Seismic zones for Azores based on statistical criteria

Abstract. The objective of this paper is to define seismic zones in the Azores based on statistical criteria. These seismic zones will likely be used in seismic simulations of occurrences in the Azores Archipelago. The data used in this work cover the time period from 1915 to 2011. The Azores region was divided into 1 ×1 area units, for which the seismicity and the maximum magnitudes of events were calculated. The seismicity, the largest earthquakes recorded and the geological characteristics of the region were used to group these area units because similar seismic zones must delineate areas with homogeneous seismic characteristics. We have identified seven seismic zones. To verify that the defined areas differ statistically, we considered the following dissimilarity measures (variables): time, size and seismic conditions - the number of seismic events with specific characteristics. Statistical tests, particularly goodness-of-fit tests, allowed us to conclude that, considering these three variables, the seven earthquake zones defined here are statistically distinct.