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Home | Read Me | Cruise Activity | Navigation Data | Seismic Data | USGS Software | Seismic Unix | Disclaimer
Identification_Information:
Citation:
Citation_Information:
Originator: Gina M. Brewer
Originator: Shawn V.
Dadisman
Originator: Jack L.
Kindinger
Originator: Dana S. Weise
Originator: James G.
Flocks
Publication_Date: 2001
Title:
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_Information:
Series_Name: U.S.
Geological Survey Open-File Report
Issue_Identification: OFR-01-165
Publication_Information:
Publication_Place: St.
Petersburg, FL
Publisher: U.S.
Geological Survey
Description:
Abstract:
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.
Purpose:
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.
Supplemental_Information:
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.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19990629
Ending_Date: 19990630
Currentness_Reference: Data
assumed to be constant over time but may change
due to geologic processes.
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None Planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:
-80.834383 W
East_Bounding_Coordinate:
-80.72581 W
North_Bounding_Coordinate: +27.19386 N
South_Bounding_Coordinate:
+27.11907 N
Keywords:
Theme:
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:
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.
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
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
Contact_Electronic_Mail_Address: jkindinger@usgs.gov
Browse_Graphic:
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
Data_Set_Credit:
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
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.
Logical_Consistency_Report:
This data set is from a single cruise with consistent
instrument calibrations.
Completeness_Report:
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.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The position accuracy
was determined with a Trimble Centurian
P-Code Receiver.
Absolute position accuracy was within 31 m.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
The vertical position
was lake level and there has been no
corrections to a datum
or for tidal variations.
Lineage:
Process_Step:
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_Step:
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_Step:
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
Spatial_Data_Organization_Information:
Indirect_Spatial_Reference:
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).
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution:
0.000278
Longitude_Resolution:
0.000278
Geographic_Coordinate_Units: decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: WGS
84
Ellipsoid_Name: WGS 1984
Semi-major_Axis: 6378137 m
Denominator_of_Flattening_Ratio: 298.257
Entity_and_Attribute_Information:
Overview_Description:
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.
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. 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.
Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Rob
Wertz
Contact_Organization:
U.S. Geological Survey
Contact_Position: Manager,
Data Management Group
Contact_Address:
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_Electronic_Mail_Address: rwertz@usgs.gov
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
Distribution_Liability:
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.
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
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
Digital_Transfer_Option:
Offline_Option:
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.
Technical_Prerequisites:
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.
Metadata_Reference_Information:
Metadata_Date: 20010320
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Gina M.
Brewer
Contact_Organization:
U.S. Geological Survey
Contact_Position:
Geologist, Data Management Group
Contact_Address:
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
Contact_Electronic_Mail_Address: gmbrewer@usgs.gov
Metadata_Standard_Name:
Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
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