Quantifying the time-clustering in SGR1806-20 bursts

The time-clustering behavior of the neutron star SGR1806-20 burst sequence (detected by the International Cometary Explorer, ICE) has been analyzed. The presence of two different timescaling regions, related to the "foreshock" and "aftershock" phases, separated by the largest event occurred on November 16, 1983, 8:34 GMT, E = 5.17 center dot 10(41)erg, has been evidenced. The results highlight that starquake foreshocks involve medium timescales from about 30 minutes to approximately 5 days, while starquake aftershocks involve longer timescales ranging up 4 months.