Seismicity and Surface Deformation in Kamanjab Inlier, Northern Namibia
DOI:
https://doi.org/10.26443/seismica.v4i2.1303Keywords:
Namibia Earthquake Swarm, Active faults in Kamanjab InlierAbstract
The last two decades have seen the onset of felt earthquakes, including occasionally damaging events, in the Kamanjab Inlier, a block of Paleoproterozoic crystalline basement in northern Namibia. The Geological Survey of Namibia (GSN) and the Council for Geoscience, South Africa (CGS) deployed a temporary network of 10 seismic stations within the Kamanjab Inlier from June to September 2018 and cataloged ~1500 events. We used a neural network-based earthquake phase detector, EQTransformer, to enhance the published GSN catalog to >9000 detections. The double-difference earthquake relocation of ~4500 events reveals two distinct major and three minor spatial clusters that we interpret as local discrete faults that intersect the NE-dipping seismogenic fault of the 4 April 2021 Mw 5.4 earthquake, which is the largest instrumentally recorded earthquake in Namibia to date. We name the Mw 5.4 host fault "Anker Fault" and constrain its orientation using Sentinel 1 Interferometric Satellite Aperture Radar (InSAR) to image surface uplift and subsidence patterns. Given the sudden onset of the 2018 seismic activity and the absence of dams, mineral or energy exploration projects nearby, we eliminated the possibility of anthropogenic triggering. We suggest that the proximal cause for 2018 seismicity is shallow groundwater migration, possibly associated with nearby hot springs and modulated by tidal forces. The Kamanjab Inlier area has shown an increase in the number and magnitude of earthquakes from 2018 to 2021, which could pose a seismic hazard in the future. Our study introduces an earthquake detection and relocation workflow that can be adopted for regions with limited instrumentation.
References
Aki, K. (1965). Maximum likelihood estimate of b in the formula log N= a-bM and its confidence limits. Bull. Earthquake Res. Inst., Tokyo Univ., 43, 237–239.
Allmendinger, R. W., Cardozo, Nestor., & Fisher, D. M. (2011). Structural geology algorithms: Vectors and tensors. Cambridge University Press. DOI: https://doi.org/10.1017/CBO9780511920202
Andreoli, M., Doucouré, M., Van Bever Donker, J., Brandt, D., & Andersen, N. (1996). Neotectonics of southern Africa – a review. In Africa Geoscience Review. 3(1):1–16.
Becker, T., Schreiber, U., Kampunzu, A. B., & Armstrong, R. (2006). Mesoproterozoic rocks of Namibia and their plate tectonic setting. Journal of African Earth Sciences, 46(1–2), 112–140. https://doi.org/https://doi.org/10.1016/j.jafrearsci.2006.01.015 DOI: https://doi.org/10.1016/j.jafrearsci.2006.01.015
Berardino, P., Fornaro, G., Lanari, R., & Sansosti, E. (2002a). A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Transactions on Geoscience and Remote Sensing, 40(11), 2375–2383. https://doi.org/https://doi.org/10.1109/TGRS.2002.803792
Berardino, P., Fornaro, G., Lanari, R., & Sansosti, E. (2002b). A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Transactions on Geoscience and Remote Sensing, 40(11), 2375–2383. https://doi.org/https://doi.org/10.1109/TGRS.2002.803792 DOI: https://doi.org/10.1109/TGRS.2002.803792
Birhanu, Y., Wilks, M., Biggs, J., Kendall, J.-M., Ayele, A., & Lewi, E. (2018). Seasonal patterns of seismicity and deformation at the Alutu geothermal reservoir, Ethiopia, induced by hydrological loading. Journal of Volcanology and Geothermal Research, 356, 175–182. DOI: https://doi.org/10.1016/j.jvolgeores.2018.03.008
Célérier, B. (2010). Remarks on the relationship between the tectonic regime, the rake of the slip vectors, the dip of the nodal planes, and the plunges of the P, B, and T axes of earthquake focal mechanisms. Tectonophysics, 482(1–4), 42–49. https://doi.org/https://doi.org/10.1016/j.tecto.2009.03.006 DOI: https://doi.org/10.1016/j.tecto.2009.03.006
Chamberlain, C. J., Hopp, C. J., Boese, C. M., Warren-Smith, E., Chambers, D., Chu, S. X., Michailos, K., & Townend, J. (2018). EQcorrscan: Repeating and near-repeating earthquake detection and analysis in Python. Seismological Research Letters, 89(1), 173–181. https://doi.org/https://doi.org/10.1785/0220170151 DOI: https://doi.org/10.1785/0220170151
Clemson, J., Cartwright, J., & Booth, J. (1997). Structural segmentation and the influence of basement structure on the Namibian passive margin. Journal of the Geological Society, 154(3), 477–482. https://doi.org/https://doi.org/10.1144/gsjgs.154.3.0477 DOI: https://doi.org/10.1144/gsjgs.154.3.0477
Clifford, T. N. (2008). The geology of the Neoproterozoic Swakop-Otavi transition zone in the Outjo District, northern Damara Orogen, Namibia. South African Journal of Geology, 111(1), 117–140. https://doi.org/https://doi.org/10.2113/gssajg.111.1.117 DOI: https://doi.org/10.2113/gssajg.111.1.117
Cocco, M., & Rice, J. R. (2002). Pore pressure and poroelasticity effects in Coulomb stress analysis of earthquake interactions. Journal of Geophysical Research: Solid Earth, 107(B2), ESE-2. DOI: https://doi.org/10.1029/2000JB000138
Corner, B., & Durrheim, R. J. (2018). An integrated geophysical and geological interpretation of the southern African lithosphere. In Geology of southwest Gondwana (pp. 19–61). Springer. https://doi.org/https://doi.org/10.1007/978-3-319-68920-3_2 DOI: https://doi.org/10.1007/978-3-319-68920-3_2
Coward, M. (1981). The junction between Pan African mobile belts in Namibia: Its structural history. Tectonophysics, 76(1–2), 59–73. https://doi.org/https://doi.org/10.1016/0040-1951(81)90253-5 DOI: https://doi.org/10.1016/0040-1951(81)90253-5
Coward, M. (1983). The tectonic history of the Damara belt. Evolution of the Damara Orogen of South West Africa/Namibia, 11, 409–421.
Cox, S. C., Menzies, C. D., Sutherland, R., Denys, P. H., Chamberlain, C., & Teagle, D. A. (2012). Changes in hot spring temperature and hydrogeology of the Alpine Fault hanging wall, New Zealand, induced by distal South Island earthquakes. Crustal Permeability, 228–248. https://doi.org/https://doi.org/10.1002/9781119166573.ch19 DOI: https://doi.org/10.1002/9781119166573.ch19
Don, J. K. (1979). A study of seismicity in the Damara Province [Phdthesis, University of Namibia]. https://doi.org/http://hdl.handle.net/11070.1/2252
Dziewonski, A. M., Chou, T.-A., & Woodhouse, J. H. (1981). Determination of earthquake source parameters from waveform data for studies of global and regional seismicity. Journal of Geophysical Research: Solid Earth, 86(B4), 2825–2852. https://doi.org/https://doi.org/10.1029/JB086iB04p02825 DOI: https://doi.org/10.1029/JB086iB04p02825
Ekström, G., Nettles, M., & Dziewoński, A. (2012). The global CMT project 2004–2010: Centroid-moment tensors for 13,017 earthquakes. Physics of the Earth and Planetary Interiors, 200, 1–9. https://doi.org/https://doi.org/10.1016/j.pepi.2012.04.002 DOI: https://doi.org/10.1016/j.pepi.2012.04.002
El-Isa, Z. H., & Eaton, D. W. (2014). Spatiotemporal variations in the b-value of earthquake magnitude–frequency distributions: Classification and causes. Tectonophysics, 615, 1–11. https://doi.org/https://doi.org/10.1016/j.tecto.2013.12.001 DOI: https://doi.org/10.1016/j.tecto.2013.12.001
ESA. (2024). Sentinel-1 Acquisition Plans. In Sentinel Online.
Ester, M., Kriegel, H.-P., Sander, J., & Xu, X. (1996). Density-based spatial clustering of applications with noise. Int. Conf. Knowledge Discovery and Data Mining, 240(6).
Farr, T. G., Rosen, P. A., Caro, E., Crippen, R., Duren, R., Hensley, S., Kobrick, M., Paller, M., Rodriguez, E., Roth, L., & others. (2007). The shuttle radar topography mission. Reviews of Geophysics, 45(2). https://doi.org/https://doi.org/10.1029/2005RG000183 DOI: https://doi.org/10.1029/2005RG000183
Farrell, J., Husen, S., & Smith, R. B. (2009). Earthquake swarm and b-value characterization of the Yellowstone volcano-tectonic system. Journal of Volcanology and Geothermal Research, 188(1–3), 260–276. https://doi.org/https://doi.org/10.1016/j.jvolgeores.2009.08.008 DOI: https://doi.org/10.1016/j.jvolgeores.2009.08.008
Foulger, G. R., Wilson, M. P., Gluyas, J. G., Julian, B. R., & Davies, R. J. (2018). Global review of human-induced earthquakes. Earth-Science Reviews, 178, 438–514. https://doi.org/https://doi.org/10.1016/j.earscirev.2017.07.008 DOI: https://doi.org/10.1016/j.earscirev.2017.07.008
Frechet, J. (1985). Sismogenese et doublets sismiques [Phdthesis]. Universite Scientifique et Medicale de Grenoble.
Frimmel, H., & Frank, W. (1998). Neoproterozoic tectono-thermal evolution of the Gariep Belt and its basement, Namibia and South Africa. Precambrian Research, 90(1–2), 1–28. https://doi.org/https://doi.org/10.1016/S0301-9268(98)00029-1 DOI: https://doi.org/10.1016/S0301-9268(98)00029-1
Geological Survey of Namibia. (2009). SHEET 1914 - KAMANJAB. Geological Survey of Namibia, Ministry of Mines.
Geological Survey of Namibia Online Database. (2024). Earth Data Namibia, Geological and Mineral Information System. https://www.mme.gov.na/edn. https://www.mme.gov.na/edn
Glazner, A. F., & McNutt, S. R. (2021). Relationship Between Dike Injection and b-Value for Volcanic Earthquake Swarms. Journal of Geophysical Research: Solid Earth, 126(12), e2020JB021631. https://doi.org/https://doi.org/10.1029/2020JB021631 DOI: https://doi.org/10.1029/2020JB021631
Goslin, J., Lourenço, N., Dziak, R. P., Bohnenstiehl, D. R., Haxel, J., & Luis, J. (2005). Long-term seismicity of the Reykjanes Ridge (North Atlantic) recorded by a regional hydrophone array. Geophysical Journal International, 162(2), 516–524. https://doi.org/https://doi.org/10.1111/j.1365-246X.2005.02678.x DOI: https://doi.org/10.1111/j.1365-246X.2005.02678.x
Gray, D. R., Foster, D., Meert, J., Goscombe, B., Armstrong, R., Trouw, R., & Passchier, C. (2008). A Damara orogen perspective on the assembly of southwestern Gondwana. Geological Society, London, Special Publications, 294(1), 257–278. https://doi.org/https://doi.org/10.1144/SP294.14 DOI: https://doi.org/10.1144/SP294.14
Gross, A., Droop, G., Porcher, C., & Fernandes, L. (2009). Petrology and thermobarometry of mafic granulites and migmatites from the Chafalote Metamorphic Suite: New insights into the Neoproterozoic P–T evolution of the Uruguayan—Sul-Rio-Grandense shield. Precambrian Research, 170(3–4), 157–174. https://doi.org/https://doi.org/10.1016/j.precamres.2009.01.011 DOI: https://doi.org/10.1016/j.precamres.2009.01.011
Hardebeck, J. L., & Okada, T. (2018). Temporal stress changes caused by earthquakes: A review. Journal of Geophysical Research: Solid Earth, 123(2), 1350–1365. https://doi.org/https://doi.org/10.1002/2017JB014617 DOI: https://doi.org/10.1002/2017JB014617
Harris, F. J. (1978). On the use of windows for harmonic analysis with the discrete Fourier transform. Proceedings of the IEEE, 66(1), 51–83. https://doi.org/https://doi.org/10.1109/PROC.1978.10837 DOI: https://doi.org/10.1109/PROC.1978.10837
Hartman, A. (24 May, 2018). Kunene school to be relocated due to tremors. The Namibian. https://www.namibian.com.na/177711/archive-read/Kunene-school-to-be-relocated-due-to-tremors
Haxel, J., & Dziak, R. (2005). Evidence of explosive seafloor volcanic activity from the Walvis Ridge, South Atlantic Ocean. Geophysical Research Letters, 32(13). https://doi.org/https://doi.org/10.1029/2005GL023205 DOI: https://doi.org/10.1029/2005GL023205
Heidbach, O., Rajabi, M., Cui, X., Fuchs, K., Müller, B., Reinecker, J., Reiterg, K., Tingay, M., Wenzel, F., Xie, F., Ziegler, M. O., Zoback, M.-L., & Zoback, M. (2018). The World Stress Map database release 2016: Crustal stress pattern across scales. Tectonophysics, 744, 484–498. https://doi.org/https://doi.org/10.1016/j.tecto.2018.07.007 DOI: https://doi.org/10.1016/j.tecto.2018.07.007
Heidbach, O., Rajabi, M., Reiter, K., Ziegler, M., & WSM Team. (2016). World Stress Map Database Release V. 1.1 [Techreport]. GFZ Data Services. https://doi.org/https://doi.org/10.5880/WSM.2016.001
Heimann, S., Isken, M., Kühn, D., Sudhaus, H., Steinberg, A., Daout, S., Cesca, S., Bathke, H., & Dahm, T. (2018). Grond: A probabilistic earthquake source inversion framework [Techreport]. GFZ Data Services. https://doi.org/https://doi.org/10.5880/GFZ.2.1.2018.003
Heimann, S., Vasyura-Bathke, H., Sudhaus, H., Isken, M. P., Kriegerowski, M., Steinberg, A., & Dahm, T. (2019). A Python framework for efficient use of pre-computed Green’s functions in seismological and other physical forward and inverse source problems. Solid Earth, 10(6), 1921–1935. https://doi.org/https://doi.org/10.5194/se-10-1921-2019 DOI: https://doi.org/10.5194/se-10-1921-2019
Hirose, F., Tamaribuchi, K., Kobayashi, A., & Maeda, K. (2024). Relation between earthquake swarm activity and tides in the Noto region, Japan. Earth, Planets and Space, 76(1), 37. https://doi.org/https://doi.org/10.1186/s40623-024-01985-x DOI: https://doi.org/10.1186/s40623-024-01985-x
Hutchins, D., & Wackerle, R. (2007). The high resolution airborne geophysical survey programme of Namibia: a success story in promoting mineral exploration. Proceedings of Exploration, 7, 879–883. https://911metallurgist.com/blog/wp-content/uploads/2015/10/The-High-Resolution-Airborne-Geophysical-Survey-Programme-of-Namibia.pdf
Iwata, D., & Nanjo, K. Z. (2024). Adaptive estimation of the Gutenberg–Richter b value using a state space model and particle filtering. Scientific Reports, 14(1), 4630. https://doi.org/https://doi.org/10.1038/s41598-024-54576-x DOI: https://doi.org/10.1038/s41598-024-54576-x
Jelsma, H. A., McCourt, S., Perritt, S. H., & Armstrong, R. A. (2018). The Geology and Evolution of the Angolan Shield, Congo Craton. In S. Siegesmund, M. A. S. Basei, P. Oyhantçabal, & S. Oriolo (Eds.), Geology of Southwest Gondwana (pp. 217–239). Springer International Publishing. https://doi.org/https://doi.org/10.1007/978-3-319-68920-3_9 DOI: https://doi.org/10.1007/978-3-319-68920-3_9
Jenatton, L., Guiguet, R., Thouvenot, F., & Daix, N. (2007). The 16,000-event 2003–2004 earthquake swarm in Ubaye (French Alps). Journal of Geophysical Research: Solid Earth, 112(B11). https://doi.org/https://doi.org/10.1029/2006JB004878 DOI: https://doi.org/10.1029/2006JB004878
Jung, S., Brandt, S., Nebel, O., Hellebrand, E., Seth, B., & Jung, C. (2014). The P–T–t paths of high-grade gneisses, Kaoko Belt, Namibia: Constraints from mineral data, U–Pb allanite and monazite and Sm–Nd/Lu–Hf garnet ages and garnet ion probe data. Gondwana Research, 25(2), 775–796. https://doi.org/https://doi.org/10.1016/j.gr.2013.05.017 DOI: https://doi.org/10.1016/j.gr.2013.05.017
Kadiri, A. U., Sitali, M., & Midzi, V. (2023). Probabilistic seismic hazard assessment in Namibia. Journal of African Earth Sciences, 202, 104933. https://doi.org/https://doi.org/10.1016/j.jafrearsci.2023.104933 DOI: https://doi.org/10.1016/j.jafrearsci.2023.104933
Kilb, D., Gomberg, J., & Bodin, P. (2002). Aftershock triggering by complete Coulomb stress changes. Journal of Geophysical Research: Solid Earth, 107(B4), ESE-2. DOI: https://doi.org/10.1029/2001JB000202
Kirkpatrick, L. H., & Green, A. N. (2018). Antecedent geologic control on nearshore morphological development: The wave dominated, high sediment supply shoreface of southern Namibia. Marine Geology, 403, 34–47. https://doi.org/https://doi.org/10.1016/j.margeo.2018.05.003 DOI: https://doi.org/10.1016/j.margeo.2018.05.003
Kissling, E., Ellsworth, W., Eberhart-Phillips, D., & Kradolfer, U. (1994). Initial reference models in local earthquake tomography. Journal of Geophysical Research: Solid Earth, 99(B10), 19635–19646. https://doi.org/https://doi.org/10.1029/93JB03138 DOI: https://doi.org/10.1029/93JB03138
Klein, J. (1980). Pleistocene to Recent faulting in the area west of Omaruru (SWA/Namibia). Reg. Geol. Ser. Open File Rep. RG, 4, 28.
Konopásek, Jiří, Košler, J., Tajčmanová, L., Ulrich, S., & Kitt, S. L. (2008). Neoproterozoic igneous complex emplaced along major tectonic boundary in the Kaoko Belt (NW Namibia): ion probe and LA-ICP-MS dating of magmatic and metamorphic zircons. Journal of the Geological Society, 165(1), 153–165. https://doi.org/https://doi.org/10.1144/0016-76492006-192 DOI: https://doi.org/10.1144/0016-76492006-192
Konopásek, Jiřı́, Kröner, S., Kitt, S. L., Passchier, C. W., & Kröner, A. (2005). Oblique collision and evolution of large-scale transcurrent shear zones in the Kaoko belt, NW Namibia. Precambrian Research, 136(2), 139–157. https://doi.org/https://doi.org/10.1016/j.precamres.2004.10.005 DOI: https://doi.org/10.1016/j.precamres.2004.10.005
Korn, H., H. &. Martin. (1951). The seismicity of South-West Africa. South African Journal of Geology, 54(1), 85–88. https://doi.org/https://doi.org/10.1016/S0040-1951(02)00047-1
Korn, H., & Martin, H. (1950). Erdbeben in Südwestafrika. Geologische Rundschau, 38(1), 19–23. https://doi.org/https://doi.org/10.1007/BF01766569 DOI: https://doi.org/10.1007/BF01766569
Kühn, D., Heimann, S., Isken, M. P., Ruigrok, E., & Dost, B. (2020). Probabilistic moment tensor inversion for hydrocarbon-induced seismicity in the Groningen gas field, The Netherlands, Part 1: Testing. Bulletin of the Seismological Society of America, 110(5), 2095–2111. https://doi.org/https://doi.org/10.1785/0120200099 DOI: https://doi.org/10.1785/0120200099
Lehmann, J., Saalmann, K., Naydenov, K. V., Milani, L., Belyanin, G. A., Zwingmann, H., Charlesworth, G., & Kinnaird, J. A. (2016). Structural and geochronological constraints on the Pan-African tectonic evolution of the northern Damara Belt, Namibia. Tectonics, 35(1), 103–135. https://doi.org/https://doi.org/10.1002/2015TC003899 DOI: https://doi.org/10.1002/2015TC003899
Li, S., Xu, W., & Li, Z. (2022). Review of the SBAS InSAR Time-series algorithms, applications, and challenges. Advances in InSAR Algorithms, Deformation Monitoring and Source Parameter Inversion, 13(2), 114–126. https://doi.org/https://doi.org/10.1016/j.geog.2021.09.007 DOI: https://doi.org/10.1016/j.geog.2021.09.007
Liu, M., Li, L., Zhang, M., Lei, X., Nedimović, M. R., Plourde, A. P., Guo, R., Wang, W., & Li, H. (2023). Complexity of initiation and evolution of the 2013 Yunlong earthquake swarm. Earth and Planetary Science Letters, 612, 118168. DOI: https://doi.org/10.1016/j.epsl.2023.118168
Lomax, A., Michelini, A., & Curtis, A. (2014). Earthquake Location, Direct, Global-Search Methods. In R. Meyers (Ed.), Encyclopedia of Complexity and Systems Science (Vol. 5, pp. 2449–2473). Springer New York, New York. https://doi.org/https://doi.org/10.1007/978-3-642-27737-5_150-2 DOI: https://doi.org/10.1007/978-0-387-30440-3_150
López-Comino, J. Á., Braun, T., Dahm, T., Cesca, S., & Danesi, S. (2021). On the source parameters and genesis of the 2017, Mw 4 Montesano earthquake in the outer border of the Val d’Agri Oilfield (Italy). Frontiers in Earth Science, 8, 617794. https://doi.org/https://doi.org/10.3389/feart.2020.617794 DOI: https://doi.org/10.3389/feart.2020.617794
Lordi, A. L., Neves, M. C., Custódio, S., & Dumont, S. (2022). Seasonal modulation of oceanic seismicity in the azores. Frontiers in Earth Science, 10, 995401. DOI: https://doi.org/10.3389/feart.2022.995401
MacQueen, J. (1967). Some methods for classification and analysis of multivariate observations. Proceedings of the Fifth Berkeley Symposium on Mathematical Statistics and Probability, 1/14, 281–297.
Mangongolo, A., Hutchins, D., & Miller, R. (2008). Seismicity of Namibia from 1910 to 2006. Geology of Namibia, 1–27.
Martin, H., & Porada, H. (1977). The intracratonic branch of the Damara orogen in South West Africa I. Discussion of geodynamic models. Precambrian Research, 5(4), 311–338. https://doi.org/https://doi.org/10.1016/0301-9268(77)90039-0 DOI: https://doi.org/10.1016/0301-9268(77)90039-0
Meert, J. G. (2003). A synopsis of events related to the assembly of eastern Gondwana. Tectonophysics, 362(1–4), 1–40. https://doi.org/https://doi.org/10.1016/S0040-1951(02)00629-7 DOI: https://doi.org/10.1016/S0040-1951(02)00629-7
Metropolis, N., & Ulam, S. (1949). The Monte Carlo Method. Journal of the American Statistical Association, 44(247), 335–341. https://doi.org/https://www.tandfonline.com/doi/abs/10.1080/01621459.1949.10483310 DOI: https://doi.org/10.1080/01621459.1949.10483310
Midzi, V, Bommer, J., Strasser, F., Albini, P., Zulu, B., Prasad, K., & Flint, N. (2013). An intensity database for earthquakes in South Africa from 1912 to 2011. Journal of Seismology, 17, 1183–1205. https://doi.org/https://doi.org/10.1007/s10950-013-9387-y DOI: https://doi.org/10.1007/s10950-013-9387-y
Midzi, V., Manzunzu, B., Zulu, B. S., Mulabisana, T., Myendeki, S., & Mangongolo, A. (2015). Impact of recent moderately sized earthquakes in South Africa: Macroseismic investigations of the 18 November and 2 December 2013 earthquakes. South African Journal of Geology, 118(4), 373–388. https://doi.org/https://doi.org/10.2113/gssajg.118.4.373 DOI: https://doi.org/10.2113/gssajg.118.4.373
Midzi, V, Saunders, I., Brandt, M. B., & Molea, T. (2010). 1-D velocity model for use by the SANSN in earthquake location. Seismological Research Letters, 81(3), 460–466. https://doi.org/https://doi.org/10.1785/gssrl.81.3.460 DOI: https://doi.org/10.1785/gssrl.81.3.460
Midzi, Vunganai, Saunders, I., Manzunzu, B., Kwadiba, M., Jele, V., Mantsha, R., Marimira, K., Mulabisana, T., Ntibinyane, O., Pule, T., & others. (2018). The 03 April 2017 Botswana M6. 5 earthquake: preliminary results. Journal of African Earth Sciences, 143, 187–194. https://doi.org/https://doi.org/10.1016/j.jafrearsci.2018.03.027 DOI: https://doi.org/10.1016/j.jafrearsci.2018.03.027
Miller, R. M. (1983). The Pan-African Damara Orogen of South West Africa/Namibia. In Evolution of the Damara Orogen of South West Africa/Namibia. Geological Society of South Africa.
Minetto, R., Helmstetter, A., Schwartz, S., Langlais, M., Nomade, J., & Guéguen, P. (2022). Analysis of the spatiotemporal evolution of the Maurienne swarm (French Alps) based on earthquake clustering. Earth and Space Science, 9(7), e2021EA002097. https://doi.org/https://doi.org/10.1029/2021EA002097 DOI: https://doi.org/10.1029/2021EA002097
Mogi, K. (1963). Some discussions on aftershocks, foreshocks and earthquake swarms-the fracture of a semi finite body caused by an inner stress origin and its relation to the earthquake phenomena. Bull. Earthq. Res. Inst., 41, 615–658.
Mousavi, S. M., & Beroza, G. C. (2019). A Machine-Learning Approach for Earthquake Magnitude Estimation. Geophysical Research Letters. https://doi.org/https://doi.org/10.1029/2019GL085976 DOI: https://doi.org/10.1029/2019GL085976
Mousavi, S. M., Ellsworth, W. L., Zhu, W., Chuang, L. Y., & Beroza, G. C. (2020). Earthquake transformer—an attentive deep-learning model for simultaneous earthquake detection and phase picking. Nature Communications, 11(1), 1–12. https://doi.org/https://doi.org/10.1038/s41467-020-17591-w DOI: https://doi.org/10.1038/s41467-020-17591-w
Muir, R., Whitehead, B., New, T., Stevens, V., Macey, P., Groenewald, C., Salomon, G., Kahle, B., Hollingsworth, J., & Sloan, R. (2023). Exceptional scarp preservation in SW Namibia reveals geological controls on large magnitude intraplate seismicity in southern Africa. Tectonics, 42(4), e2022TC007693. https://doi.org/https://doi.org/10.1029/2022TC007693 DOI: https://doi.org/10.1029/2022TC007693
Münchmeyer, J. (2023). PyOcto: A high-throughput seismic phase associator. ArXiv Preprint ArXiv:2310.11157. DOI: https://doi.org/10.26443/seismica.v3i1.1130
Namibian Broadcasting Corporation. (2021). Anker residents share earthquake experiences. https://www.youtube.com/watch?v=JljzlbISNxE. https://www.youtube.com/watch?v=JljzlbISNxE
O’Connor, J. M., & Duncan, R. A. (1990a). Evolution of the Walvis Ridge-Rio Grande Rise hot spot system: Implications for African and South American plate motions over plumes. Journal of Geophysical Research: Solid Earth, 95(B11), 17475–17502. https://doi.org/https://doi.org/10.1029/JB095iB11p17475
O’Connor, J. M., & Duncan, R. A. (1990b). Evolution of the Walvis Ridge-Rio Grande Rise hot spot system: Implications for African and South American plate motions over plumes. Journal of Geophysical Research: Solid Earth, 95(B11), 17475–17502. https://doi.org/https://doi.org/10.1029/JB095iB11p17475 DOI: https://doi.org/10.1029/JB095iB11p17475
Omori, F. (1895). On the after-shocks of earthquakes [Phdthesis, The University of Tokyo]. https://doi.org/https://doi.org/10.15083/00037562
Parsons, T. (2002). Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock zone. Journal of Geophysical Research: Solid Earth, 107(B9), ESE-9. https://doi.org/https://doi.org/10.1029/2001JB000646 DOI: https://doi.org/10.1029/2001JB000646
Passchier, C., Trouw, R., Ribeiro, A., & Paciullo, F. (2002). Tectonic evolution of the southern Kaoko belt, Namibia. Journal of African Earth Sciences, 35(1), 61–75. https://doi.org/https://doi.org/10.1016/S0899-5362(02)00030-1 DOI: https://doi.org/10.1016/S0899-5362(02)00030-1
Petersen, G. M., Cesca, S., Heimann, S., Niemz, P., Dahm, T., Kühn, D., Kummerow, J., & Plenefisch, T. (2021). Regional centroid moment tensor inversion of small to moderate earthquakes in the Alps using the dense AlpArray seismic network: Challenges and seismotectonic insights. Solid Earth, 12, 1233–1257. https://doi.org/https://doi.org/10.5194/se-12-1233-2021 DOI: https://doi.org/10.5194/se-12-1233-2021
Pickford, M. (2023). The geology of the Kamanjab Inlier, northern Namibia. Memoir of the Geological Suvery of Namibia, 23, 1–136. https://doi.org/https://doi.org/10.1016/j.tecto.2009.03.006
Porada, H, Ahrendt, H., Behr, H.-J., & Weber, K. (1983). The join of the coastal and intracontinental branches of the Damara Orogen, Namibia, South West Africa. In Intracontinental fold belts (pp. 901–912). Springer. https://doi.org/https://doi.org/10.1007/978-3-642-69124-9_40 DOI: https://doi.org/10.1007/978-3-642-69124-9_40
Porada, Hubertus. (1979). The damara-ribeira orogen of the Pan-Africanbrasiliano cycle in Namibia (Southwest Africa) and Brazil as interpreted in terms of continental collision. Tectonophysics, 57(2–4), 237–265. https://doi.org/https://doi.org/10.1016/0040-1951(79)90150-1 DOI: https://doi.org/10.1016/0040-1951(79)90150-1
Prave, A. R. (1996). Tale of three cratons: Tectonostratigraphic anatomy of the Damara orogen in northwestern Namibia and the assembly of Gondwana. Geology, 24(12), 1115–1118. https://doi.org/https://doi.org/10.1130/0091-7613(1996)024%3C1115:TOTCTA%3E2.3.CO;2 DOI: https://doi.org/10.1130/0091-7613(1996)024<1115:TOTCTA>2.3.CO;2
Qin, Y., Chen, X., Carpenter, B. M., & Kolawole, F. (2018). Coulomb stress transfer influences fault reactivation in areas of wastewater injection. Geophysical Research Letters, 45(20), 11–059. DOI: https://doi.org/10.1029/2018GL079713
Raab, M. J., Brown, R. W., Gallagher, K., Carter, A., & Weber, K. (2002). Late Cretaceous reactivation of major crustal shear zones in northern Namibia: constraints from apatite fission track analysis. Tectonophysics, 349(1–4), 75–92. https://doi.org/https://doi.org/10.1016/S0040-1951(02)00047-1 DOI: https://doi.org/10.1016/S0040-1951(02)00047-1
Richter, C. F. (1935). An instrumental earthquake magnitude scale. Bulletin of the Seismological Society of America, 25(1), 1–32. https://doi.org/https://doi.org/10.1785/BSSA0250010001 DOI: https://doi.org/10.1785/BSSA0250010001
Rousseeuw, P. J. (1987). Silhouettes: a graphical aid to the interpretation and validation of cluster analysis. Journal of Computational and Applied Mathematics, 20, 53–65. https://doi.org/https://doi.org/10.1016/0377-0427(87)90125-7 DOI: https://doi.org/10.1016/0377-0427(87)90125-7
Salomon, G., New, T., Muir, R., Whitehead, B., Scheiber-Enslin, S., Smit, J., Stevens, V., Kahle, B., Kahle, R., Eckardt, F., & others. (2022). Geomorphological and geophysical analyses of the Hebron Fault, SW Namibia: implications for stable continental region seismic hazard. Geophysical Journal International, 229(1), 235–254. https://doi.org/https://doi.org/10.1093/gji/ggab466 DOI: https://doi.org/10.1093/gji/ggab466
Sandwell, D., Mellors, R., Tong, X., Wei, M., & Wessel, P. (2011a). GMTSAR: An InSAR processing system based on generic mapping tools [Techreport]. UC San Diego: Scripps Institution of Oceanography. https://escholarship.org/uc/item/8zq2c02m DOI: https://doi.org/10.2172/1090004
Sandwell, D., Mellors, R., Tong, X., Wei, M., & Wessel, P. (2011b). Open radar interferometry software for mapping surface deformation. Wiley Online Library. https://doi.org/https://doi.org/10.1029/2011EO280002 DOI: https://doi.org/10.1029/2011EO280002
Saunders, I., Ottemöller, L., Brandt, M. B., & Fourie, C. J. (2013). Calibration of an ML scale for South Africa using tectonic earthquake data recorded by the South African National Seismograph Network: 2006 to 2009. Journal of Seismology, 17, 437–451. https://doi.org/https://doi.org/10.1007/s10950-012-9329-0 DOI: https://doi.org/10.1007/s10950-012-9329-0
Schmidt, D. A., & Bürgmann, R. (2003). Time-dependent land uplift and subsidence in the Santa Clara valley, California, from a large interferometric synthetic aperture radar data set. Journal of Geophysical Research: Solid Earth, 108(B9). https://doi.org/https://doi.org/10.1029/2002JB002267 DOI: https://doi.org/10.1029/2002JB002267
Scholz, C. H., Tan, Y. J., & Albino, F. (2019). The mechanism of tidal triggering of earthquakes at mid-ocean ridges. Nature Communications, 10(1), 2526. DOI: https://doi.org/10.1038/s41467-019-10605-2
Sharma, S., Hainzl, S., Zöeller, G., & Holschneider, M. (2020). Is Coulomb stress the best choice for aftershock forecasting? Journal of Geophysical Research: Solid Earth, 125(9), e2020JB019553. https://doi.org/https://doi.org/10.1029/2020JB019553 DOI: https://doi.org/10.1029/2020JB019553
Shcherbakov, R., Turcotte, D. L., & Rundle, J. B. (2004). A generalized Omori’s law for earthquake aftershock decay. Geophysical Research Letters, 31(11). https://doi.org/https://doi.org/10.1029/2004GL019808 DOI: https://doi.org/10.1029/2004GL019808
Sitali, M., Manzunzu, B., Midzi, V., Shipena, S., & Lushetile, B. (2022). Seismotectonic analysis of the Anker area, Kunene region north-western Namibia. Journal of Seismology, 1–13. https://doi.org/https://doi.org/10.1007/s10950-022-10079-8 DOI: https://doi.org/10.1007/s10950-022-10079-8
Soetaert, F., Wanke, H., Dupuy, A., Lusuekikio, V., Gaucher, E. C., Bordmann, V., Fleury, J.-M., & Franceschi, M. (2022). Toward the sustainable use of groundwater springs: A case study from Namibia. Sustainability, 14(7), 3995. https://doi.org/https://doi.org/10.3390/su14073995 DOI: https://doi.org/10.3390/su14073995
Sracek, O., Wanke, H., Ndakunda, N., Mihaljevič, M., & Buzek, F. (2015). Geochemistry and fluoride levels of geothermal springs in Namibia. Journal of Geochemical Exploration, 148, 96–104. https://doi.org/https://doi.org/10.1016/j.gexplo.2014.08.012 DOI: https://doi.org/10.1016/j.gexplo.2014.08.012
Sumy, D. F., Cochran, E. S., Keranen, K. M., Wei, M., & Abers, G. A. (2014). Observations of static Coulomb stress triggering of the November 2011 M5. 7 Oklahoma earthquake sequence. Journal of Geophysical Research: Solid Earth, 119(3), 1904–1923. DOI: https://doi.org/10.1002/2013JB010612
Swart, R. (1992). The sedimentology of the Zerrissene turbidite system, Damara Orogen, Namibia. Commun. Geol. Surv. Namibia, 13, 57.
Sykes, L. R. (1970). Earthquake swarms and sea-floor spreading. Journal of Geophysical Research, 75(32), 6598–6611. DOI: https://doi.org/10.1029/JB075i032p06598
Sylvander, M., Chevrot, S., Ammirati, J.-B., Calassou, S., Collin, M., Diaz, J., Martakis, N., Polychronopoulou, K., & Villaseñor, A. (2023). Spatiotemporal behavior of an extremely small seismic swarm in Pyrenean Foreland, France. Bulletin of the Seismological Society of America, 113(5), 2041–2055. DOI: https://doi.org/10.1785/0120220263
Tong, X., & Schmidt, D. (2016). Active movement of the Cascade landslide complex in Washington from a coherence-based InSAR time series method. Remote Sensing of Environment, 186, 405–415. https://doi.org/10.1016/j.rse.2016.09.008 DOI: https://doi.org/10.1016/j.rse.2016.09.008
Trnkoczy, A. (2009). Understanding and parameter setting of STA/LTA trigger algorithm. In New manual of seismological observatory practice (NMSOP) (pp. 1–20). Deutsches GeoForschungsZentrum GFZ. https://gfzpublic.gfz-potsdam.de/rest/items/item_4097/component/file_4098/content
Trugman, D. T., & Shearer, P. M. (2017). GrowClust: A hierarchical clustering algorithm for relative earthquake relocation, with application to the Spanish Springs and Sheldon, Nevada, earthquake sequences. Seismological Research Letters, 88(2A), 379–391. https://doi.org/https://doi.org/10.1785/0220160188 DOI: https://doi.org/10.1785/0220160188
Tymofyeyeva, E., & Fialko, Y. (2015). Mitigation of atmospheric phase delays in InSAR data, with application to the eastern California shear zone. Journal of Geophysical Research: Solid Earth, 120(8), 5952–5963. https://doi.org/https://doi.org/10.1002/2015JB011886 DOI: https://doi.org/10.1002/2015JB011886
United States Geological Survey. (2021). M 5.4 - 68 km NNW of Khorixas, Namibia [Web Interface; Latest Earthquakes Database]. USGS National Earthquake Information Center. https://doi.org/https://doi.org/10.1144/gsjgs.154.3.0477
U.S. Geological Survey. (2024). Earthquake Lists, Maps, and Statistics. https://www.usgs.gov/natural-hazards/earthquake-hazards/lists-maps-and-statistics
Van Der Elst, N. J., Delorey, A. A., Shelly, D. R., & Johnson, P. A. (2016). Fortnightly modulation of San Andreas tremor and low-frequency earthquakes. Proceedings of the National Academy of Sciences, 113(31), 8601–8605. DOI: https://doi.org/10.1073/pnas.1524316113
Verdecchia, A., Onwuemeka, J., Liu, Y., & Harrington, R. M. (2022). Depth-Dependent Crustal Stress Rotation and Strength Variation in the Charlevoix Seismic Zone (CSZ), Québec, Canada. Geophysical Research Letters, 49(22), e2022GL100276. https://doi.org/https://doi.org/10.1029/2022GL100276 DOI: https://doi.org/10.1029/2022GL100276
Vidale, J. E., & Shearer, P. M. (2006). A survey of 71 earthquake bursts across southern California: Exploring the role of pore fluid pressure fluctuations and aseismic slip as drivers. Journal of Geophysical Research: Solid Earth, 111(B5). https://doi.org/https://doi.org/10.1029/2005JB004034 DOI: https://doi.org/10.1029/2005JB004034
Viola, G., Andreoli, M., Ben-Avraham, Z., Stengel, I., & Reshef, M. (2005). Offshore mud volcanoes and onland faulting in southwestern Africa: neotectonic implications and constraints on the regional stress field. Earth and Planetary Science Letters, 231(1–2), 147–160. https://doi.org/https://doi.org/10.1016/j.epsl.2004.12.001 DOI: https://doi.org/10.1016/j.epsl.2004.12.001
Waldhauser, F., & Ellsworth, W. L. (2000). A double-difference earthquake location algorithm: Method and application to the northern Hayward fault, California. Bulletin of the Seismological Society of America, 90(6), 1353–1368. https://doi.org/https://doi.org/10.1785/0120000006 DOI: https://doi.org/10.1785/0120000006
Wang, R. (1999). A simple orthonormalization method for stable and efficient computation of Green’s functions. Bulletin of the Seismological Society of America, 89(3), 733–741. https://doi.org/https://doi.org/10.1785/BSSA0890030733 DOI: https://doi.org/10.1785/BSSA0890030733
Wessel, P., Luis, J. F., Uieda, L., Scharroo, R., Wobbe, F., Smith, W. H. F., & Tian, D. (2019). The Generic Mapping Tools Version 6. Geochemistry, Geophysics, Geosystems, 20(11), 5556–5564. https://doi.org/10.1029/2019GC008515 DOI: https://doi.org/10.1029/2019GC008515
Weston, J., Ferreira, A. M., & Funning, G. J. (2012). Systematic comparisons of earthquake source models determined using InSAR and seismic data. Tectonophysics, 532, 61–81. https://doi.org/https://doi.org/10.1016/j.tecto.2012.02.001 DOI: https://doi.org/10.1016/j.tecto.2012.02.001
White, S., Stollhofen, H., Stanistreet, I. G., & Lorenz, V. (2009). Pleistocene to recent rejuvenation of the Hebron Fault, SW Namibia. Geological Society, London, Special Publications, 316(1), 293–317. https://doi.org/https://doi.org/10.1144/SP316.18 DOI: https://doi.org/10.1144/SP316.18
Xavier, C., & Reporter, S. (19 May, 2022). Anker school receives earthquake hostel blocks. New Era Newspaper. https://neweralive.na/os/posts/anker-school-receives-earthquake-hostel-blocks
Xiao, Z., Wang, J., Liu, C., Li, J., Zhao, L., & Yao, Z. (2021). Siamese earthquake transformer: A pair-input deep-learning model for earthquake detection and phase picking on a seismic array. Journal of Geophysical Research: Solid Earth, 126(5), e2020JB021444. https://doi.org/https://doi.org/10.1029/2020JB021444 DOI: https://doi.org/10.1029/2020JB021444
Xu, W., Dutta, R., & Jónsson, S. (2015). Identifying active faults by improving earthquake locations with InSAR data and Bayesian estimation: the 2004 Tabuk (Saudi Arabia) earthquake sequence. Bulletin of the Seismological Society of America, 105(2A), 765–775. https://doi.org/https://doi.org/10.1785/0120140289 DOI: https://doi.org/10.1785/0120140289
Xu, X., Sandwell, D. T., Tymofyeyeva, E., González-Ortega, A., & Tong, X. (2017). Tectonic and Anthropogenic Deformation at the Cerro Prieto Geothermal Step-Over Revealed by Sentinel-1A InSAR. IEEE Transactions on Geoscience and Remote Sensing, 55(9), 5284–5292. https://doi.org/https://doi.org/10.1109/TGRS.2017.2704593 DOI: https://doi.org/10.1109/TGRS.2017.2704593
Yamanaka, T., & Adachi, I. (2024). Hot springs reflect the flooding of slab-derived water as a trigger of earthquakes. Communications Earth & Environment, 5(1), 459. https://doi.org/ https://doi.org/10.1038/s43247-024-01606-1 DOI: https://doi.org/10.1038/s43247-024-01606-1
Yan, R., Chen, X., Sun, H., Xu, J., & Zhou, J. (2023). A review of tidal triggering of global earthquakes. Geodesy and Geodynamics, 14(1), 35–42. https://doi.org/https://doi.org/10.1016/j.geog.2022.06.005 DOI: https://doi.org/10.1016/j.geog.2022.06.005
Yan, X., Shi, Z., Zhou, P., Zhang, H., & Wang, G. (2020). Modeling earthquake-induced spring discharge and temperature changes in a fault zone hydrothermal system. Journal of Geophysical Research: Solid Earth, 125(7), e2020JB019344. https://doi.org/https://doi.org/10.1029/2020JB019344 DOI: https://doi.org/10.1029/2020JB019344
Yunjun, Z., Fattahi, H., Pi, X., Rosen, P., Simons, M., Agram, P., & Aoki, Y. (2022). Range geolocation accuracy of C-/L-band SAR and its implications for operational stack coregistration. IEEE Transactions on Geoscience and Remote Sensing, 60, 1–19. https://doi.org/https://doi.org/10.1109/TGRS.2022.3168509 DOI: https://doi.org/10.1109/TGRS.2022.3168509
(2021). Geological Survey of Namibia.
(2016–2021). Chamber of Mines Namibia.
(2000–2021). International Seismological Centre & World Data Center for Seismology, Denver.
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