The 30 October 2020 Samos (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions

In this context, the region accommodates M 6+ earthquakes as documented by the historical and the instrumental period records (Stiros et al., 2000;Eyidoğan, 2020).Investigating Coulomb stress changes following such strong earthquakes is therefore crucial as they might suddenly load years of strain storage in a few seconds shortening the interseismic stages of adjacent fault segments. To investigate the Coulomb stress change generated by the M w 6.92 mainshock on nearby faults, its rupture geometry, size, and slip distribution must be identified accurately.

Section: Discussionsupporting

confidence: 86%

Anatomy of October 30, 2020, Samos (Sisam) –Kuşadası earthquake (MW 6.92) and its influence on Aegean earthquake hazard

Bulut¹,

Dogru²,

Yaltırak³

et al. 2021

“…In addition to that, fault plane solutions evaluated from both P-wave polarity data and moment tensor analysis with magnitude of up to Mw :4.9 in 2008-2012 show the predominance of normal faulting, along with strong contribution of the strike slip motion, with a N-S trending extension (Tan et al, 2014). After the 30 October 2020 Samos earthquake, other seismotectonic studies were carried out focusing on the fault model, the tsunami, the deformation field, and aftershocks that were the source of the earthquake in and around the island of Samos were evaluated (Çetin et al;2020/2;Ganas et al, 2020;Papadimitrou et al, 2020;Akıncı et al, 2021;Doğan et al, 2021;Elias et al, 2021;Evelpidou et al, 2021).…”

Section: Seismo-tectonic Settingmentioning

confidence: 99%

GPS derived finite source mechanism of the 30 October 2020 Samos earthquake, Mw = 6.9, in the Aegean extensional region

Aktuğ¹,

Tiryakioğlu²,

Sözbi̇li̇r³

et al. 2021

A submarine area close to the Turkish and Greek border between the cities of Samos-Greece and Seferihisar-Turkey has been shaked on October 30, 2020 by a Mw= 6.9 earthquake. In this study, the finite source mechanism of the Samos earthquake was investigated using geodetic methods and the coseismic behavior of the earthquake was modeled. The observed coseismic displacements at 62 sites were inverted for the fault geometry and the slips. The mainshock did not generate an on-land surface rupture. However, the uniform slip modeling shows a finite source of 43.1 km long and 16 km wide rupture, which slips 1.42 m along a north dipping normal fault extending from the Aegean Sea floor to a depth down to ~13 km. While the uniform slip model is consistent with the seismological solutions and provides a sufficient fit to the far field coseismic offsets, a distributed slip model is necessary to account for the near field coseismic displacements.

“…The recent earthquake's proximity to, sometimes densely, inhabited areas, like the 2017 Kos-Bodrum M w 6.4 earthquake, occurred offshore between the Kos Island in Greece and Bodrum town on the Turkish coast (e.g., Karasözen et al, 2018;Sboras et al, 2020), the 2020 Samos M w 7.0 earthquake, occurred again offshore and caused extensive damage in İzmir (e.g., Akinci et al, 2021;Sboras et al, this volume), and the 2021, Tyrnavos-Elassona M w 6.3 earthquake, just 15 km away from Larissa with major impact in local villages, are extremely valuable for the seismic hazard community. All these recently emerging data can be a crucial input in active fault databases aiming at contributing to the SHA, to simulate the ground motions and consequently enhance the building codes.…”

Section: Other 'Surprising' Earthquakes In Mainland Greecementioning

confidence: 99%

Recent earthquake activity of March 2021 in northern Thessaly unlocks new scepticism on Faults

Pavlides¹

2021

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 (M w 6.3 and M w 6.0, 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.