We tend to think earthquakes are predominantly driven by deep-Earth forces. But in Kenya’s Lake Turkana Rift, researchers recently found that as surface water levels dropped roughly 100 to 150 meters (328 to 492 ft), fault activity accelerated and increased magma flux. The discovery reshapes long-held assumptions about what drives tectonic change. If lake-level fluctuations can stir the shallow crust, then our climate’s past and future may matter more than we realize.
In northern Kenya’s remote Turkana Basin, where a fractured landscape stretches across an ancient rift, geologists have uncovered a surprising factor driving earthquake activity. A new study from Syracuse University and the University of Auckland found that climate-driven drops in Lake Turkana’s water levels were associated with increased fault activity in the East African Rift Valley and influenced magma upwelling beneath the crust.
For decades, tectonic activity has been understood as a deep-Earth process, mostly driven by forces like mantle convection, plate motion, and crustal deformation. Surface changes, especially those tied to climate, have rarely been considered significant enough to affect fault behavior.
The Lake Turkana study not only challenges that assumption, but suggests that activity on the Earth’s surface and climate history can play a more active role in shaping tectonic motion than previously thought.
To better understand this connection between shifting water levels and tectonic behavior, the research team combined paleoclimate data with geophysical modeling. They reconstructed Lake Turkana’s water level changes over the past 20,000 years and compared those shifts to patterns in fault slip and magma flux below the crust.
The results showed that as lake levels dropped, the reduced load on the crust allowed faults to slip more easily and supported increased melt production. The data revealed that when lake levels were lower during drier periods, fault lines moved faster and magma flux was higher.
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. Taken together, these parallels widen the frame. They point to a deeper link between changes on the surface and the movement of faults and magma below.
These results not only broaden our understanding of what drives tectonic activity, they show that climate and surface-water changes can actively shape how faults behave over time. And if large drops in lake or reservoir levels can shift the crust in a region as active as the East African Rift, it may be that similar processes are at work elsewhere.
This change in perspective could redefine how scientists evaluate earthquake hazards, especially in places facing rapid climate change or human-driven water fluctuations. It also raises questions about the past. This same rift zone played a central role in human evolution, and shifts in volcanic and tectonic activity could have influenced the landscapes where early humans lived.
In the near term, climate projections for Lake Turkana have shifted. Instead of shrinking, recent models suggest the lake could rise over the next two decades due to increased rainfall in its river inflows, raising the risk of flooding. These fluctuations in water levels, whether driven by climate shifts or changes in water use, could also influence crustal pressure dynamics.
“Climate change, whether human-induced or not, will likely impact the probability of future volcanic and tectonic activity in East Africa,” explains James Muirhead, lead researcher on the project. “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.”
Muirhead’s comment suggests the need for a more integrated view of Earth’s systems.
“We are heading towards a more holistic understanding of the processes that drive plate tectonics, 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," Muirhead says.
And as the climate changes, so too does the surface of the Earth. The Lake Turkana study demonstrates how even the impact of the rise or fall of a lake can ripple through the crust, influencing processes we usually associate with deeper forces. And with projections now pointing toward rising lake levels, the next chapter in the East African rift’s geologic story may look very different from its past.
This study was published in the journal Scientific Reports.
Source: University of Auckland
