Student Short Biography:
Mr. Benson Nyamboga Onguso is a geologist who believes that geology should have a human face and impact positively in societal needs. He specializes in seismology techniques that guide in to discovery of natural resources like petroleum apart from monitoring hazards, and has expertise in 3D refraction and reflection seismic modeling. Awarded the University of Nairobi Masters Scholarship 2011/2012 academic year, Mr. Onguso is currently working on research work, 3D volume (Voxel) rendering in seismology and short term crustal structure evolution studies on subsurface earthquake precursors’ delineation and characterization, to be published late 2021 or early 2022. He holds a geology degree from the University of Nairobi, where he is to earn a Master of Science degree in the field of geology on 25th September 2020.
Project Summary
Thesis / Project Title: Crustal Structure Evolution in Magadi Area, Kenya, Using 3D Seismic Tomography
Thesis / Project Abstract:
3D seismic tomography model illustrated in form of 2D slices has been generated. Updated seismicity map for southern Kenya has been generated by location and relocation using tomo3d software of 1997-1998 seismic data and integration of crafti 2013-2014 seismic data sub-set. 3D model shows one high absolute velocity intrusive body within Magadi crust, 35.60 E to 36.20 E, 2.10 S to 1.70 S and depths of about 0 to 15 kilometers. Similarly, Roecker work has three high absolute velocity intrusive bodies and in contrast has about six small oval shaped pockets of low absolute velocity anomalies which possibly could represent small magma injections into country rocks from upper mantle repository. Surrounding high velocity zones, region with relatively constant absolute velocity which increases with depth is evident. This change in velocity with depth in this zone is thought to be associated with poor ray-paths coverage. It is evident that there exist high absolute velocity zones within Magadi through which small pockets of magma have intruded forming small hot magma chambers. These small magma chambers are fed by deep seated magma repository chamber. This repository chamber is located at bottom of Magadi crust. It extends to top of mantle layer. This supports fact that Magadi is undergoing continuous crustal structure changes through magmatic-tectonic movements. Faulting process occurring in this area has played key role in forming conduits through which magma moves upwards through Magadi crust. This study confirms continuous small crustal structure changes of Magadi basin through small magmatic intrusion and tectonism.