Quantitative Estimation of Bubble Volume Fraction of Submarine Seep Plumes by Modeling Seismic Oceanography Data

Submarine seep plumes are a natural phenomenon in which different types of gases migrate through deep or shallow subsurface sediments and leak into seawater in pressure gradient. When detected using acoustic data, the leaked gases frequently exhibit a flame-like structure. We numerically modelled the relationship between the seismic response characteristic and bubble volume fraction to establish the bubble volume fraction in the submarine seep plume. Results show that our models are able to invert and predict the bubble volume fraction from field seismic oceanography data, by which synthetic seismic sections in different dominant frequencies could be numerically simulated, seismic attribute sections（e.g., instantaneous amplitude, instantaneous frequency, and instantaneous phase） extracted, and the correlation between the seismic attributes and bubble volume fraction be quantitatively determined with functional equations. The instantaneous amplitude is positively correlated with bubble volume fraction, while the instantaneous frequency and bubble volume fraction are negatively correlated. In addition, information entropy is introduced as a proxy to quantify the relationship between the instantaneous phase and bubble volume fraction. As the bubble volume fraction increases, the information entropy of the instantaneous phase increases rapidly at the beginning, followed by a slight upward trend, and finally stabilizes. Therefore, under optimal noise conditions, the bubble volume fraction of submarine seep plumes can be inverted and predicted based on seismic response characteristics in terms of seismic attributes.