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Earth, Planets and Space
Fig. 1 | Earth, Planets and Space

Fig. 1

From: A new seismic survey technology using underwater speaker detected a low-velocity zone near the seafloor: an implication of methane gas accumulation in Tokyo Bay

Fig. 1

a An example of source wavelet of the air gun (IAGC 2002), which instantly shoots an impulsive wave. b An example of source wavelet of the UWS, which generates a non-impulsive wave for a certain period. c An example of cross-correlated wavelet between the UWS source wave and an observed wave. d The sound pressure levels (SPLs) of the air gun and the UWS. The solid line shows the SPL of the air gun (IAGC 2002). The broken line and dotted line represent the SPLs of the UWS (provided by UETAX Corporation) before and after cross-correlation processing, respectively. SPL1 and SPL2 are the SPLs that harm fish and pose a threat to fish, respectively (Hatakeyama et al. 1997)

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