Boomer
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The boomer is a broad-band sound source operating in the 300 Hz – 3 kHz range. By sending electrical energy from the power supply through the wire coils (see figure to the right), the two spring loaded plates in the boomer transducer are electrically charged causing the plates to repel, thus generating an acoustic pulse. This system is commonly mounted on a sled (like the yellow runners in the photograph below) and towed behind the boat.Dependant on subsurface material types, resolution of the boomer system ranges from 0.5 to 1 m, penetration from 25 to 50 m. The reflected signal is received by a towed hydrophone streamer.
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System Operation
The Woods Hole Science Center boomer system (300 Hz - 3 kHz) is a high-voltage system and requires a large and heavy power supply to generate the voltages necessary for operation, on the order of 5000 volts. It creates a very stable source signature.As mentioned above, the boomer is mounted on a sled that is towed off the stern or alongside the ship, and is more difficult to deploy than the air guns or the sparker due to its size and weight. The tow configuration somewhat limits the ship’s speed. Also, wave motion can distort the signal.
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| View of boomer being deployed from the starboard side of the ship | Bottom view of the boomer plate attached to the towing sled | View of the boomer being towed behind the ship |
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System Usage
The boomer is often deployed along with other higher-frequency systems in a high-resolution survey to attempt to extend penetration. In very shallow water or a very hard-bottom environment, the boomer is used in a lower power mode to eliminate ‘ringing’ (reverberations, or unwanted multiple reflections) – usually run at 100-175 joules. Boomer sources provide good subbottom records in geologic environments where sands and gravels or glacial deposits are dominant.
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| Boomer data collected in Bear Lake, Idaho, Utah. The bottom surface is a relatively soft lacustrine deposit. Section has been (approximately) depth converted |
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| Boomer data collected on Washington shelf. Vertical scale is in seconds two-way travel time. Archive of SIS-1000, Boomer, and Sparker subbottom data, collected during USGS cruise MCAR 98008 (M#-98-WO) Washington Shelf, 24 June-5 July 1998. |
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| Outer Cape Cod - Interpretive cross section and section of Boomer seismic profile located east of Orleans and Eastham , outer Cape Cod, MA. The unit above the undulating reflector is dominated by fluvial cut-and-fill structures. |
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| Outer Cape Cod - Interpretive cross section and Boomer profile located east of South Wellfleet and North Eastham. The interpretation shows the extent of glaciolacustrine deposits (Qdl). Within this unit there are closely spaced (rhythmic) reflectors. |
References
Foster, D.S. and L.J. Poppe, 2003, High-resolution seismic-reflection surveys in the nearshore of outer Cape Cod, Massachusetts, USGS Open File report 03-235.
Kramer, F.S., Peterson, R.A. and Walter, W.C., eds., 1980, Seismic Energy Sources 1968 Handbook. United Geophysical Corporation, p. 50.
