Rupture Process of the 2020 M_w7.0 Samos Earthquake and its Effect on Surrounding Active Faults

Abstract

The M w 7.0 Samos earthquake 11:51 GMT) struck the eastern Aegean Sea in the area between the Samos Island and the western Turkish coasts. The epicenter of the main shock lies about 10 km offshore of the north coast of Samos Island (37.9020°N-26.7942°E; Bogazici University, Kandilli Observatory and Earthquake Research Institute's Regional Earthquake-Tsunami Monitoring Center-BDTIM), and at a focal depth of 10-12 km, according to the majority of the published point source mechanism solutions (Table S1). The earthquake was felt over a large area across both Greece and Turkey at distances exceeding 250 km. In Samos, the main shock caused two fatalities and structural damage in hundreds of buildings and infrastructures. In western Turkey, however, about 65 km to the NNE of the epicenter, the city of Izmir suffered much more damage. At least 20 buildings collapsed and hundreds were heavily damaged, while 116 people lost their lives and 1,035 more were reported injured, making this earthquake the deadliest to hit Turkey in nearly a decade. In Samos, the seismic shaking triggered secondary effects including coseismic coastal uplift, liquefaction phenomena, and various types of ground failures, while a tsunami that struck the surrounding coastal regions and flooded the port of Samos was generated.Moment tensor solutions computed by various institutes employing either teleseismic methods or utilizing regional data, as well as InSAR and GPS ground deformation maps (

Source modelling and stress transfer scenarios of the October 30, 2020 Samos earthquake: seismotectonic implications

“…Since their calculations are based on a different fault model and aftershock spatial distribution, there is no common ground for comparing their results with ours. On the other hand, great similarities can be observed with the results of Chousianitis and Konca (2021), who also show that the aftershock sequence is exclusively constrained in stress rise areas. However, using the optimum oriented normal receiver-faults in their calculations, instead of ours which involves receiver faults identical to the slipped one (source fault), Chousianitis and Konca (2021) show that the cluster C/"2" (Figures 2 and 3b, respectively) falls entirely in a stress-rise area, in contrast with our results which show that the respective cluster lies in a stress-drop area and, thus, implying a triggered reactivation of a yet unknown smaller fault.…”

“…Concerning the postsequence effects and triggering scenarios on the other surrounding faults, notably the Karlovasi-Fourni and the Kuşadası (Yavansu) faults, and less the Ikaria and Chios-Çeşme faults (the latter shows diverse stress change along its strike), show stress increase, matching the results of Chousianitis and Konca (2021). The other faults show either stress-drop or negligible stress change, matching again the results of Chousianitis and Konca (2021), with the only exception the Karaburun fault which in the results of the latter authors, a low and partial stress rise is demonstrated. It must be noted that triggering or delaying effects on nearby faults due to static stress changes is a relative information which depends on the state of stress in which every fault is (maturity stage) and cannot be used to predict the time of the next rupture.…”

“…It is obvious that numerous fault models can be proposed depending on the methodology applied. Our model, combining seismological, geodetic and geological information, aims at giving another perspective from most of the other ones above, which show significant differences in most of their parameters, The big resemblance of our model with the one of Chousianitis and Konca (2021), each using different approach of modelling, gives more confidence to ours.…”

“…In fact, the latter proposed a south dipping finite model. The closest fault model to ours is the one proposed by Chousianitis and Konca (2021). The authors used joint slip inversion to reach to their model, which differs slightly in geometry and dimensions.…”

Modeling of Continental Normal Fault Earthquakes

“…(2021), the numerical models' slip has a smaller maximum slip and a deeper location of the modeled maximum slip. The maximum slip in Chousianitis and Konca (2021) is significantly bigger than in the numerical model. For slip from Sakkas (2021) best fits are the models with $$\lambda =0.2$$ and $$\lambda =0.1$$, at the surface and at a dip distance of 8 km, respectively.…”