@article{1b8215af74f64feba81edd92673f8039,
title = "Active Deformation Constraints on the Nubia-Somalia Plate Boundary Through Heterogenous Lithosphere of the Turkana Depression",
abstract = "The role of lithospheric heterogeneities, presence or absence of melt, local and regional stresses, and gravitational potential energy in strain localization in continental rifts remains debated. We use new seismic and geodetic data to identify the location and orientation of the modern Nubia-Somalia plate boundary in the 300-km-wide zone between the southern Main Ethiopian Rift (MER) and Eastern Rift (ER) across the Mesozoic Anza rift in the Turkana Depression. This region exhibits lithospheric heterogeneity, 45 Ma-Recent magmatism, and more than 1,500 m of base-level elevation change, enabling the assessment of strain localization mechanisms. We relocate 1716 earthquakes using a new 1-D velocity model. Using a new local magnitude scaling with station corrections, we find 1 ≤ ML ≤ 4.5, and a b-value of 1.22 ± 0.06. We present 59 first motion and 3 full moment tensor inversions, and invert for opening directions. We use complementary geodetic displacement vectors and strain rates to describe the geodetic strain field. Our seismic and geodetic strain zones demonstrate that only a small part of the 300 km-wide region is currently active; low elevation and high-elevation regions are active, as are areas with and without Holocene magmatism. Variations in the active plate boundary's location, orientation and strain rate appear to correspond to lithospheric heterogeneities. In the MER-ER linkage zone, a belt of seismically fast mantle lithosphere generally lacking Recent magmatism is coincident with diffuse crustal deformation, whereas seismically slow mantle lithosphere and Recent magmatism are characterized by localized crustal strain; lithospheric heterogeneity drives strain localization.",
keywords = "crust, geodetic, heterogeneity, mantle-lithosphere, seismic, strain",
author = "M. Musila and Ebinger, {C. J.} and Bastow, {I. D.} and G. Sullivan and Oliva, {S. J.} and E. Knappe and M. Perry and R. Kounoudis and Ogden, {C. S.} and R. Bendick and S. Mwangi and N. Mariita and G. Kianji and E. Kraus and F. Illsley-Kemp",
note = "Funding Information: We thank reviewers A. Koptev and D. B. Keir for their constructive comments. We acknowledge the collaborative efforts of the University of Nairobi, Dedan Kimathi University, and Addis Ababa University, our local university partners in Kenya and Ethiopia, for helping establish the Turkana Rift Array to Investigate Lithospheric Structure (TRAILS) network. Notable are Emma Chambers and the graduate students from local universities: S. Mwangi, M. Karanja, M. Wanyaga, B. Onguso and S. Alemayehu for assisting in the installation and servicing of the TRAILS seismic and geodetic networks. C. Ebinger and M. Musila acknowledge the support of the National Science Foundation Grant 1824417. R. Bendick, E. Knappe and M. Perry acknowledge support from the National Science Foundation Grant 1824199, 1824417, 17277277, and 1551823. I. Bastow, C. Ogden and R. Kounoudis acknowledge support from National Environment Research Council Grant NE/S014136/1. R. Kounoudis also acknowledges support from the Imperial College President's PhD Scholarship. F. Illsley‐Kemp is supported by the ECLIPSE program, which is funded by the New Zealand Ministry of Business, Innovation and Employment (MBIE), the New Zealand Earthquake Commission Programme in Earthquake Seismology and Tectonic Geodesy at Victoria University of Wellington, and by the Marsden Fund of the Royal Society of New Zealand (Grant VUW2109). For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) license to any Author Accepted Manuscript (AAM) version arising. Funding Information: We thank reviewers A. Koptev and D. B. Keir for their constructive comments. We acknowledge the collaborative efforts of the University of Nairobi, Dedan Kimathi University, and Addis Ababa University, our local university partners in Kenya and Ethiopia, for helping establish the Turkana Rift Array to Investigate Lithospheric Structure (TRAILS) network. Notable are Emma Chambers and the graduate students from local universities: S. Mwangi, M. Karanja, M. Wanyaga, B. Onguso and S. Alemayehu for assisting in the installation and servicing of the TRAILS seismic and geodetic networks. C. Ebinger and M. Musila acknowledge the support of the National Science Foundation Grant 1824417. R. Bendick, E. Knappe and M. Perry acknowledge support from the National Science Foundation Grant 1824199, 1824417, 17277277, and 1551823. I. Bastow, C. Ogden and R. Kounoudis acknowledge support from National Environment Research Council Grant NE/S014136/1. R. Kounoudis also acknowledges support from the Imperial College President's PhD Scholarship. F. Illsley-Kemp is supported by the ECLIPSE program, which is funded by the New Zealand Ministry of Business, Innovation and Employment (MBIE), the New Zealand Earthquake Commission Programme in Earthquake Seismology and Tectonic Geodesy at Victoria University of Wellington, and by the Marsden Fund of the Royal Society of New Zealand (Grant VUW2109). For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) license to any Author Accepted Manuscript (AAM) version arising. Publisher Copyright: {\textcopyright} 2023 The Authors. Geochemistry, Geophysics, Geosystems published by Wiley Periodicals LLC on behalf of American Geophysical Union.",
year = "2023",
month = sep,
doi = "10.1029/2023GC010982",
language = "English",
volume = "24",
journal = "Geochemistry, Geophysics, Geosystems",
issn = "1525-2027",
publisher = "John Wiley and Sons Inc.",
number = "9",
}