On 30 October 2020, an earthquake of Mw 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia on Samos Island, and 25 km southwest of Seferihisar, Turkey, triggering also a tsunami. The event has been followed by >4,000 aftershocks up to Mw 5.2 The Earthquake Engineering Field Investigation Team (EEFIT) has immediately gathered a team to conduct a hybrid reconnaissance study, bringing together remote and field investigation techniques. The mission took place between 16 November and 17 December, inclusive of three sets of field study carried out by the field crews for building damage assessment in the affected areas in Turkey and Greece under the coordination of the remote team. The mission also aimed to assess the viability of alternative data sources for an appraisal of the future viability of hybrid missions. This paper summarises the mission setup and findings, and discusses the benefits of and difficulties encountered during this hybrid reconnaissance activity.

No abstract

<p>This paper presents the work we conducted for the estimation of strong ground motion and building damage distributions after the 6 February 2023, Kahramanmaraş – Türkiye M7.7 Earthquake. The following outcomes were made available to the research community within the 18 hours of the earthquake occurrence and updated on a daily basis: Maps of the spatial distributions of peak ground acceleration and velocity, spectral accelerations at 0.2s and 1.0s, instrumental intensity and, number of damaged buildings distributions at regional and urban scale. The ground motion distribution maps with different ground motion and intensity prediction equations were re-produced and further improved with the incorporation of recorded strong motion data. Damage estimations were also updated based on the new ground motion inputs.</p>

The eastern parts of the Aegean Sea were struck by a destructive MW 6.9 earthquake on 30 October 2020 at 11:51:27 UTC. The earthquake ruptured an East-West trending normal fault in the Aegean Sea between the northern coast of Samos Island and the southern coast of İzmir and also triggered a medium level tsunami and thousands of aftershocks across the region. 119 fatalities, 1,051 injuries, and many collapsed buildings were reported due to the earthquake in the affected region. The most catastrophic consequences of the earthquake were registered in the Bayraklı and Bornova districts, which are built on a deep alluvial Basin approximately 60–70 km away from the epicentre of the mainshock. This paper explains the damage with an extensive dataset of ground motion records of the mainshock and aftershocks, which are provided by both Greek and Turkish networks. A set of ground motion parameters such as peak ordinates, spectral quantities, intensity measures and duration parameters are calculated and analysed. The closest softer soil station in Samos Island produces the highest peak ground acceleration and velocity. The ground motion models employed commonly for the region overestimate the observed data beyond 60–70 km of Joyner-Boore distance except for the recently published local ground motion model, which utilises local earthquakes in the derivation of the model. Contrary to expectations, stiff soil recordings exhibit considerable spectral accelerations in the long period region, similar to those in soft soils. The calculated ground motion parameters are correlated with the results of the hybrid reconnaissance mission, organized by the Earthquake Engineering Field Investigation Team (EEFIT). Although the peak values and regarded intensity measures clearly highlight the variability in soil conditions in the most damaged area (Bayraklı and Bornova), velocity-based ground motion parameters seem to be the more responsive damage indicators. The spectral shapes of the normalised response spectra in the İzmir Basin are not compatible with the 2018 Turkish seismic code spectrum whereas their response spectra are below the 475-years return period design spectra provided in outdated and current Turkish seismic codes.