  In the early stages of running of the CRESST dark matter search using
sapphire detectors at very low temperature, an unexpectedly high rate of signal
pulses appeared. Their origin was finally traced to fracture events in the
sapphire due to the very tight clamping of the detectors. During extensive runs
the energy and time of each event was recorded, providing large data sets for
such phenomena. We believe this is the first time the energy release in
fracture has been directly and accurately measured on a microscopic
event-by-event basis. The energy threshold corresponds to the breaking of only
a few hundred covalent bonds, a sensitivity some orders of magnitude greater
than that of previous technique.
  We report some features of the data, including energy distributions, waiting
time distributions, autocorrelations and the Hurst exponent. The energy
distribution appear to follow a power law, $dN/dE\propto E^{-\beta}$, similar
to the power law for earthquake magnitudes, and after appropriate translation,
with a similar exponent. In the time domain,the waiting time $w$ or gap
distribution between events has a power law behavior at small $w$ and an
exponential fall-off at large $w,$ and can be fit $\propto
w^{-\alpha}e^{-w/w_0}$. The autocorrelation function shows time correlations
lasting for substantial parts of an hour. An asymmetry is found around large
events, with higher count rates after, as opposed to before,the large event .
