Explosions recorded underwater offshore of southern California

Sounds from explosions can travel long distances underwater due to their high sound pressure levels, potentially impacting marine life. We evaluated and characterized explosion sounds from underwater recordings to better understand the signature of these sounds, how they propagate in the ocean, and how they may be differentiated for different source types. A controlled experiment using small (∼2 g) “seal bomb” sources at various source-receiver ranges was conducted offshore of southern California to characterize their waveform signature, including bubble pulses due to subsurface explosions ∼4 m depth and peak source level estimate of 234 dB re 1 µPa at 1 m. Opportunistic recordings of missile explosions during military exercises offshore of southern California were made by autonomous hydrophone recorders ∼1000 m deep. The military explosions were presumably at or near the sea surface and did not exhibit bubble pulses, allowing them to be differentiated from fisheries seal bomb sources for manual or automatic signal classification in underwater acoustic recordings.