Identification_Information:

Citation:

Citation_Information:

Originator: Gina M. Brewer

Originator: Shawn V. Dadisman

Originator: James G. Flocks

Originator: Dana S. Wiese

Originator: Jeffrey B. Davis

Publication_Date: 2001

Title:

Archive of Boomer Seismic Reflection Data

Collected on USGS Cruise 99LCA01,

Crescent Beach Spring, Florida,

26 April - 27 April, 1999.

Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section

Series_Information:

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

Issue_Identification: 01-355

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 Crescent Beach Spring, Florida.

These data were acquired in April of 1999 with the Research Vessel

G.K. Gilbert. The data are available in a variety of formats, including

binary, ASCII, HTML, and GIF images. Binary data are in Society of

Exploration Geophysicists (SEG) SEG-Y format and may be downloaded

for further processing or display. Trackline maps and GIF images

of the profiles may be viewed with your WWW browser.

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 the extent, the subsurface structure of the spring,

the depths to various stratigraphic horizons, and in assessing other

submarine geologic characteristics and features near Crescent Beach Spring.

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 the data presented

in this report are stored in SEG-Y, integer, Motorola format. The SEG-Y

formatted trace data files are located in the SEGY folder at the top

level of this disc and 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 trim_gga.pln

file are only needed to replay the data with Triton Elics Delph Seismic

software. WARNING: In order to comply with ISO 9660 naming standards

tracklines d118_1806, d118_1812, and d118_1840 have been changed

to d1806, d1812, and d1840 respectively on the trackline maps,

navigation files, and the SEG-Y data files.

The seismic source employed here was a boomer transducer towed

on a sled at the sea surface providing 100 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 GPS antennae. The sample frequency of the

data was 16000 Hz and the total record length was 100 ms, except

for lines d118_12 and d118_1840 which were recorded to 200 ms. The

fire rate was every 0.5 sec, 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 every second. The accuracy

of this receiver is within 15 m. However, the SEG-Y format only allows

for seconds of arc which is equivalent to 31 m. The shotpoint navigation

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

offset of the source to the GPS antenna. All navigation data are

stored in flat ASCII files containing latitude and longitude values that can

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

projection desired. The trackline maps provided on this disc are geographic

projections (no datum), and were created with ESRI's GIS software

ArcView 3.2, exported to Adobe Illustrator and then saved as a GIF images.

The images are viewable with your WWW browser.

Also provided on this CD-ROM are Seismic Unix (SU) scripts that allow

the user to strip off navigation fixes from the SEG-Y headers along with

a fix for every 500th shot. The seismic data is then converted to SU

format, filtered, gained and both Postscript and GIF formatted images

are produced. These images can them be displayed using a variety of

shareware programs such as ghostview (Unix, Linux, MAC, Windows),

kview (Linux), or a web browser.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19990426

Ending_Date: 19990427

Currentness_Reference:

Data assumed to be consistent 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: -80.21 W

East_Bounding_Coordinate: -80.20 W

North_Bounding_Coordinate: +29.77 N

South_Bounding_Coordinate: +29.75 N

Keywords:

Theme:

Theme_Keyword_Thesaurus: none

Theme_Keyword: marine seismic reflection

Theme_Keyword: boomer

Theme_Keyword: 99LCA01

Theme_Keyword: ISO 9660 CD-ROM

Theme_Keyword: SEG-Y

Place:

Place_Keyword_Thesaurus: none

Place_Keyword: Crescent Beach Spring

Place_Keyword: Florida

Place_Keyword: Anastasia Island

Place_Keyword: Crescent Beach

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

Use_Constraints:

The U.S. Geological Survey ask 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: James G. Flocks

Contact_Organization: U.S. Geological Survey

Contact_Position: Geologist

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 X3012

Contact_Electronic_Mail_Address: jflocks@usgs.gov

Browse_Graphic:

Browse_Graphic_File_Name: CDROM/MAPS/alllines.GIF

Browse_Graphic_File_Description:

Map of trackline data collected on USGS cruise 99LCA01

in April of 1999, in Crescent Beach Spring, off the coast

of Florida. This map is a geographic projection (no datum),

which was created in ESRI's GIS software ArcView 3.2.

It was then exported to Adobe Illustrator for further editing,

and saved as a GIF image.

Browse_Graphic_File_Type: gif

Browse_Graphic:

Browse_Graphic_File_Name: CDROM/MAPS/ln1_9.GIF

Browse_Graphic_File_Description:

A geographic projection of a trackline map, created in

ArcView, and displaying data for tracklines cres1-9,

collected during USGS cruise 99LCA01 at Crescent

Beach Spring, Fla. This map also contains every 500th

shotpoint position information.

Browse_Graphic_File_Type: gif

Browse_Graphic:

Browse_Graphic_File_Name: CDROM/MAPS/ln10_14.GIF

Browse_Graphic_File_Description:

A geographic projection of a trackline map, created in

ArcView, and displaying data for tracklines cres10-14,

collected during USGS cruise 99LCA01 at Crescent

Beach Spring, Fla. This map also contains every 500th

shotpoint position information.

Browse_Graphic_File_Type: gif

Browse_Graphic:

Browse_Graphic_File_Name: CDROM/MAPS/15_1806.GIF

Browse_Graphic_File_Description:

A geographic projection of a trackline map, created in

ArcView, and displaying data for tracklines cres15, cres16,

cres16b, and d1806, collected during USGS cruise 99LCA01 at

Crescent Beach Spring, Fla. This map also contains every 500th

shotpoint position information.

Browse_Graphic_File_Type: gif

Browse_Graphic:

Browse_Graphic_File_Name: CDROM/MAPS/1812_40.GIF

Browse_Graphic_File_Description:

A geographic projection of a trackline map, created in

ArcView, and displaying data for tracklines d1812 and

d1840, collected during USGS cruise 99LCA01 at

Crescent Beach Spring, Fla. This map also contains every

500th shotpoint position information.

Data_Set_Credit:

This work was partially funded by the St. John's River Water

Management District located in Palatka, Fla. We thank

Rich Young, 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; Trent

Faust and Rob Wertz with the USGS in St. Petersburg, Fla. for

their help in the web design and technical layout of the CD-ROM;

and Jack Kindinger and Peter Swarzenski also with the USGS in

St. Petersburg, Fla. for their technical and editorial reviews.

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,

with the exception of an added 6 ms to the top of each record that was

detected on future data sets.

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 cres1-16, and d1806 were recorded to

100 ms, and lines d1812 and d1840 were recorded to 200 ms.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The position accuracy was determined with Trimble Centurian

P-Code Receiver. This receiver's accuracy is within 15 m.

However, the SEG-Y format only allows for seconds of arc

which is equivalent to 31 m.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

The vertical position was local

sea level and there has been no corrections to a datum or for tidal

variations. However, future data collected with this same system

have shown that up to 6 ms has been added to the top of each record.

Lineage:

Process_Step:

Process_Description: Boomer processing

Raw SEG-Y data was processed with Seismic Unix (SU) and

(Triton Elics Software) 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

4)Convert Postscripts 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 continuously determined 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.

Process_Date: 2001

Process_Step:

Process_Description: Editing Navigation

The ASCII navigation files were extracted from the SEG-Y headers,

and then run through a filter to edit out the spurious fixes.

The filtered data was also reformatted for use with ESRI's GIS

software ArcView 3.2

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:

Longitude_Resolution:

Geographic_Coordinate_Units: decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: WGS 84

Ellipsoid_Name: WGS 84

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 unit less 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 2.3 MB to 60 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 84KB to 1.3MB.

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 on-line 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 does not 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 a 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.

File_Decompression_Technique: none

Transfer_Size: 650MB

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, prices vary.

Ordering_Instructions: Most open-file reports are available from USGS Information Services,

Box 25286, Federal Center, Denver, CO 80225

(telephone: 303-202-4210; e-mail: infoservices@usgs.gov).

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: 20010328

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