Lake Turkana in northern Kenya is often called the cradle of humankind. Home to some of the earliest hominids, its fossil-rich basin has helped scientists piece together the story of human evolution. Now, researchers from Syracuse University and the University of Auckland are revealing that the lake's geologic history may be just as significant as its anthropological one.
Their findings, published in Scientific Reports, show that climate-driven changes in lake levels have influenced fault activity and magma production in the East African Rift Valley—challenging the long-held belief that continental rifting is governed solely by solid Earth processes.
"Continental break-up ('rifting') is generally thought of as a process fundamentally rooted in plate tectonics," explains Chris Scholz, professor of Earth sciences at Syracuse University and co-author of the study. "Our research shows that rifting is also shaped by surface processes, including regional climate."
Lead author James Muirhead, senior lecturer at the University of Auckland, emphasizes the study's implications for understanding human evolution. "This work reveals a complex environmental backdrop to the landscape occupied by early hominids, early modern humans and recent members of our species," says Muirhead, who conducted much of the research and analysis as a postdoctoral associate in Scholz's lab at Syracuse.
Climate and the Crust
Lake Turkana's formation is a story of tectonic forces, volcanic eruptions and climate shifts. Around 2.2–2.0 million years ago, volcanic activity blocked the basin's natural outlet, forming Lake Lorenyang, which eventually evolved into Lake Turkana. Over millennia, fluctuating climate patterns caused dramatic changes in lake levels—sometimes rising over 350 feet higher than today. These changes, the researchers found, had a profound effect on the Earth's crust.
"Water levels in Lake Turkana reflect regional 'hydroclimate', and during wetter intervals approximately 9,600-5,300 years ago the lake was hundreds of feet higher than today," Scholz explains. "We found that faults slipped faster and that more magma was produced under the regional volcanoes when the lake was lower."
According to Muirhead, this is because during drier periods with lower lake levels, less water weight presses down on the Earth's surface, reducing pressure in the crust. "These pressure changes lead to increased melting in hot regions deep in the Earth and also make faulting or earthquakes more likely to occur," he says.
Fieldwork in the Rift
Researchers in Syracuse's Department of Earth and Environmental Sciences (EES) conducted fieldwork in Turkana—an extremely challenging environment. "The conditions on Lake Turkana in the northern part of the Kenya Rift were among the most challenging our team has encountered anywhere in the world," says Scholz. "The lake is the largest in the world in a desert, is in one of the windiest places in Africa and is extremely remote."
The team transported their research vessels overland to Lake Turkana and carried out surveys and sampling with meticulous care, as there are no coast guard or marine rescue operations available on the lake. Despite the logistical hurdles, their efforts paid off: they successfully collected subsurface data across 27 faults below the lake. These high-resolution fault scans, Muirhead notes, provide "arguably the best estimates on fault activity rates over the past 10,000 years of any rift basin in the East African Rift System."
The data revealed that fault lines moved faster and more magma was produced during drier periods when lake levels were lower. This finding aligns with similar studies in places like Iceland and the western United States, where the loss of glacial ice weighing-down the earth's surface, has been linked to increased tectonic activity.
"What was surprising was just how much the rate of faulting can change due to just a few hundred meters of lake level change," Muirhead says. "This is likely because rock melting and the generation of magma below the rift further enhances the tectonic response to these lake level changes."
Consequences for Early Humans—and Us
The research offers a vivid glimpse into the environmental pressures faced by early human ancestors. During drier climate phases, they likely endured heightened volcanic and seismic activity, which reshaped landscapes and affected access to vital resources like food and water.
Today, the implications go well beyond anthropology. As climate change continues to alter hydrological systems, the study suggests that tectonic and volcanic activity could also be influenced—though such changes would unfold over geological spans.
"Climate change, whether human-induced or not, will likely impact the probability of future volcanic and tectonic activity in East Africa," Muirhead explains. "However, these changes occur over geological rather than human timescales, so their effects would be subtle and largely imperceptible within a single lifetime or even across generations."
In the near term, climate projections for Lake Turkana show a dramatic shift from earlier expectations. Rather than shrinking, models now suggest the lake could rise over the next two decades due to increased rainfall in its river inflows—raising the risk of flooding. These changes in water levels, whether through natural events or human-driven water resource development, could also influence crustal pressure dynamics.
A New Framework for Hazard Assessment
The findings contribute to a growing body of evidence supporting an Earth Systems view of plate tectonics—one that integrates atmospheric and hydrospheric influences, not just those below the surface.
"We are heading towards a more holistic understanding of the processes that drive plate tectonics," Muirhead says, "and also recognizing the role of plate tectonics in controlling long-term climate and its impact on the evolutionary trajectory of life on our planet."
This shift in perspective has real-world implications for hazard assessment and policy. Fault lines in continental rift zones may behave differently depending on the climate state they are experiencing. Muirhead believes that future assessments must account for these variables.
"If I were doing a hazard assessment for a fault line in a continental rift like Turkana," he says, "I would need to consider how its rate of activity, and resulting likelihood of an earthquake, is affected by the current climate state and associated lake water volumes."
Building a Safer Future
By revealing the deep connections between climate and tectonic activity, the team's research is helping to reshape how scientists—and policymakers—think about Earth's dynamic systems. As climate change continues to unfold, understanding these connections will be critical for building resilient communities and preparing for the geologic challenges of tomorrow.
