Unveiling Earthquakes: Thermoluminescence Signal Resetting of Laboratory-Produced Fault Gouge

Unravelling a reliable timing of past earthquakes through luminescence dating of fault gouge depends on sufficient frictional heat during a co-seismic event to fully reset the luminescence signal. Laboratory fault gouge production using a rotary shear apparatus has gained some interest as a method to probe the degree of signal resetting of quartz during friction experiments. However, natural fault gouges are complex, exhibiting a mixture of minerals that are specific to the host rocks. Here, we employed a host rock sample from the Alborz Mountains (Iran) and subjected it to a friction experiment without any chemical treatment, after being reset and irradiated with a known gamma dose. We performed a medium-slip velocity friction experiment with a slip velocity of 0.05 m/s ^{and a normal stress of 12 MPa, while the temperature evolution of the gouge zone was recorded using an infrared camera. The thermographic images show a transient temperature of approximately 296 °C, with luminescence signal resetting at a small, extremely localised slip patch, which confirms the challenges involved in identifying the best spot for signal resetting. However, we identified a high-temperature signal enhancement of the TL curves that might be used as a marker for fault gouge formation.}