Simulation of seismic triggering and failure time perturbations associated with the 30 October 2020 Samos earthquake (Mw 7.0)

Sopaci, Eyup
Özacar, Atilla Arda
The 30 October 2020 Samos earthquake (Mw = 7.0) ruptured a north-dipping offshore normal fault north of the Samos Island with an extensional mechanism. Aftershocks mainly occurred at the western and eastern ends of the rupture plane in agreement with the Coulomb static stress changes. Mechanism of aftershocks located west of the rupture supported activation of the neighboring strike-slip fault almost instantly. In addition, a seismic cluster including events with Mw similar to 4 has emerged two days later at the SE side of Samos Island. This off-plane cluster displays a clear example of delayed seismic triggering at nearby active faults. In this study, numerical simulations are conducted to mimic the instant and delayed seismic triggering observed after this event and evaluate resultant seismic cycle perturbations at adjacent faults and near Izmir, where amplified ground motions caused heavy damage. For this purpose, Coulomb static stress changes and seismic waveforms recorded by strong-motion stations are combined as static and dynamic triggers on a rate-and-state friction dependent quasi-dynamic spring slider model with shear-normal stress coupling. According to our results, earthquakes with Mw = 4 events noticeably advance in failure time. However, instant triggering occurs only when static stress loading is very high, and the fault is close to fail, explaining the delayed triggering observed SE of Samos Island. Simulations also revealed that the shear-normal stress coupling increases static loading but does not affect the dynamically controlled failure time advances observed at the end of the seismic cycle. After the earthquake, some of the faults adjacent to the rupture are more likely to fail, especially the long strike-slip fault segment capable of generating large earthquakes at the western edge. On the other hand, the Samos earthquake induced no significant dynamic triggering on far away faults near Izmir.


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The Samos Island (Aegean Sea) Earthquake occurred on 30 October 2020. It produced a tsunami that impacted coastal communities, ground shaking that was locally amplified in some areas and that led to collapse of structures with 118 fatalities in both Greece and Turkey, and wide-ranging geotechnical effects including rockfalls, landsliding, and liquefaction. As a result of the global COVID-19 pandemic, the reconnaissance of this event did not involve the deployment of international teams, as would be typical ...
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On October 30, 2020 14:51 (UTC), a moment magnitude (Mw) of 7.0 (USGS, EMSC) earthquake occurred in the Aegean Sea north of the island of Samos, Greece. Turkish and Hellenic geotechnical reconnaissance teams were deployed immediately after the event and their findings are documented herein. The predominantly observed failure mechanism was that of earthquake-induced liquefaction and its associated impacts. Such failures are presented and discussed together with a preliminary assessment of the performance of ...
Citation Formats
E. Sopaci and A. A. Özacar, “Simulation of seismic triggering and failure time perturbations associated with the 30 October 2020 Samos earthquake (Mw 7.0),” TURKISH JOURNAL OF EARTH SCIENCES, vol. 30, no. 5, pp. 653–664, 2021, Accessed: 00, 2021. [Online]. Available: