DGPS accuracy is 1 to 3 meters (<http://www.navcen.uscg.gov/>). Error in horizontal position is introduced due to uncertainty in the measurement of layback of the seismic source. Overall horizontal accuracy is assumed to be on the order of 5 meters.
Chirp sub-bottom profiles were collected using a dual-frequency (3.5 and 200 kHz) Knudsen Engineering Limited (KEL) Chirp 3200 system. Chirp sub-bottom data with a peak frequency of 3.5 kHz were recorded in SEG-Y format with DGPS navigation logged to the SEG-Y file trace headers. The Chirp system was fired at a rate of 0.25 or 0.5 s. The trace length was set to 67 ms. A total of 80 km of Chirp sub-bottom data were collected.
Sioseis 2008; Seismic Unix 4.1; Proj, 4.6.0
Sioseis 2008; Seismic Unix 4.1; Proj, 4.6.0
Geographix Discovery SeisVision R5000
Geographix Discovery SeisVision R5000
Dynamic Graphics, Inc. EarthVision version 7
ArcGIS 9.2
ArcGIS 9.2
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To utilize these data, the user must have a GIS software package capable of reading ESRI Binary grids or ASCII grids with ESRI headers, or be able to manipulate an ASCII matrix with a geospatial header. The ASCII raster files can be easily converted to ESRI grid format in either ArcView with Spatial Analyst extension (Import Data Source: ASCII Raster) or ArcGIS with Spatial Analyst extension (ASCII to Raster). The user should select floating point grid (as opposed to integer grid) when converting the data.