Data Acquisition

A Huntec sled and ORE Geopulse power supply (fig. 5) accompanied by a Benthos hydrophone receiver was used during the Erda 90-1 cruise to collect the seismic profiles. The analog boomer data were plotted in real time using an electrostatic plotter. The paper printouts were annotated with shot number, time, environmental conditions, and equipment status. The fire and sweep rate for each line segment was 250 ms and 125 ms, respectively, with a sample rate of 0.2 to 1.4 ms. Navigation data (latitude and longitude) were recorded using a LORAN navigation system and exported as an ASCII text file. The Erda 91-3 geophysical cruise used the same equipment setup as both the 90-1 cruises; however, the sample rate for this survey was 0.3 to 3 ms. The vessel traveled at a speed of about 4 knots (kts) during data acquisition. For each cruise, additional information related to environmental conditions, equipment operation, and trackline details were written into a field logbook. These logs can be accessed from Bosse and others (2017).

Figure 5.  Seismic profiling system and its components. A, transmitter; B, hydrophone receiver; C, power supply; D, electrostatic plotter; and E, processing computer. Photograph from Kindinger and others (1997). [Click figure to enlarge]