Figure 2 | Scientific Reports

Figure 2

From: Discovery and quantification of a widespread methane ebullition event in a coastal inlet (Baltic Sea) using a novel sonar strategy

Figure 2

Spatial distribution and the diagnostic line pattern in the sonar representation of rising gas bubbles in the water column released from shallow gas in the Eckernförde Bay. (a) Overview of gas seepage locations and individual bubbles (red) in Eckernförde Bay, including the survey lines used for analysis (white). (b) Time-stacked multibeam echosounding (MBES) water-column imaging data showing the distinct pattern of inclined lines indicative of rising gas bubble tracks. The survey speed was <1 knot and the recording was made outside of a pockmark for 2.5 minutes. The fine-tuned sonar survey allowed the detection of Type A single rising gas bubbles; these were seen in most of the echograms and occurred in most parts of the bay. Type B refers to multiple gas bubbles (flares) in the water column; they occurred only in some locations. The quantitative analysis is based on split-beam echosounding (SBES) data on Type A, including single-echo detection for single targets (Methods). (c) Sediment echo-sounding profile crossing both the largest pockmark and the featureless Holocene mud. Note the extensive acoustic turbidity in the direction of the open bay, indicating shallow gas-bearing sediments.

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