This directory and its subdirectories contain seismic reflection data acquired in 2004 in Eld, Totten, and Budd Inlets of southern Puget Sound. 

The data were collected with a uniboom transducer seismic system powered by a 300 Joule power supply. The data were recorded using an ~8-m, single-channel hydrophone streamer. A PC-based recording system (USGS’ Mudseis system) was used to record the digital data.

Two problems occurred in the data collection. First, the computer only recorded about half of the data. The record length was set to 0.5 sec, but the bottom 0.25 sec are blank. We do not know why this occurred. Second, some of the files seem to be corrupted so that the dynamic range was very limited. This may be that we are reading it in the wrong format – we could not figure it out despite experimenting with a number of things.

The data were processed using the Seismic Unix software package available from the Colorado School of Mines. The data were bandpass filtered, deconvolved, and broken into individual line segments based on changes in the direction of the boat. The individual line segments were then migrated using an f-k (Stolt) migration algorithm and a constant velocity of 1500 m/sec. The “Seismic Unix” directory contains the data in SU format (essentially segy format without the tape headers, and in native floating-point format) and the scripts used to process the data. The scripts contain the processing parameters such as the deconvolution gap length and the filter parameters.

The navigation subdirectory contains R01 files that are recordings of the GPS string, and a navigation file that contains the location at 10-sec intervals. The format of the nav files is:

20040832054101   latitude    longitude
YYYYDDDHHMMSS  = Y=year, D=day of year, H=hour, M=minute, S=second. The final number is 10th of a second. The latitude and longitude are in decimal degrees.

 

The navigation files show the Greenwich mean time; the segy file headers may have local time, which is 8 hours different.