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      Originator: Gina M. Brewer

      Originator: Shawn V. Dadisman

      Originator: Jack L. Kindinger

      Originator: Dana S. Weise

      Originator: James G. Flocks

      Publication_Date: 2001


        Archive of Boomer Seismic Reflection Data,

        collected on USGS Cruise 99ASR01, Lake Okeechobee,

        Florida, 29 June - 30 June, 1999.

      Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section


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

        Issue_Identification: OFR-01-165


        Publication_Place: St. Petersburg, FL

        Publisher: U.S. Geological Survey



      This report consists of two-dimensional marine seismic reflection profile

      data from Lake Okeechobee, Fla., that were acquired in June of

      1999 aboard the R/V G. K. Gilbert. These data are available in a variety

      of formats, including binary, ASCII and GIF images. Binary data are in

      Society of Exploration Geophysicists (SEG) SEG-Y format and may be

      downloaded for further processing or display.


      Marine seismic reflection data are used to image and map sedimentary and

      structural features of the seafloor and subsurface. The main objective of this

      cruise was to ascertain if data useful to the Everglades Aquifer Storage and

      Recovery Project could be acquired using seismic techniques. These data

      proved to be useful in mapping the extent and thickness of shallow

      sedimentary units beneath Lake Okeechobee, Fla., and in assessing other

      submarine geologic characteristics and features. 


      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 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 files and the cent_rmc.pln file are

      only needed to replay the data with Triton Elics Delph Seismic software.


      The seismic energy source employed here was a boomer transducer towed on

      a sled at the lake surface providing 200 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 Global Positioning System (GPS)

      antennae. The sample frequency of the data was 16000 Hz and the total

      record length was 200 ms for tracklines oke699_1 to oke699_7 and 300 ms

      for tracklines oke699_8 to oke69911. The fire rate was every 0.5 s, 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. The shotpoint navigation provided

      in this report has not been corrected to reflect the 20 m offset of the

      source to the GPS antenna. The horizontal accuracy of the navigation data

      was within 31m.


      The navigation data are stored as flat ASCII files. The raw navigation

      files were generated by the Delph Seismic Software for each trackline

     and provide the following information for each unique position fix, all

      separated by commas: shotpoint number, longitude, latitude, heading,

      speed, date, and Greenwich Mean Time(GMT). The edited navigation file

      contains all the unique fixes for each trackline with spurious points removed.

      A separate file containing edited navigation for every 500th shotpoint interval

      is also provided. Both the edited navigation and the 500th shotpoint navigation

      files contain six fields separated by commas: shotpoint number, date, GMT,

      longitude, latitude, and the trackline number. This navigation data can be

      used to plot trackline maps of the seismic profiles at any scale or map

      projection desired. The trackline map provided on this disc is a Mercator

      projection and was created with ESRI's GIS software ArcView 3.2. The map

      was then exported to Adobe Illustrator and saved as a GIF image. This GIF

      image is viewable with your WWW browser.




        Beginning_Date: 19990629

        Ending_Date: 19990630

    Currentness_Reference: Data assumed to be constant over time but may change

      due to geologic processes.


    Progress: Complete

    Maintenance_and_Update_Frequency: None Planned



      West_Bounding_Coordinate: -80.834383 W

      East_Bounding_Coordinate: -80.72581 W

      North_Bounding_Coordinate: +27.19386 N

      South_Bounding_Coordinate: +27.11907 N



      Theme_Keyword_Thesaurus: none

      Theme_Keyword: marine seismic reflection

      Theme_Keyword: boomer

      Theme_Keyword: 99ASR01

      Theme_Keyword: ISO 9660 CD-ROM

      Theme_Keyword: SEG-Y

      Theme_Keyword: Aquifer Storage and Recovery


      Place_Keyword_Thesaurus: none

      Place_Keyword: Lake Okeechobee

      Place_Keyword: Florida

      Place_Keyword: Everglades

      Place_Keyword: Martin County

      Place_Keyword: Okeechobee County

      Place_Keyword: Glades County

  Access_Constraints: None. These data are held in the public domain.


    The U.S. Geological Survey requests to be acknowledged

    as the originator of the data in future products or derivative research.




        Contact_Person: Jack Kindinger

        Contact_Organization: U.S. Geological Survey

      Contact_Position: Oceanographer


      Address_Type: mailing address

        Address: 600 Fourth Street South

        City: St. Petersburg

        State_or_Province: FL

        Postal_Code: 33701

        Country: USA

      Contact_Voice_Telephone: (727)803-8747 X3018



    Browse_Graphic_File_Name: CD-ROM/MAPS/okeemap.GIF

    Browse_Graphic_File_Description: Map of trackline data collected on

       USGS Cruise 99ASR01, in June of 1999, in Lake Okeechobee, Fla.

       This map is a mercator projection prepared in ESRI's ArcView 3.2,

       exported to Adobe Illustrator for further editing and then saved

       as a GIF image.

    Browse_Graphic_File_Type: GIF


    We thank Keith Ludwig, 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; and Trent Faust and Rob Wertz with the USGS here in

    St.Petersburg, Fla., for their help in the web design and technical layout of

    the CD-ROM.

  Native_Data_Set_Environment: 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.

  Logical_Consistency_Report: 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 oke699_1 to oke699_7 were recorded

    to 200 ms. Tracklines oke699_8 to oke69911 were recorded to 300 ms.




        The position accuracy was determined with a Trimble Centurian

        P-Code Receiver. Absolute position accuracy was within 31 m.



        The vertical position was lake level and there has been no

        corrections to a datum or for tidal variations.



      Process_Description: Boomer processing:

        Raw SEG-Y data was processed with SU 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 for tracklines

        oke699_1 to oke699_7 and at 75 ms/in and 300 shots/in for tracklines

        oke699_8 to oke699_11;

        4)Convert Postscript files to GIF format

      Process_Date: 2001


      Process_Description: Positional (navigation) data:

        As the seismic reflection data were acquired, the position of the

        vessel was determined continuously 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 and edited for

        obvious spurious data values.

      Process_Date: 2001


      Process_Description: 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.

      Process_Date: 2001



    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).




      Latitude_Resolution: 0.000278

      Longitude_Resolution: 0.000278

      Geographic_Coordinate_Units: decimal degrees


      Horizontal_Datum_Name: WGS 84

      Ellipsoid_Name: WGS 1984

      Semi-major_Axis: 6378137 m

      Denominator_of_Flattening_Ratio: 298.257



    Entity_and_Attribute_Overview:  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 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. These .tra files range in

      size from 21 MB to 80 MB.


      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:


    Entity_and_Attribute_Overview:  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 508KB to 1.9MB.





        Contact_Person: Rob Wertz

        Contact_Organization: U.S. Geological Survey

      Contact_Position: Manager, Data Management Group


        Address_Type: mailing address

        Address: 600 Fourth Street South

        City: St. Petersburg

        State_or_Province: FL

        Postal_Code: 33701

        Country: USA

      Contact_Voice_Telephone: (727)803-8747 X3045


      Contact_Instructions: Data may be available online only by special

        arrangement with the distributor above.

  Resource_Description: 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

    by trade name, trademark, manufacturer, or otherwise does not necessarily

    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.




        Format_Name: 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 an 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. Our data uses an

          ASCII header block instead of the standard EBCDIC.

        File_Decompression_Technique: none

        Transfer_Size: 650 MB



          Offline_Media: CD-ROM

          Recording_Format: ISO 9660

          Compatibility_Information: Unix, Linux, DOS, MAC

    Fees: available from the Denver Open-File Sales Department, for $50.00.

    Ordering_Instructions: This archive is stored on an ISO 9660 CD-ROM.


    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 <>

    free of charge.


  Metadata_Date: 20010320




        Contact_Person: Gina M. Brewer

        Contact_Organization: U.S. Geological Survey

      Contact_Position: Geologist, Data Management Group


        Address_Type: mailing address

        Address: 600 Fourth Street South

        City: St. Petersburg

        State_or_Province: FL

        Postal_Code: 33701

        Country: USA

      Contact_Voice_Telephone: (727)803-8747 X3120


  Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata

  Metadata_Standard_Version: FGDC-STD-001-1998

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