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7. All scales must be considered to understand rifts

Author

Ebinger, Cynthia J, van Wijk, Jolante, Olaka, Lydia, Mériaux, Catherine, Fontijn, Karen, Ebinger, Cynthia J, van Wijk, Jolante, Olaka, Lydia, Mériaux, Catherine, and Fontijn, Karen

Abstract

SCOPUS: no.j, info:eu-repo/semantics/published

Published
2023

13. The impact of complex volcanic plumbing on the nature of seismicity in the developing magmatic Natron rift, Tanzania

Author

Reiss, Miriam Christina, Muirhead, James D., Laizer, Amani S., Link, Frederik, Kazimoto, Emmanuel Owden, Ebinger, Cynthia J., Rümpker, Georg, Reiss, Miriam Christina, Muirhead, James D., Laizer, Amani S., Link, Frederik, Kazimoto, Emmanuel Owden, Ebinger, Cynthia J., and Rümpker, Georg

Abstract

Constraining the architecture of complex 3D volcanic plumbing systems within active rifts, and their impact on rift processes, is critical for examining the interplay between faulting, magmatism and magmatic fluids in developing rift segments. The Natron basin of the East African Rift System provides an ideal location to study these processes, owing to its recent magmatic-tectonic activity and ongoing active carbonatite volcanism at Oldoinyo Lengai. Here, we report seismicity and fault plane solutions from a 10-month temporary seismic network spanning Oldoinyo Lengai, Naibor Soito volcanic field and Gelai volcano. We locate 6827 earthquakes with ML -0.85 to 3.6, which are related to previous and ongoing magmatic and volcanic activity in the region, as well as regional tectonic extension. We observe seismicity down to ~17 km depth north and south of Oldoinyo Lengai and shallow seismicity (3 - 10 km) beneath Gelai, including two swarms. The deepest seismicity (~down to 20 km) occurs above a previously imaged magma body below Naibor Soito. These seismicity patterns reveal a detailed image of a complex volcanic plumbing system, supporting potential lateral and vertical connections between shallow- and deep-seated magmas, where fluid and melt transport to the surface is facilitated by intrusion of dikes and sills. Focal mechanisms vary spatially. T-axis trends reveal dominantly WNW-ESE extension near Gelai, while strike-slip mechanisms and a radial trend in P-axes are observed in the vicinity of Oldoinyo Lengai. These data support local variations in the state of stress, resulting from a combination of volcanic edifice loading and magma-driven stress changes imposed on a regional extensional stress field. Our results indicate that the southern Natron basin is a segmented rift system, in which fluids preferentially percolate vertically and laterally in a region where strain transfers from a border fault to a developing magmatic rift segment.

Published
2021

18. Volcanic Rifted Margins

Author

Menzies, Martin A., primary, Klemperer, Simon L., additional, Ebinger, Cynthia J., additional, and Baker, Joel, additional

Published
2002
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19. ICDP workshop on the Lake Tanganyika Scientific Drilling Project: A late Miocene-present record of climate, rifting, and ecosystem evolution from the world's oldest tropical lake

Author

Russell, James, Barker, P A, Cohen, Andrew S, Ivory, Sarah J, Kimirei, I A, Lane, Christine S, Leng, Melanie J., Maganza, Neema, McGlue, Michael Matthew, Msaky, Emma S, Noren, Anders J, Boush, Lisa Park, Salzburger, Walter, Scholz, Christopher A, Tiedemann, Ralph, Nuru, Shaidu, Albrecht, Christian, Ali, Rahma, Arrowsmith, Ramón Ja, Asanga, Danstan, Asmerom, Yemane, Bakundukize, Charles, Bauersachs, Thorsten, Beck, Catherine C, Berke, Melissa A, Beverley, Emily, Blaauw, Martin, Brown, Erik T, Campisano, Christopher J, Carrapa, Bárbara, Castaûeda, Isla, Dee, Sylvia G, Deino, Alan L, Ebinger, Cynthia J, Ellis, Geoffrey S, Foerster, Verena E, Fontijn, Karen, Gehrels, George E, Indemaur, Adrian, Jovanovska, Elena, Junginger, Annett, Kaboth, Stefanie, Kallmeyer, Jens, King, John W, Konecky, Bronwen L, Mark, Darren F, McIntyre, Peter B, Michel, Ellinor, Mkuu, Doreen, Morgan, Leah, Mtetela, Cassy, Muderwha, Nshombo, Muirhead, James D, Mumbi, Cassian T, Muschick, Mo, Nahimana, David, Ngowi, Venosa, Njiko, Pashcal, Nkenyeli, Simon, Nkotagu, Hudson H, Ntakimazi, Gaspard, Oppo, Davide, Purkamo, Lotta, Rick, Jessica A, Roberts, Helen M, Ronco, Fabrizia, Sangweni, Charles, Shaghude, Yohanna W, Shigela, Josephat, Shillington, Donna J, Sophia, Chen Shuang, Sier, Mark Jan, Soreghan, Michael James, Spanbauer, Trisha L, Spencer-Jones, Charlotte L, Staff, Richard A, Stone, Jeffery R, Todd, Jonathan A, Trauth, Martin H, Van Bocxlaer, Bert, Viehberg, Finn A, Vogel, Hendrik, Vonhof, Hubert, Wolff, Christian, Wu, Qinglong, Yost, Chad L, Zeeden, Christian, Russell, James, Barker, P A, Cohen, Andrew S, Ivory, Sarah J, Kimirei, I A, Lane, Christine S, Leng, Melanie J., Maganza, Neema, McGlue, Michael Matthew, Msaky, Emma S, Noren, Anders J, Boush, Lisa Park, Salzburger, Walter, Scholz, Christopher A, Tiedemann, Ralph, Nuru, Shaidu, Albrecht, Christian, Ali, Rahma, Arrowsmith, Ramón Ja, Asanga, Danstan, Asmerom, Yemane, Bakundukize, Charles, Bauersachs, Thorsten, Beck, Catherine C, Berke, Melissa A, Beverley, Emily, Blaauw, Martin, Brown, Erik T, Campisano, Christopher J, Carrapa, Bárbara, Castaûeda, Isla, Dee, Sylvia G, Deino, Alan L, Ebinger, Cynthia J, Ellis, Geoffrey S, Foerster, Verena E, Fontijn, Karen, Gehrels, George E, Indemaur, Adrian, Jovanovska, Elena, Junginger, Annett, Kaboth, Stefanie, Kallmeyer, Jens, King, John W, Konecky, Bronwen L, Mark, Darren F, McIntyre, Peter B, Michel, Ellinor, Mkuu, Doreen, Morgan, Leah, Mtetela, Cassy, Muderwha, Nshombo, Muirhead, James D, Mumbi, Cassian T, Muschick, Mo, Nahimana, David, Ngowi, Venosa, Njiko, Pashcal, Nkenyeli, Simon, Nkotagu, Hudson H, Ntakimazi, Gaspard, Oppo, Davide, Purkamo, Lotta, Rick, Jessica A, Roberts, Helen M, Ronco, Fabrizia, Sangweni, Charles, Shaghude, Yohanna W, Shigela, Josephat, Shillington, Donna J, Sophia, Chen Shuang, Sier, Mark Jan, Soreghan, Michael James, Spanbauer, Trisha L, Spencer-Jones, Charlotte L, Staff, Richard A, Stone, Jeffery R, Todd, Jonathan A, Trauth, Martin H, Van Bocxlaer, Bert, Viehberg, Finn A, Vogel, Hendrik, Vonhof, Hubert, Wolff, Christian, Wu, Qinglong, Yost, Chad L, and Zeeden, Christian

Abstract

The Neogene and Quaternary are characterized by enormous changes in global climate and environments, including global cooling and the establishment of northern high-latitude glaciers. These changes reshaped global ecosystems, including the emergence of tropical dry forests and savannahs that are found in Africa today, which in turn may have influenced the evolution of humans and their ancestors. However, despite decades of research we lack long, continuous, well-resolved records of tropical climate, ecosystem changes, and surface processes necessary to understand their interactions and influences on evolutionary processes. Lake Tanganyika, Africa, contains the most continuous, long continental climate record from the mid-Miocene (∼ 10 Ma) to the present anywhere in the tropics and has long been recognized as a top-priority site for scientific drilling. The lake is surrounded by the Miombo woodlands, part of the largest dry tropical biome on Earth. Lake Tanganyika also harbors incredibly diverse endemic biota and an entirely unexplored deep microbial biosphere, and it provides textbook examples of rift segmentation, fault behavior, and associated surface processes. To evaluate the interdisciplinary scientific opportunities that an ICDP drilling program at Lake Tanganyika could offer, more than 70 scientists representing 12 countries and a variety of scientific disciplines met in Dar es Salaam, Tanzania, in June 2019. The team developed key research objectives in basin evolution, source-to-sink sedimentology, organismal evolution, geomicrobiology, paleoclimatology, paleolimnology, terrestrial paleoecology, paleoanthropology, and geochronology to be addressed through scientific drilling on Lake Tanganyika. They also identified drilling targets and strategies, logistical challenges, and education and capacity building programs to be carried out through the project. Participants concluded that a drilling program at Lake Tanganyika would produce the first continuous Mioce, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2020

20. Rescuing Legacy Seismic Data FAIR’ly

Author

Hwang, Lorraine J., primary, Ahern, Tim, primary, Ebinger, Cynthia J., primary, Ellsworth, William L., primary, Euler, Garrett G., primary, Okal, Emile A., primary, Okubo, Paul G., primary, and Walter, William R., primary

Published
2020
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23. Initial Cenozoic magmatic activity in East Africa: new geochemical constraints on magma distribution within the Eocene continental flood basalt province

Author

Steiner, R. Alex, Rooney, Tyrone O., Girard, Guillaume, Rogers, Nick, Ebinger, Cynthia J., Peterson, Liam, and Phillips, Rayn K.

Abstract

The initial interaction between material rising from the African Large Low Shear Velocity Province and the African lithosphere manifests as the Eocene continental large igneous province (LIP), centred on southern Ethiopia and northern Kenya. Here we present a geographically well-distributed geochemical dataset comprising flood basalt lavas of the Eocene continental LIP to refine the regional volcano-stratigraphy into three distinct magmatic units: (1) the highly alkaline small-volume Akobo Basalt (49.4–46.6 Ma), representing the initial phase of flood basalt volcanism derived from the melting of lithospheric–mantle metasomes; (2) the primitive and spatially restricted Amaro Basalt (45.2–39.8 Ma), representing the early main phase of flood basalt volcanism derived from the melting of the upwelling thermochemical anomaly; and (3) the spatially extensive Gamo–Makonnen magmatic unit (38–28 Ma), representing the mature main phase of flood basalt volcanism that has undergone significant processing within the lithosphere and resulted in relatively homogeneous compositions. The focused intrusion of these main phase magmas over 10 myr preconditioned the African lithosphere for the localization of strain during subsequent episodes of lithospheric stretching. The focusing of strain into the region occupied by this continental LIP may have contributed to the initial extension in SW Ethiopia that is associated with the East African Rift.

Published
2022
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24. Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa

Author

Grijalva, Ashley, primary, Nyblade, Andrew A., additional, Homman, Kyle, additional, Accardo, Natalie J., additional, Gaherty, James B., additional, Ebinger, Cynthia J., additional, Shillington, Donna J., additional, Chindandali, Patrick R. N., additional, Mbogoni, Gabriel, additional, Ferdinand, Richard Wambura, additional, Mulibo, Gabriel, additional, O'Donnell, J. P., additional, Kachingwe, Marsella, additional, and Tepp, Gabrielle, additional

Published
2018
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25. Crustal structure surrounding the northern Malawi rift and beneath the Rungwe Volcanic Province, East Africa

Author

Borrego, David, primary, Nyblade, Andrew A, additional, Accardo, Natalie J, additional, Gaherty, James B, additional, Ebinger, Cynthia J, additional, Shillington, Donna J, additional, Chindandali, Patrick RN, additional, Mbogoni, Gabriel, additional, Ferdinand, Richard Wambura, additional, Mulibo, Gabriel, additional, O'Donnell, JP, additional, Kachingwe, Marsella, additional, and Tepp, Gabrielle, additional

Published
2018
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31. Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift

Author

Shillington, Donna J., primary, Gaherty, James B., additional, Ebinger, Cynthia J., additional, Scholz, Christopher A., additional, Selway, Kate, additional, Nyblade, Andrew A., additional, Bedrosian, Paul A., additional, Class, Cornelia, additional, Nooner, Scott L., additional, Pritchard, Matthew E., additional, Elliott, Julie, additional, Chindandali, Patrick R. N., additional, Mbogoni, Gaby, additional, Ferdinand, Richard Wambura, additional, Boniface, Nelson, additional, Manya, Shukrani, additional, Kamihanda, Godson, additional, Saria, Elifuraha, additional, Mulibo, Gabriel, additional, Salima, Jalf, additional, Mruma, Abdul, additional, Kalindekafe, Leonard, additional, Accardo, Natalie J., additional, Ntambila, Daud, additional, Kachingwe, Marsella, additional, Mesko, Gary T., additional, McCartney, Tannis, additional, Maquay, Melania, additional, O’Donnell, J. P., additional, Tepp, Gabrielle, additional, Mtelela, Khalfan, additional, Trinhammer, Per, additional, Wood, Douglas, additional, Aaron, Ernest, additional, Gibaud, Mark, additional, Rapa, Martin, additional, Pfeifer, Cathy, additional, Mphepo, Felix, additional, Gondwe, Duncan, additional, Arroyo, Gabriella, additional, Eddy, Celia, additional, Kamoga, Brian, additional, and Moshi, Mary, additional

Published
2016
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40. Evolution of the Kivu Rift, East Africa: interplay among tectonics, sedimentation and magmatism.

Author

Wood, Douglas A., Zal, Hubert J., Scholz, Christopher A., Ebinger, Cynthia J., and Nizere, Irénée

Subjects
RIFTS (Geology), PLATE tectonics, SEDIMENTATION & deposition, MAGMATISM, TOPOGRAPHY
Abstract

The seismically and volcanically active Kivu Rift, in the western branch of the East African Rift System, is a type locale for studies of high-elevation, humid-climate rift basins, as well as magmatic basin development. Interpretations of offshore multi-channel seismic ( MCS) reflection data, terrestrial radar topography, lake bathymetry and seismicity data recorded on a temporary array provide new insights into the structure, stratigraphy and evolution of the Kivu rift. The Kivu rift is an asymmetric graben controlled on its west side by a ca. 110 km-long, N-S striking border fault. The southern basins of the lake and the upper Rusizi river basin are an accommodation zone effectively linking 1470 m-high Lake Kivu to 770 m-high Lake Tanganyika. MCS data in the eastern Kivu lake basin reveal a west-dipping half graben with at least 1.5 km of sedimentary section; most of the ca. 2 km of extension in this sub-basin is accommodated by the east-dipping Iwawa normal fault, which bounds an intrabasinal horst. Lake Kivu experienced at least three periods of near desiccation. The two most recent of these approximately correlate to the African Megadrought and Last Glacial Maximum. There was a rapid lake level transgression of at least 400 m in the early Holocene. The line load of the Virunga volcanic chain enhances the fault-controlled basin subsidence; simple elastic plate models suggest that the line load of the Virunga volcanic chain depresses the basin by more than 1 km, reduces flank uplift locally and broadens the depocentre. Not only do the voluminous magmatism and degassing to the lake pose a hazard to the riparian population, but our studies demonstrate that magmatism has important implications for short-term processes such as lake levels, inflow and outlets, as well as long term modification of classic half-graben basin morphology. [ABSTRACT FROM AUTHOR]

Published
2017
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43. A kinematic model for the East African Rift

Author

Stamps, D. Sarah, primary, Calais, Eric, additional, Saria, Elifuraha, additional, Hartnady, Chris, additional, Nocquet, Jean-Mathieu, additional, Ebinger, Cynthia J., additional, and Fernandes, Rui M., additional

Published
2008
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45. Seismicity of the central Afar rift and implications for Tendaho dam hazards

Author

Ayele, Atalay, Ebinger, Cynthia J., van Alstyne, Carolyn, Keir, Derek, Nixon, Casey W., Belachew, Manahloh, and Hammond, James O. S.

Abstract

Temporary broadband seismic networks deployed from 2007 to 2011 around the Afar triple junction of the East African Rift System provide insights into seismicity patterns of the actively deforming crust around the 1.86 km3impounded lake system behind the Tendaho dam. The observed seismicity correlates well with the active magmatic centres around central Afar. The area around the dam site is characterized by a network of intersecting NNE- and NW-trending faults. Seismicity clusters observed in the specified time interval indicate that both fault sets are active and are potential sources of seismogenic hazards. The dam neighbourhood is naturally active and it is a challenge to associate the observed seismic activity to either a change in magmato-tectonic conditions or attribute it to the influence of reservoir load. It is evident that the dam region experiences high levels of seismic and volcano-tectonic unrest, regardless of the origin of the activity. The spatial overlap of narrow zones of crustal seismicity and upper mantle low velocity zones observed in S-wave tomography models suggests that melt production zones guide the distribution of strain during continental rupture. Given its volcanically and seismically active setting, the Tendaho dam site and the surrounding region require continuous monitoring for the safety of downstream populations and development infrastructures in the Afar National Regional State of Ethiopia.

Published
2016
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47. Low-Frequency Hybrid Earthquakes near a Magma Chamber in Afar: Quantifying Path Effects.

Author

Coté, Dustin M., Belachew, Manahloh, Quillen, Alice C., Ebinger, Cynthia J., Keir, Derek, Ayele, Atalay, and Wright, Tim

Subjects
EARTHQUAKES, SEISMIC event location, IGNEOUS intrusions, MAGMAS, VOLCANIC eruptions
Abstract

Areas of active volcanism contain elaborate velocity structures that complicate interpretations of earthquake source mechanisms. We examine the spectral characteristics of 805 earthquakes that immediately followed a large volume basaltic dike intrusion and associated silicic flank eruption of Dabbahu volcano in the Afar Depression as recorded on near-source seismometers. We use these results to quantify the contribution of scattering and attenuation to the observed spectra of low-frequency hybrid and volcano-tectonic earthquake clusters from beneath Dabbahu volcano and around the dike zone. We find strong variations in the signal amplitude and frequency content of earthquakes recorded at stations separated by as little as 2 km, caused by preferential attenuation of high frequencies depending on the vantage point. These observations imply that there are large impedance contrasts near the cooling, solidifying, and recently intruded dike. We estimate the intrinsic absorption attenuation coefficient, Q1, and inverse scattering length, 90, averaged over a 300-sq-km area beneath Dabbahu. Our results are consistent with the highest attenuation coefficients from studies of volcanic provinces in Italy (Q-1I ≈~ 0.02, g0 ≈ 0.1 km-1 for a signal at 2 Hz). The magnitude of these two parameters indicates there are large impedance contrasts present in the area due to the recent intrusion of magma and associated fracturing. [ABSTRACT FROM AUTHOR]

Published
2010
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49. Geometric and kinematic development of border faults and accommodation zones, Kivu-Rusizi Rift, Africa.

Author

Ebinger, Cynthia J.

Abstract

Three representative basins in the Western rift system of East Africa are bordered along one side by high-angle normal faults with 2- to 5-km throws (border faults). In plan view ∼100-km-long systems of linear border faults form curvilinear border fault segments bounding the East Kivu, West Kivu, and Rusizi basins. The opposite sides of these asymmetric basins are bounded by lower relief faulted monoclines or en echelon ramps. The largely unfaulted rift flanks have been uplifted 2 km above the 1.3-km-high East African plateau, with uplift narrowing basins during Quaternary time. Maximum estimates of ∼E-W crustal extension within basins are less than 25% (< 16 km), and planar border faults may penetrate the crust. The East Kivu and West Kivu basins are linked across the rift valley by a horst that serves as a hinge for subsidence in both basins. The westward tilted East Kivu and eastward tilted Rusizi border fault segments are linked along the rift by oblique-slip transfer faults that also accommodate along-axis differences in elevation. Upper Miocene-Recent eruptive volcanic centers within the comparatively high-strain interbasinal region (accommodation zone) generally coincide with the tips of border fault segments and transfer faults. The orientations of Miocene-Recent dip-slip and oblique-slip faults show little correlation with Precambrian shear zones or foliations in metamorphic basement. Differences between the East Kivu, West Kivu, and Rusizi basins in the age of initial faulting, subsidence, and age/composition of volcanic products suggest that border fault segments developed diachronously and propagated along the length of the rift. This along-axis border fault propagation and the crosscutting geometry of transfer faults contribute to the segmentation of the Western rift valley. [ABSTRACT FROM AUTHOR]

Published
1989
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