Spatial Variation of Precursory Seismic Quiescence Observed Before Earthquake from 01.04.2010 in the Region of Crete

Statistical analysis was performed, which reveals statistical parameters of the seismic setting before the earthquake in the region of Crete (01.04.2011 with coordinates 26.56o E, 35.64o N; Ml = 6.2, h = 63 km and T0 = 13: 29: 10.5). For this purpose, the spatial and temporal changes in the b-value and the value of the Z-seismic lull were estimated. The temporary change in the b-value shows that the average value of b decreased from 1.75 ± 0.02 between 1985 and 2002 to 1.4 ± 0.02 between 2003 and 2011. A significant decrease in the b-value and clear anomalies of calm in the Z-value in early 2011 were also observed in several neighbouring areas. The epicenter of the earthquake falls in an area with a relatively low value of the a-parameter estimated for the entire previous period. In the study area, the abnormal decreasing trend of the b-value may be an indicator of increased stress, and the increasing trend of the Z-value may indicate areas of calm before the studied earthquake.