reported for the California catalog too [10]. The invariance of l ∗ m for the actual catalog was attributed to the causal structure of seismicity and is therefore expected to reflect the features of the underlying dynamics [10]. An useful outcome of constructing such a network of recurrent events is, being able to arrive at an estimate for the rupture length in the region, from its earthquake catalog. The values of l ∗ m are identified as the rupture lengths and in the case of the California region the values obtained were reported to be in good agreement with the estimates given in [13, 14]. The identification of l ∗ m as the rupture length is further established by the appearance of the same distances in the distribution of the distances of the first recurrences. The distribution of the first recurrences for California had the form The rupture lengths for Japan estimated using eqn. 2 compares favourably with the values estimated using L$_{R}$ ( m $^{′}$) ≈ 0 . 02 × 10 0 . 5 m ′ [13] and L$_{R}$ ( m $^{′}$) ≈ 0 . 018 × 10 0 . 46 m ′ [14] as seen from Table I with δ$_{r}$ = 0 . 6 and the scaling function ¯ F has the same form as F in fig. 4. with δ$_{r}$ = 0 . 6. The first recurrence of an event i is the distance between the i th and ( i + 1) th event. The distances of the first recurrence is estimated for all the events in the catalog and its distribution for the actual catalog is shown in fig.5. We also observe the peaks for the different m$_{th}$ values appearing at the same distances as in fig. 4 and therefore the l ∗ m values estimated from fig. 4 can be considered as the rupture lengths as indicated in [10]. The distribution of first recurrences in our analysis can be written as P m 1 ( l ) = l − δ r ¯ F ( l/ 10 0 . 41 m th ) (4) P m 1 ( l ) = l − δ r ¯ F ( l/ 10 0 . 45 m th ) (3) 1. Identifcation with rupture length 9