Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa

C. J. Ebinger, Sarah Jaye Oliva, Thi Quan Pham, Katherine Peterson, Patrick Chindandali, Finnigan Illsley-Kemp, Connor Drooff, Donna J. Shillington, Natalie J. Accardo, Ryan J. Gallacher, J. Gaherty, Andrew Arnold Nyblade, Gabriel Mulibo

Research output: Contribution to journalArticle

Abstract

Although the deep, wide basins of the Western rift, Africa, have served as analogues for the evolution of half-graben basins, the geometry and kinematics of the border, intrabasinal, and transfer fault systems have been weakly constrained. Despite the >100-km-long fault systems bounding basins, little was known of seismicity patterns or the potential for M > 7.5 earthquakes. Using our new local earthquake database from the 2013-2015 Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) seismic array (57 onshore, 32 lake-bottom stations) and TANGA14 (13 stations), we examine the kinematics and extension direction of the Rungwe Volcanic Province and northern Malawi rift. We relocated earthquakes using a new 1-D velocity model and both absolute and double-difference relocation methods. Local magnitudes of 1,178 earthquakes within the array are 0.7 < ML < 5.2 with a b-value 0.77 ± 0.03, and magnitude of completeness ML 1.9. Focal mechanism solutions for 63 earthquakes reveal predominantly normal and oblique-slip motion, and full moment tensor solutions for ML 4.5, 5.2 earthquakes have centroid depths within 2 km of catalog depths. The preferred nodal planes dip more than 40° from surface to >25-km depths. Extension direction from local earthquakes and source mechanisms of teleseismically detected earthquakes are approximately N58°E and N65°E, respectively, refuting earlier interpretations of a NW-SE transform fault system. The low b-value indicating strong coupling across crustal-scale border faults, border fault lengths >100 km, and evidence for aseismic deformation together indicate that infrequent M > 7.5 earthquakes are possible within this cratonic rift system.

Original languageEnglish (US)
Pages (from-to)3928-3951
Number of pages24
JournalGeochemistry, Geophysics, Geosystems
Volume20
Issue number8
DOIs
StatePublished - Aug 1 2019

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Malawi
volcanology
Earthquakes
Kinematics
kinematics
earthquakes
earthquake
borders
Transform faults
stations
basin
Tanzania
relocation
Relocation
transform fault
Africa
province
lakes
graben
Lakes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

Ebinger, C. J., Oliva, S. J., Pham, T. Q., Peterson, K., Chindandali, P., Illsley-Kemp, F., ... Mulibo, G. (2019). Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa. Geochemistry, Geophysics, Geosystems, 20(8), 3928-3951. https://doi.org/10.1029/2019GC008354
Ebinger, C. J. ; Oliva, Sarah Jaye ; Pham, Thi Quan ; Peterson, Katherine ; Chindandali, Patrick ; Illsley-Kemp, Finnigan ; Drooff, Connor ; Shillington, Donna J. ; Accardo, Natalie J. ; Gallacher, Ryan J. ; Gaherty, J. ; Nyblade, Andrew Arnold ; Mulibo, Gabriel. / Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa. In: Geochemistry, Geophysics, Geosystems. 2019 ; Vol. 20, No. 8. pp. 3928-3951.
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Ebinger, CJ, Oliva, SJ, Pham, TQ, Peterson, K, Chindandali, P, Illsley-Kemp, F, Drooff, C, Shillington, DJ, Accardo, NJ, Gallacher, RJ, Gaherty, J, Nyblade, AA & Mulibo, G 2019, 'Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa', Geochemistry, Geophysics, Geosystems, vol. 20, no. 8, pp. 3928-3951. https://doi.org/10.1029/2019GC008354

Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa. / Ebinger, C. J.; Oliva, Sarah Jaye; Pham, Thi Quan; Peterson, Katherine; Chindandali, Patrick; Illsley-Kemp, Finnigan; Drooff, Connor; Shillington, Donna J.; Accardo, Natalie J.; Gallacher, Ryan J.; Gaherty, J.; Nyblade, Andrew Arnold; Mulibo, Gabriel.

In: Geochemistry, Geophysics, Geosystems, Vol. 20, No. 8, 01.08.2019, p. 3928-3951.

Research output: Contribution to journalArticle

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AU - Mulibo, Gabriel

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Ebinger CJ, Oliva SJ, Pham TQ, Peterson K, Chindandali P, Illsley-Kemp F et al. Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa. Geochemistry, Geophysics, Geosystems. 2019 Aug 1;20(8):3928-3951. https://doi.org/10.1029/2019GC008354