Sarah Stamps has just published a paper in Geophysical Research Letters which discusses present-day continental extension along the East African Rift System (EARS). It has often been attributed to diverging sublithospheric mantle flow associated with the African Superplume. This implies a degree of viscous coupling between mantle and lithosphere that remains poorly constrained. Recent advances in estimating present-day opening rates along the EARS from geodesy offer an opportunity to address this issue with geodynamic modeling of the mantle-lithosphere system. Here we use numerical models of the global mantle-plates coupled system to test the role of present-day mantle flow in Nubia-Somalia plate divergence across the EARS. The scenario yielding the best fit to geodetic observations is one where torques associated with gradients of gravitational potential energy stored in the African highlands are resisted by weak continental faults and mantle basal drag. These results suggest that shear tractions from diverging mantle flow play a minor role in present-day Nubia-Somalia divergence.
Aradhna Tripati was presented the annual E.O. Wilson Award for Outstanding Science in Biodiversity Conservation Dec. 17 by the Center for Biological Diversity for her “groundbreaking research on carbon dioxide’s role in climate change.” She was presented the award at the American Geophysical Union’s fall meeting in San Francisco.
According to UCLA professor Aradhna Tripati, the lead author on that paper, "The last time carbon dioxide levels were apparently as high as they are today ...global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland."
EPSS Professor Yin and his colleagues analysed modern and historical records of earthquakes in northern China. Mapping their locations revealed a 160-kilometre-long fault segment running through Tianjin, roughly 100 kilometers southeast of Beijing. This area has not experienced a major tremor for about 8,400 years, and the authors estimate that a quake of roughly magnitude 7.5 is either overdue or will strike in the next 2,000 to 3,000 years. Given the region's complex fault structure, however, other factors could explain the lack of major earthquakes, such as multiple smaller quakes releasing energy from the fault.
Graduate student Patrick Boehnke has just received the Eugene M. Shoemaker Impact Cratering Award. The prize is awarded to undergraduate or graduate students in the disciplines of geology, geophysics, geochemistry, astronomy, or biology for the study of impact craters, either on Earth or on the other solid bodies in the solar system. EPSS alumni Matt Mielicki also received this award.
Despite extensive studies on the occurrence and stability of carbonate-rich melts, physical properties (such as density, viscosity, and mobility) of carbonate melts have not been well understood. In a paper published in Nature Communications , Yoshio Kono, Dan Hummer, Abby Kavner, Craig Manning and colleagues report viscosities of calcite and natural dolomite melts up to 6.2 GPa using an advanced technique of viscosity measurement with ultrafast synchrotron X-ray imaging. The imaging rate of 1,000 frames per second (fps), more than 15 times faster than that of conventional X-ray radiography (typically 30 to 60 fps) in large volume presses, enables precise determination of very low viscosity values. This study reveals that viscosities of calcite and dolomite melts are surprisingly low: in the range of 0.006-0.010 Pa s. These low viscosity values are more similar to those of water than to silicate melts.
The SpinLab is featured on a popular fluid dynamics website. SPINLab scientists used a tank, a record player, and dye to create an exciting video that illustrates the formation of Taylor columns. These striking columns are fluid dynamics phenomenon that occur as fluid moves around an obstacle in a rotating system.