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

Owing to the strict restrictions on the use of air guns in marine seismic surveys due to concerns about their potential impact on the marine ecosystem, there have been several cases where seismic surveys were not permitted. This tendency has been particularly significant in coastal waters where fishing activity is flourishing, which creates blank zones in seismic surveys. The authors, therefore, adopted underwater speakers as...