USGS - science for a changing world

U.S. Geological Survey Data Series 420

FGDC Metadata


Home | Acronyms | Contents | Navigation | Profiles | Logs | Metadata | Software



Identification_Information:
Citation:
Citation_Information:
Originator: Arnell S. Harrison
Originator: Shawn V. Dadisman
Originator: W. Scott McBride
Originator: James G. Flocks
Originator: Dana S. Wiese
Publication_Date: 2009
Title:
Archive of Digital Boomer and CHIRP Seismic Reflection Data Collected During USGS Field Activity 08LCA03 in Lake Panasoffkee, Florida, May 2008
Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section
Series_Information:
Series_Name: U.S. Geological Survey Data Series
Issue_Identification: 420
Publication_Information:
Publication_Place: St. Petersburg, FL
Publisher: U.S. Geological Survey
Description:
Abstract:
From May 13 to May 14 of 2008, the U.S. Geological Survey conducted geophysical surveys in Lake Panasoffkee, Florida. Thisreport serves as an archive of unprocessed digital boomer and CHIRP seismic reflection data, trackline maps, navigation files, GIS information, FACS logs, and formal FGDC metadata. Filtered and (or) 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 Lakes and Coastal Aquifers (LCA) study.
Supplemental_Information:
The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 08LCA03 tells us the data were collected in 2008 for the Lakes and Coastal Aquifers (LCA) 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 or field activity ID. The naming convention used for each seismic line is as follows: yye##a, where 'yy' are 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 2-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, sediment column, or rock beneath. The acoustic energy is reflected at density boundaries (such as the seafloor, sediment, or rock 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 (2-D) vertical image of the shallow geologic structure beneath the ship track is produced.

A C-Products C-Boom Low Voltage Boomer System contained a power supply, which provided 100 J per shot. Reflected energy was received by a Teledyne Instruments SDS-55 array and recorded by Chesapeake Technology, Inc. (CTI) SonarWiz.SBP and Triton Elics Delph Seismic v. 2.7 acquisition software. Lines 08b01 - 08b07 were collected using SonarWiz software, and all associated SEG-Y files have a .sgy file extension extension; lines 08b09 - 08b19 used Delph Seismic and have a .tra extension. The streamer contains 10 hydrophones evenly spaced every 1.5 m. During data acquisition, all phones were used. The streamer was positioned approximately 8 m behind the research vessel and laterally separated from the boomer sled by about 3 m. Refer to figures 1 and 2 included with this archive (Data Series 420) for a diagram of the acquisition geometries. The sample frequency of the data was 20 kHz, and record length was 100 ms. Based on survey speeds of approximately 2.5 knots and a shot rate of every 0.500 s, shot spacing was about 0.6425 m.

The CHIRP system uses a signal of continuously varying frequency. The towfish is a sound source and receiver, which is typically towed 2 - 5 m above the seafloor. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by a receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.125 s) and recorded for specific intervals of time (for example, 50 ms). Likewise, the resulting profiles are two-dimensional vertical images of the shallow geologic structure beneath the ship track.

The seismic source employed for CHIRP data collection consisted of an EdgeTech SB-424 towfish running Triton Imaging SB Logger (FSSB) v. 1.6.421 acquisition software and towed about 3 m behind the GPS antenna. The CHIRP SEG-Y data files have a .sgy file extension. The frequency range for line 08c01 was between 4 and 16 kHz and 4 and 24 kHz for line 08c02. Sample frequency of the data was 25 kHz, the shot rate was every 0.250 s, and the record length was approximately 50 ms. Shot spacing was approximately 0.3213 m.

For each recorded shot of the CHIRP data, three channels of trace data are collected. Channel 2 is the "real," or in-phase component of the signal, channel 1 is the "imaginary," or quadrature component of the signal, and channel 0 is the "envelope," or product of channels 1 and 2. Only channel 0 was used to produce the profiles presented here. However, all channels are included in the SEG-Y data files.

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 .sgy or .tra extension. Additional recording parameters for each trace file can also be found in the .par file associated with each boomer .tra file. However, the .par files included here are only needed to process or display the data with Delph Seismic software. 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 or 1000 shots, and produce a filtered and (or) gained GIF image of each profile.

The printable profiles provided here are GIF images that were filtered and (or) gained using Seismic Unix software. The processed SEG-Y data were exported to Chesapeake Technology, Inc. (CTI) SonarWeb software to produce interactive profiles that allow the user to obtain a geographic location and depth for a cursor position on the profile. This information is displayed in the status bar of the browser. NOTE: The only supported Web browsers that properly display all features of the interactive profiles are Internet Explorer 6 or greater for Windows and Firefox 1.5 or greater 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. If using Internet Explorer 7, you must disable Active Content/Active X controls. To do this, right-click the information bar (found at the top of the page), left-click "Allow Blocked Content...", and then select "Yes." 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: 20080513
Ending_Date: 20080514
Currentness_Reference: Data collection interval
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -82.141740
East_Bounding_Coordinate: -82.098478
North_Bounding_Coordinate: 28.826330
South_Bounding_Coordinate: 28.757145
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: Marine seismic reflection
Theme_Keyword: Boomer
Theme_Keyword: CHIRP
Theme_Keyword: SEG-Y
Theme_Keyword: 08LCA03
Theme_Keyword: Lakes and Coastal Aquifers
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Florida
Place_Keyword: Lake Panasoffkee
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
The U.S. Geological Survey requests to be acknowledged as originator of the data in future products or derivative research.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: W. Scott McBride
Contact_Organization: USGS
Contact_Position: Hydrologist
Contact_Address:
Address_Type: mailing and physical
Address: 10500 University Center Drive, Suite 215
City: Tampa
State_or_Province: FL
Postal_Code: 33612
Country: USA
Contact_Voice_Telephone: (813) 975-8620
Contact_Electronic_Mail_Address:wmcbride@usgs.gov
Browse_Graphic:
Browse_Graphic_File_Name: CD/maps/cruisenav/08lca03_location.jpg
Browse_Graphic_File_Description:
Location map of all digital boomer and CHIRP seismic reflection data collected during USGS field activity 08LCA03. This map was created at a scale of 1:263,700. Refer to the Lineage section below for the trackline map creation process and other details.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: CD/maps/cruisenav/08lca03_panasoffkee.jpg
Browse_Graphic_File_Description:
Trackline map of digital boomer and CHIRP seismic reflection data collected in Lake Panasoffkee (refer to Lake Panasoffkee area on the location map) during USGS field activity 08LCA03. This map was created at a scale of 1:42,000.
Browse_Graphic_File_Type: JPEG
Data_Set_Credit:
Funding for this study was provided by the USGS Water Resources Discipline and Coastal and Marine Geology Program. This document was improved by the reviews of Jordan Sanford (USGS) and Xan Yates (Jacobs Technology Inc.) at the FISC - St. Petersburg, FL.

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; however, no data were collected for trackline 08b08, so no data exist for this line in this archive.
Logical_Consistency_Report:
This data set is from one field activity 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.
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 Garmin GPS 18 WAAS receiver, which is accurate within 3 - 5 m. Positions were recorded and written to the trace headers in latitude and longitude coordinates about every 1 s. NOTE: A mechanical malfunction caused the recording of duplicate navigation points for each navigation fix during data collection of lines 08b05 - 08b07; repetitive trackline data are listed for each line. The ASCII navigation files and trackline maps have not been corrected to reflect the approximately 8-m offset between the boomer and GPS antenna and about 4-m offset between the CHIRP and GPS antenna. Refer to figures 1 and 2 included with this archive for a diagram of the acquisition geometries, including the GPS offset measurements. 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 boomer and CHIRP data are relative to lake level. However, varying recorded static shifts of the data have been known to occur. Therefore, these data are not to be used for bathymetry. Depths shown on the CHIRP profiles are relative to the depth of the towfish, not to lake level.
Lineage:
Process_Step:
Process_Description:
Boomer processing: 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) running a bandpass filter of 300-500-2500-3000 Hz, (2) applying a scalar and automatic gain control, (3) displaying PostScript, and (4) converting of PostScript image to a GIF image.

CHIRP processing: The SEG-Y data were also processed with Seismic Unix to produce GIF images of the seismic profiles included in this report. A representative CHIRP data processing sequence consisted of (1) stripping off channel 0 for each shot and converting to SU format, (2) applying automatic gain control, (3) displaying PostScript, and (4) converting of PostScript image to a GIF image.

All 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: 2008
Process_Step:
Process_Description:
Navigation processing: Shotpoint navigation files, 500-shot-interval location files, and 1000-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software. These files were then processed with PROJ.4 software (http://trac.osgeo.org/proj/) to generate UTM coordinates from latitude and longitude coordinates and reformatted for use with Environmental Systems Research Institute (ESRI) GIS software.
Process_Date: 2008
Process_Step:
Process_Description:
Trackline map creation: The trackline maps provided in this archive were created using the Points to Lines ArcScript (D. Rathert, http://arcscripts.esri.com/details.asp?dbid=12702) along with ESRI ArcGIS 9.2 software and then exported to Adobe Illustrator for further editing. The maps were later converted into JPEG format by Adobe GoLive. The maps are unprojected (geographic coordinates, NAD83). The florida_cities, florida_interstates, and florida_roads layers used on the trackline maps were created by the Florida Division of Emergency, U.S. Census Bureau, and Geographic Data Technology, respectively. The USGS is the originator of all other layers used. A map of trackline navigation for each seismic profile was also produced with CTI SonarWeb software.
Process_Date: 2008
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 logs 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: 2008

Spatial_Data_Organization_Information:
Indirect_Spatial_Reference:
Horizontal X and Y locations (latitude and longitude coordinates and Zone 17 UTM coordinates) for each shot are provided as ASCII text files, along with the day of year and time (UTC) the shot was recorded.

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.0000027
Longitude_Resolution: 0.0000027
Geographic_Coordinate_Units: decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: WGS84
Ellipsoid_Name: Geodetic Reference System 80
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 .sgy and .tra extension and range in size from 2 to 46 MB (boomer) and 93 to 142 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 on-line at: http://www.seg.org/publications/tech-stand.
Entity_and_Attribute_Detail_Citation:
Cohen, J.K., and Stockwell, J.W., Jr., 2005, CWP/SU: Seismic Unix Release 39: A free package for seismic research and processing: Golden, CO, Center for Wave Phenomena, Colorado School of Mines. Available on-line at http://www.cwp.mines.edu/cwpcodes/.
Entity_and_Attribute_Detail_Citation:
Zihlman, F.N., 1992, DUMPSEGY V.1.0: 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 on-line at http://pubs.er.usgs.gov/usgspubs/ofr/ofr92590.
Entity_and_Attribute_Overview:
Graphic image file: Printable profiles are available as GIF images. Interactive profiles are available as HTML pages with accompanying JPEG images. The line navigation maps and trackline maps are JPEG images. The trackline maps contain links to the seismic profiles and line navigation maps.
Entity_and_Attribute_Overview:
Navigation file: Navigation files are available as ASCII text files. Provided are raw (unprocessed) shotpoint navigation files, processed shotpoint navigation files, and processed 500- (boomer) and 1000-shot-interval (CHIRP) location files.
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.

Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell Harrison
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. 3111
Contact_Electronic_Mail_Address: aharrison@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 420
Distribution_Liability:
This CD publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein 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.
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: 570 MB
Digital_Transfer_Option:
Offline_Option:
Offline_Media: CD
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. Map documents were created with ESRI ArcGIS 9.2 software. The shapefiles provided may also be viewed using other versions of ArcView, ArcGIS, or public domain software ArcExplorer (http://www.esri.com/software/arcexplorer/).
File_Decompression_Technique: unzip
Transfer_Size: 25.0 MB
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: CD/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/).

Metadata_Reference_Information:
Metadata_Date: 20090326
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell Harrison
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. 3111
Contact_Electronic_Mail_Address: aharrison@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

Home | Acronyms | Contents | Navigation | Profiles | Logs | Metadata | Software

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: pubs.usgs.gov/ds/420/html/metadata.html
Page Contact Information: Feedback
Page Last Modified: March 26, 2009 15:25 EST