Deformation of olivine. (a) Reflected light micrograph of the deformed sample in cross-section. Brittle deformation of the olivine sample resulted in a conjugate set of faults (dashed lines). Fault displacement is indicated by gold markers (arrow). (b–d) 2-D projections of hypocentres for events >70 dB onto the sample cross-section in (a). Hypocentre annotation: closed-large = inside the sample, closed-small = inside the sample using location error range, open-small = outside the sample. (b) ‘cold’ axial compression of olivine to 2 GPa is marked by hypocentres near the large conjugate fault set. (c) Hypocentres are more dispersed at the top of the sample during ‘hot’ compression to 6 GPa at 900 °C. The inset (view perpendicular to (c)) shows location clusters outside the sample. (d) Events during ‘cold’ decompression from 6 GPa locate near the large sample faults again. Parameters used in the location algorithm: (a) V_p= 5.7, mm μs⁻¹, σ_t= 0.5 μs, error ellipsoid =[0.69 0.69 1.10], (b) V_p= 6.25 mm μs⁻¹, σ_t= 0.8 μs, error ellipsoid =[0.77 0.79 1.40], (c) V_p= 6.6 mm μs⁻¹, σ_t= 0.2 μs, error ellipsoid =[0.58 0.57 0.72].