Citation_Information:

Originator: Karynna Calderon

Originator: Shawn V. Dadisman

Originator: Jack L. Kindinger

Originator: James G. Flocks

Originator: Dana S. Wiese

Publication_Date: 2003

Title:

Archive of Boomer Seismic Reflection Data Collected During USGS Cruise 96CCT01, Nearshore South Central South Carolina Coast, June 26 - July 1, 1996

Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section

Series_Information:

Series_Name: U.S. Geological Survey Open-File Report

Issue_Identification: 03-239

Publication_Information:

Publication_Place: St. Petersburg, FL

Publisher: U.S. Geological Survey

Abstract:

This archive consists of marine seismic reflection profile data collected in four survey areas from southeast of Charleston Harbor to the mouth of the North Edisto River of South Carolina. These data were acquired June 26 - July 1, 1996, aboard the R/V G.K. Gilbert. Included here are data in a variety of formats including binary, American Standard Code for Information Interchange (ASCII), Hyper Text Markup Language (HTML), Portable Document Format (PDF), Rich Text Format (RTF), Graphics Interchange Format (GIF) and Joint Photographic Experts Group (JPEG) images, and shapefiles. Binary data are in Society of Exploration Geophysicists (SEG) SEG-Y format and may be downloaded for further processing or display. Reference maps and GIF images of the profiles may be viewed with a web browser. The Geographic Information Systems (GIS) map documents provided were created with Environmental Systems Research Institute (ESRI) GIS software ArcView 3.2 and 8.1.

Purpose:

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 stratigraphy and in assessing other submarine geologic characteristics and features. These data were collected in cooperation with Coastal Carolina University (CCU) as part of the U.S. Geological Survey (USGS) Coastal Change and Transport (CCT) Project.

Supplemental_Information:

The USGS Center for Coastal and Watershed Studies team in St. Petersburg, Florida, assigns a unique identifier to all seismic data collected during each cruise or field activity. The method used to assign the identifier for the activity is as follows: YYPPP##, where YY stands for the last 2 digits of the year in which the fieldwork is conducted, PPP is a 3-letter abbreviation for the project the data were collected for, and ## is a 2-digit event tag that represents a discreet leg or time period of fieldwork. Here, for example, 96CCT01 tells us the data were collected in 1996 for the Coastal Change and Transport Project and that the data were collected during the first field activity for that project in that calendar year.

Seismic reflection profiles are acquired by means of an acoustic source (usually generated electronically) and hydrophone or receiver arrays. Both elements are typically towed in the water behind a survey vessel. The sound source 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) and detected at the receiver. This process is repeated at intervals ranging between 100 milliseconds (ms) and 1 second (s) depending on the seismic source employed. In this way, a two-dimensional vertical image of the geologic structure beneath the ship track is constructed.

The boomer energy source consists of capacitors that are charged to a high voltage and then discharged through a transducer in the water. The frequency range of the source is between 300 and 3,000 hertz (Hz). The transducer was towed on a sled at the sea surface providing 105 joules per shot. The reflected energy was received by an Innovative Technologies, Inc. (ITI) ST5 streamer and recorded by PC-based Triton Elics Delph Seismic acquisition software. The streamer contains 10 hydrophones, all of which were used. The phones are evenly spaced every 2 feet (0.6 m). The streamer was positioned parallel to the boomer sled and laterally separated from it by about 7 m. The sled was towed about 20 m behind the Global Positioning System (GPS) antenna, and no correction for this offset has been made. The sample frequency of the data was 12 kilohertz (kHz). All tracklines were recorded to 100 ms. Based on survey speeds of 3.5-4 knots and a shot rate of every 0.25 s, the shot spacing was about 0.5 m.

Seismic data were 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 3,200-byte descriptive header that contains detailed information regarding the data acquisition and processing parameters. All data presented here are stored in SEG-Y, integer, Motorola format. The SEG-Y formatted trace data files 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 and .PLN files included are only needed to process or display the data with Triton Elics Delph Seismic software. No SEG-Y data exists for tracklines SC696_12, SC696_13, SC696_14, SB629_19, and SB629_20.

GPS navigation was provided to the acquisition system approximately every 2 seconds by a Rockwell PLGR GPS receiver. The accuracy of this receiver is within about 15 m. The data required some editing to remove spurious data values. The edited results were used to generate the trackline maps presented here. The navigation data have not been corrected to reflect the 20 m offset between the shotpoint and the GPS antenna. Position fixes for every 500 shots and for the start of lines are also provided as an aid for registering of the data after plotting. All navigation files are stored as flat ASCII text files.

The trackline maps provided in this archive are unprojected, set in geographic coordinates, World Geodetic System 1984 (WGS84). They were created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. These JPEG images are viewable with a web browser. Also included on this disc are the ArcView map documents and shapefiles used to create the trackline maps presented here. The map documents are compatible with ArcGIS 8.x (Windows). The shapefiles can also be viewed using ArcView 3.x or public domain software ArcExplorer 2.0 (Windows) and 4.0 (Windows, Mac OSX, Unix, Linux), which can currently be downloaded from the ESRI website at <http://www.esri.com/software/arcexplorer/index.html>.

Field Activity Collection System (FACS) logs are available in both HTML and Rich Text Format. Scanned versions of the handwritten logbooks are provided as PDF files.

Also included on this disc are example Seismic Unix (SU) scripts that allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 500 shots, and produce a filtered and gained GIF image of each profile. These images can then be displayed using a variety of shareware programs such as ImageMagick (Unix, Linux) or a web browser.

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19960626

Ending_Date: 19960701

Currentness_Reference: Data collection interval

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Bounding_Coordinates:

West_Bounding_Coordinate: -80.232900

East_Bounding_Coordinate: -79.797243

North_Bounding_Coordinate: 32.716896

South_Bounding_Coordinate: 32.536945

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: marine seismic reflection

Theme_Keyword: boomer

Theme_Keyword: SEG-Y

Theme_Keyword: 96CCT01

Theme_Keyword: Coastal Change and Transport Project

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: Charleston

Place_Keyword: South Carolina

Place_Keyword: Atlantic Ocean

Place_Keyword: North Edisto River

Place_Keyword: Bohicket Creek

Contact_Information:

Contact_Person_Primary:

Contact_Person: Jack L. Kindinger

Contact_Organization: U.S. Geological Survey

Contact_Position: Oceanographer

Contact_Address:

Address_Type: mailing and physical address

Address: 600 4th Street South

City: St. Petersburg

State_or_Province: FL

Postal_Code: 33701

Country: USA

Contact_Voice_Telephone: 727-803-3747, ext. 3018

Contact_Electronic_Mail_Address: jkindinger@usgs.gov

Browse_Graphic_File_Name: DVD\maps\all.jpg

Browse_Graphic_File_Description:

Trackline map of all boomer seismic reflection data collected during USGS Cruise 96CCT01. These data were collected in four survey areas from southeast of Charleston Harbor to the mouth of the North Edisto River of South Carolina in June and July of 1996. This map is set in geographic coordinates, WGS84 (unprojected) and was created at a scale of 1:250,000. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating the maps presented in this archive. The state and cities layers are ESRI data sets. The roads layer is an ESRI/Geographic Data Technology, Inc. (GDT) data set. The coastline layer is a National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey data set.

Browse_Graphic_File_Type: JPEG

Browse_Graphic_File_Name: DVD\maps\area_a.jpg

Browse_Graphic_File_Description:

Trackline map of boomer seismic reflection data collected in Area A (refer to Area A of the full survey map) of Bohicket Creek and the mouth of the North Edisto River, South Carolina, during USGS Cruise 96CCT01 in June of 1996. This map is set in geographic coordinates, WGS84 (unprojected) and was created at a scale of 1:53,500. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The state and cities layers are ESRI data sets.

Browse_Graphic_File_Type: JPEG

Browse_Graphic_File_Name: DVD\maps\area_b.jpg

Browse_Graphic_File_Description:

Trackline map of boomer seismic reflection data collected in Area B (refer to Area B of the full survey map) of the Atlantic Ocean south of Seabrook and Kiawah Islands, South Carolina, during USGS Cruise 96CCT01 in June of 1996. This map is set in geographic coordinates, WGS84 (unprojected) and was created at a scale of 1:53,500. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The state layer is an ESRI data set. The roads layer is an ESRI/GDT data set.

Browse_Graphic_File_Type: JPEG

Browse_Graphic_File_Name: DVD\maps\area_c.jpg

Browse_Graphic_File_Description:

Trackline map of boomer seismic reflection data collected in Area C (refer to Area C of the full survey map) of the Atlantic Ocean southeast of Kiawah Island, South Carolina, during USGS Cruise 96CCT01 in June and July of 1996. This map is set in geographic coordinates, WGS84 (unprojected) and was created at a scale of 1:53,500. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The state layer is an ESRI data set.

Browse_Graphic_File_Type: JPEG

Browse_Graphic_File_Name: DVD\maps\area_d.jpg

Browse_Graphic_File_Description:

Trackline map of boomer seismic reflection data collected in Area D (refer to Area D of the full survey map) of the Atlantic Ocean southeast of Charleston Harbor and Morris Island, South Carolina, during USGS Cruise 96CCT01 in June of 1996. This map is set in geographic coordinates, WGS84 (unprojected) and was created at a scale of 1:53,500. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The state layer is an ESRI data set.

Browse_Graphic_File_Type: JPEG

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.

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The positional accuracy was determined with a Rockwell PLGR GPS receiver. The accuracy of this receiver is within about 15 m. The GPS string was fed to the Delph Seismic acquisition system approximately every 2 seconds, and navigation fixes were recorded in latitude and longitude in the SEG-Y headers. The sled was towed about 20 m behind the GPS antenna, and no correction for this offset has been made.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

Boomer data are relative to sea level. However, varying recorded static shifts of the data have been known to occur. Therefore, these data are not to be used for bathymetry.

Process_Step:

Process_Description:

Boomer processing: Raw SEG-Y data were processed with Seismic Unix to produce the GIF 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 4) Convert Postscript to GIF format

Process_Date: 2002

Process_Step:

Process_Description:

Positional (navigation) data: As the seismic reflection data were acquired, the position of the vessel was continuously determined by a GPS receiver. Positions were recorded approximately every 2 seconds and written to the SEG-Y header. The ASCII navigation and 500-shot interval navigation files were extracted from the SEG-Y headers using Seismic Unix scripts.

Process_Date: 2003

Process_Step:

Process_Description:

Editing navigation: The ASCII navigation files were extracted from the SEG-Y headers and edited to remove spurious data points. The data were then processed using PROJ.4 freeware to convert latitude and longitude to Zone 17 Universal Transverse Mercator (UTM) coordinates and reformatted for use with ESRI ArcView GIS software. Both sets of coordinates are provided for all lines. ArcView 3.2 was used to create a trackline navigation layer that was used in the final ArcView 8.1 map documents.

Process_Date: 2003

Process_Step:

Process_Description:

Open-file preparation: No processing has been done to the SEG-Y data files provided on this disc. The data were displayed as 8-bit grayscale Postscript files using the Seismic Unix 'psimage' algorithm. The Postscript images were then converted to GIF images.

Process_Date: 2003

Geographic:

Latitude_Resolution: 0.0000027

Longitude_Resolution: 0.0000027

Geographic_Coordinate_Units: decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: WGS84

Ellipsoid_Name: WGS84

Semi-major_Axis: 6378137 m

Denominator_of_Flattening_Ratio: 298.25722

Entity_and_Attribute_Overview:

Binary data file: Each profile is available as a binary file in Society of Exploration Geophysicists (SEG) SEG-Y format. A SEG-Y file consists of 1) a 3,200-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, with one seismic reflection trace per record for boomer data. 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 unitless 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 and range in size from 2.4 to 103.5 MB.

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, n.2, p. 344-352. Also available online at: <http://www.seg.org/publications/tech-stand/index_body.html>.

Entity_and_Attribute_Overview:

Graphic Image File: Each profile is available as a GIF image. These profiles range in size from 4.7 to 15.3 MB. The trackline maps provided are JPEG images that contain hotlinks to the seismic profile GIF images.

Contact_Information:

Contact_Person_Primary:

Contact_Person: Shawn V. Dadisman

Contact_Organization: U.S. Geological Survey

Contact_Position: Geologist

Contact_Address:

Address_Type: mailing and physical address

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.

Although all data 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 this data, software, or related materials.

Digital_Form:

Digital_Transfer_Information:

Format_Name: SEG-Y

Format_Information_Content:

The SEG-Y standard format (Barry et al., 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: No compression applied

Transfer_Size: 1,110 MB

Digital_Transfer_Option:

Offline_Option:

Offline_Media: DVD

Recording_Format: UDF (Universal Disc Format)

Compatibility_Information: UNIX, LINUX, DOS, MAC

Digital_Form:

Digital_Transfer_Information:

Format_Name: ESRI map document, shapefile, metadata

Format_Information_Content:

GIS projects and layers used to create the trackline maps presented in this archive and associated metadata.

File_Decompression_Technique: unzip

Transfer_Size: 41.7 MB

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name: DVD\software\arc\arc.zip

Fees: Available from USGS Information Services. Prices vary.

Ordering_Instructions:

Most open-file reports are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS; email: infoservices@usgs.gov).

Contact_Information:

Contact_Person_Primary:

Contact_Person: Karynna Calderon

Contact_Organization: U.S. Geological Survey

Contact_Position: Geographer, Data Management Group

Contact_Address:

Address_Type: mailing and physical address

Address: 600 4th Street South

City: St. Petersburg

State_or_Province: FL

Postal_Code: 33701

Country: USA

Contact_Voice_Telephone: 727-803-8747, ext. 3143

Contact_Electronic_Mail_Address: kcalderon@usgs.gov