This is a subset of the seismic GI gun data recorded on the CHIMNEY JC152 cruise in 2017 (further information and nomenclature in Bull et al. 2018). Data were recorded on Ocean Bottom Seismic Receivers 1 and 19, and shots were selected to maintain offsets of approximately 200m, with a wide but uneven azimuth distribution. This was done to study azimuthal attenuation anisotropy for near-vertically travelling P-waves. The data are in SEGY format, with file names in the form: Rec*_**_***_nmo.sgy where * is receiver number ** is GI for the GI gun source and Dura for the surface sparker source *** is X for X component, Y for Y component, Z for Z component and H for hydrophone. Reference: Bull, J. M. (2018). Cruise Report – RRS James Cook JC152: CHIMNEY - Characterisation of Major Overburden Pathways above Sub-seafloor CO2 Storage Reservoirs in the North Sea Scanner and Challenger Pockmark Complexes,University of Southampton, 55 pp. Available at: https://eprints.soton.ac.uk/420257/ NERC Grant - Characterization of major overburden leakage pathways above sub-seafloor CO2 storage reservoirs in the North Sea (CHIMNEY)