SCALING BEHAVIOR OF AFTERSHOCKS SEQUENCE OF AL HOCEIMA FEBRUARY 24, 2004 EARTHQUAKE (MOROCCO)

Al Hoceima region (northern Morocco) was struck by an important earthquake (Mw~6.3) on February 24, 2004; inducing a devastating damage and 629 victims.

The time dynamics of the sequence following the main event (838 shocks) has been investigated by non-linear tools. The sequence of the occurrence times of the events with threshold magnitude M ³ 3.2 is characterized by a time-clustering behavior, identified using different fractal methods (Fano Factor, Allan Factor, Hurst exponent, Count-based Periodogram, etc.), well suited to reveal scaling features in point processes. The presence of power-law behavior in the performed statistics indicates the existence of fluctuations on many timescales and therefore of fractal clustering.

The obtained results not only show the presence of memory phenomena and correlation structures in the Al-Hoceima aftershocks, but also furnish quantitatively the estimate of the magnitude of such correlation by means of the estimate of the scaling exponents.