  Continuous GPS and broadband seismic monitoring have revealed a variety of
disparate slip patterns especially in shallow dipping subduction zones, among
which regular earthquakes, slow slip events and silent quakes1,2. Slow slip
events are sometimes accompanied by Non Volcanic Tremors (NVT), which origin
remains unclear3, either related to fluid migration or to friction. The present
understanding of the whole menagerie of slip patterns is based upon numerical
simulations imposing ad hoc values of the rate and state parameters a and b4-6
derived from the temperature dependence of a and b of a wet granite gouge7.
Here we investigate the influence of the cumulative slip on the frictional and
acoustic patterns of a lab scale subduction zone. Shallow loud earthquakes
(stick-slip events), medium depth slow, deeper silent quakes (smooth sliding
oscillations) and deepest steady-state creep (continuous sliding) are
reproduced by the ageing of contact interface with cumulative displacement8.
The Acoustic Emission evolves with cumulative displacement and interface
ageing, following a trend from strong impulsive events, similar to earthquake
seismic signals, to a collection of smaller amplitude and longer duration
signals, similar to Non Volcanic Tremors. NVT emerge as the recollection of the
local unstable behaviour of the contact interface globally evolving towards the
stable sliding regime.
