Tectonic Influence on Ecosystem Dynamics in the Kenya Rift and Tanzanian Craton

Whilst earthquakes cause destruction, the faults along which they occur are responsible for building varied landscapes and influencing ecosystems by controlling topography, hydrology, soil properties, and vegetation patterns. Faulting acts as both a water conduit and a hydrological barrier, channeling groundwater and creating localized zones of moisture retention. Surface faulting and the resulting topographic complexity contribute to heterogeneous vegetation patterns, with denser vegetation often developing along steep fault escarpments where grazing and agricultural activities are limited. Erosion along fault scarps enriches soils with nutrients and clays, supporting vegetation growth, while also posing risks such as the release of harmful substances like fluoride and arsenic, especially in geothermal regions.

We carry out a broad interdisciplinary study within the East African Rift System to explore the connections between tectonic processes and ecosystem dynamics. By combining geomorphological analysis, soil and geochemical studies, and remote sensing techniques, we investigate how faulting shapes soil fertility, hydrology, and vegetation patterns in these regions. Here, we focus on three illustrative case studies: the southern and central Kenyan Rifts and the Serengeti-Mara ecosystem.

In the southern Kenya Rift, fault-driven erosion and volcanic ash deposition around Lake Magadi enhance soil fertility, sustaining vegetation in this climatically vulnerable area. In contrast, uplifted footwalls and eroded substrates exhibit nutrient deficiencies, limiting ecological productivity. In the central Kenya Rift, near Lake Nakuru, elevated fluoride levels in ground- and surface water are among the highest globally and pose significant health risks to humans and animals. Fluoride concentrations are driven by the naturally high fluoride content in trachytic pyroclastics, which leach into the hydrological system through geothermal activity along active normal faults.

The Serengeti-Mara ecosystem is largely situated on the ancient continental crust of the Tanzanian Craton, where fault activity in the northern and southeastern sectors locally enhances soil moisture and vegetation stability. These tectonically influenced areas provide fertile hotspots within a landscape otherwise characterized by highly dynamic seasonal vegetation patterns. This patchy nutrient distribution is crucial for grazing animals, whose migrations are shaped by the shifting availability of fertile areas, driving ecological connectivity and long-term resource distribution.

Our studies highlight the dual role of fault activity in sustaining biodiversity while presenting challenges through earthquake activity and the release of potentially harmful elements. These findings contribute to a broader understanding of the interplay between geological processes and ecological resilience in tectonically active landscapes.