A COMPLETE SONAR THUMPER SEISMIC SYSTEM 
by EARL D. VAN REENAN, Senior Geophysicist 
Edgerton, Germeshausen&Grier, Inc. 
Boston, Massachusetts 
ABSTRACT 
A complete continuous seismic pro- 
filing system consists of the Sonar Thumper 
unit, Sonar Recorder, transducer fish, re- 
ceiving hydrophone, preamplifier if necessary 
and variable filter. Sonar Thumper units are 
available from 1,000 watt-sec models up to 
13,000 watt-sec experimental models. Thumpers 
have been extensively used for marine geo- 
logical studies and dredging surveys. The 
safety and economy of the large thumper units 
make them ideal for reconnaissance off- 
shore oil prospecting. 
I. INTRODUCTION 
Major oil companies and off-shore 
seismic contractors often conduct extensive 
seismic surveys which expend as much as 2 tons 
of explosives daily. High explosives generally 
give great reflection penetrations, but they 
are costly and hazardous to use. Several con- 
tinous sub-bottom profiling devices have been 
developed such as the Sparker, Gas Popper, and 
Marine Sonoprobe. These devices have found 
considerable application to limited depth pene- 
tration problems. 
This report describes a complete 
and effective seismic profiling system con- 
sisting of the Sonar Thumper and Sonar Recorder 
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along with all necessary auxiliary equipment. 
The Sonar Thumper is available in the standard 
1,000 watt-sec unit on up to an experimental 
13,000 watt-sec unit. The complete thumper 
seismic system fulfills a need by research 
organizations, educational institutions, and 
government of a safe, simple, effective, and 
inexpensive system for marine geological studies. 
The high power, low frequency pulse generated 
by large thumper units give them a great po- 
Figure l. Sonar Thumper seismic system with 
all necessary auxiliary equipment. 
