Articles | Volume 15, issue 7
https://doi.org/10.5194/se-15-747-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-15-747-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 Jul 2024
Research article |
| 05 Jul 2024
| 05 Jul 2024
Propagating rifts: the roles of crustal damage and ascending mantle fluids
Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, United States
Department of Earth and Environmental Sciences, Columbia University, New York, New York 10027, United States
Rasheed Ajala
Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, United States
Related authors
Jack N. Williams, Luke N. J. Wedmore, Åke Fagereng, Maximilian J. Werner, Hassan Mdala, Donna J. Shillington, Christopher A. Scholz, Folarin Kolawole, Lachlan J. M. Wright, Juliet Biggs, Zuze Dulanya, Felix Mphepo, and Patrick Chindandali
Nat. Hazards Earth Syst. Sci., 22, 3607–3639, https://doi.org/10.5194/nhess-22-3607-2022, https://doi.org/10.5194/nhess-22-3607-2022, 2022
Short summary
Short summary
We use geologic and GPS data to constrain the magnitude and frequency of earthquakes that occur along active faults in Malawi. These faults slip in earthquakes as the tectonic plates on either side of the East African Rift in Malawi diverge. Low divergence rates (0.5–1.5 mm yr) and long faults (5–200 km) imply that earthquakes along these faults are rare (once every 1000–10 000 years) but could have high magnitudes (M 7–8). These data can be used to assess seismic risk in Malawi.
Jack N. Williams, Luke N. J. Wedmore, Åke Fagereng, Maximilian J. Werner, Hassan Mdala, Donna J. Shillington, Christopher A. Scholz, Folarin Kolawole, Lachlan J. M. Wright, Juliet Biggs, Zuze Dulanya, Felix Mphepo, and Patrick Chindandali
Nat. Hazards Earth Syst. Sci., 22, 3607–3639, https://doi.org/10.5194/nhess-22-3607-2022, https://doi.org/10.5194/nhess-22-3607-2022, 2022
Short summary
Short summary
We use geologic and GPS data to constrain the magnitude and frequency of earthquakes that occur along active faults in Malawi. These faults slip in earthquakes as the tectonic plates on either side of the East African Rift in Malawi diverge. Low divergence rates (0.5–1.5 mm yr) and long faults (5–200 km) imply that earthquakes along these faults are rare (once every 1000–10 000 years) but could have high magnitudes (M 7–8). These data can be used to assess seismic risk in Malawi.
Cited articles
Aanyu, K. and Koehn, D.: Influence of pre-existing fabrics on fault kinematics and rift geometry of interacting segments: analogue models based on the Albertine Rift (Uganda), Western Branch-East African Rift System, J. Afr. Earth Sci., 59, 168–184, 2011.
Acocella, V., Faccenna, C., Funiciello, R., and Rossetti, F.: Sand-box modelling of basement-controlled transfer zones in extensional domains, Terra Nova, 11, 149–156, 1999.
Ajala, R. and Kolawole, F.: Propagating rifts: the roles of crustal damage and ascending mantle fluids, Zenodo [data set], https://doi.org/10.5281/zenodo.8302196, 2023.
Ajala, R. and Persaud, P.: Effect of Merging Multiscale Models on Seismic Wavefield Predictions Near the Southern San Andreas Fault, J. Geophys. Res.-Solid, 126, 1–23, 2021.
Ajala, R., Kolawole, F., and Menke, W.: Blind magmatism abets nonvolcanic continental rifting, Commun. Earth Environ., 5, 80, https://doi.org/10.1038/s43247-024-01244-7, 2024.
Allam, A. A., Ben-Zion, Y., Kurzon, I., and Vernon, F.: Seismic velocity structure in the Hot Springs and Trifurcation areas of the San Jacinto fault zone, California, from double-difference tomography, Geophys. J. Int., 198, 978–999, 2014.
Allken, V., Huismans, R. S., and Thieulot, C.: Factors controlling the mode of rift interaction in brittle-ductile coupled systems: A 3D numerical study, Geochem. Geophy., Geosy., 13, 1–18, https://doi.org/10.1029/2012GC004077, 2012.
Blanpied, M. L., Lockner, D. A., and Byerlee, J. D.: Fault stability inferred from granite sliding experiments at hydrothermal conditions, Geophys. Res. Lett., 18, 609–612, 1991.
Bosworth, W.: Geometry of propagating continental rifts, Nature, 316, 625–627, https://doi.org/10.1038/316625a0, 1985.
Boven, A., Theunissen, K., Sklyarov, E., Klerkx, J., Melnikov, A., Mruma, A., and Punzalan, L.: Timing of Exhumation of a High-Pressure Mafic Granulite Terrane of the Paleoproterozoic Ubende belt (West Tanzania), Precambrian Res., 93, 119–137, https://doi.org/10.1016/s0301-9268(98)00101-6, 1999.
Brune, S., Kolawole, F., Olive, J. A., Stamps, D. S., Buck, W. R., Buiter, S. J., Furman, T., and Shillington, D. J.: Geodynamics of continental rift initiation and evolution, Nat. Rev. Earth Environ., 4, 235–253, 2023.
Carpenter, B. M., Marone, C., and Saffer, D. M.: Weakness of the San Andreas Fault revealed by samples from the active fault zone, Nat. Geosci., 4, 251–254, 2011.
Celli, N. L., Lebedev, S., Schaeffer, A. J., and Gaina, C.: African cratonic lithosphere carved by mantle plumes, Nat. Commun., 11, 1–10, 2020.
Chatterjee, S. N., Pitt, A. M., and Iyer, H. M.:
Chorowicz, J.: The East African Rift System, J. Afr. Earth Sci., 43, 379–410, https://doi.org/10.1016/j.jafrearsci.2005.07.019, 2005.
Cormier, V. F. and Spudich, P.: Amplification of ground motion and waveform complexity in fault zones: examples from the San Andreas and Calaveras Faults, Geophys, J. Roy. Astron. Soc., 79, 135–152, 1984.
Corti, G.: Centrifuge modelling of the influence of crustal fabrics on the development of transfer zones: insights into the mechanics of continental rifting architecture, Tectonophysics, 384, 191–208, 2004.
Corti, G.: Evolution and characteristics of continental rifting: Analog modeling-inspired view and comparison with examples from the East African Rift System, Tectonophysics, 522, 1–33, https://doi.org/10.1016/j.tecto.2011.06.010, 2012.
Craig, T. J., Jackson, J. A., Priestley, K., and McKenzie, D.: Earthquake distribution patterns in Africa: Their relationship to variations in lithospheric and geological structure, and their rheological implications, Geophys. J. Int., 185, 403–434, 2011.
Daly, M. C.: Crustal Shear Zones in Central Africa: a Kinematic Approach to Proterozoic Tectonics, Episodes, 11, 5–11, 1988.
Daly, M. C., Green, P., Watts, A. B., Davies, O., Chibesakunda, F., and Walker, R.: Tectonics and Landscape of the Central African Plateau, and their implications for a propagating Southwestern Rift in Africa, Geochem. Geophy. Geosy., 21, e2019GC008746, https://doi.org/10.1029/2019GC008746, 2020.
Delvaux, D.: The Karoo to recent rifting in the western branch of the East-African Rift System: a bibliographical synthesis, in: Mus. Roy. Afr. Centr., Tervuren (Belg.), Dept. Geol. Min., Ra Ann, 1990, 1991, 63–83, https://www.africamuseum.be/publication_docs/1991_Delvaux_Karoo to Recent rifting.pdf (last access: 1 July 2024), 1989.
Delvaux, D.: Karoo Rifting in Western Tanzania: Precursor of Gondwana Breakup. Contributions to Geology and Paleontology of Gondwana in Honor of Helmut Wopfner, Geological Institute, University of Cologne, Cologne, 111–125, https://www.africamuseum.be/publication_docs/2001_Delvaux_Karoo rifting in western Tanzania.pdf (last access: 3 July 2024), 2001.
Delvaux, D. and Barth, A.: African stress pattern from formal inversion of focal mechanism data, Tectonophysics, 482, 105–128, 2010.
Delvaux, D., Kervyn, F., Macheyeki, A. S., and Temu, E. B.: Geodynamic Significance of the TRM Segment in the East African Rift (W-Tanzania): Active Tectonics and Paleostress in the Ufipa Plateau and Rukwa basin, J. Struct. Geol., 37, 161–180, 2012.
Ebinger, C. J., Deino, A. L., Drake, R. E., and Tesha, A. L.: Chronology of volcanism and rift basin propagation: Rungwe volcanic province, East Africa, J. Geophys. Res.-Solid, 94, 15785–15803, https://doi.org/10.1029/JB094iB11p15785, 1989.
Ebinger, C. J., Jackson, J. A., Foster, A. N., and Hayward, N. J.: Extensional basin geometry and the elastic lithosphere, Philos. T. Roy. Soc. Lond. A, 357, 741–765, https://doi.org/10.1098/rsta.1999.0351, 1999.
Fang, H., Yao, H., Zhang, H., Thurber, C., Ben-Zion, Y., and van der Hilst, R. D.:
Fernandez-Alonso, M., Delvaux, D., Klerkx, J., and Theunissen, K.: Structural link between Tanganyika-and Rukwa-rift basins at Karema-Nkamba (Tanzania): Basement structural control and recent evolution, Annual Report, Royal Museum for Central Africa, Department of Geology and Mineralogy, Tervuren, Belgium, 91–100, https://www.africamuseum.be/publication_docs/2001_Fernandez et al_ Structural link Tanganyika-Rukwa .pdf (last access: 3 July 2024), 2001.
Foster, A. N. and Jackson, J. A.: Source parameters of large African earthquakes: Implications for crustal rheology and regional kinematics, Geophys. J. Int., 134, 422–448, 1998.
Gaherty, J. B., Zheng, W., Shillington, D. J., Pritchard, M. E., Henderson, S. T., Chindandali, P. R. N., Mdala, H., Shuler, A., Lindsey, N., Oliva, S. J., and Nooner, S.: Faulting processes during early-stage rifting: Seismic and geodetic analysis of the 2009–2010 Northern Malawi earthquake sequence, Geophys. J. Int., 217, 1767–1782, 2019.
Ganbat, A., Tsujimori, T., Boniface, N., Pastor-Galán, D., Aoki, S., and Aoki, K.: Crustal evolution of the Paleoproterozoic Ubendian Belt (SW Tanzania) western margin: a Central African Shield amalgamation tale, Gondwana Res., 91, 286–306, 2021.
Goebel, T. H. W., Rosson, Z., Brodsky, E. E., and Walter, J. I.: Aftershock deficiency of induced earthquake sequences during rapid mitigation efforts in Oklahoma, Earth Planet. Sc. Lett., 522, 135–143, 2019.
Goetze, C. and Evans, B.: Stress and temperature in the bending lithosphere as constrained by experimental rock mechanics, Geophys. J. Int., 59, 463–478, 1979.
Hanson, R. E.: Proterozoic geochronology and tectonic evolution of southern Africa, Geol. Soc. Lond. Spec. Publ., 206, 427–463, 2003.
Hauksson, E. and Unruh, J.: Regional tectonics of the Coso geothermal area along the intracontinental plate boundary in central eastern California: three-dimensional Vp and
Heilman, E., Kolawole, F., Atekwana, E. A., and Mayle, M.: Controls of Basement Fabric on the Linkage of Rift Segments, Tectonics, 38, 1337–1366, 2019.
Hodgson, I., Illsley-Kemp, F., Gallacher, R., Keir, D., Ebinger, C. J., and Mtelela, K.: Crustal Structure at a Young Continental Rift: A Receiver Function Study from the Tanganyika Rift, Tectonics, 36, 1–17, 2017.
Hole, J. A.: Nonlinear high-resolution three-dimensional seismic travel time tomography, J. Geophys. Res.-Solid, 97, 6553–6562, 1992.
Hua, Y., Zhang, S., Li, M., Wu, T., Zou, C., and Liu, L.: Magma system beneath Tengchong volcanic zone inferred from local earthquake seismic tomography, J. Volcanol. Geoth. Rese., 377, 1–16, https://doi.org/10.1016/j.jvolgeores.2019.04.002, 2019.
Jones, D. J. R.: A summary of the East Africa Rift Temperature and Heat flow Model (EARTH), Brit. Geol. Surv. Open Rep. OR/20/006, Brit. Geol. Surv., 1–24, https://www2.bgs.ac.uk/nationalgeosciencedatacentre/citedData/catalogue/e1bc2841-81c2-4b6e-ae5b-301f3bf82b68.html (last access: 1 July 2024), 2020.
Klerkx, J., Theunissen, K., and Delvaux, D.: Persistent Fault Controlled basin Formation since the Proterozoic along the Western Branch of the East African Rift, J. Afr. Earth Sci., 26, 347–361, https://doi.org/10.1016/s0899-5362(98)00020-7, 1998.
Kolawole, F., Atekwana, E. A., Laó-Dávila, D. A., Abdelsalam, M. G., Chindandali, P. R., Salima, J., and Kalindekafe, L.: High-resolution electrical resistivity and aeromagnetic imaging reveal the causative fault of the 2009 Mw 6.0 Karonga, Malawi earthquake, Geophys. J. Int., 213, 1412–1425, https://doi.org/10.1093/gji/ggy066, 2018a.
Kolawole, F., Atekwana, E. A., Laó-Dávila, D. A., Abdelsalam, M. G., Chindandali, P. R., Salima, J., and Kalindekafe, L.: Active Deformation of Malawi Rift's north basin Hinge Zone Modulated by Reactivation of Preexisting Precambrian Shear Zone Fabric, Tectonics, 37, 683–704, https://doi.org/10.1002/2017tc004628, 2018b.
Kolawole, F., Johnston, C. S., Morgan, C. B., Chang, J. C., Marfurt, K. J., Lockner, D. A., Reches, Z., and Carpenter, B. M.: The susceptibility of Oklahoma's basement to seismic reactivation, Nat. Geosci., 12, 839–844, 2019.
Kolawole, F., Firkins, M. C., Al Wahaibi, T. S., Atekwana, E. A., and Soreghan, M. J.: Rift interaction zones and the stages of rift linkage in active segmented continental rift systems, Basin Res., 33, 2984–3020, 2021a.
Kolawole, F., Phillips, T. B., Atekwana, E. A., and Jackson, C. A. L.: Structural inheritance controls strain distribution during early continental rifting, rukwa rift, Front. Earth Sci., 9, 707869, https://doi.org/10.3389/feart.2021.707869, 2021b.
Kolawole, F., Xue, L., and Dulanya, Z.: Rapid Versus Delayed Linkage and Coalescence of Propagating Rift Tips, Authorea [preprint], https://doi.org/10.22541/essoar.168167202.29986035/v1, 2023.
Kranz, R. L.: Crack-crack and crack-pore interactions in stressed granite, Int. J. Rock Mech. Min. Sci. Geomech. Abs., 16, 37–47, 1979.
Lavayssière, A., Drooff, C., Ebinger, C. J., Gallacher, R., Illsley-Kemp, F., Oliva, S. J., and Keir, D.: Depth Extent and Kinematics of Faulting in the Southern Tanganyika Rift, Africa, Tectonics, 38, 842–862, 2019.
Lemna, O. S., Stephenson, R., and Cornwell, D. G.: The Role of Pre-existing Precambrian Structures in the Development of Rukwa Rift Basin, Southwest Tanzania, J. Afr. Earth Sci., 150, 607–625, 2019.
Lenoir, J. L., Liégeois, J.-P., Theunissen, K., and Klerkx, J.: The Palaeoproterozoic Ubendian Shear belt in Tanzania: Geochronology and Structure, J. Afr. Earth Sci., 19,, 169–184, https://doi.org/10.1016/0899-5362(94)90059-0, 1994.
Le Pourhiet, L., Chamot-Rooke, N., Delescluse, M., May, D. A., Watremez, L., and Pubellier, M.: Continental break-up of the South China Sea stalled by far-field compression, Nat. Geosci., 11, 605–609, 2018.
Molnar, N. E., Cruden, A. R., and Betts, P. G.: Interactions between propagating rifts and linear weaknesses in the lower crust, Geosphere, 15, 1617–1640, 2019.
Morley, C. K., Cunningham, S. M., Harper, R. M., and Wescott, W. A.: Geology and Geophysics of the Rukwa Rift, East Africa, Tectonics, 11, 69–81, 1992.
Morley, C. K., Wescott, W. A., Harper, R. M., and Cunningham, S. M.: Geology and Geophysics of the Rukwa Rift. Geoscience of Rift Systems-Evolution of East Africa, AAPG Stud. Geol., 44, 91–110, 1999.
Muirhead, J. D., Wright, L. J., and Scholz, C. A.: Rift evolution in regions of low magma input in East Africa, Earth Planet. Sc. Lett., 506, 332–346, 2019.
Mulaya, E., Gluyas, J., McCaffrey, K., Phillips, T., and Ballentine, C.: Structural geometry and evolution of the Rukwa Rift Basin, Tanzania: Implications for helium potential, Basin Res., 34, 938–960, 2022.
Nakajima, J., Matsuzawa, T., Hasegawa, A., and Zhao, D.: Three-dimensional structure of Vp, Vs, and
Nelson, R. A., Patton, T. L., and Morley, C. K.: Rift-segment interaction and its relation to hydrocarbon exploration in continental rift systems, AAPG Bull., 76, 1153–1169, 1992.
Neuharth, D., Brune, S., Glerum, A., Heine, C., and Welford, J. K.: Formation of continental microplates through rift linkage: Numerical modeling and its application to the Flemish Cap and Sao Paulo Plateau, Geochem. Geophy. Geosy., 22, e2020GC009615, https://doi.org/10.1029/2020GC009615, 2021.
Njinju, E. A., Atekwana, E. A., Stamps, D. S., Abdelsalam, M. G., Atekwana, E. A., Mickus, K. L., Fishwick, S., Kolawole, F., Rajaonarison, T. A., and Nyalugwe, V. N.: Lithospheric structure of the Malawi Rift: Implications for magma-poor rifting processes, Tectonics, 38, 3835–3853, 2019.
Nunn, J. A.: State of stress in the northern Gulf Coast, Geology, 13, 429–432, 1985.
Olson, J. E.: Predicting fracture swarms – The influence of subcritical crack growth and the crack-tip process zone on joint spacing in rock, Geol. Soc. Lond. Spec. Publ., 231, 73–88, 2004.
Pérez-Gussinyé, M., Collier, J. S., Armitage, J. J., Hopper, J. R., Sun, Z., and Ranero, C. R.: Towards a process-based understanding of rifted continental margins, Nat Rev. Earth Environ., 4, 166–184, 2023.
Raggiunti, M., Keir, D., Pagli, C., and Lavayssière, A.: Evidence of Fluid Induced Earthquake Swarms From High Resolution Earthquake Relocation in the Main Ethiopian Rift, Geochem. Geophy. Geosy., 24, 1–16, 2023.
Reasenberg, P.: Second-Order Moment of Central California Seismicity, 1969–1982, J. Geophys. Res., 90, 5479–5495, 1985.
Roberts, E. M., Stevens, N. J., O'Connor, P. M., Dirks, P. H. G. M., Gottfried, M. D., Clyde, W. C., Armstrong, R. A., Kemp, A. I. S., and Hemming, S.: Initiation of the western branch of the East African Rift coeval with the eastern branch, Nat. Geosci., 5, 289–294, 2012.
Roland, M. and McGuire, J. J.: Earthquake swarms on transform faults, Geophys. J. Int., 178, 1677–1690, 2009.
Saeidi, H., Hansen, S. E., Nyblade, A. A., and Haag, R.: Mantle structure beneath the Damara Belt in south-central Africa imaged using adaptively parameterized P-wave tomography, J. Geophys. Res.-Solid, 129, e2023JB027965, https://doi.org/10.1029/2023JB027965, 2024.
Shaban, S., Kolawole, F., and Scholz, C. A.: The Deep Basin and Underlying Basement Structure of the Tanganyika Rift, Tectonics, 42, e2022TC007726, https://doi.org/10.1029/2022TC007726, 2023.
Stamps, D. S., Calais, E., Saria, E., Hartnady, C., Nocquet, J. M., Ebinger, C. J., and Fernandes, R. M.: A kinematic model for the East African Rift, Geophy. Res. Lett., 35, L05304, https://doi.org/10.1029/2007GL032781, 2008.
Stein, S., Sleep, N. H., Geller, R. J., Wang, S. C., and Kroeger, G. C.: Earthquakes along the passive margin of eastern Canada, Geophy. Res. Lett., 6, 537–540, 1979.
Stevens, V. L., Sloan, R. A., Chindandali, P. R., Wedmore, L. N., Salomon, G. W., and Muir, R. A.: The entire crust can be seismogenic: evidence from Southern Malawi, Tectonics, 40, 1–17, https://doi.org/10.1029/2020TC006654, 2021.
Theunissen, K., Klerkx, J., Melnikov, A., and Mruma, A.: Mechanisms of Inheritance of Rift Faulting in the Western branch of the East African Rift, Tanzania, Tectonics, 15, 776–790, https://doi.org/10.1029/95tc03685, 1996.
Tiercelin, J. J., Pflumio, C., Castrec, M., Boulégue, J., Gente, P., Rolet, J., Coussement, C., Stetter, K. O., Huber, R., Buku, S., and Mifundu, W.: Hydrothermal vents in Lake Tanganyika, East African, Rift system, Geology, 21, 499–502, 1993.
van Herwaarden, D. P., Thrastarson, S., Hapla, V., Afanasiev, M., Trampert, J., and Fichtner, A.: Full‐waveform tomography of the African Plate using dynamic mini‐batches, J. Geophys. Res.-Solid, 128, e2022JB026023, https://doi.org/10.1029/2022JB026023, 2023.
Van Wijk, J. K. and Blackman, D. K.: Dynamics of continental rift propagation: the endmember modes, Earth Planet. Sc. Lett., 229, 247–258, 2005.
Veatch, A. C.: Evolution of the Congo Basin, GSA Memoir, 3, 1–177, https://doi.org/10.1130/MEM3, 1935.
Versfelt, J. and Rosendahl, B.: Relationship between pre-rift structure and rift architecture in Lakes Tanganyika and Malawi, East Africa, Nature, 337, 354–357, 1989.
Vidale, J. E.: Finite-difference calculation of traveltimes in three dimensions, Geophysics, 55, 521–526, 1990.
Wessel, P., Luis, J. F., Uieda, L., Scharroo, R., Wobbe, F., Smith, W. H. F., and Tian, D.: The generic mapping tools version 6, Geochem. Geophy. Geosy., 20, 1–20, 2019.
Wheeler, W. H. and Karson, J. A.: Extension and Subsidence Adjacent to a “weak” continental Transform: An Example from the Rukwa Rift, East Africa, Geology, 22, 625–628, https://doi.org/10.1130/0091-7613(1994)022<0625:EASATA>2.3.CO;2, 1994.
Yang, Z. and Chen, W. P.: Earthquakes along the East African Rift System: A multiscale, system-wide perspective, J. Geophys. Res., 115, B12309, https://doi.org/10.1029/2009JB006779, 2010.
Zaliapin, I. and Ben-Zion, Y.: Earthquake clusters in southern California I: Identification and stability, J. Geophys. Res.-Solid, 118, 2847–2864, 2013.
Zaliapin, I., Gabrielov, A., Keilis-Borok, V., and Wong, H.: Clustering Analysis of Seismicity and Aftershock Identification, Phys. Rev. Lett., 101, 1–4, 2008.
Zhang, Q. and Shearer, P.: A new method to identify earthquake swarms applied to seismicity near the San Jacinto Fault, California, Geophys. J. Int., 205, 995–1005, 2016.
Zheng, W., Oliva, S. J., Ebinger, C., and Pritchard, M. E.: Aseismic deformation during the 2014 Mw 5.2 Karonga earthquake, Malawi, from satellite interferometry and earthquake source mechanisms, Geophy. Res. Lett., 47, e2020GL090930, https://doi.org/10.1029/2020GL090930, 2020.
Zwaan, F. and Schreurs, G.: Rift segment interaction in orthogonal and rotational extension experiments: Implications for the large-scale development of rift systems, J. Struct. Geol., 140, 104119, https://doi.org/10.1016/j.jsg.2020.104119, 2020.
Zwaan, F., Schreurs, G., Naliboff, J., and Buiter, S. J.: Insights into the effects of oblique extension on continental rift interaction from 3D analogue and numerical models, Tectonophysics, 693, 239–260, 2016.
Short summary
We investigate the upper-crustal structure of the Rukwa–Tanganyika rift zone in East Africa, where the Tanganyika rift interacts with the Rukwa and Mweru-Wantipa rifts, coinciding with abundant seismicity at the rift tips. Seismic velocity structure and patterns of seismicity clustering reveal zones around 10 km deep with anomalously high Vp / Vs ratios at the rift tips, indicative of a localized mechanically weakened crust caused by mantle volatiles and damage associated with bending strain.
We investigate the upper-crustal structure of the Rukwa–Tanganyika rift zone in East Africa,...
