Physical and acoustic properties of shallow gas accumalations in the Eastern Black Sea and Gwanyang Bay

High resolution acoustic and multichannel seismic surveys were carried out in two different regions in the World (Eastern Black Sea, Turkish continental shelf and Gwangyang Bay in South Korea) which have different geological history and different acoustic and phyiscal properties due to gas accumulations. Probable free gas and gas hydrate areas are mapped. In the cruise of R/V K. Piri Reis planned on the Turkish margin of the eastern Black sea basin. Both scientific and technical cooperation were performed between Institute of Marine Sciences and Technology (IMST) and Pukyong National University (PKNU). In this context both in Black Sea and South Korea (Gwangyang Bay) shallow gas accumulations and gas hydrates, mud volcanoes and faults that are pathways for seeps are mapped. Piston coring helped to investigate the physical and acoustic properties of sediments.The cruise were realised in the Eastern Black Sea are onboard R/V K.Piri Reis with the participation of both scientists from IMST and PKNU. Approximately 1700 km multichannel seismic and chirp data simultaneously were acquired and processed.BSR, bright spots and gas masking were observed on the eastern seismic profiles of the survey area. Also two mud volcanoes are discovered and named as Pusan and İzmir. Slumps are observed on the slopes. In the attribute analysis high amplitude horzions with reverse polarity are observed in instantaneous frequency, envelope and apparent polarity sections also with low frequency at instantaneous frequency sections. These analysis verify existence of gas accumulations in the sediments. AVO analysis and cross section drawing and Gradient analysis show Class 1 AVO anomaly and indicate gas in sediments. Approximately 1000 line-km of chirp sonar data were acquired and 34 piston core samples were collected in Gwangyang Bay. Core samples were analyzed for sediment texture (grain size as well as, fractions of sand, silt, and clay), physical properties (porosity, water content, bulk density, grain density and shear strength), and acoustic properties (compressional wave velocity and attenuation).