Characteristics of source wavelets generated by two sparkers

Sparker is used as an explosive seismic source in high-resolution oceanic explorations, however, further analysis is necessary to evaluate the source level, dominant frequency, and bandwidth of the generated source wavelets. In this study, we investigated source wavelets produced by two commercial sparkers with a multi-electrode array. All recorded signals were obtained in shallow water. A SIG 5mille (Services and Instruments of Geophysique) sparker generates a typical wavelet with an expansion pulse, ghosts and a notable collapse pulse, whereas the collapse pulse generated by a ZJUPSS (Plasma Seismic Source of Zhejiang University) sparker is much weaker because of the lower discharge energy per electrode. Nevertheless, the ZJUPSS expansion pulse magnitude is substantially higher than that of the SIG 5mille, and the former's sound source level reaches 223 dB at only 900 J. The SIG 5mille expansion pulse width is broader than that of the ZJUPSS, resulting in a lower dominant frequency down to 232 Hz at 2500 J, but the latter has more high-frequency components leading to better vertical resolution. The acoustic energy efficiency of the ZJUPSS ranges up to 4% higher than that of the SIG 5mille (<1%). (C) 2019 Published by Elsevier B.V.