Processed seismic data were converted to PNG format for ease of seismic trace display. Quality control was conducted during processing.
Lines were serially recorded during the survey in the format "LXF1". When a file is named "LXF2" or has a file number greater than 2, the recording parameters were usually changed (record length and shot rate), as recorded in the ship's log. The following lines were either not recorded or excluded from this data release: L3F2 (negligible length), L4F1 (line name error, never recorded), L15F1 (negligible length), L25F2 (small, noisy, no features of interest), L47F1 (negligible length).
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: Unpublished Material
Title: raw seismic data
Type_of_Source_Media: disc
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20120523
Beginning_Time: 1011
Ending_Date: 20120524
Ending_Time: 1126
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: Information unavailable from original metadata.
Source_Contribution:
Seismic-reflection data acquisition: Chirp seismic data were collected using an EdgeTech SB-0512i towfish (0.5-4.5 kHz pulse, 50 ms pulse length, except for L19F3-L28F1, which were 0.5-2.7 kHz, 40 ms length), which was towed astern of the M/V Tiki XIV of Ocean City, MD. Chesapeake Technologies' SonarWiz (v.4.04.0031) seismic acquisition software was used to control the chirp, digitally log trace data in the SEG-Y Rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arc seconds of Latitude and Longitude, multiplied by a scalar of 100). Trace lengths are constant within lines, but vary from line to line due to variable water depth in the survey area (the minimum trace length was 250 ms and the maximum 1400 ms). This yields a range of samples per trace from approximately 5435 (250 ms trace length) to 30435 (1400 ms trace length). Sample interval was kept at a constant .000046 s. The ping rate was set to be consistent with the trace length, so it varied between 250 ms and 1400 ms.
Process_Step:
Process_Description:
SIOSEIS (version 2010.2.11) was used to mute the first 10 ms of each seismic trace of select lines (this process step is indicated in the line name by the _topmute suffix). SIOSEIS was then used to predict the vertical location of the sea floor for traces by identifying the first downtrace instance of an amplitude that exceeded a user-defined threshold value. This seafloor pick was then used by SIOSEIS process 'swell' to minimize the effect of sea surface heave. The output SEG-Y file is in the format <LxFx_topmute_sf>, and these files were then used to create browse images and digital interpretation.
Process_Date: 201206
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
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 x. 2245
Contact_Electronic_Mail_Address: jobelcz@usgs.gov
Process_Step:
Process_Description:
SEG-Y trace data of lines that SIOSEIS could not seafloor autopick (usually due to an acoustically faint seafloor-sediment interface) were imported into IHS Kingdom Suite (version 8.7.1), a digital seismic interpretation software. The seafloor was manually picked using an interactive horizon digitizer tool, and seafloor horizons for these lines were exported as trace-time (one-way travel time) pair ASCII text files.
Process_Date: 201206
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
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 x. 2245
Contact_Electronic_Mail_Address: jobelcz@usgs.gov
Process_Step:
Process_Description:
SIOSEIS is used to insert the trace-time pairs exported from Kingdom Suite (detailed in process step 2) into the SEG-Y trace headers and minimize the effect of sea surface heave using process 'swell'. The output files are in the format <LxFx_sf> (images that are in the format LxFx_topmute_sf described in process step 1 did not need to be manually picked in Kingdom Suite), and were the SEG-Y files used for creation of browse images and digital interpretation.
Process_Date: 201206
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
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 x. 2245
Contact_Electronic_Mail_Address: jobelcz@usgs.gov
Process_Step:
Process_Description:
Seismic Unix (version 4.2) was used to read all SEG-Y files produced in process steps 1 and 3 and write a Seismic Unix file for each corresponding SEG-Y file. Seismix Unix was then used to plot the SU files as 8 bit grayscale Postscript files using the SU 'psimage' algorithm. Images were created with a variable horizontal scale and variable TWTT depending on trace length of a given line. Each image is not representative of the entire SEG-Y file; the top and bottom of each profile is cropped to only display areas of subbottom penetration. Postscript images were converted to PNG format using ImageMagick (version 6.7.0). The x-axis of the images represents ffid and the y-axis is two-way travel time in seconds.
Process_Date: 201305
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
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 x. 2245
Contact_Electronic_Mail_Address: jobelcz@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 as the first link in the identification section. Updated the link to the field activity. 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: 20171004
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
