T & uuml;rkiye is located in an earthquake-prone region where almost all of its population resides in risky areas. In the past 100 years, there has been a strong earthquake every two years and a major one every 3 years. This study investigates the impact of four recent earthquakes, that occurred between 2020 and 2023, on reinforced concrete (RC) buildings. The first, Sivrice-Elaz & imath;& gbreve;, struck the eastern part of T & uuml;rkiye on January 24, 2020, with a moment magnitude of Mw = 6.8. The second, the Aegean Sea, hit the western part of the country on October 30, 2020, with an Mw of 6.6. The third and fourth are the February 6, 2023 dual Kahramanmara & scedil; earthquakes with Mws of 7.7 and 7.6, which struck the eastern part of T & uuml;rkiye approximately 9 h apart. Immediately following these earthquakes, a technical team investigated each of the damaged areas. This study summarizes their findings on RC buildings. It was discovered that the majority of the collapsed or severely damaged RC buildings were constructed before 2000. The main reasons for this included technological limitations, specifically on producing high-quality concrete, as well as a lack of public policies and enforced laws in the construction sector to maintain an acceptable international standard. Furthermore, the damage patterns of buildings from these four earthquakes indicated poor workmanship, low material quality, improper structural framing, a common appearance of soft and weak stories, the inadequate use of shear walls, and defective reinforcement configuration. The significance of soil studies and the enforcement of building inspections are also discussed, along with the earthquake codes. The study concludes that the maximum peak ground accelerations from the dual Kahramanmara & scedil; earthquakes were almost triple the code-prescribed values. Therefore, it is recommended that the current mapped spectral acceleration values be revised and that buildings constructed before 2000 should be prioritized while determining their structural performances.

Post-earthquake scientific investigation is considered as one of the pillars supporting earthquake engineering. On the 6th of February, 2023, two deadly strong earthquakes, which magnitudes were M(w)7.8 and M(w)7.5, respectively, shook Southern-Central Turkiye, caused significantly large casualties and tremendous economy loss. Through on-site field survey, liquefaction phenomena and liquefaction-induced damage to buildings were observed. The observations are: (1) the consequences of soil liquefaction included sandboils, lateral spreading, ground subsidence and ground failure caused by loss of bearing capacity; (2) in two liquefied areas, lateral spreading was investigated and the spreading displacement ranged from several centimeters to meters, resulting in damage or demolishing of buildings; (3) in Golbasi town, many 6 to 10-story buildings significantly subsided and tilted due to liquefaction-induced loss of ground bearing capacity. Buildings subsided by tens of centimeters to 2 similar to 3 m, and tilted by several degrees to tens of degrees; (4) ground subsidence of tens of centimeters with respect to adjacent buildings was detected. The liquefaction phenomena were compared with those triggered by the 2008 Wenchuan, China, earthquake which maintained similar in magnitude and focal depth. The findings and lessons learnt will enhance the understanding of liquefaction hazard, challenge the current liquefaction countermeasures, and eventually facilitate to improve liquefaction mitigation techniques.

This study investigates the effects of the February 6, 2023, earthquakes in T & uuml;rkiye, measuring 7.8 and 7.6 magnitudes (Mercalli intensities XI and X). It comprehensively assesses their impact, along with the subsequent Hatay earthquake (Mw 6.4), on various structures, including residential RC buildings, commercial, industrial, and strengthened structures, as well as critical lifeline components such as roads, bridges, power, and telecommunication systems, and areas affected by soil failures. Immediate field observations were conducted to assess changes and gather insights. The findings will contribute to the development of recommendations for future seismic damage prevention and mitigation strategies.

On February 6th, 2023, southeastern T & uuml;rkiye was shaken by two catastrophic earthquakes, close to northwestern Syrian border. The first earthquake (Pazarc & imath;k) occurred 45 km west of Gaziantep at 1:17:32 (UTC), with a shallow strike-slip faulting at a depth of approximately 8.6 km and a moment magnitude (MW) of around 7.7. The second event (Elbistan) took place 9 h later, 66 km north-east of Kahramanmaras, city center, also with shallow strike-slip faulting at a depth approximately 7 km and an MW of around 7.6. Turkish authorities reported a death toll of over 59,000 in T & uuml;rkiye and about 8500 in Syria. The destructive effect of the earthquake resulted from widespread strong ground shaking, a rupture length exceeding 300 km, causing collapse of a large number of buildings. The catastrophic destruction of the built environment was accompanied by a range of other earthquake-related effects, including fault ruptures, landslides, and soil liquefaction. The aim of the study is to analyze the distribution of ground motion and their relationships with the observed damages for the two events. Spectral accelerations of key importance were assessed across a large area in the southeastern part of T & uuml;rkiye. Notably, these accelerations were generally much higher than existing design spectra. A significant correlation between the observed concentration of damage and the significant amplification of motion induced by local soil conditions (such as soft soils and valley effects). The distinct tectonic structure of the region could be the main reason for the high amplification in the valleys (associated with basin effects), even at large distances from the epicenter, especially in correspondence with the bidimensional grabentype geological structures. The investigation delved into the analysis of four specific regions in detail: Antakya and Hassa (both in the Hatay province), Kahramanmaras, and Goksun. Notably, the observable valley effects were found to play a significant role and could account for the significant damage observed in these regions.

This study was conducted during 2021-2022 to detect and determine distribution and population of cyst nematodes, Heterodera spp. (Tylenchida: Heteroderidae) in black cabbage Brassica oleracea var. acephala L. (Brassicales: Brassicaceae) production areas of the Eastern Black Sea Region of T & uuml;rkiye. For it, a total of 77 samples were taken from 53 districts belonging to the Artvin, Giresun, Ordu, Rize, and Trabzon provinces in the region. Soil samples were taken from around the root of the kale plants. Nematodes were extracted by using the centrifugal flotation technique. The nematodes were identified using morphological features and molecular analysis based on Polymerase Chain Reaction (PCR) method. For molecular analysis, the ribosomal DNA region including the gene region of 28S ribosomal RNA (rRNA) (ITS1, 5.8S, ITS2) was amplified using primer sets TW81/AB28. Additionally, a species-specific primer set (Car-F/Car-R) covering the Cytochrome Oxidase I (cox1) region of mitochondrial DNA (mtDNA) was used. As a result of the analysis, cyst nematodes Heterodera cruciferae Franklin, 1945 , Heterodera carotae Jones, 1950 and Heterodera fici Kirjanova, 1954 species were identified in the kale production areas in the region. Heterodera carotae is the first record of the cyst nematode species in T & uuml;rkiye. Heterodera cruciferae, H. carotae, and H. fici were detected from the total collected soil samples at 16.9%, 3.9%, and 1.3% relative frequency, respectively. Among all, Giresun was the most infected province with 35.3% infection rate, followed by Trabzon with 26.3%, Ordu with 21.1% and Rize with 13.3%.