Thorsten W. Becker

Jackson School of Geosciences
The University of Texas at Austin

Seismology research
[news] [teaching] [team] [publications] [CV] [downloads] [contact]
[geodynamics] [seismology] [fieldwork] [downloads]
[stress] [faults] [tomography] [plumes] [anisotropy]

  • Earthquake source and fault system dynamics

    • Megathrust Modeling Framework (MTMOD)

      A five-year, collaborative, NSF FRES funded effort to advance integrative modeling capabilties within the megathrust context to advance the use of physics-based models for earthquake hazard asssessment. Read more on the MTMOD web page.

    • New inverse approaches to visco-elastic earthquake deformation problems

      Collaborative work on using flexible finite element frameworks for accurate solutions to the faulting problem for forward and inverse approaches, including for the inversion of geodetic data for 3-D elastic property variations.

      • Puel, S., Becker, T.W., Villa, U., Ghattas, O., and Liu, D.: Volcanic arc rigidity variations illuminated by coseismic deformation of the 2011 Tohoku-oki M9, Science Adv., 10, doi:10.1126/sciadv.adl4264, 2024. (PDF)
      • Puel, S., Becker, T. W., Villa, U., Ghattas, O., and Liu, D.: An adjoint-based optimization method for jointly inverting heterogeneous material properties and fault slip from earthquake surface deformation data. Geophys. J. Int., doi:10.1093/gji/ggad442, 2023. (PDF)
      • Puel, S., Khattatov, E., Villa U., Liu, D., Ghattas, O. and Becker, T. W.: A Mixed, unified forward/inverse framework for earthquake problems: Fault implementation and coseismic slip estimate. Geophys. J. Int., 230, 733-758, 2022. (PDF)

    • Co- and post-seismic deformation after the 2011 Tohoku-oki M9 event

      Collaborative work with colleagues at Purdue and ERI, University of Tokyo. We explore the mechanics of elastic heterogeneity for co-seismic deformation, and show that post-seismic deformation may indicate the presence of Peierls creep within the subducting lithosphere, in the depth region suggested by Buffett and Becker (2012). We also explore the time-dependence of crustal stress before and after the M9.

      • Puel, S., Becker, T.W., Villa, U., Ghattas, O., and Liu, D.: Volcanic arc rigidity variations illuminated by coseismic deformation of the 2011 Tohoku-oki M9, Science Adv., 10, doi:10.1126/sciadv.adl4264, 2024. (PDF)
      • Becker, T. W., Hashima, A., Freed, A. M., and Sato, H.: Stress change before and after the 2011 M9 Tohoku-oki earthquake. Earth Planet Sci. Lett., 504, 174-184, 2018. (PDF)
      • Freed, A. M., Hashima, A., Becker, T. W., Okaya, D. A., Sato, H., and Hatanaka. Y.: Resolving depth-dependent subduction zone viscosity and afterslip from postseismic displacements following the 2011 Tohoku-oki, Japan earthquake. Earth Planet. Sci. Lett., 459, 279-290, 2017. (PDF)
      • Hashima, A., Becker, T. W., Freed, A. M., Sato, H., and Okaya, D. A.: Coseismic deformation due to the 2011 Tohoku-oki earthquake: influence of 3-D elastic structure around Japan. Earth, Planet., Space, 68, 159, doi:10.1186/s40623-016-0535-9, 2016. (PDF)

    • Stick slip seismicity and roughness evolution from acoustic emission experiments

      We study stick-slip frictional sliding in laboratory experiments, focusing on natural seismicity analogs such as the spatio-temporal evolution of fore and aftershock sequences, b values, and roughness evolution as well as seismicity decay from the fault surface. A project in collaboration with GeoForschungsZentrum Potsdam and funded by NSF/USGS SCEC.

      • Goebel, T. H. W., Kwiatek, G., Becker, T.W., Brodsky, E. E. and Dresen, G.: What allows seismic events to grow big?: Insights from b-value and fault roughness analysis in laboratory stick-slip experiments. Geology, 44, 815-818, 2017. (PDF)
      • Uhl, J. T. et al.: Universal quake statistics: From compressed nanocrystals to earthquakes. Sci. Rep., 5, 16493, doi: 10.1038/srep16493, 2015. (PDF)
      • Goebel, T. H. W., Becker, T. W., Sammis, C. G., Dresen. G., and Schorlemmer, D.: Off-fault damage and acoustic emission distributions during the evolution of structurally-complex faults over series of stick-slip events. Geophys. J. Int., 197, 1705-1718, 2014. (PDF)
      • Goebel, T. H. W., Candela, T., Sammis, C. G., Becker, T. W., Dresen, G., and Schorlemmer, D.: Seismic event distributions and off-fault damage during frictional sliding of saw-cut surfaces with predefined roughness. Geophys. J. Int., 196, , 612-625, doi:10.1093/gji/ggt401, 2014. (PDF)
      • Goebel, T. H. W., Sammis, C. G., Becker, T. W., Dresen, G., and Schorlemmer, D.: A comparison of seismicity characteristics and fault structure between stick-slip experiments and nature. Pure Appl. Geophys., doi:10.1007/s00024-013-0713-7, 2013. (PDF)
      • Goebel, T. H. W., Schorlemmer, D., Becker, T. W., Dresen, G., and Sammis, C. G.: Acoustic emissions document stress changes over many seismic cycles in stick-slip experiments. Geophys. Res. Lett., 40, 2049-2054, doi:10.1002/grl.50507, 2013. (PDF)
      • Goebel, T. H. W., Becker, T. W., Schorlemmer, D., Stanchits, S., Sammis, C., Rybacki, E., and Dresen, G.: Identifying fault heterogeneity through mapping spatial anomalies in acoustic emission statistics. J. Geophys. Res., 117, B03310, doi:10.1029/2011JB008763, 2012. (PDF)

    • Stress, strain, and dynamic topography patterns in the western US and southern California

      We model the effect of crustal structure, gravitational potential energy variations, and mantle flow on the large-scale stress field, seismicity, and topography of the western United States. We also analyze seismically and geodetically imaged strain release on the smaller scales of the western US plate boundary.

      • Becker, T. W., Lowry, A. R., Faccenna, C., Schmandt, B., Borsa, A., and Yu, C. (2015): Western U.S. intermountain seismicity caused by changes in upper mantle flow. Nature, 524, 458-461. (PDF)
      • Becker, T. W., Faccenna, C., Humphreys, E. D., Lowry, A. R., and Miller, M. S.: Static and dynamic support of western U.S. topography. Earth Planet. Sci. Lett., 402, 234-246, 2014. (PDF, dynamic topography models)
      • Ghosh, A., Becker, T. W., and Humphreys, E. D.: Dynamics of the North American continent. In press at Geophys. J. Int., 2013. (PDF)
      • Bailey, I. W., Ben-Zion, Y., Becker, T. W., and Holschneider, M.: Quantifying focal mechanism heterogeneity for fault zones in central and southern California. Geophys. J. Int., 183, 267–276, 2010. (PDF)
      • Bailey, I. W., Becker, T. W., and Ben-Zion, Y.: Patterns of co-seismic strain computed from southern California focal mechanisms. Geophys. J. Int., 177, 1015-1036, 2009. (PDF).
      • Fay, N. P., Becker, T. W., and Humphreys, E. D.: Southern California Modeling of Geodynamics in 3D (SMOG3D): Toward quantifying the state of tectonic stress in the southern California crust, 2008 SCEC Annual Meeting, 1-122, 2008.
      • Becker, T. W., Bailey, I. W., and Y. Ben-Zion: Stress and strain in southern California, Southern California Earthquake Center Meeting, Palm Springs CA, September 2006. (invited)

      I was also involved in the

      • SCEC Community Stress Model (CSM) project.
        SCEC IV committed to the development of a Community Stress Model to provide better constraints on the stress field, and with a means to formally test physical connections between observations and stress models. We put together a web site to allow inter-model comparison and validation.

    • Fault slip rates and crustal state of stress

      We construct a simple model of interseismic strain and stress accumulation on southern California faults. The joint inversion of GPS velocities and focal mechanisms for fault slip rates of the southern San Andreas contributes to an improved understanding of plate boundary processes.

      • Becker, T. W., Hardebeck, J. L., and Anderson, G.: Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions. Geophys J. Int., 160, 634-650, 2005. (PDF).

    • Transform fault mechanics and transpressional tectonics

      We explore how crustal thinning and thickening may result along a continental transform such as the San Andreas fault, and explore other aspects of the interpretation of geodetic and seismic measures of strain-rate in terms of fault mechanics in particular in transpressional systems.

      • Conrad, E. M., Reitano, R., Faccenna, C., Becker, T. W.: Morpho-tectonics of transpressional systems: insights from analog modeling. Tectonics, 23, doi:10.1029/2023TC007865, 2023. (PDF)
      • Platt, J. P. and Becker, T. W.: Kinematics of rotating panels of E-W faults in the San Andreas system: what can we tell from geodesy? Geophys. J. Int., 194, 1295-1301, 2013. (PDF)
      • Platt, J. P. and Becker, T. W.: Where is the real transform boundary in California? Geochem., Geophys., Geosys., 11(Q06013), doi:10.1029/2010GC003060, 2010. (PDF)
      • Platt, J. P., Kaus, B. J. P. and Becker, T. W.: The mechanics of continental transforms: An alternative approach with applications to the San Andreas system and the tectonics of California. Earth Planet. Sci. Lett., 274, 380-391, 2008. (PDF)

    • Slab stress state from moment tensors and geodynamic modeling

      We analyze the deep deformation state of subduction zones world wide by means of geodynamic modeling and Kostrov summation, focusing on the origin of the depth-dependent CLVD signal and how deep earthquakes can be used to constrain mantle rheology.

      • Bailey, I. W., Alpert, L. A., Becker, T. W., and Miller, M. S.: Co-seismic deformation of deep slabs based on summed CMT data. J. Geophys. Res., 117, B04404, doi:10.1029/2011JB008943, 2012. (PDF)
      • Alpert, L. A., Becker, T. W., and Bailey, I. W.: Global slab deformation and centroid moment tensor constraints on viscosity. Geochem., Geophys. Geosys., 11,(Q12006), doi:10.1029/2010GC003301, 2010. (PDF)

    • Chaos in friction

      Two state-variable rate and state friction on faults can result in deterministic chaos in the seismicity of a simple spring-slider model. The system follows the universal period doubling cascade into chaos; sliding events can, however, be predicted with some accuracy. Coupled sliders show more regular seismicity, implying a regularizing effect of interactions.

      • Becker, T. W.: Deterministic Chaos in two State-variable Friction Sliders and the Effect of Elastic Interactions, in GeoComplexity and the physics of earthquakes, edited by J. B. Rundle, D. L. Turcotte, and W. Klein, p. 5-26, AGU, Washington D. C., 2000. (PDF)

    • Single fault and shear zone earthquake recurrence time variations

      We study earthquake interactions using 2-D elastic models, and apply analytical and finite element methods. We show that the orientation of faults in the background stress-field can lead to variations in the seismic cycle even without fault interactions.

      • Becker, T. W. and Schmeling, H.: Earthquake recurrence time variations with and without fault zone interactions. Geophys. J. Int., 135, 165-176, 1998. (PDF)

    • Effective shear modulus of crack-filled media

      We study micro-crack interaction and the mechanical properties of a crack-filled medium using finite element and boundary element techniques. We find that interactions should be taken into account; a modified self-consistent approach is best suited to the problems under consideration.

      • Dahm, T. and Becker, T.: On the elastic and viscous properties of media containing strongly interacting in-plane cracks. Pure Applied Geophys., 151, 1-16, 1998. (PDF)

    • Boundary element package interact

      interact is a boundary element program which implements Okada's (1992) and Nikkhoo and Walter's (2015) solutions for stress in an elastic half-space (Greens' functions for constant slip on rectangular or triangular dislocation elements) as well as Petsc enabled parallel solves. The interact package is modularly programmed in C and FORTRAN, GNU-licensed, and, used to study geometrically complex fault systems and earthquake cycles.

      • Interact software on GitHub
      • Becker, T. W., Hardebeck, J. L., and Anderson, G.: Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions. Geophys. J. Int., 160, 634-650, 2005. (PDF)
      • Becker, T. W. and Schott, B.: On boundary-element models of elastic fault interaction (abstract). Eos Trans. AGU, 83(47), Fall Meet. Suppl., Abstract NG62A-0925, 2002. (PDF)
      • our software pages

    • Modeling Collaboratory for Subduction RCN

      A four year, collaborative, NSF funded Research Collaboration Network to plan for Modeling Collaboratory for Subduction to address the physics of megathrust and volcano subduction systems with an eye toward decadal scale forecasting in multi-sensor monitoring networks. Read more on the MCS RCN web page.

    • Commentary on Tectonic Precursors arising out of our COSEG 2019 workshop

      • Pritchard, M. E., R. M., Allen, T. W. Becker, M. D. Behn, E. E. Brodsky, R. Bürgmann, C. Ebinger, J. T. Freymueller, M. Gerstenberger, B. Haines, Y. Kaneko, S. D. Jacobsen, N. Lindsey, J. J. McGuire, M. Page, S. Ruiz, M. Tolstoy, L. Wallace, W. R. Walter, W. Wilcock, and H. Vincent: New opportunities to study earthquake precursors. Seismol. Res. Lett., 91, 2444-2447, 2020. (PDF)

  • Structural seismology/tomography

    • 20 years of linking seismic topography and mantle convection

      Lapo Boschi, Steve Grand and I chat about the last 20 years of linking seismic tomography and global mantle dynamics and interdisciplinary collaboration from our perspective, sponsored by the Modeling Collaboratory for Subduction RCN.

    • Mantle plume dynamics, detection, primordial reservoirs, and the origins of geochemical reservoirss

      We analyze geodynamic and seismological models of the mantle and demonstrate that tomography images deep mantle plumes that connect to surface hotspots, if plume conduit distortion in the mantle wind is accounted for. We also analyze a range of geochemical and geophysical parameters to better understand the distribution of EM1, HIMU, and high 3/4He. In particular, the high 3/4He component appears associated with a primordial, deep mantle reservoir that is only entrained by the hottest plumes.

      • Koppers, A., Becker, T.W., Jackson, M., Konrad, K., Müller, R.D., Romanowicz, B., Steinberger, B. and Whittaker, J.: Mantle plumes and their role in Earth processes. Nature Rev. Earth & Environ., 2, 382-401, 2021. (PDF)
      • Jackson, M. G., Becker, T. W., and Steinberger, B.: Spatial characteristics of recycled and primordial reservoirs in the deep mantle. Geochem., Geophys., Geosys., 22, doi:10.1029/2020GC009525, 2021. (PDF)
      • Jackson, M. G., Blichert-Toft, J., Halldórsson, S. A., Mundl-Petermeier, A., Bizimis, M., Kurz, M. D., Price, A. A., Harðardóttir, S., Willhite, L. N., Breddam, K., Becker T. W., and Fischer, R. A.: Ancient helium and tungsten isotopic signatures preserved in mantle domains least modified by crustal recycling. Proc. Nat. Acad. Sci., 117, 30,993-31,001, 2020. (PDF)
      • Jackson, M.G., Becker, T. W., and Konter, J. G.: Geochemistry and distribution of recycled domains in the mantle inferred from Nd and Pb isotopes in oceanic hotspots: implications for storage in the large low shear wave velocity provinces (LLSVPs) G-Cubed, 19, 3496-3519, doi:10.1029/2018GC007552, 2018. (PDF)
      • Jackson, M. G., Becker, T. W., and Konter, J. G.: Evidence for a deep mantle source for EM and HIMU domains from integrated geochemical and geophysical constraints. Earth Planet. Sci. Lett., 484, 154-167, 2018. (PDF)
      • Jackson, M. G., Konter, J. G., and Becker, T. W.: Primordial helium entrained by the hottest mantle plumes. Nature, 542, 340-343, 2017. (PDF)
      • Konter, J. G. and Becker, T. W.: Shallow lithospheric contribution to mantle plumes revealed by integrating seismic and geochemical data. Geochem., Geophys., Geosys., 13, Q02004, doi:10.1029/2011GC003923, 2012. (PDF)
      • Boschi, L., Becker, T. W., and Steinberger, B.: On the statistical significance of correlations between synthetic mantle plumes and tomographic models. Physics Earth Planet. Int., 260, 230-238, 2008. (PDF)
      • Boschi, L., T. W. Becker, and B. Steinberger, Mantle plumes: Dynamic models and seismic images, Geochem. Geophys. Geosyst., 8, Q10006, doi:10.1029/2007GC001733, 2007. (PDF)

    • Plume talk-back terminating subduction

      We use convection models with damage rheologies to show that slabs can not only trigger plume upwellings at the CMB, but plumes arising along slabs may shut off subduction at the surface. This bottom-up interaction may have been relevant particularly for the early Earth.

      • Heilman, E. and Becker, T. W.: Plume-driven subduction termination in 3-D mantle convection models. G-Cubed, 25, doi:10.1029/2024GC011523, 2024. (PDF)
      • Heilman, E. and Becker, T. W.: Plume-slab interactions can shut off subduction. Geophys. Res. Lett., 49, e2022GL099286, 2022. (PDF)
      • Gerya, T. V., Bercovici, D., and Becker, T. W.: Dynamic slab segmentation due to brittle-ductile damage in the outer rise. Nature, 599, 245-250, 2021. (PDF)

    • Generation and character of whole mantle seismic heterogeneity

      Joint, multidisciplinary work on imaging and modeling global isotropic and radially anisotropic mantle structure.

      • Hua, J., Fischer, K., Becker, T.W., Gazel, E. and Hirth, G.: Asthenospheric low-velocity zone consistent with globally prevalent partial melting. Nature Geosc., doi:10.1038/s41561-022-01116-9, 2023. (PDF)
      • Porritt, R., Becker, T.W., Boschi, L., and Auer, L.: Multi-scale, radially anisotropic shear wave imaging of the mantle underneath the contiguous United States through joint inversion of USArray and global datasets. Geophys. J. Int., 2021. (PDF, SI, SAVANI-US model download)
      • Lai, H., Garnero, E., Grand, S., Porritt, R. W., and Becker, T. W.: Global travel time dataset from adaptive empirical wavelet construction. Geochem., Geophys., Geosys., 20, doi:10.1029/2018GC007905, 2019. (PDF)
      • Auer, L., Boschi , L., Becker, T. W., Nissen-Meyer, T. and Giardini, D.: Savani: a variable-resolution whole-mantle model of anisotropic shear-velocity variations based on multiple datasets. J. Geophys. Res., 119, 3006-3034, doi:10.1002/2013JB010773, 2014. (PDF, model)
      • Boschi, L. and Becker, T. W.: Vertical coherence in mantle heterogeneity from global seismic data. Geophys. Res. Lett., 38, (L20306), doi:10.1029/2011GL049281, 2011. (PDF)
      • Foley, B. and Becker, T. W.: Generation of plate-like behavior and mantle heterogeneity from a spherical, visco-plastic convection model. Geochem., Geophys., Geosys., 10, Q08001, doi:10.1029/2009GC002378, 2009. (PDF)
      • Boschi, L., Becker, T. W., Soldati, G., and Dziewonski, A. M.: On the relevance of Born theory in global seismic tomography. Geophys. Res. Lett., 33, L06302, doi:10.1029/2005GL025063, 2006. (PDF).

    • Lithospheric thickness models based on seismic tomography

      We analyze seismic tomography models and describe a new method of inferring lithospheric thickness.

      • Steinberger, B. and Becker, T. W.: A comparison of lithospheric thickness models. Tectonophys., doi:10.1016/j.tecto.2016.08.001, 2016. (PDF)
      • lithospheric thickness models

    • Global (S/PMEAN) and western US (S/PMEAN-WUS) composite tomography model download and model comparisons

    • Seismic tomography, power, validation and filtering

      We study long-period, surface wave seismograms from actual earthquakes and synthetics using the global spectral element method in order to validate and analyze different global mantle tomography models.

      • Qin, Y., Capdeville, Y., Montagner, J.-P., Boschi, L., and Becker, T. W.: Reliability of mantle tomography models assessed by spectral-element simulation. Geophys. J. Int., 177, 125-144, 2009. (PDF)

      The effects of tomographic resolution and filtering are explored in the context of global mantle circulation models; velocities between original input geodyamic model and tomo-filtered output match well.

      • Bull, A. L., McNamara, A. K., Becker, T. W., and Ritsema, J.: Global scale models of the mantle flow field predicted by synthetic tomography models. Phys. Earth Planet. Int., 182, 129-138, 2010. (PDF)

    • A comparison of seismologic and geodynamic mantle models

      We discuss several quantitative comparisons between seismological and geodynamic models of the Earth's mantle. Our global tomography analyses are compatible with whole mantle convection with reorganization of flow at 660-km due to the viscosity jump.

      • Steinberger, B., Torsvik, T. H., and Becker, T. W.: Subduction to the lower mantle - a comparison between geodynamic and tomographic models. Solid Earth, 3, 415-432, 2012. (PDF)
      • Becker, T. W. and Boschi, L.: A comparison of tomographic and geodynamic mantle models, Geochem., Geophys., Geosys., 3, 2001GC000168, 2002. (PDF)

      Additional online material is on the Becker & Boschi (2002): Correlations between models page. All tomographic models from that repository can be used directly as input for the hc mantle flow computation program, as provided in the Solid Earth Research and Teaching Environment (SEATREE).

    • North American plate regional upper mantle seismic tomography

      • Porritt, R., Becker, T.W., Boschi, L., and Auer, L.: Multi-scale, radially anisotropic shear wave imaging of the mantle underneath the contiguous United States through joint inversion of USArray and global datasets. Geophys. J. Int., 2021. (PDF, SI, SAVANI-US model download)
      • Wang, W. and Becker, T. W.: Upper mantle seismic anisotropy as a constraint for mantle flow and continental dynamics of the North American Plate. Earth Planet. Sci. Lett., 514, 143-155, 2019. (PDF)
      • Becker, T. W., Faccenna, C., Humphreys, E. D., Lowry, A. R., and Miller, M. S.: Static and dynamic support of western U.S. topography. Earth Planet. Sci. Lett., 402, 234-246, 2014. (PDF, dynamic topography models)
      • Becker, T. W.: On recent seismic tomography for the western United States. Geochem., Geophys., Geosys., 13, Q01W10, doi:10.1029/2011GC003977, 2012. (PDF)

    • Teaching interface to seismic tomography codes

      Larry Boschi's seismic tomography codes for global body wave and surface wave inversions are available for teaching and research purposes via a GUI in the Solid Earth Research and Teaching Environment (SEATREE)

      • Milner, K., Becker, T. W., Boschi, L., Sain, J., Schorlemmer, D. and H. Waterhouse: The Solid Earth Research and Teaching Environment: a new software framework to share research tools in the classroom and across disciplines. Eos Trans. AGU, 90, 12, 2009. (PDF).
      • Waterhouse, H. D., K. Milner, T. W. Becker, J. Sain, and D. Schorlemmer: A Solid Earth Research and Teaching Environment, Opportunities and Challenges in Computational Geophysics workshop, Caltech, 2009. (PDF).
      • See also the Unified Geodynamics Earth Science Computing Environment (UGESCE) which has SEATREE preinstalled.

    • NSF-CD project Program to Investigate Convective Alboran Sea System Overturn (PICASSO)

      We were part of a multi-institutional, multi-disciplinary continental dynamics research effort funded by NSF-CD to study subduction dynamics and lithospheric delamination mechanisms in the westernmost terminus of the Tethyan collision.
      • Conference presentation summarizing some of the USC led findings:
        • Miller, M. S.: Pockets, conduits, channels, and plumes: links to volcanism and orogeny in the western Meditteranean. Presentation at CIDER 2016, (video)
      • Geodynamics team project publications
        • Sun, D., Miller, M. S., Holt, A. F., and Becker, T. W.: Hot upwelling conduit beneath the Atlas Mountains, Morocco. Geophys. Res. Lett., 41, 8037-8044, doi:10.1002/2014GL061884, 2014. (PDF, supp. mat.)
        • Faccenna, C., Becker, T. W., Auer, L., Billi, A., Boschi, L., Brun, J.-P., Capitanio, F. A., Funiciello, F., Horvath, F., Jolivet, L., Piromallo, C., Royden, L., Rossetti, F., and Serpelloni, E.: Mantle dynamics in the Mediterranean. Rev. Geophys., 52, doi:10.1002/2013RG000444, 2014. (PDF)
        • Miller, M. S. and Becker, T. W.: Reactivated lithospheric-scale discontinuities localize dynamic uplift of the Moroccan Atlas Mountains. Geology, doi:10.1130/G34959, 2014. (PDF)
          • Miller, M. S. and Becker, T. W.: Reactivated lithospheric-scale discontinuities localize dynamic uplift of the Moroccan Atlas Mountains: Comment - Reply. Geology, 42, 338, 2014. (PDF)
          • Nature Geoscience highlight by Whitchuch
        • Alpert, L. A., Miller, M. S., Becker, T. W., and Allam, A. A.: Structure beneath the Alboran from geodynamic flow models and seismic anisotropy. J. Geophys. Res., 118, 4265--4277, doi:10.1002/jgrb.50309, 2013. (PDF)
        • Faccenna, C., Becker, T. W., Jolivet, L., and Keskin, M.: Mantle convection in the Middle East: Reconciling Afar upwelling, Arabia indentation and Aegean trench rollback. Earth Planet. Sci. Lett., 375, 254-269, 2013. (PDF)
        • Miller, M. S., Allam, A. A., Becker, T. W., Di Leo, J., and Wookey, J.: Constraints on the geodynamic evolution of the westernmost Mediterranean and northwestern Africa from shear wave splitting analysis. Earth Planet. Sci. Lett., 375, 234-243, 2013. (PDF)
        • Becker, T. W. and Faccenna, C.: Mantle conveyor beneath the Tethyan collisional belt. Earth Planet. Sci. Lett., 310, 453-461, 2011. (PDF)
        • Faccenna, C. and Becker, T. W.: Shaping mobile belts by small-scale convection. Nature, 465, 602-605, 2010. (PDF)

  • Seismic anisotropy and upper mantle dynamics

    • Seismic anisotropy from global mantle flow LPO model

    • A comprehensive reference frame for present-day plate motions

      We show that a spreading-aligned absolute plate motion reference frame can be constructed and fits a number of observations, including azimuthal anisotropy and hotspot motions, well. This has implications for transform fault weakness, passive spreading, and trench motions statistics.
      • Schaeffer, A., Lebedev, S., and Becker, T. W.: Azimuthal seismic anisotropy in the Earth's upper mantle and the thickness of tectonic plates. Geophys. J. Int., 207, 901-933, 2016. (PDF, supp. mat.)
      • Becker, T. W., Schaeffer, A. J., Lebedev, S., and Conrad, C. P.: Toward a generalized plate motion reference frame. Geophys. Res. Lett., 42, doi:10.1002/2015GL063695, 3188-3196, 2015. (PDF, supp. mat.)
      • download plate velocities in new reference frame

    • Regional anisotropy and lithosphere-asthenosphere interactions

      We study regional shear wave splitting, receiver function, and surface wave based lithospheric and mantle anisotropy for the North and South American Cordillera, the the Mediterranean and Alaska, and interpret them in terms of upper mantle, small-scale convection, slab-keel interactions, and lithospheric deformation.

      • Liu, C., Becker, T. W., Wu, M., Han, S., and Ritzwoller, M. H.: Seismic azimuthal anisotropy within the Juan de Fuca - Gorda plate system. Geophys. Res. Lett., doi:10.1029/2024GL111835, 2024. (PDF)
      • Schulte-Pelkum, V., Becker, T. W., Behr, W. M., and Miller, M. S.: Tectonic inheritance during plate boundary evolution in southern California constrained from seismic anisotropy. Geochem., Geophys., Geosys., 22, doi:10.1029/2021GC010099, 2021. (PDF)
      • Schulte-Pelkum, V., Cain, J. S, Jones II, J. V., and Becker, T. W: Imaging the tectonic grain of the Northern Cordillera orogen using Transportable Array receiver functions. Seismol. Res. Lett., 91, 3086-3105, 2020. (PDF, SI)
      • Wang, W. and Becker, T. W.: Upper mantle seismic anisotropy as a constraint for mantle flow and continental dynamics of the North American Plate. Earth Planet. Sci. Lett., 514, 143-155, 2019. (PDF)
      • Jolivet, L., Faccenna, C., Becker, T. W., Tesauro, M., Sternai, P., and Bouihol, P.: Mantle flow and deforming continents: From India-Asia convergence to Pacific subduction. Tectonics, 37, 2887-2914, doi:10.1029/2018TC005036, 2018. (PDF)
      • Porritt, R. W., Becker, T. W., and Monsalve, G.: Seismic anisotropy and slab dynamics from SKS splitting recorded in Colombia. Geophys. Res. Lett., 41, doi:10.1002/2014GL061958, 2014. (PDF)
      • Faccenna, C., Becker, T. W., Auer, L., Billi, A., Boschi, L., Brun, J.-P., Capitanio, F. A., Funiciello, F., Horvath, F., Jolivet, L., Piromallo, C., Royden, L., Rossetti, F., and Serpelloni, E.: Mantle dynamics in the Mediterranean. Rev. Geophys., 52, doi:10.1002/2013RG000444, 2014. (PDF)
      • Miller, M. S. and Becker, T. W.: Reactivated lithospheric-scale discontinuities localize dynamic uplift of the Moroccan Atlas Mountains. Geology, 42, 35-38, 2014. (PDF)
      • Miller, M. S., Allam, A. A., Becker, T. W., Di Leo, J., and Wookey, J.: Constraints on the geodynamic evolution of the westernmost Mediterranean and northwestern Africa from shear wave splitting analysis. Earth Planet. Sci. Lett., 375, 234-243, 2013. (PDF)
      • Alpert, L. A., Miller, M. S., Becker, T. W., and Allam, A. A.: Structure beneath the Alboran from geodynamic flow models and seismic anisotropy. J. Geophys. Res., 118, 1-13, doi:10.1002/jgrb.50309, 2013. (PDF)
      • Faccenna, C., Becker, T. W., Jolivet, L., and Keskin, M.: Mantle convection in the Middle East: Reconciling Afar upwelling, Arabia indentation and Aegean trench rollback. Earth Planet. Sci. Lett., 375, 254-269, 2013. (PDF, velocity grids)
      • Miller, M. S. and Becker, T. W.: Mantle flow deflected by interactions between subducted slabs and cratonic keels. Nature Geosc., 5, 726-730, 2012. (PDF)
      • Becker, T. W., Schulte-Pelkum, V., Blackman, D. K., Kellogg, J. B., and O'Connell, R. J.: Mantle flow under the western United States from shear wave splitting, Earth Planet. Sci. Lett., 247, 235-251, 2006. (PDF)

    • Review articles and chapters on seismic anisotropy

    • Radial anisotropy as a constraint for regional tectonics, mantle rheology, and volatile content

      We explore radial anisotropy by means of improved global and regional imaging and forward models based on stochastic and mantle flow computations. The geoynamic models are able to match both global radial anisotropy averages and most of the anomaly patterns. The mismatch between seismology and geodynamic reference, residual anisotropy, yields information on the frozen-in structure of the oceanic and continental lithosphere and the volatile and melt content and viscosity of the asthenosphere.

      • Seismic anisotropy from global mantle flow model download
      • Hua, J., Fischer, K., Becker, T.W., Gazel, E. and Hirth, G.: Asthenospheric low-velocity zone consistent with globally prevalent partial melting. Nature Geosc., 16, 175-181, 2023. (PDF)
      • Porritt, R., Becker, T.W., Boschi, L., and Auer, L.: Multi-scale, radially anisotropic shear wave imaging of the mantle underneath the contiguous United States through joint inversion of USArray and global datasets. Geophys. J. Int., 265, 1730--1746, 2021. (PDF, SI, SAVANI-US model download)
      • Auer, L., Becker, T. W., Boschi, L., and Schmerr, N.: Thermal structure, radial anisotropy, and dynamics of oceanic boundary layers. Geophys. Res. Lett., 42, 9740-9749, doi:10.1002/2015GL06624, 2015. (PDF)
      • Auer, L., Boschi , L., Becker, T. W., Nissen-Meyer, T. and Giardini, D.: Savani: a variable-resolution whole-mantle model of anisotropic shear-velocity variations based on multiple datasets. J. Geophys. Res., 119, 3006-3034, doi:10.1002/2013JB010773, 2014. (PDF, model)
      • Schaefer, J. F., Boschi, L., Becker, T. W. and Kissling, E.: Radial anisotropy in the European mantle: Tomographic studies explored in terms of mantle flow. Geophys. Res. Lett., 38 (L23304), doi:10.1029/2011GL049687, 2011. (PDF).
      • Becker, T. W., Kustowski, B. and Ekström, G.: Radial seismic anisotropy as a constraint for upper mantle rheology. Earth Planet. Sci. Lett., 267, 213-237, 2008. (PDF, model)

    • Anisotropy provides a speed limit for net rotations

      We show that anisotropy constrains net rotations of the lithosphere to be smaller than in some hotspot reference frame models, and that spreading-aligned plate motion reference frames are consistent with azimuthal anisotropy.

      • Becker, T. W., Schaeffer, A. J., Lebedev, S., and Conrad, C. P.: Toward a generalized plate motion reference frame. Geophys. Res. Lett., 42, doi:10.1002/2015GL063695, 3188-3196, 2015. (PDF, supp. mat., model)
      • Becker, T. W.: Azimuthal seismic anisotropy constrains net rotation of the lithosphere. Geophys. Res. Lett., 35, L05303, doi:10.1029/2007GL032928, 2008. (Correction: 2008GL033946, PDF)
      • Becker, T. W., Ekström, G., Boschi, L., and Woodhouse, J.: Length scales, patterns, and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves. Geophysical J. Int., 171 451-462, 2007. (PDF)

    • Length scales and origin of upper mantle anisotropy

      We analyze the lateral variations in anisotropic length scales as inferred from SKS splitting and azimuthal anisotropy tomography, and CPO field studies.

      • seismic anisotropy from global mantle flow model download
      • JSG Geodynamics SKS splitting compilation, previous version used in Becker et al. (2012).
      • Bernard, R., Behr, W. M., Becker, T. W., and Young, D.: Relationships between olivine CPO and deformation parameters in naturally deformed rocks and implications for mantle seismic anisotropy. Geochem., Geophys., Geosys., 20, 1-27, doi:10.1029/2019GC008289, 2019. (PDF)
      • Becker, T. W., Lebedev, S., and Long, M. D.: On the relationship between azimuthal anisotropy from shear wave splitting and surface wave tomography. J. Geophys. Res., 117, B01306, doi:10.1029/2011JB008705, 2012. (PDF)
      • Becker, T. W., Browaeys, J. T., and Jordan, T. H.: Stochastic Analysis of Shear Wave Splitting Length Scales. Earth Planet. Sci. Lett., 259, 526-540, 2007. (PDF)
      • Becker, T. W., Ekström, G., Boschi, L., and Woodhouse, J.: Length scales, patterns, and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves. Geophysical J. Int., 171 451-462, 2007. (PDF)

    • Mantle flow, crytallographic (or lattice) preferred orientation (CPO/LPO) fabrics, and viscous anisotropy

      We study upper mantle fabrics from field samples and theoretical texturing models and mantle convection models. We also explore the role of mechanical anisotropy for boundary layer flow. Previously NSF-CSEDI funded.

      • seismic anisotropy from global mantle flow model download
      • Liu, D., Puel, S., Becker, T. W., and Moresi, L. N.: Analytical and numerical models of viscous anisotropy: A toolset to constrain the role of mechanical anisotropy for regional tectonics and fault loading. Geophys. J. Int., 239, 950-963, 2024.
      • Bernard, R., Behr, W. M., Becker, T. W., and Young, D.: Relationships between olivine CPO and deformation parameters in naturally deformed rocks and implications for mantle seismic anisotropy. Geochem., Geophys., Geosys., doi:10.1029/2019GC008289, 2019. (PDF)
      • Wang, W. and Becker, T. W.: Upper mantle seismic anisotropy as a constraint for mantle flow and continental dynamics of the North American Plate. Earth Planet. Sci. Lett., 514, 143-155, 2019. (PDF)
      • Becker, T. W.: Superweak asthenosphere in light of upper-mantle seismic anisotropy, Geochem., Geophys., Geosys., 18, 1986-2003, doi:10.1002/2017GC006886, 2017. (PDF)
      • Schaeffer, A., Lebedev, S., and Becker, T. W.: Azimuthal seismic anisotropy in the Earth's upper mantle and the thickness of tectonic plates. Geophys. J. Int., 207, 901-933, 2016. (PDF, supp. mat.)
      • Auer, L., Becker, T. W., Boschi, L., and Schmerr, N.: Thermal structure, radial anisotropy, and dynamics of oceanic boundary layers. Geophys. Res. Lett., 42, 9740-9749, doi:10.1002/2015GL066246, 2015. (PDF)
      • Becker, T. W., Conrad, C. P., Schaeffer, A. J., and Lebedev, S.: Origin of azimuthal seismic anisotropy in oceanic plates and mantle. Earth Planet. Sci. Lett., 401, 246-250, 2014. (PDF, model)
      • Becker, T. W. and Kawakatsu, H.: On the role of anisotropic viscosity for plate-scale flow. Geophys. Res. Lett., 38, L17307, doi:10.1029/2011GL048584, 2011. (PDF)
      • Castelnau, O., Blackman, D. K. and Becker, T. W.: Numerical simulations of texture development and associated rheological anisotropy in regions of complex mantle flow. Geophys. Res. Lett, 36, L12304, doi:10.1029/2009GL038027, 2009. (PDF)
      • Becker, T. W., Ekström, G., Boschi, L., and Woodhouse, J.: Length scales, patterns, and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves. Geophysical J. Int., 171 451-462, 2007. (PDF)
      • Becker, T. W., Chevrot, S., Schulte-Pelkum, V., and Blackman, D. K.: Statistical properties of seismic anisotropy predicted by upper mantle geodynamic models. J. Geophys. Res., 111, B08309, doi:10.1029/2005JB004095, 2006. (PDF).
      • Becker, T. W., Kellogg, J. B., Ekström, G., and O'Connell, R. J.: Comparison of azimuthal seismic anisotropy from surface waves and finite-strain from global mantle-circulation models, Geophys. J. Int., 155, 696-714, 2003. (PDF)
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Updated: November 11, 2024. (c) Thorsten Becker, 1997-2024.