In this note, we study the distribution of earthquake numbers in both worldwide and regional catalogs: Global Centroid Moment Tensor catalog, from 1980 to 2019 for magnitudes Mw 5. 5+ 6.5+ first case, Italian instrumental catalog 1960 2021 4.0+ 5.5+ second case. A subset global is also used Japanese region. We will focus our attention on short-term time windows 1, 7, 30 days, which have been po...