Turkish Journal of Earth Sciences




This short opinion article presents and highlights new and old problems related to active geological faults, as seismic sources, after the experience of the last March 3 and 4, 2021 (Mw6.3 and Mw6.0, respectively) Tyrnavos-Elassona earthquakes in northern Thessaly, Greece. Although the active faults in the area are very well studied, demonstrating typical geomorphic features that intensely affect the morphological relief, it seems that the earthquakes were produced by unknown faults emerging in the mountainous area (alpine basement). Primary (?) coseismic ruptures, however, were also observed northwards along the Titarissios valley. A geological interpretation of the faulting mechanism is also proposed. The existence of a new unknown source in an intermontane area is problematic. The role of inherited alpine structures seems more important today than in the past. The strike of the two new seismogenic sources, responsible for the two strongest events of the 2021 earthquake succession, differs from the previously known active faults. This forces us to reconsider older views on the direction of development of active faults and the orientation of the stress field. Concerns are being raised about how new structures can be detected and their role in seismic hazard assessment, especially when located near or within the urban fabric, in cities that are now constantly expanding and being established in new, often loose soils.


Seismotectonics, northern Thessaly earthquake, detachment fault, hidden faults

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