After my PhD, I spent 4 years as a visiting scientist at the Colorado Center for Chaos and Complexity, University of Colorado. During this period, I got involved in an active multi-institutional research group on the dynamics of seismic sources, under the direction of Professor J.B. Rundle. My main colaborators in this field are M. Anghel (LANL), E.F. Preston (Indiana State University) and K.F. Tiampo (University of Western Ontario), other than J.B. Rundle, now the Chair of the Center for Computational Science and Engineering at the University of California.