Plate tectonic theory can be used to explain movement of the Earth’s crust in Tibet—a key discovery in advancing the understanding of long-term seismic action—according to a study published last month by two Harvard researchers.
Associate Professor Brendan J. Meade and Research Associate Jack Loveless, both of the Earth and Planetary Sciences Department, took a new approach toward the decades-long debate over how continental shifts occur.
Plate tectonics theory, which describes the gradual movement of and interaction between large plates of the Earth’s crust, is generally accepted as a large-scale phenomenon. However, scientists have questioned its utility within smaller regions, maintaining that this deformation is too complex to be explained by a relatively simple theory like plate tectonics.
“What we wanted to do was to determine how much of the deformation could be understood through plate tectonics,” said Loveless, in explaining the motivations behind the project.
“We wanted to get to the bottom of how continents really behave,” Meade added.
The pair chose to study the Tibetan Plateau because of the relative lack of existing geological data there, which have made it the subject of various unproved theories that Meade and Loveless hoped to counter with quantitative analysis.
“Tibet is the ultimate testing ground for continental tectonics,” said Meade. “What we really wanted to do here was research things quantitatively.”
Using advanced GPS data, Meade and Loveless found that 85 percent of the surface motion on the Tibetan Plateau resulted from activity on faults mapped in the field. By including the faults in a mathematical model, the researchers could determine how quickly strain was building up in the surrounding crust, giving them a formal estimate of the amount of activity on known fault lines.
“It turns out that we could explain this broad deformation using a relatively simple theory,” said Loveless.
By looking at the behavior on fault lines, they could predict deformation patterns of the block of crust as a whole—revealing that plate tectonics can, in fact, explain smaller-scale continental interaction.
While the results are significant, their practical implications will be more important for the long-term.
“[The study] allows for a better understanding for how faults behave over long time periods,” said Loveless, “which is important for assessing long-term seismic hazards.”
Meade also underlined the real-world implications of the research, which he hopes will be expanded to study the tectonic movements that have provoked seismic activity in the past.