Rupture Process of the 2020 Mw7.0 Samos Earthquake and its Effect on Surrounding Active Faults

다국어 초록 (Multilingual Abstract)

On October 30, 2020, a Mw7.0 normal faulting earthquake struck the eastern Aegean Sea, causing casualties, and substantial damage at Samos island and Izmir province. We constrained the rupture history of the main shock by jointly inverting GPS static offsets, high‐rate GPS recordings, strong motion waveforms, and teleseismic broadband data. The results revealed that the slip distribution was dominated by a slip patch which spans a depth range of 3–13 km and occupies ∼30 km along strike. The rupture propagated toward SW and updip and the maximum slip amplitude reached 4.6 m at 7 km depth. The remarkably low aftershock productivity within the main asperity suggests a near complete stress release. Coseismic Coulomb stress changes effectively explain the entire aftershock sequence implying absence of short‐term postseismic stress transfer mechanisms. The static stress change calculations also suggest that active faults around Sıgacık and Kusadasi Bays have been brought closer to rupture.
The Mw7.0 earthquake that occurred at eastern Aegean Sea on October 30, 2020 was among the largest recorded earthquakes in that area. It was an extensional faulting earthquake which occurred along an E‐W trending and north‐dipping fault and was followed by an intense aftershock activity. Joint analysis of seismic and geodetic data for the spatial and temporal evolution of the main shock rupture process revealed the main slip zone and the rupture duration. The remarkably low aftershock productivity within the area of the main slip zone argues for a nearly complete stress release during the seismic rupture. The stress changes that were induced by the main shock to the neighboring crust halted the occurrence of aftershocks toward Samos island and toward Sıgacık Bay and favored their distribution along an E‐W trending zone. In addition, the 2020 Samos rupture raised the stress on active faults around Sıgacık and Kusadasi Bays and brought them closer to failure. This could further be indicative of increased probability of moderate‐sized shocks on these faults and consequently increased seismic risk.



Inversion of seismic and geodetic data for the rupture history indicates a main slip patch occupying 30 km along strike at 3–13 km depth

The rupture propagated updip to the SW and the low aftershock productivity within the ruptured area suggests a near complete stress release

The occurrence of the 2020 Samos main shock brought active faults around Sıgacık and Kusadasi Bays from 0.2 to 1.2 bars closer to rupture


Inversion of seismic and geodetic data for the rupture history indicates a main slip patch occupying 30 km along strike at 3–13 km depth
The rupture propagated updip to the SW and the low aftershock productivity within the ruptured area suggests a near complete stress release
The occurrence of the 2020 Samos main shock brought active faults around Sıgacık and Kusadasi Bays from 0.2 to 1.2 bars closer to rupture