Measuring earth’s activity in Turkana

Monday May 1 2017

Crater Island in Lake Turkana. PHOTO| KAMWETI

Crater Island in Lake Turkana. PHOTO| KAMWETI MUTU 

By KARI MUTU

GPS (global positioning system) technology is used to pinpoint locations, map out areas and determine direction and speed of movement. This technology is now being used to map the movement of the earth’s crust in the Lake Turkana region of northern Kenya.

A GPS instrument called the Trimble netR9 has been set up at the Turkana Basin Institute (TBI), a science research station established by renowned paleoanthropologists Richard and Meave Leakey and the Stony Brook University of the US.

The semi-arid Turkana Basin is famous for prehistoric fossils dating back millions of years, but little research has been done so far to understand the earth movements that formed the region. In a joint project between Kenyan and American universities, scientists hope to measure how the earth’s surface is moving and stretching around the lake.

The Trimble equipment, a white disc on a tall steel tripod, is stationed in an open field at the institute. A solar panel powers the computer and data logger that records information to the precision of a millimetre. Currently the data is manually collected by a TBI staff member, but once cellular service is established it will be generated automatically.

The theory being tested is that much of the continental breakup in the Turkana area is happening because of volcanic activity, specifically “molten rock being injected into the crust as it stretches.

The GPS will help us identify where this process is happening, and how fast,” said Rebecca Bendick, associate professor at the University of Montana, and director of the project.

Geological activity causes the earth’s tectonic plates to bend and glide because of energy released at faults caused by earthquakes, expansion and contraction of magma chambers under volcanoes, and the amount of water in the lake.
“The data collected will be analysed for tectonic and hydrologic signals. Longer data series can provide a snapshot of how Africa slowly breaks into pieces as tectonic plates evolve,” said Bendick.

Miniscule earth motions over long periods of time are restructuring the map of East Africa. A similar study in Ethiopia shows that the Somali Plate is moving east, while further north the Arabia Plate is shifting northeast.

“In a million years, which is a pretty short time in geologic terms, Ethiopia will be 6km wider, and there could be a shallow sea in the northernmost part of the Rift system,” said Bendick.

The researchers hope their findings will help to explain the Turkana Basin, one of the lowest points in the Great Rift Valley, compared with the Ethiopian and Kenyan highlands to the north and south. “We would like to find out how it is moving tectonically and to monitor groundwater changes,” said geologist Gladys Kianji of the University of Nairobi.

The geophysical data from Lake Turkana could also be used for other fields of science such as ground-mapping, space-based observations and unusual events such as geothermal eruptions or moderate-sized earthquakes.

Additionally, the researchers can measure the weight of rain falling into the lake, and collect information that could point to long-term trends in climate change.

The experiment will run continuously for three years, with scientific results expected after one year.