Decarbonation embrittlement of scapolite as a trigger for earthquakes in the lower crust

Recent studies and seismological data have reported numerous earthquakes in the lower continental crust ^1–7 . However, the mechanisms triggering earthquakes in the lower crust remain unclear. Here, we present results from the experimental deformation of granulite in simple shear at the pressures of 0.7 to 1.5 GPa and temperatures of 600–830 ℃ using a modified Griggs apparatus. We found faults in the deformed granulite in which the scapolite grains were devolatilized. Notably, most Raman spectra of the deformed scapolites did not have peaks at 1100 cm ^− 1 due to the vibrations of carbonate ions, indicating that carbon dioxide gas was released following the breakdown of scapolite. Therefore, our data suggest that the decarbonation embrittlement of scapolite can trigger earthquakes in the continental lower crust.