Knowledge and visualization of the present-day relationship between earthquakes, active tectonics and crustal deformation is a key to understanding geodynamic processes, and is also essential for risk mitigation and the management of geo-reservoirs for energy and waste. The study of the complexity of the Greek tectonics has been the subject of intense efforts of our working group, employing multidisciplinary methodologies that include detailed geological mapping, geophysical and seismological data processing using innovative methods and geodetic data processing, involved in surveying at various scales. The data and results from these studies are merged with existing or updated datasets to compose the new Seismotectonic Atlas of Greece. The main objective of the Atlas is to harmonize and integrate the most recent seismological, geological, tectonic, geophysical and geodetic data in an interactive, online GIS environment. To demonstrate the wealth of information available in the end product, herein, we present thematic layers of important seismotectonic and geophysical content, which facilitates the comprehensive visualization and first order insight into seismic and other risks of the Greek territories. The future prospect of the Atlas is the incorporation of tools and algorithms for joint analysis and appraisal of these datasets, so as to enable rapid seismotectonic analysis and scenario-based seismic risk assessment.

We investigate a seismic crisis that occurred in the western Gulf of Corinth (Greece) between December 2020 and February 2021. This area is the main focus of the Corinth Rift Laboratory (CRL) network, and has been closely monitored with local seismological and geodetic networks for 20 yr. The 2020–2021 seismic crisis evolved in three stages: It started with an $Mw$ 4.6 event near the northern shore of the Gulf, opposite of Aigion, then migrated eastward toward Trizonia Island after an $Mw$ 5.0 event, and eventually culminated with an $Mw$ 5.3 event, $∼3km$ northeast of the Psathopyrgos fault. Aftershocks gradually migrated westward, triggering another cluster near the junction with the Rion–Patras fault. Moment tensor inversion revealed mainly normal faulting; however, some strike‐slip mechanisms also exist, composing a complex tectonic regime in this region dominated by east–west normal faults. We employ seismic and geodetic observations to constrain the geometry and kinematics of the structures that hosted the major events. We discuss possible triggering mechanisms of the second and third stages of the sequence, including fluids migration and aseismic creep, and propose potential implications of the $Mw$ 5.3 mainshock for the seismic hazard of the region.

On 30 October 2020 11:51 UTC, a Mw=6.9 earthquake struck the offshore region north of Samos Island, Greece, in the Gulf of Ephesos/Kuşadasi, causing two fatalities and 19 minor injuries at Samos Island, as well as 115 casualties and over 1,030 injuries in Western Turkey. Preliminary results indicate that the mainshock occurred on a north-dipping normal fault, with a focal mechanism of 270º/50º/-81º. The selection of the fault plane is supported by evidence of uplift at western Samos and over 10 cm of subsidence at the northernmost edge of the central part of the island. The distribution of relocated hypocenters shows clustering of events, east of the mainshock’s epicenter, where most major aftershocks have occurred. To the west, a smaller group of aftershocks is observed, separated by a spatial gap in seismicity. The latter is likely related to the region of the fault plane where most of the co-seismic slip occurred, with Coulomb stress-transfer towards the western and eastern margins of the rupture triggering aftershock activity. The apparent complexity of the mainshock’s source time function, supported by preliminary results, could indicate the rupture of more than one structures. This could explain the relatively weak magnitude of the largest aftershock (Mw=5.0). The mainshock caused damage mainly to non-engineered constructions, i.e. old residential buildings, churches and monuments in Samos Island, and minor damage to the majority of the building stock of the island built according to the National Seismic Code. On the other hand, it caused severe damage at Izmir, especially to high-rise buildings. The mainshock also triggered a small tsunami that reached heights of over 1 m, mainly affecting the Turkish coast.

Knowledge of the present-day relationships between earthquakes, active tectonics, and crustal deformation is a key for understanding the geodynamics, ongoing surface processes (i.e. erosion, sedimentation, etc.) and is also essential for the risk assessment and management of geo-reservoirs for energy and waste.Greece is characterized by the most tectonically active regime in the eastern Mediterranean, involving (a) intense crustal deformation and thickening, with an uplift rate of a few mm/yr along the Hellenic Arc due to accretion of sediments of the African plate beneath the overriding Aegean plate, (b) wide-spread extension in the back-arc region (for example in the Gulf of Corinth) due to retreat of the African slab and (c) significant strike-slip motions due to offset between oceanic-continental subduction in the west and the westward propagation of Anatolia in the east. Study of the complexity of the contemporary Greek tectonics has been the subject of intense efforts of our working group during the last decade, employing multidisciplinary state-of-the-art methodologies regarding geological mapping, seismological and geodetic surveying and numerical analyses at various scales. The products of these studies are the pieces of a puzzle that we aim to merge with existing data (topography, bathymetry, land-use, etc) in order to compose the digital version of the modern Seismotectonic Atlas of Greece.It has been over 30 years since the first edition of the seismotectonic map was published by Greece's Geological Institute in 1989, which emerges the need for an update, as soon as dozens of strong earthquakes have occurred both on mainland and offshore, whose locations and fault kinematics have been studied and this information has to be taken into account in city and infrastructure planning. Moreover, the patterns of active tectonics and stress, the tectonic strain distribution, the annual ratio between seismic and geodetic moment release, the precise location of onshore active faults and the slip-rates of major faults are much better known today than they were 30 years ago.Open-source mapping software and GIS tools are being used to showcase important up-to-date seismotectonic features together with critical geospatial information (motorways, railways, gas pipelines, electricity plants, etc) at a nationwide scale of 1:500,000. This updated product aims to reveal a comprehensive image of the regional crustal deformation in a useful manner for scientists, students, and stakeholders to obtain a first-order perception of seismic risk in the Greek territory, but, also, to be used as a basis for other applications in Geosciences.