The use of fallout radionuclides techniques (Caesium-137-Lead-210 in excess and Radon-222) to study earth surface movement and geodynamic process (case studies Morocco and Türkiye)
Bildiriler > Özet Bildiri · 2023
Yazarlar: Meryem Moustakim, Moncef Benmansour, Mutlu İÇHEDEF, Caner TAŞKÖPRÜ, Nouriddine Amenzou, Azouz Benkdad, Brahim Damnati
International Symposium on Georisks and Catastrophes Prediction 2023, Fas, Meknes, Uluslararası, Sözlü Sunum, Özet Bildiri, 2023-2023, ss 111-112
Özet
<p>The use of the radionuclides techniques to study Earth's surface and deep movements has provided several advantages over conventional methods. They </p><p>permitted to overcome the limitations of time and costs, provide qualitative and quantitative assessment, and obtain spatially distributed data, directly </p><p>comparable and representative. This work focuses on the use of a particular group of environmental radionuclides, mainly Cesium-137 which is an </p><p>anthropocentric radionuclide permitting mid-term retrospective erosion estimates (ca. 60 years), Lead-210 in excess which is a natural geogenic radionuclide permitting long term retrospective erosion estimates (over 100 years) and Radon-222 which is produced naturally within the Earth crust and one of the most studied precursors for earthquake forecasting. For instance, the combination of Cesium-137 and Lead-210 in excess has been an excellent alternative to studying soil erosion and sedimentation processes in Morocco. The measured activities of one or both isotopes in the soil samples </p><p>provide information on sites of soil loss and gain, compared to the mean reference inventory obtained in a stable site with minimum or absence of slope, </p><p>close to the studied fields and at the same altitude. Then, specific conversion models for cultivated and non-cultivated fields are used to convert the activities into a quantitative estimate of erosion or deposition rates across the site. Based on MBM2 and the Cesium-137 technique, the mean erosion rates ranged from 10.9 t ha-1 yr-1 in the Raouz watershed to 31.4 t ha-1 yr-1 in the El Hachef watershed. Quantification of water erosion with excess Lead-210 in a field within the Nakhla watershed indicated a rate of 27 t ha-1 yr-1. Lead-210 in excess was also used to study the sedimentation process within El Hachef Dam, an important water reservoir in Northwest Morocco. Furthermore, Radon-222 activities were measured in several studies in Türkiye to delineate active faults leading to earthquakes which caused several damages in Türkiye. The earthquake which occurred in 2020 with a magnitude of 6.9 caused great damage to Izmir, western Anatolia. The study area is located between the Izmir and Bornova faults within Izmir city, whose seismic activity has not been studied before. Measurements of Radon-222 are performed using the RAD7 in the ca. 1-1.5 Km spacing grid. The preliminary results show that the study area has an active tectonic structure and the variability of the Radon concentrations may be associated with the structure of the fault zone</p>