Estimate of the scaling between total seismic moment and areal extent of earthquake cluster, which depends on the average stress drop released during the seismic sequence. The method is suitable only for clustered seismicity associated to a single epizode with areal extent limited to few kilometers. For more details on the method please check Fischer, T. and Hainzl, S. (2017) Effective Stress Drop of Earthquake Clusters. Bulletin of the Seismological Society of America, 107 (5). pp. 2247-2257.