Civil Engineering / İnşaat Mühendisliği
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Article Citation - WoS: 13Citation - Scopus: 12Geotechnical Reconnaissance Findings of the October 30 2020, Mw7.0 Samos Island (aegean Sea) Earthquake(Springer, 2022) Ziotopoulou, Katerinaa; Pelekis, Panagiotis; Klimis, Nikolaos; Çetin, Kemal Önder; Altun, Selim; Sezer, Alper; Ecemiş, NurhanOn 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 building foundations, slopes and deep excavations, retaining structures and quay walls. On the Anatolian side (Turkey), and with the exception of the Izmir-Bayrakli region where significant site effects were observed, no major geotechnical effects were observed in the form of foundation failures, surface manifestation of liquefaction and lateral soil spreading, rock falls/landslides, failures of deep excavations, retaining structures, quay walls, and subway tunnels. In Samos (Greece), evidence of liquefaction, lateral spreading and damage to quay walls in ports were observed on the northern side of the island. Despite the proximity to the fault (about 10 km), the amplitude and the duration of shaking, the associated liquefaction phenomena were not pervasive. It is further unclear whether the damage to quay walls was due to liquefaction of the underlying soil, or merely due to the inertia of those structures, in conjunction with the presence of soft (yet not necessarily liquefied) foundation soil. A number of rockfalls/landslides were observed but the relevant phenomena were not particularly severe. Similar to the Anatolian side, no failures of engineered retaining structures and major infrastructure such as dams, bridges, viaducts, tunnels were observed in the island of Samos which can be mostly attributed to the lack of such infrastructure.Article Citation - WoS: 13Citation - Scopus: 15A Survey of Damage Observed in Izmir Due To 2020 Samos-Izmir Earthquake(Springer, 2021) Demirci, Hasan Emre; Karaman, Mustafa; Bhattacharya, SubhamoyAn earthquake of magnitude 6.9 hit the city of Izmir (Turkey) on 30 October 2020, resulting in 117 deaths (in Turkey) and considerable economic losses. The earthquake also triggered a tsunami. Following the earthquake, field surveys are being conducted in a Covid-secure way to study and document the damages caused. The earthquake caused significant damages to residential buildings mainly located in the district of Bayrakli and Bornova. However, no damages were observed in railway and roadway bridges or tunnels and that helped the rescue operations. The damages were mainly structural which included the so-called pancake collapse (where the entire building collapsed) and soft storey type collapse (weak storey characterised with weak columns collapsed), and in some cases, only the ground floor completely collapsed. Due to the proximity of the epicentre and the geology of the area, it seemed that the ground motions were amplified. This technical note provides a summary of the seismological and recorded ground characteristics of the earthquake together with the lessons learnt.Article Citation - WoS: 4Citation - Scopus: 15Effects of Seismic Activity on Groundwater Level and Geothermal Systems in İzmir, Western Anatolia, Turkey: the Case Study From October 30, 2020 Samos Earthquake(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2021) Uzelli, Taygun; Bilgiç, Esra; Öztürk, Bahadır; Baba, Alper; Sözbilir, Hasan; Tatar, OrhanThe October 30, 2020 Samos earthquake (Mw 6.6) affected the Aegean Sea and environs, caused destruction and loss of life in the city of İzmir located 70 km away from the earthquake epicenter. Before this earthquake, water resources were monitored in the areas of Bayraklı, Gülbahçe, and Seferihisar. For this purpose, 10 groundwater monitoring wells were drilled in the Bayraklı area, where groundwater level, temperature, and electrical conductivity changes were monitored at 1-h intervals in 5 wells. Besides physical parameters such as groundwater levels, temperatures and electrical conductivities, hydrogeochemical cations, and anions measured in the study area. Change in the groundwater levels was observed before, during, and after the Samos earthquake. A trend of rising groundwater level was observed two days before the mainshock, to a height of 10 cm, and the level was maintained till the end of the earthquake. The water levels returned to its original height after about 7 to 10 days of the earthquake. Moreover, electrical conductivity (EC) values were changed because of the interaction with the surrounding rocks and well walls, mixing with different waters during the earthquake shaking. The essential anomalies were observed in the geothermal fields of Gülbahçe and Seferihisar. Due to this earthquake, new geothermal springs emerged along the NE-SW trending Gülbahçe and Tuzla faults, located about 50 to 20 km from the Samos earthquake epicenter, respectively. The new geothermal waters are in Na-Cl composition and similar to other geothermal springs in the region. While the recorded water temperatures in the new geothermal springs vary from 40 to 45 °C in Seferihisar, it was measured between 35 and 40 °C in Gülbahçe. Due to these anomalies, it is found essential to monitor the effect of the earthquake on the physical and chemical characteristics of the groundwater and its usefulness in earthquake predictions.Article Citation - WoS: 61Citation - Scopus: 60Performance of Structures in Izmir After the Samos Island Earthquake(Springer, 2021) Yakut, Ahmet; Sucuoğlu, Haluk; Binici, Barış; Canbay, Erdem; Dönmez, Cemalettin; İlki, Alper; Caner, AlpThe October 30, 2020 Earthquake caused unexpectedly significant damage in Izmir considering its distance to the city. This paper evaluates the recorded ground motions, summarizes the performance of structures affected from the earthquake with emphasis on the reasons of damage. A detailed damage assessment was carried out by the Earthquake Engineering Research Center of Middle East Technical University to compile data on the damage of RC and masonry buildings. It was observed that majority of the damage was concentrated in the Bayrakli district due to its peculiar soil properties where many 7-10 story mid-rise RC buildings suffered heavy damage and collapse. The level of amplified ground motions combined with deficiencies of apparently non-code compliant buildings exacerbated the damage. The main reasons of damage were mainly attributed to the presence of soft stories, lack of proper detailing, poor construction quality, presence of heavy overhangs, and hence significant lack of code-compliance in essence. The influence of infill walls on seismic performance of deficient and inadequate buildings was clearly seen in this earthquake. This paper also discusses seismic code requirements in effect and their influence on the observed building performance. The recorded ground motions were compared with the code spectra to evaluate the performance of the buildings. The code response spectra were found to be well above the recorded ground motion spectra at the sites where significant damage was observed.Article Citation - WoS: 10Citation - Scopus: 10A Reconnaissance Study in Izmir (bornova Plain) Affected by October 30, 2020 Samos Earthquake(Elsevier, 2021) Nuhoğlu, Ayhan; Erener, Mehmet Fahrettin; Hızal, Çağlayan; Kıncal, Cem; Erdoğan, Devrim Şüfa; Özdağ, Özkan Cevdet; Akgün, MustafaOn October 30th of 2020, 14:51 (GMT+3:00), Izmir city was hit by an earthquake of Mw = 7.0 magnitude (according to USGS). A rupture of 30-40 km of a west-east normal fault, which is roughly 12 km north to Samos Island caused significant damage, particularly in Izmir (Bornova plain). This study aims to present the preliminary field investigations, evaluation of structural damage as well as the possible geotechnical phenomenon affecting the damage that occurred. In this context, an extensive analysis of spectral characteristics of the earthquake and local site effects is presented. Field investigations reveal that there is a significant amplification of the rock acceleration along with a basin effect in the region, which results in a wider constant acceleration region. In addition, analysis of earthquake records shows a remarkable level of soil nonlinearity. Considering all these aspects, a detailed assessment of structural damage observed in Izmir Bayrakli District is presented. It is evident that, structures of poor construction details behaved as if they were affected by a near field earthquake. The structures to be constructed in alluvial zones such as Manavkuyu neighborhood should be designed considering the effects of soil amplification including basin effects and soil nonlinearity. To fulfill this aim, comparative results of 1D/2D/3D ground response analyses should be performed, for revising current earthquake codes.