The dose response of the 375 degrees C. 470 nm TL peak in fired quartz is studied by using thermoluminescence emission spectra and monochromatic glow curves. The blue emission displays a significant sensitivity increase for doses in excess of 1000 Gy, subsequent saturation at 16 kGy and a pre-dose effect over the entire dose range. Comparison with the growth of the known electron paramagnetic resonance (EPR) centres and radioluminescence emission spectra indicates that the [AlO4] centre is the recombination site for the blue emission, whereas the electron trap remains unknown. The sensitivity change seems to be linked to the dose-induced reduction of the [GeO4/Li] centre. Possible mechanisms for the observed dose response are discussed.