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The Zagros fold-thrust belt of Iran, as a continental-continental collision zone, is one of the most seismically active regions of the world. In this research, statistical point pattern analysis of earthquake locations in this region during 1976-2019 and the assessment of spatial association between earthquakes and major active faults of the region were carried out. For this purpose, different measures, (e.g., Nearest Neighbor Ratio, Global Moran's I and Local Getis-Ord's Gi* indices) were estimated and computed for the data catalog. Additionally, the directional anisotropy of the earthquake epicenters distribution and earthquake-fault association were assessed. Results obtained indicate a completely clustered pattern of epicenters for the whole region and also indicate that earthquakes with greater magnitudes show higher degrees of clustering. Also, a spatial autocorrelation of higher values of magnitudes are observed. The spatial relationships of earthquake locations and active faults pattern indicates that the trend of maximum dispersion of epicenters for the whole region is remarkably parallel with the general trend of this belt, as well as with the dominant trend of the major active faults of the region. Moreover, toward the south of the region, an obvious change in the directional anisotropy of epicenters is observed. The results of this study indicate that spatial analysis techniques reliably could be employed for revealing the seismicity pattern in tectonically active regions. [ABSTRACT FROM AUTHOR]

In this study, the waiting time, spatial distance, and migrating trend pattern of successive large earthquakes in Iran have been investigated. In order to carry out this work, the earthquake data of Iran with M ³ 4.5 (1976-2018) have been obtained from the USGS catalog. Then, the statistical distribution of the Interevent time, migrating distance, and directional trend of migration of successive events were studied using different lower magnitude thresholds. The statistical and probability distributions of inter-event times of earthquakes were assessed and modelled by different distribution models. Furthermore, the directional analysis of migrating trends, as well as the spatial distances of successive events with different lower magnitude, was carried out. It is observed that the inter-event time distribution of earthquakes can be quite well fitted by the Gamma distribution model. The results obtained also indicate a decreasing trend in spatial distance distribution and a meaningful correlation between the directional pattern of the migrating trends of successive events and the dominant trends of the active faults of the region. The results of this study can be considered as an effective step to better understanding the temporal-spatial pattern of seismicity in Iran and also as an attempt to achieve earthquake prediction in this country, in a regional scale. [ABSTRACT FROM AUTHOR]