Gina M. Brewer
Shawn V. Dadisman
James G. Flocks
Dana S. Weise
Jeffrey B. Davis
2001
Archive of Boomer Seismic Reflection Data Collected on USGS Cruise 99LCA01, Crescent Beach Spring, Florida, 26 April - 27 April, 1999.
Seismic Reflection Profile Section
U.S. Geological Survey Open-File Report
01-355
St. Petersburg, FL
U.S. Geological Survey
http://pubs.usgs.gov/of/2001/of01-355/
This report consists of two-dimensional marine seismic reflection profile data from Crescent Beach Spring, Florida.
These data were acquired in April of 1999 with the Research Vessel G.K. Gilbert. The data are available in a variety of formats, including binary, ASCII, HTML, and GIF images. Binary data are in Society of Exploration Geophysicists (SEG) SEG-Y format and may be downloaded for further processing or display. Trackline maps and GIF images of the profiles may be viewed with your WWW browser.
For more information on the seismic surveys see http://walrus.wr.usgs.gov/infobank/g/g199fl/html/g-1-99-fl.meta.html
These data are also available via GeoMapApp (http://www.geomapapp.org/) and Virtual Ocean ( http://www.virtualocean.org/) earth science exploration and visualization applications.
Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data are useful in mapping the extent, the subsurface structure of the spring, the depths to various stratigraphic horizons, and in assessing other submarine geologic characteristics and features near Crescent Beach Spring.
Seismic reflection profiles are acquired by means of an acoustic source (usually generated electronically), and a hydrophone or hydrophone array. Both elements are typically towed in the water behind a survey vessel. The sound source emits a short acoustic pulse, which propagates through the water and sediment columns. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), and detected at the hydrophone. This process is repeated at intervals ranging between 100 ms and 1 s depending on the source type. In this way a two-dimensional image of the geologic structure beneath the ship track is constructed. Seismic data are stored in SEG-Y format, which is a standard digital format that can be read and manipulated by most seismic-processing software packages. The SEG-Y file format includes a 3200-byte descriptive header that contains detailed information regarding the data acquisition and processing parameters. All the data presented in this report are stored in SEG-Y, integer, Motorola format. The SEG-Y formatted trace data files are located in the SEGY folder at the top level of this disc and have a .tra extension. Additional recording parameters for each seismic data file can also be found in the .par file associated with each .tra file. However, the .par files and the trim_gga.pln file are only needed to replay the data with Triton Elics Delph Seismic software. WARNING: In order to comply with ISO 9660 naming standards tracklines d118_1806, d118_1812, and d118_1840 have been changed to d1806, d1812, and d1840 respectively on the trackline maps, navigation files, and the SEG-Y data files. The seismic source employed here was a boomer transducer towed on a sled at the sea surface providing 100 joules per shot. The reflected energy was received by an Innovative Transducer Inc.(ITI) solid core streamer and recorded by PC-based Triton-Elics Delph Seismic acquisition software. The ITI streamer contains 10 hydrophones evenly spaced over 6 meters however only data received by elements 5-8 where summed, resulting in a higher signal to noise ratio for the data. The streamer was positioned parallel to the boomer sled and laterally separated from it by 7 m. The sled was towed 20 m behind the GPS antennae. The sample frequency of the data was 16000 Hz and the total record length was 100 ms, except for lines d118_12 and d118_1840 which were recorded to 200 ms. The fire rate was every 0.5 sec, which resulted in a shot spacing of about 1 m based on survey speeds of 3.5-4 knots. GPS navigation was provided by a Trimble Centurian P-Code receiver directly fed to the acquisition system every second. The accuracy of this receiver is within 15 m. However, the SEG-Y format only allows for seconds of arc which is equivalent to 31 m. The shotpoint navigation provided in this report has not been corrected to reflect the 20 m offset of the source to the GPS antenna. All navigation data are stored in flat ASCII files containing latitude and longitude values that can be used to plot trackline maps of the seismic profiles at any scale or map projection desired. The trackline maps provided on this disc are geographic projections (no datum), and were created with ESRI's GIS software ArcView 3.2, exported to Adobe Illustrator and then saved as a GIF images. The images are viewable with your WWW browser. Also provided on this CD-ROM are Seismic Unix (SU) scripts that allow the user to strip off navigation fixes from the SEG-Y headers along with a fix for every 500th shot. The seismic data is then converted to SU format, filtered, gained and both Postscript and GIF formatted images are produced. These images can them be displayed using a variety of shareware programs such as ghostview (Unix, Linux, MAC, Windows), kview (Linux), or a web browser.
19990426
19990427
Data assumed to be consistent over time but may change due to geologic processes.
None Planned
-80.21 W
-80.20 W
+29.77 N
+29.75 N
USGS Metadata Identifier
USGS:e4277494-d38c-44f0-8045-7403b9583b9f
none
marine seismic reflection
boomer
99LCA01
ISO 9660 CD-ROM
SEG-Y
Data Categories for Marine Planning
distributions
substrate
Marine Realms Information Bank (MRIB) Keywords
seismic reflection
marine geophysics
USGS Thesaurus
seismic reflection methods
sub-bottom profiling
marine geophysics
none
Crescent Beach Spring
Florida
Anastasia Island
Crescent Beach
None. These data are held in the public domain.
The U.S. Geological Survey ask to be acknowledged as the originator of the data in future products or derivative research.
James G. Flocks
U.S. Geological Survey
Geologist
mailing address
600 Fourth Street South
St. Petersburg
FL
33701
USA
(727) 803-8747 X3012
jflocks@usgs.gov
http://pubs.usgs.gov/of/2001/of01-355/MAPS/alllines.GIF
Map of trackline data collected on USGS cruise 99LCA01 in April of 1999, in Crescent Beach Spring, off the coast of Florida. This map is a geographic projection (no datum), which was created in ESRI's GIS software ArcView 3.2. It was then exported to Adobe Illustrator for further editing, and saved as a GIF image.
gif
http://pubs.usgs.gov/of/2001/of01-355/MAPS/ln1_9.GIF
A geographic projection of a trackline map, created in ArcView, and displaying data for tracklines cres1-9, collected during USGS cruise 99LCA01 at Crescent Beach Spring, Fla. This map also contains every 500th shotpoint position information.
gif
http://pubs.usgs.gov/of/2001/of01-355/MAPS/ln10_14.GIF
A geographic projection of a trackline map, created in ArcView, and displaying data for tracklines cres10-14, collected during USGS cruise 99LCA01 at Crescent Beach Spring, Fla. This map also contains every 500th shotpoint position information.
gif
http://pubs.usgs.gov/of/2001/of01-355/MAPS/15_1806.GIF
A geographic projection of a trackline map, created in ArcView, and displaying data for tracklines cres15, cres16, cres16b, and d1806, collected during USGS cruise 99LCA01 at Crescent Beach Spring, Fla. This map also contains every 500th shotpoint position information.
gif
http://pubs.usgs.gov/of/2001/of01-355/MAPS/1812_40.GIF
A geographic projection of a trackline map, created in ArcView, and displaying data for tracklines d1812 and d1840, collected during USGS cruise 99LCA01 at Crescent Beach Spring, Fla. This map also contains every 500th shotpoint position information.
gif
This work was partially funded by the St. John's River Water Management District located in Palatka, Fla. We thank Rich Young, captain of the R/V G.K. Gilbert for his help in the data collection; Dave Foster and Jenna Hill, of the USGS Seafloor Mapping Group in Woods Hole, Mass. for providing examples of their archives; Jon Childs with the USGS in Menlo Park, Calif. who provided examples of his formal metadata; Trent Faust and Rob Wertz with the USGS in St. Petersburg, Fla. for their help in the web design and technical layout of the CD-ROM; and Jack Kindinger and Peter Swarzenski also with the USGS in St. Petersburg, Fla. for their technical and editorial reviews.
SEG-Y
The validity or accuracy of marine seismic reflection profiles is highly qualitative, and depends on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show any major anomalies, with the exception of an added 6 ms to the top of each record that was detected on future data sets.
This data set is from a single cruise with consistent instrument calibrations.
These data are collected along tracklines (2D). Therefore, data are inherently incomplete. Geologic details between lines must be inferred. Tracklines cres1-16, and d1806 were recorded to 100 ms, and lines d1812 and d1840 were recorded to 200 ms.
The position accuracy was determined with Trimble Centurian P-Code Receiver. This receiver's accuracy is within 15 m. However, the SEG-Y format only allows for seconds of arc which is equivalent to 31 m.
The vertical position was local sea level and there has been no corrections to a datum or for tidal variations. However, future data collected with this same system have shown that up to 6 ms has been added to the top of each record.
Boomer processing Raw SEG-Y data was processed with Seismic Unix (SU) and (Triton Elics Software) to produce the GIF formatted seismic profiles included in this report. A representative data processing sequence consisted of: 1)Bandpass filter: 300-500-2500-3000 Hz; 2)Automatic gain control; 3)Postscript display at 50 ms/in and 300 shots/in 4)Convert Postscripts to GIF format
2001
Positional (navigation) data As the seismic reflection data were acquired, the position of the vessel was continuously determined with the Global Positioning System (GPS). GPS positions were recorded approximately every second, and written to the SEG-Y header. The ASCII navigation files were extracted from the SEG-Y headers using SU scripts.
2001
Editing Navigation The ASCII navigation files were extracted from the SEG-Y headers, and then run through a filter to edit out the spurious fixes. The filtered data was also reformatted for use with ESRI's GIS software ArcView 3.2
2001
Open File preparation: No processing has been done to the SEG-Y data files provided on this CD-ROM. The data were displayed as 8-bit gray scale Postscript files using the Seismic Unix 'psimage' algorithm. The Postscript images were then converted to GIF images with Aladdin Ghostscript. Only the GIF images are presented here.
2001
Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.
20170124
U.S. Geological Survey
Alan O. Allwardt
Contractor -- Information Specialist
mailing and physical address
2885 Mission Street
Santa Cruz
CA
95060
831-460-7551
831-427-4748
aallwardt@usgs.gov
Added keywords section with USGS persistent identifier as theme keyword.
20201013
U.S. Geological Survey
VeeAnn A. Cross
Marine Geologist
Mailing and Physical
384 Woods Hole Road
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
Horizontal X and Y locations for each shot location are provided in ASCII position files, along with the time the shot was recorded in Greenwich Mean Time (GMT).
Point
0.000001
0.000001
Decimal degrees
WGS 84
WGS 84
6378137 m
298.257
Binary data file: Each profile is available as a binary file in Society of Exploration Geophysicists SEG-Y format. A SEG-Y file consists of 1) a 3200-byte file identification record of ASCII formatted general information; 2) a 400-byte binary record with information such as sample rate and record length specific to the data set; and 3) multiple records, one seismic reflection trace per record. Each trace record is preceded by a 240-byte "trace header" containing information such as trace number and acquisition day and time specific to each trace. The trace data are represented as a time series of unit less 16-bit integer or 32-bit real numbers proportional to the reflection coefficient. The SEG-Y file is useful only if you have access to specialized software designed to process and display seismic reflection data. These SEG-Y files have a .tra extension. These .tra files range in size from 2.3 MB to 60 MB.
Graphic image file: Each profile is available as a GIF image. The trackline maps provided are GIF images that contain hot-links to the seismic profile GIF images. The profiles range in size from 84KB to 1.3MB.
Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, n. 2, p. 344 - 352. Also available online at:<http://www.seg.org/publications/tech-stand/index_body.HTMl>
Rob Wertz
U.S. Geological Survey
Manager, Data Management Group
mailing address
600 Fourth Street South
St. Petersburg
FL
33701
USA
(727) 803-8747 X3045
rwertz@usgs.gov
Data may be available on-line only by special arrangement with the distributor above.
U.S. Geological Survey Open-File Report 01-XXX CD-ROM
This Compact Disc-Read Only Memory (CD-ROM) publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.
SEG-Y
The SEG-Y standard format (Barry and others, 1975) consists of the following: A 3600-byte reel identification header with the first 3200 bytes consisting of a EBCDIC header block and a 400-byte binary header block. Both headers include information specific to line and reel number. The trace data block follows the reel identification header. The first 240 bytes of each trace block is the binary trace identification header. The seismic data samples follow the trace identification header.
none
650
CD-ROM
ISO 9660
Unix, Linux, DOS, MAC
SEGY data download
The SEG-Y standard format (Barry and others, 1975) consists of the following: A 3600-byte reel identification header with the first 3200 bytes consisting of a EBCDIC header block and a 400-byte binary header block. Both headers include information specific to line and reel number. The trace data block follows the reel identification header. The first 240 bytes of each trace block is the binary trace identification header. The seismic data samples follow the trace identification header.
none
650
http://cmgds.marine.usgs.gov/data/99lca01/boomer/
available from the Denver Open-File Sales Department, prices vary.
Most open-file reports are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225 (telephone: 303-202-4210; e-mail: infoservices@usgs.gov).
Use of SEG-Y data requires specialized seismic processing software, such as Unix or Linux based public domain software Seismic Unix developed by the Colorado School Of Mines Center for Wave Phenomena, which can be downloaded from <http://www.cwp.mines.edu/cwpcodes> free of charge.
20201013
Gina M. Brewer
U.S. Geological Survey
Geologist, Data Management Group
mailing address
600 Fourth Street South
St. Petersburg
FL
33701
USA
(727) 803-8747 X3120
gmbrewer@usgs.gov
Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998