On 27 September 2021, a shallow earthquake with focal depth of 10 km and moment magnitude M_w6.0 occurred onshore in central Crete (Greece). The evolution of possible preseismic patterns in the area of central Crete before the M_w6.0 event was investigated by applying the method of multiresolution wavelet analysis (MRWA), along with that of natural time (NT). The monitoring of preseismic patterns by critical parameters defined by NT analysis, integrated with the results of MRWA as the initiation point for the NT analysis, forms a promising framework that may lead to new universal principles that describe the evolution patterns before strong earthquakes. Initially, we apply MRWA to the interevent time series of the successive regional earthquakes in order to investigate the approach of the regional seismicity towards critical stages and to define the starting point of the natural time domain. Then, using the results of MRWA, we apply the NT analysis, showing that the regional seismicity approached criticality for a prolonged period of ~40 days before the occurrence of the M_w6.0 earthquake, when the κ₁ natural time parameter reached the critical value of κ₁ = 0.070, as suggested by the NT method.

Greece exhibits the highest seismic activity in Europe, manifested in intense seismicity with large magnitude events and frequent earthquake swarms. In the present work, we analyzed the spatiotemporal properties of recent earthquake swarms that occurred in the broader area of Greece using the Non-Extensive Statistical Physics (NESP) framework, which appears suitable for studying complex systems. The behavior of complex systems, where multifractality and strong correlations among the elements of the system exist, as in tectonic and volcanic environments, can adequately be described by Tsallis entropy (S_q), introducing the Q-exponential function and the entropic parameter q that expresses the degree of non-additivity of the system. Herein, we focus the analysis on the 2007 Trichonis Lake, the 2016 Western Crete, the 2021–2022 Nisyros, the 2021–2022 Thiva and the 2022 Pagasetic Gulf earthquake swarms. Using the seismicity catalogs for each swarm, we investigate the inter-event time (T) and distance (D) distributions with the Q-exponential function, providing the q_T and q_D entropic parameters. The results show that q_T varies from 1.44 to 1.58, whereas q_D ranges from 0.46 to 0.75 for the inter-event time and distance distributions, respectively. Furthermore, we describe the frequency–magnitude distributions with the Gutenberg–Richter scaling relation and the fragment–asperity model of earthquake interactions derived within the NESP framework. The results of the analysis indicate that the statistical properties of earthquake swarms can be successfully reproduced by means of NESP and confirm the complexity and non-additivity of the spatiotemporal evolution of seismicity. Finally, the superstatistics approach, which is closely connected to NESP and is based on a superposition of ordinary local equilibrium statistical mechanics, is further used to discuss the temporal patterns of the earthquake evolution during the swarms.

Strong motion sensor networks deployed in metropolitan areas are able to provide valuable information for civil protection Decision Support Systems (DSSs) aiming to mitigate seismic risk and earthquake social-economic impact. To this direction, such a network is installed and real-time operated in Chania (Crete Island, Greece), city located in the vicinity of the seismically active south front of the Hellenic Subduction Zone. A blend of both traditional and advanced analysis techniques and interpretation methods of strong ground motion data are presented, studying indicative cases of Chania shaking due to earthquakes in the last couple years. The orientation independent spectral acceleration as well as the spatial distribution of the strong ground motion parameters such as the Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), Peak Ground Displacement (PGD) and Arias Ιntensity observed at the urban area of Chania are presented with the use of a Geographic Information System (GIS) environment. The results point to the importance of the strong ground motion networks as they can provide valuable information on earthquake hazards prior to and after detrimental seismic events to feed rapid systems supporting civil protection decisions for prevention and emergency response.

A widely felt strong shallow earthquake with Mw 6.3 magnitude occurred in Thessaly (Central Greece) on March 3, 2021. This recent strong event attracted our interest to apply and evaluate the capabilities of the Accelerating Deformation method. Based on the recently proposed generalized Benioff strain idea which could be justified by the terms of Non-Extensive Statistical Physics (NESP), the common critical exponent was calculated in order to define the critical stage before a strong event. The present analysis comprised a complex spatiotemporal iterative procedure to examine the possible seismicity patterns at a broad region and identify the best one associated with the preparation process before the strong event. The starting time of the accelerating period, the size and location of the critical area are unknown parameters to be determined. Furthermore, although, the time of failure is already known, in the present research it was not set as a fixed value in the algorithm to define the other unknown parameters but instead different catalogue ending dates have been tried out to be with an objective way. The broad region to be investigated was divided with a square mesh and the search of events around a point has been carried on with different size circular and elliptical shapes. Among the obtained results, the solution which exhibits the most dominant scaling law behavior as well as the one which exhibits the smallest spatial area and yet the more dominant scaling law behavior are presented.