الفهرس 
Chapter One Basics of Infrasound TechniqueOnly 14 pages are availabe for public view
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Abstract
The infrasound technology is one of four techniques for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. Generally, the infrasound wave is a low-frequency sound wave (˂ 20 Hz) lower than the bottom limit of human audibility. Furthermore, it can propagate for long distances through the atmospheric layers with a velocity ” ” " ~ " ” ” 343 m/s at 20° C without considerable attenuation. The International Monitoring System (IMS) infrasound stations are established to monitor nuclear explosions in the atmosphere. Nowadays, the IMS infrasound network has about 53 certified stations out of 60 planned to be constructed. Data from seven IMS infrasound stations for a period from the 1st January 2013 until the 20th April 2018 is used in this study to estimate the detectability of events around Africa and the Middle East. These stations are ; I17CI in Cote d’Ivoire, I19DJ in Djibouti, I26DE in Germany, I31KZ in Kazakhstan, I32KE in Kenya, I43RU in Russia, and T48TN in Tunisia. The quality control of the data is firstly studied to present the data availability. It proved that the average data availability was very high during this period as it attained 99.29%. The progressive Multichannel Cross Correlation (PMCC) algorithm developed by the Commissariat à l’Energie Atomique (CEA) (French Atomic Energy Commission) is used for data analysis. About 11 frequency bands are used as parameters in the data processing. These bands start from a very low frequency of 0.07 Hz and end at 4 Hz. The PMCC produces detections around the station in all directions. The study area occurs between latitudes 20-40˚ N and longitudes 20-40˚ E. The data is then filtered to show the detectability in the study area direction. In addition, statistical analysis is applied for qualitative and quantitative descriptions of the detections at each station. The Dase Tool Kit (Détections Infrasons Valorisées Automatiquement) (DTK-DIVA) is the software used for studying the statistical merit for a short and long period. The detections are scattered to display seasonal variations, in addition, one-D histograms are produced to study the influence of diurnal variations. In conclusion, the PMCC algorithm shows much detection at each station. The statistical analysis carried out for the seven stations surrounding the study area showed the quantitative description of their detections. Moreover, it also gives an inverse qualitative description of the state of the atmosphere such as the direction of the winds. The stations show a clear difference in detections number between day and night hours (the day/night effect) as the events in the daytime hours are less than the night hours (without using any filters) at all stations except at the Germany I26DE station which has no noticeable diurnal difference. The reason for the stability of detection numbers in this station may be due to climatic and meteorological factors as most of the other stations have tropical and dry climates but this station has a temperate oceanic climate. The results also showed a vital relationship between seasons and the number of detections, as infrasound waves are affected by temperature and climatic changes, so the events numbers differ in all stations during the different seasons.