Processed seismic CDP navigation data were processed for display in a GIS. Quality control was conducted during processing. File naming is Lx.png, where x is the survey line number.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Information unavailable from original metadata - assumed USGS
Publication_Date: unknown
Title: Information unavailable from original metadata
Type_of_Source_Media: disc
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20110106
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: USGS
Source_Contribution:
Approximately 21 km of high-resolution multichannel boomer seismic-reflection profiles were collected. The Applied Acoustics boomer source was towed on the starboard side of the RV Rafael, 10 meters aft of the GPS antenna, and was fired at a power level of 100 joules at 1-second intervals with trace lengths of 250 milliseconds and 1000 samples per trace. The Geometrics GeoEel, eight-channel liquid filled digital streamer was towed from the port side of the vessel, and the center of the first channel of the active section was 22 meters aft of the boomer source. The streamer had a group interval of 3.125 meters connected to Geometrics Streamer Power Supply Unit (SPSU). Data acquired in Geometrics SEG-D format on Windows PC controller system using Geometrics CNT-1 software. The sample interval was 0.25 ms.
Process_Step:
Process_Description:
A SIOSEIS seismic processing software script was used as follows: The raw SEG-D shot files were read with the process SEGDDIN specifying geometrics format; for lines L1 and L2, the process HEADER was used to correct time of day because of random incorrect values of time and position recorded in the header (correct time in the header was needed for the next process); the process GEOM was used to describe the shot and streamer geometries and to calculate the reflection point (CDP) numbers used to gather (sort traces by CDP) the seismic line. Process GEOM was used to set the shot-receiver distance into the trace header of every trace. For lines L1 and L2, GEOM type 6 was specified, which computes a distance from last shot (DFLS) for each shot based on the corrected shot time in the header and the navigation from an ASCII file containing time and position. The ASCII shot navigation file was derived from the HYPACK navigation data. Geom type 9 was specified for line L3, which calculates DFLS based on position in the SEG-D header that was verified to be correct; a normal move out (NMO) applied a travel time correction to each trace based on offset and a velocity of 1500 m/s; process GATHER was used to sort the shot order traces in to traces sorted by the CDP numbers computed by the process GEOM; lastly, the CDP trace gathers were written with the process in SEG-Y rev. 1, IEEE floating point format.
Process_Date: 20110120
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Suvrvey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2271
Contact_Facsimile_Telephone: 508-457-2271
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
A SIOSEIS script was used to stack the CDP gathers, apply a bandpass filter and automatic gain control. The process DISKIN read the CDP sorted SEG-Y file and renumbered CDP starting at one and incremented CDP number by one. The process STACK was used to sum traces, compute the average amplitude for each trace sample, and write the computed samples to one trace. The trace header values of the first trace in the gather were used for the stacked trace. The process FILTER applied a zero-phase bandpass frequency domain filter between 600 and 2000 Hz with a slope of 48 decibel per octave slope. The process AGC applied an automatic gain control (AGC) with a window length of 5 ms. The computed multiplier for each AGC window was reduced by fifty percent. Lastly, the processed stacked traces were written to disk with the process DISKOX in SEG-Y rev. 1, IEEE floating point format.
Process_Date: 20110120
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2271
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
A Seismic Unix script was used to read the trace headers of the stacked SEG-Y files and write CDP, source X and Y, year, day, hour minute, seconds only where the original channel number was equal to one (the channel closest to the source). Some CDP gathers did not contain a trace with channel one in the header and were eliminated. The coordinates represent the position of the GPS antenna, which has a constant offset of 10 meters to the source. The source to receiver offset was 22 meters. Half the distance between source and receiver represents the location of the common reflection point. A layback correction of 21 meters was applied to the navigation using an AWK script written by Wayne Baldwin, USGS. An AWK script was used to format the trace navigation with corrected layback positions in a comma-delimited file.
Process_Date: 20110124
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2271
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
Text files created in the previous step were concatenated into a comma-delimited text file, then imported into ArcMap (version 9.3) using 'Create Feature Class from XY Table' and saved as points (UTM Zone 19, WGS84) in the Esri shapefile format.
Process_Date: 20130409
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2271
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
The shapefile created in the previous step was converted from points to polylines using VAC Extras Points to Line v2. The 'Line' field was used to define which points were used to generate each polyline feature. Finally, ArcToolbox (9.3) was used to reproject from UTM projection to Geographic coordinate system.
Process_Date: 20130409
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2271
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Added the DOI link in the Identification section - both as the first link and as part of the Larger Work citation. Fixed the publication date and also the Larger Work citation title to match what is available online. Updated the link to the project page in the abstract as well as the field activity links. The source information was incomplete and had to be modified to meet the standard. Fixed a link in the distribution section. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.
Process_Date: 20171005
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: USGS Thesaurus keywords added to the keyword section.
Process_Date: 20180720
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
