Chirp

To complement the lower-frequency, higher penetration Boomer profiles, seismic reflection data were also acquired using the University of Southampton’s higher-frequency, lower-penetration Chirp sub-bottom profiler. Consisting of a modified GeoAcoustics digital GeoPulse and 7-element mini-streamer (1.0m long active section), this system produces a swept-frequency (1.5-13.0 kHz), tunable, highly repeatable (99.9%) source waveform 32.74ms in length. Data were recorded using a CODA Octopus acquisition system (version 5.4) as unprocessed SEG-Y files.

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Chirp catamaran on launch boat

During acquisition, the Chirp catamaran was towed in a similar manner to that of the Boomer catamaran; c.5m astern of the launch boat, c.20m astern of the MV Koklimoni. The streamer was towed directly behind the catamaran, using an extension cable to provide source-receiver offsets of order 5m. Due to the weight of the Chirp catamaran and logistical difficulties in deploying it the GPS was not mounted directly onto the catamaran, but was instead mounted onto the launch boat for greater stability and safety, layback correction is therefore applied to the GPS positions.

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Chirp being towed behind launch boat, note GPS system mounted onto launch boat

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