Spatiotemporal forecast of extreme events in a dynamical model of earthquake sequences

Seismic (‘earthquakes’) and aseismic (‘slow earthquakes’) slip events result from episodic slips on faults and are often chaotic due to stress heterogeneity. Their predictability in nature is a widely open question. Here, we forecast extreme events in a numerical model of a single fault governed by rate-and-state friction, which produces realistic sequences of slow events with a wide range of magnitudes and inter-event times. The complex dynamics of this system arise from partial ruptures. As the system self-organizes, prestress is confined to a chaotic attractor of a relatively small dimension. We identify the instability regions (corresponding to particular stress distributions) within this attractor which are precursors of large events. We show that large events can be forecasted in time and space based on the determination of these instability regions in a low-dimensional space and the knowledge of the current slip rate on the fault.