacific Rise, J. Geophys. Res., 99, 9097-9116, 1994.
• Kent, G. M., A. J. Harding, and J. A. Orcutt, Distribution of magma beneath the East Pacific Rise near the 9 03° N Overlapping Spreading Center from forward modeling of Common Depth Point data, J. Geophys. Res., 98, 13,971-13,995, 1993.
• Kent, G. M., A. J. Harding S. Singh, M. Sinha, P. Barton, J. Orcutt, R. White and ARAD group, The ARAD 3-D seismic experiment: A detailed reflection and tomographic investigation of the 9° 03' N Overlapping Spreading Center, East Pacific Rise, InterRidge News, 7, 33-39, 1998. Article
• Kent, G. M. , A. J. Harding,, & J. A. Orcutt, Distribution of magma beneath the East Pacific Rise between the Clipperton Transform and the 9° 17' N Deval from forward modeling of common depth point data, J. Geophys. Res., 98, 13,945-13,969, 1993.
• Kennett, B. L. N., & Harding A. J., Is ray theory adequate for reflection seismic modelling (A survey of modelling methods) First Break, 3, 9-14, 1985.
• Kennett, B. L. N., & Harding A. J., Guided low frequency noise from airgun sources, Geophysical Prospecting, 32, 690-705, 1984.
• Kappus, M. E., Harding A. J., & Orcutt J. A., A comparison of tau-p transform methods, Geophysics., 55, 1202-1215, 1990.
• Kappus, M. E. , A. J. Harding., and J. A. Orcutt, A baseline for upper crustal velocity variations along the East Pacific Rise at 13°N, J. Geophys. Res., 100, 6143-6161, 1995.
• Jacobs, A. M., A. J. Harding and G. M. Kent, Axial crustal structure of the Lau back-arc basin from velocity modeling of multichannel seismic data, Ear. Sci. Planet. Lett., 259, 239-255, doi:10.1016/j.epsl.2007.04.021, 2007.
• J. P. Canales, R. S. Detrick, S. M. Carbotte, G. M. Kent, J. B. Diebold, A. Harding, J. Babcock, M. R. Nedimovic, and E. van Ark, Upper crustal structure and axial topography at intermediate spreading ridges: Seismic constraints from the southern Juan de Fuca Ridge, J. Geophys. Res., 110, doi:10.1029/2005JB003630, 2005.
• Hussenoeder, S. A., J. A. Collins, G. M. Kent, R. S. Detrick, and the TERA group (A. J. Harding & J. A. Orcutt), Seismic analysis of the axial magma chamber reflector along the southern East Pacific Rise from conventional reflection profiling, J. Geophys. Res., 101, 22087-22105, 1996.
• Hussenoeder, S. A., G. M. Kent, R. S. Detrick, H. Schouten, and A. J. Harding, Fine Scale seismic structure of young upper crust at 17° 20' S on the fast spreading East Pacific Rise, J. Geophys. Res. 107, EPM(2) 1-29, 2002.
• Harding, A.J., G. M. Kent, & J. A. Orcutt, A multichannel seismic investigation of upper crustal structure at 9° N on the East Pacific Rise: Implications for crustal accretion. J. Geophys. Res., 98, 13,925-13,944, 1993.
• Harding, A.J., G. M. Kent, M.E. Kappus and J.A. Orcutt, The Upper crust at 9° N East Pacific Rise, RIDGE Events, 2, 8-10, 1991.
• Harding, A. J., Slowness-time mapping of near offset seismic reflection data, Geophys. J. R. astr. Soc., 80, 463 - 492, 1985.
• Harding, A. J., Seismic Structure, in Encyclypedia of Ocean Sciences, ed. J. H. Steele, Academic Press, New York, 6pp, 2figs, 2001.
• Harding, A. J., Orcutt J. A., Kappus. M.E., Vera E.E., Buhl P., Mutter J. C., Detrick R. S., & Brocher T. M., The structure of young oceanic crust at 13°N on the East Pacific Rise from Expanding Spread Profiles, J. Geophys. Res., 94, 12,163-12,196, 1989.
• Harding, A. J., M .A. H. Hedlin, and J. A. Orcutt, Migration of backscatter data from the Mid-Atlantic Ridge. J. Acoust. Soc. Am., 103, 1787-1803, 1998.
• Harding, A. J., Inversion methods for t - p maps of near offset data. Linear inversion. Geophysical Prospecting, 33, 674 - 695, 1985.
• Harding, A. J., Book review: Deconvolution by Anton Ziolkowski, Geophys. J. R. astr. Soc., 82, 141, 1985.
• Hallenborg, E., A. J. Harding, G. M. Kent, and D. S. Wilson, “Seismic structure of 15 Ma oceanic crust formed at an ultra-fast spreading East Pacific Rise: Evidence for kilometer-scale fracturing from dipping reflectors”, J. Geophys. Res., 108, EPM(11) 1-22, 2003.
• G.M. Kent, J. M. Babcock, N. W. Driscoll, A. J. Harding, J. A. Dingler, G. G. Seitz, J. V. Gardner, L. A. Mayer, C. R. Goldman, A. C. Heyvaert, R. C. Richards, R. Karlin, P. T. Gayes, and C. W. Morgan, A 60ka record of extension across the western boundary of the basin and range province: Slip-rate estimation from offset shorelines and a catastrophic slide beneath Lake Tahoe, Geology, 33, 365-368, 2005.
• Forsyth, D. W., D. S. Scheirer, S. C. Webb, L. M. Dorman, J. A. Orcutt, A. J. Harding, D. K. Blackman, J. Phipps Morgan, R. S. Detrick, Y. Shen, C. J. Wolfe, J. P. Canales, D. R. Toomey, A. F. Sheehan, S. C. Solomon, and W. S. D. Wilcock, Imaging the deep seismic structure beneath a mid-ocean ridge: the MELT Experiment. Science, 280, 1215-1218, 1998.
• Detrick, R. S., A. J. Harding, G. M. Kent, J. A. Orcutt, J. C. Mutter, P. Buhl, Seismic Structure of the Southern East Pacific Rise, Science, 259, 499-503, 1993.
• Chereskin, T. K., Levine M.D., Harding A.J., & Regier L. A., Observation of near-inertial waves in acoustic Doppler current profiler measurements made during MILDEX, J. Geophys. Res., 94, 8135-8145 1989.
• Chereskin, T. K., and A. J. Harding, Modeling the performance of an acoustic Doppler current profiler, J. Atmos. and Oceanic Tech., 10, 41-63, 1993.
• Chereskin, T. K., and A. J. Harding, A model approach to predicting errors in acoustic doppler current profiles., Proc. Oceans, ‘92, 602-606, 1992.
• Carbotte, S. M., M. R. Nedimoviç, J. P Canales, G. M. Kent, A. J. Harding, and M. Marjanoviç, Variable crustal structure along the Juan de Fuca Ridge: Influence of on-axis hot spots and absolute plate motions, Geochem. Geophys. Geosyst., 9, Q08001, doi:10.1029/2007GC001922, 2008.
• Canales, J.P., R. S. Detrick, S. Bazin, A. J. Harding, and J. A. Orcutt, Off-axis crustal thickness across and along the East Pacific Rise within the MELT area. Science, 280, 1218-1221, 1998.
• Canales, J. P., Singh, S. C.; Detrick, R. S.; Carbotte, S. M.; Harding, A.; Kent, G. M.; Diebold, J. B.; Babcock, J.; Nedimovic, M. R.,Seismic evidence for variations in axial magma chamber properties along the southern Juan de Fuca Ridge, Earth Planet. Sci. Lett., 246, 353-366, 2006.
• C.H. Tong, R.S. White, M.R. Warner,and the ARAD Working Group, Effects of tectonism and magmatism on crack structure in oceanic crust: A seismic anisotropy study,Geology, 32, 25-28, 2004.
• C. H. Tong, C. Lana, R. S. White, M. R. Warner and ARAD Working Group,Subsurface tectonic structure between overlapping mid-ocean ridge segments, Geology, 33, 409-412, 2005.
• Begnaud, M.L., J. S. McClain, G. A. Barth, J. A. Orcutt, and A. J. Harding,Velocity structure from forward modeling of the eastern ridge-transform intersection area of the Clipperton Fracture Zone, East Pacific Rise. J. Geophys. Res, 102, 7803-7820, 1997.
• Bazin, S., H. van Avendonk, A. J. Harding, J. A. Orcutt, J. P. Canales, and R. S. Detrick, Crustal structure of the flanks of the East Pacific Rise: implications for overlapping spreading centers, Geophys. Res. Lett., 25, 2213-2216, 1998.
• Bazin, S., A. J. Harding, G. M. Kent, J. A. Orcutt, S. C. Singh, C. H. Tong, J. W. Pye, P. J. Barton, M. C. Sinha, R. S. White, R. W. Hobbs, and H. J. A. Van Avendonk, A three-dimensional study of a crustal low velocity region beneath the 9°03’N overlapping spreading center, Geophys. Res. Lett., 30, (11) 14, 2003.
• Bazin, S., A. J. Harding, G. M. Kent, J. A. Orcutt, C. H. Tong, J. W. Pye, S. C. Singh, P. J. Barton, M. C. Sinha, R. S. White, R.W. Hobbs, and H. J. A. Van Avendonk, Three-dimensional shallow crustal emplacement at the 9°03'N overlapping spreading center on the East Pacific Rise: Correlations between magnetization and tomographic images J. Geophys. Res.,106,16,101-16,117,2001.
• Babcock, J. M., A. J. Harding, G. M. Kent, and J. A. Orcutt, An examination of along-axis variation of magma chamber width and crustal structure on the East Pacific Rise between 13° 30' N and 12° 20' N, J. Geophys. Res.103,30451-30467, 1998.