  An accurate understanding of the interplay between random and deterministic
processes in generating extreme events is of critical importance in many
fields, from forecasting extreme meteorological events to the catastrophic
failure of materials and in the Earth. Here we investigate the statistics of
record-breaking events in the time series of crackling noise generated by local
rupture events during the compressive failure of porous materials. The events
are generated by computer simulations of the uni-axial compression of
cylindrical samples in a discrete element model of sedimentary rocks that
closely resemble those of real experiments. The number of records grows
initially as a decelerating power law of the number of events, followed by an
acceleration immediately prior to failure. We demonstrate the existence of a
characteristic record rank k^* which separates the two regimes of the time
evolution. Up to this rank deceleration occurs due to the effect of random
disorder. Record breaking then accelerates towards macroscopic failure, when
physical interactions leading to spatial and temporal correlations dominate the
location and timing of local ruptures. Sub-sequences of bursts between
consecutive records are characterized by a power law size distribution with an
exponent which decreases as failure is approached. High rank records are
preceded by bursts of increasing size and waiting time between consecutive
events and they are followed by a relaxation process. As a reference, surrogate
time series are generated by reshuffling the crackling bursts. The record
statistics of the uncorrelated surrogates agrees very well with the
corresponding predictions of independent identically distributed random
variables, which confirms that the temporal and spatial correlation of cracking
bursts are responsible for the observed unique behaviour.
