by Duke University, January 17, 2019 in ScienceDaily/Nature
Engineers at Duke University have devised a model that can predict the early mechanical behaviors and origins of an earthquake in multiple types of rock. The model provides new insights into unobservable phenomena that take place miles beneath the Earth’s surface under incredible pressures and temperatures, and could help researchers better predict earthquakes — or even, at least theoretically, attempt to stop them.
The results appear online on January 17 in the journal Nature Communications.
“Earthquakes originate along fault lines deep underground where extreme conditions can cause chemical reactions and phase transitions that affect the friction between rocks as they move against one another,” said Hadrien Rattez, a research scientist in civil and environmental engineering at Duke. “Our model is the first that can accurately reproduce how the amount of friction decreases as the speed of the rock slippage increases and all of these mechanical phenomena are unleashed.”
For three decades, researchers have built machines to simulate the conditions of a fault by pushing and twisting two discs of rock against one another. These experiments can reach pressures of up to 1450 pounds per square inch and speeds of one meter per second, which is the fastest underground rocks can travel. For a geological reference point, the Pacific tectonic plate moves at about 0.00000000073 meters per second.
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Hadrien Rattez, Manolis Veveakis. Weak phases production and heat generation control fault friction during seismic slip. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-019-14252-