Below:
Spacetime plots (left) and difference patterns (right) for the states
of rest between earthquakes, as simulated with a cellular automaton.
(a) lowest dissipation of energy, chaotic behaviour; (b) "class 4" behaviour,
i.e. erratic alternation of chaotic and predictable behaviour; (c) highest
dissipation, predictable behaviour.
States of rest between earthquakes
(time downwards) 
Difference patterns  
(a)
Chaotic: 

(b)
undecidable:


(c)
predictable: 
Publications:
M. Markus, H. Emmerich, C. Schäfer, P. Almeida and A. Ribeiro, "A binary description of earthquakes", in: 'Fractals and Dynamic Systems in Geosciences', (ed. by J. Kruhl), Wuerz Publ. Co., Winnipeg (1994), pp. 181196
M. Markus, A. Czajka, D. Boehm, T. Hahn, T. Schulte and A. Ribeiro,
Phenomenology of Cellular Automata Simulations of Natural Processes, in:
Cellular Automata and
Complex System (ed. by E. Goles & S. Martinez), Kluwer, Dordrecht,
pp. 2347 (1999)
M. Markus, I. Kusch, A. Ribeiro and P. Almeida, "Class 4 cellular automata
simulating diverse physical systems", Int. J. Bifurcation & Chaos 6,
18171827 (1996)