Normal-Incidence, High-Frequency Bottom Penetration in the Soft Gassy Sediment of Eckernforde Bay, Germany

Normal incidence, high frequency acoustic bottom penetration measurements were made in the gassy sediment of Eckernfoerde Bay, Germany. Measurements were made of water sediment insertion loss and signal level as a function of frequency and hydrophone depth. Results showed that hydrophones located in a gassy sublayer had signal levels that were higher than the signal level at a hydrophone located just below the sediment water interface. This increase in amplitude is attributed to reverberation from free methane bubbles excited near and above their resonant frequency.