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U.S. Geological Survey Data Series 238

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Identification_Information:
Citation:
Citation_Information:
Originator: Karynna Calderon
Originator: Shawn V. Dadisman
Originator: Jack L. Kindinger
Originator: James G. Flocks
Originator: Dana S. Wiese
Originator: Arnell S. Harrison
Publication_Date: 2006
Title:
Archive of Digital Boomer and Chirp Seismic Reflection Data Collected During USGS Cruise 03SCC03 in Lake Pelto and Timbalier and Terrebonne Bays, Louisiana, September 2003
Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section
Series_Information:
Series_Name: U.S. Geological Survey Data Series
Issue_Identification: 238
Publication_Information:
Publication_Place: St. Petersburg, FL
Publisher: U.S. Geological Survey
Description:
Abstract:
In September of 2003, the U.S. Geological Survey conducted geophysical surveys in Lake Pelto, Timbalier Bay, Terrebonne Bay, and nearby waterbodies offshore south-central Louisiana. This report serves as an archive of unprocessed digital boomer and chirp seismic reflection data, trackline maps, navigation files, GIS information, Field Activity Collection System (FACS) logs, observer's logbook, and formal FGDC metadata. Filtered and gained digital images of the seismic profiles are also provided.

The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.

Purpose:
The data archived here were collected as part of the USGS Subsidence and Coastal Change (SCC) study.
Supplemental_Information:
The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 03SCC03 tells us the data were collected in 2003 for the Subsidence and Coastal Change (SCC) study and the data were collected during the third field activity for that study in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the cruise ID. The naming convention used for each seismic line is as follows: yye###a, where yy is the last two digits of the year in which the data were collected, e is a 1-letter abbreviation for the equipment type (for example, b for boomer and c for chirp), ### is a 3-digit number representing a specific track, and a is a letter representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems.

The boomer plate is an acoustic energy source that consists of capacitors charged to a high voltage and discharged through a transducer in the water. The transducer is towed on a sled at the sea surface and when discharged emits a short acoustic pulse, or shot, that propagates through the water and sediment column. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by the receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). In this way, a two-dimensional vertical image of the shallow geologic structure beneath the ship track is produced.

A C-Products C-Boom power supply provided 100 joules per shot. Reflected energy was received by a Benthos MESH streamer and recorded by Triton Elics Delph Seismic acquisition software. The streamer, which was positioned parallel to the boomer sled and laterally separated from it by about 7 m, contains 10 hydrophones evenly spaced about every 30.5 cm (every 12 inches). Refer to figure 1 included with this archive (Data Series 238) for a diagram of acquisition geometry. The sample frequency of the data was 24 kHz. Record length for all tracklines was 100 ms. Based on survey speeds of 3.5-4 knots and a shot rate of every 0.5 s, shot spacing was about 1 m.

The chirp system uses a signal of continuously varying frequency. The sound source and receiver is a towfish, which is typically flown 2-5 m above the seafloor. For each recorded shot of the chirp data, 3 channels of trace data are collected. Channel 3 is the "real," or in-phase component of the signal, channel 2 is the "imaginary," or quadrature component of the signal, and channel 1 is the "envelope," or product of channels 2 and 3. Only channel 1 was used to produce the profiles presented here. However, all channels are included in the SEG-Y data files.

The seismic source employed for chirp data collection consisted of an EdgeTech X-Star SB-424 towfish running Triton Elics Delph Seismic FSSB software. Refer to figure 1 included with this archive (Data Series 238) for a diagram of acquisition geometry. The frequency range was 4-24 kHz, and the sample frequency of the data was 25 kHz. Record length was 30-48 ms. Based on survey speeds of 3.5-4 knots and a shot rate of 0.125 s, shot spacing was about 0.25 m.

The unprocessed seismic data are stored in SEG-Y, integer, Motorola format, which is a standard digital format that can be read and manipulated by most seismic processing software packages (Barry and others, 1975). The SEG-Y formatted trace files have a .TRA extension. Additional recording parameters for each trace file can also be found in the .PAR file associated with each .TRA file. However, the .PAR and .PLN files included here are only needed to process or display the data with Triton Elics Delph Seismic software. The SEG-Y files will not fit on one disc. They are distributed onto two DVDs with the SEG-Y files for chirp lines 03c01-03c47 on disc 1 and the SEG-Y files for all boomer lines (03b48-03b62) and chirp lines 03c48a-03c62 on disc 2.

Also provided are example Seismic Unix scripts that allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 500 shots (boomer) or every 1,000 shots (chirp), and produce a filtered and gained GIF image of each profile.

The printable profiles provided here are GIF images that were filtered and gained using Seismic Unix software. The processed SEG-Y data were exported to Chesapeake Technology, Inc. (CTI) SonarWeb software to produce interactive versions of the profiles that allow the user to obtain a geographic location and depth from the profile for a curser position. This information is displayed in the status bar of the browser. Warning! The only supported web browsers that properly display all features of the interactive profiles are Internet Explorer 6 for Windows and Firefox 1.5 for all platforms. For all browsers, the status bar and JavaScript must be enabled. Firefox also requires "Change status bar text" to be checked under Advanced JavaScript Options. Caution– use of other browsers may result in spurious or no information given in the status window. Firefox may be downloaded at http://www.mozilla.org/products/firefox.

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20030906
Ending_Date: 20030911
Currentness_Reference: Data collection interval
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -90.787076
East_Bounding_Coordinate: -90.295770
North_Bounding_Coordinate: 29.259299
South_Bounding_Coordinate: 29.038281
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: marine seismic reflection
Theme_Keyword: boomer
Theme_Keyword: chirp
Theme_Keyword: SEG-Y
Theme_Keyword: 03SCC03
Theme_Keyword: Subsidence and Coastal Change
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Louisiana
Place_Keyword: Lake Pelto
Place_Keyword: Whiskey Pass
Place_Keyword: Old Camp Pass
Place_Keyword: Bay Blanc
Place_Keyword: Bodwin Cutoff
Place_Keyword: Lake Raccourci
Place_Keyword: Pelican Pass
Place_Keyword: Timbalier Bay
Place_Keyword: Lake Barre
Place_Keyword: Jacko Bay
Place_Keyword: Terrebonne Bay
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
The U.S. Geological Survey requests to be acknowledged as the originator of the data in future products or derivative research.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jack Kindinger
Contact_Organization: U.S. Geological Survey
Contact_Position: Oceanographer
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3018
Contact_Electronic_Mail_Address: jkindinger@usgs.gov
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/boomer.jpg
Browse_Graphic_File_Description:
Trackline map of all digital boomer seismic reflection data collected during USGS Cruise 03SCC03. This map was created at a scale of 1:230,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp.jpg
Browse_Graphic_File_Description:
Trackline map of all digital chirp seismic reflection data collected during USGS Cruise 03SCC03. This map was created at a scale of 1:230,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp_a.jpg
Browse_Graphic_File_Description:
Trackline map of digital chirp seismic reflection data collected in Area A (refer to Area A of the chirp map) during USGS Cruise 03SCC03. This map was created at a scale of 1:110,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp_a1.jpg
Browse_Graphic_File_Description:
Trackline map of digital chirp seismic reflection data collected in Area A1 (refer to Area A1 of the chirp Area A map) during USGS Cruise 03SCC03. This map was created at a scale of 1:15,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp_a2.jpg
Browse_Graphic_File_Description:
Trackline map of digital chirp seismic reflection data collected in Area A2 (refer to Area A2 of the chirp Area A map) during USGS Cruise 03SCC03. This map was created at a scale of 1:15,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp_a3.jpg
Browse_Graphic_File_Description:
Trackline map of digital chirp seismic reflection data collected in Area A3 (refer to Area A3 of the chirp Area A map) during USGS Cruise 03SCC03. This map was created at a scale of 1:15,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/cruisenav/chirp_b.jpg
Browse_Graphic_File_Description:
Trackline map of digital chirp seismic reflection data collected in Area B (refer to Area B of the chirp map) during USGS Cruise 03SCC03. This map was created at a scale of 1:110,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Data_Set_Credit:
Funding for this study was provided by the USGS Coastal and Marine Geology Program. We thank R/V G.K. Gilbert captain Dave Bennett of Eckerd College for his assistance in data collection. This document was improved by the reviews of Karen L.M. Morgan of the USGS Florida Integrated Science Center - St. Petersburg and Kathryn E.L. Smith of the USGS National Wetlands Research Center in Lafayette, Louisiana.

Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
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. The coastline layer used to create the trackline maps includes swamps and shallow, sandy areas exposed at low tide. For this reason, the tracklines sometimes appear to traverse land.
Logical_Consistency_Report:
This data set is from one cruise with consistent instrument calibrations.
Completeness_Report:
These data are collected along tracklines (2-D) and are therefore inherently incomplete. Geologic details between lines must be inferred. No data were collected for lines 03b01 - 03b47. Only the upper 50 ms of a total 100 ms are displayed on the printable boomer profiles because little useful information was observed deeper in the sections. For the same reason, only the upper 20 ms of a total 30-48 ms are displayed on the printable chirp profiles. Navigation is intermittent for lines 03c56a and 03c56b. On the trackline maps, missing navigation data within a line is inferred by linear interpolation of the first and last known data points and is represented by a dashed yellow line.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
As the seismic reflection data were acquired, the position of the vessel was continuously determined by a CSI Wireless DGPS Max receiver, which is accurate within 3-5 m. Positions were recorded and written to the trace headers in Zone 15 UTMs about every 1 s. The ASCII navigation files and trackline maps have not been corrected to reflect the approximately 20-m offset between the boomer midpoint and GPS antenna or the roughly 6-m offset between the chirp and GPS antenna. Refer to figure 1 included with this archive (Data Series 238) for a diagram of acquisition geometry. Line navigation maps and interactive profiles generated with CTI SonarWeb software have been corrected for the GPS offset.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
These data are not to be used for bathymetry. Boomer data are relative to sea level. However, varying recorded static shifts of the data have been known to occur. Depths shown on the chirp profiles are relative to the depth of the towfish, not to sea level. Furthermore, the raising or lowering of the towfish during a survey (to avoid obstacles or follow relief) produces a relative shift in the multiple reflections seen in the profile, which may be confused as a geologic feature. Any elevation change of the towfish is recorded in the logbooks and is evident on the seismic profiles by steep, abrupt shifts in the seafloor return.
Lineage:
Process_Step:
Process_Description:
Boomer and chirp processing: The original trace files for lines 03c48-03c50, 03c52, and 03c54-03c61 were divided into two or more trace files each (for example, 03c48 became 03c48a and 03c48b) because the original total number of traces exceeded the maximum allowed by the processing software. Original line 03c56a was renamed 03c56c. The SEG-Y data were processed with Seismic Unix to produce GIF images of the seismic profiles included in this report. A representative boomer processing sequence consisted of 1) bandpass filtering: 300-500-2500-3000 Hz, 2) applying automatic gain control, 3) displaying PostScript, and 4) converting PostScript image to GIF image. A representative chirp data processing sequence consisted of 1) stripping off channel 1 for each shot and converting to SU format, 2) applying automatic gain control, 3) displaying PostScript, and 4) converting PostScript image to a GIF image. The processed SEG-Y data were then exported to CTI SonarWeb software to produce an interactive version of each profile that allows the user to obtain a geographic location and depth from the profile for a cursor position. Refer to the Supplemental Information section above for details on how to use the interactive profiles.
Process_Date: 2004
Process_Step:
Process_Description:
Navigation processing: Shotpoint navigation files and 500- or 1,000-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software. These files were processed with PROJ.4 software (http://www.remotesensing.org/proj) to generate latitude and longitude from Zone 15 UTMs and reformatted for use with Environmental Systems Research Institute (ESRI) GIS software.
Process_Date: 2004
Process_Step:
Process_Description:
Trackline map creation: The trackline maps provided in this archive were created using ESRI ArcView 3.3 and ArcGIS 8.3 software, exported to Adobe Illustrator for further editing, and saved in JPEG format. The maps are unprojected (geographic coordinates, NAD83). The USGS is the originator of all layers except for the Louisiana water bodies layer, which is a Louisiana Oil Spill Coordinator's Office/ESRI/Geographic Data Technology, Inc. data set. A map of trackline navigation for each seismic profile was also produced with CTI SonarWeb software.
Process_Date: 2004
Process_Step:
Process_Description:
Data Series preparation: In addition to the process steps described above, the following steps were taken to produce this Data Series: the handwritten logbooks were scanned and saved as PDF files, digital FACS logs were created using the handwritten logs and personal accounts of the crew members and saved as PDF files, and an HTML-based format was used to present the various parts of this archive.
Process_Date: 2004

Spatial_Data_Organization_Information:
Indirect_Spatial_Reference:
Horizontal X and Y locations (latitude and longitude and UTMs) for each shot are provided as ASCII text files, along with the date and time (UTC) the shot was recorded.

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.000009
Longitude_Resolution: 0.000009
Geographic_Coordinate_Units: decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: WGS84
Ellipsoid_Name: WGS84
Semi-major_Axis: 6378137
Denominator_of_Flattening_Ratio: 298.257

Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Binary data file: Trace data are available as binary files in SEG-Y format. These files have a .TRA extension and range in size from 4.5 to 46.7 MB (boomer) and 12 to 141 MB (chirp).
Entity_and_Attribute_Detail_Citation:
Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, no. 2, p. 344-352. Also available online at http://www.seg.org/publications/tech-stand.
Entity_and_Attribute_Detail_Citation:
Zihlman, F.N., 1992, DUMPSEGY V1.0: A program to examine the contents of SEG-Y disk-image seismic data: U.S. Geological Survey Open-File Report 92-590, 28 p. Also available online at http://pubs.er.usgs.gov/usgspubs/ofr/ofr92590.
Entity_and_Attribute_Overview:
Graphic image file: Printable profiles are GIF images that range in size from 171 KB to 2.78 MB. Interactive profiles are HTML pages that range in size from 25.8 KB - 1.4 MB. Accompanying JPEG images range in size from 419 KB to 13.8 MB. Line navigation maps are JPEG images that range in size from 57.1 to 211 KB. Trackline maps, which range in size from 121 to 412 KB, are JPEG images that contain links to the seismic profiles and line navigation maps.
Entity_and_Attribute_Overview:
Navigation file: Navigation files are available as ASCII text files. Raw (unprocessed) navigation files range in size from 7.9 to 205 KB, processed navigation files range in size from 2.4 to 5.9 MB, and processed 500- or 1,000-shot-interval location files range in size from 13.3 to 51.5 KB.
Entity_and_Attribute_Overview:
GIS file: The GIS project used to create the trackline maps is provided as a zip file composed of ESRI map documents, shapefiles, and metadata. Map documents range in size from 490 to 624 KB, and shapefiles range in size from 2.6 KB to 29 MB.

Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Shawn Dadisman
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3029
Contact_Electronic_Mail_Address: sdadisman@usgs.gov
Contact_Instructions:
Data may be available on-line only by special arrangement with the distributor above.
Resource_Description: U.S. Geological Survey Data Series 238
Distribution_Liability:
This DVD 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 makes 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 by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

Although all data and software published on this DVD 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 these data, software, or related materials.

Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: SEG-Y
Format_Information_Content:
The SEG-Y standard format (Barry and others, 1975) consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which include information specific to line and reel number; a trace data block that follows the reel identification header, with the first 240 bytes of each trace block consisting of the binary trace identification header; and seismic data samples that follow the trace identification header.
File_Decompression_Technique: None
Transfer_Size: 5,890 MB
Digital_Transfer_Option:
Offline_Option:
Offline_Media: DVD
Recording_Format: ISO 9660
Compatibility_Information: UNIX, LINUX, DOS, Macintosh
Digital_Form:
Digital_Transfer_Information:
Format_Name: map document, shapefile, metadata
Format_Information_Content:
The GIS project used to create the trackline maps is composed of map documents, shapefiles, and metadata. The map documents were created using ESRI ArcGIS 8.3 software. The shapefiles provided may also be viewed using other versions of ArcView, ArcGIS, or public domain software ArcExplorer, available from the ESRI website at http://www.esri.com/software/arcexplorer/index.html.
File_Decompression_Technique: unzip
Transfer_Size: 21.4 MB
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: DVD/software/arc/arc.zip
Fees:
Prices vary.
Ordering_Instructions:
Publications are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS, e-mail: infoservices@usgs.gov).
Technical_Prerequisites:
Use of SEG-Y data requires specialized seismic processing software, such as public domain software Seismic Unix (http://www.cwp.mines.edu/cwpcodes/index.html).

Metadata_Reference_Information:
Metadata_Date: 20061127
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell Harrison
Contact_Organization: ETI, contracted by USGS
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3111
Contact_Electronic_Mail_Address: aharrison@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998