We collect acoustic emissions and map shear stresses across serpentine compressed in the
laboratory up to 25 GPa. At these conditions, relevant to deep-focus earthquakes, serpentine
releases acoustic energy and undergoes brittle-like failure as it transforms from crystalline to
amorphous states. Maps of the local stress tensor are generated with~ 0.7 μm transverse
resolution using optically detected magnetic resonance (ODMR) spectroscopy of nitrogen
vacancy centers implanted in the tips of the pressure-transmitting diamonds. Acoustic …