HOW THE FINANCIAL CRASH OF OCTOBER 1997 COULD HAVE BEEN PREDICTED

From the analysis of (closing value) stock market index like the Dow J ones Industrial average and the S&P500 it is possible to observe the p recursor of a so-called crash. This is shown on the Oct. 1987 and Oct. 1997 cases. The data analysis indicates that the index divergence has followed twice a ''universal': behavior, i.e. a logarithmic dependenc e, superposed on a well defined oscillation pattern. The prediction of the crash date is remarkable and can be done two months in advance. I n the spirit of phase transition phenomena, the economic index is said to be analogous to a signal signature found in a two dimensional flui d of vortices.