This shapefile represents the 100 shot interval navigation for all the seismic lines collected on this cruise.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located above the seismic towfish tow point. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface. GPS data are assumed to be accurate within 10 meters on this survey.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
Although bathymetry was not recorded directly with this system, bathymetry can be derived by tracing the seafloor reflector in the seismic-reflection profiles. The seismic towfish was attached to a cleat by a short line on the starboard side of the boat. The transducer draft was approximately 0.5 m below the water surface. The draft offset was not included in the data acquisition.
Process_Step:
Process_Description:
The seismic acquisition system used on this cruise was an EdgeTech 424 Chirp sub-bottom system with a 4 to 24 kHz pulse bandwidth and a 2 ms pulse. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface. The acquisition software used to record the data was Discover 3100 version 7.01. The data were recorded in the SEG-Y data format IBM floating point with navigation supplied by the Lowrance GPS system. The navigation was recorded in the header of the seismic data in an arc second format. The record length is 133 ms, with a sample interval of 23 micro-seconds and 5788 samples per trace. The fire-rate was between 4 and 6 shots per second. The GPS antenna was located above the tow position of the seismic transducer.
Process_Date: 2010
Process_Step:
Process_Description:
Using the calibrated polyline shapefile (ir_Routes_Calib available at
https://pubs.usgs.gov/of/2011/1039/html/ofr2011-1039-catalog.html), hatches were added at the beginning and end of each line, as well as at 100 shot spacing. This was done in ArcMap 9.2 by opening the layer properties and selecting the Hatches tab. Create a hatch interval of 100 for the Hatch Class, then for Hatch Def(1) place a marker hatch every 1 hatch interval. From the Hatch Class Add a Hatch Definition - Add End Hatch Definition and set these to a marker Hatch. By displaying the labels for both Hatch Definitions, a quick comparison between the hatches and the unique shot navigation makes sure things are behaving as intended. Then turn the labels off.
This process step and all subsequent process steps were performed by the same person: VeeAnn A. Cross.
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
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:
Within ArcMap 9.2 - by going to Tools - Customize - Commands and scrolling down to the Category "Linear Referencing", the icon for the command "Convert Hatches to Graphics can be added to a toolbar. Once this is done, that tool can be used to convert the hatches to graphics.
Source_Used_Citation_Abbreviation: ir_Routes_Calib.shp
Process_Date: 201101
Source_Produced_Citation_Abbreviation: graphics
Process_Step:
Process_Description:
Convert these graphics to a shapefile using XTools Pro version 5.2. XTools Pro - Feature Conversions - Convert Graphics to Shapes. Source graphics layer: default, graphics element type: points. Output: ir_100shot_graphics.shp
Source_Used_Citation_Abbreviation: graphics
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_100shot_graphics.shp
Process_Step:
Process_Description:
Use ArcMap 9.2 - ArcToolbox - Linear Referencing Tools - Locate Features Along Route. Use the following parameters: input - ir_100shot_graphics; input route features - ir_Routes_Calib; route identifier field - linename; search radius - 5 meters; output event table - ir_100shot_LocateFeatures.dbf. Output event table properties: route identifier field - linename; event type - point (default); measure field - shot. Left rest of options at default (all checked).
Source_Used_Citation_Abbreviation: ir_Routes_Calib.shp
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_100shot_LocateFeatures.dbf
Process_Step:
Process_Description:
Use ArcMap 9.2 - ArcToolbox - Linear Referencing Tools - Make route Event Layer to create an event feature using the following parameters: input route features - ir_Routes_Calib; route identifier field - linename; input event table - ir_100shot_LocateFeatures; route identifier field - linename; event type - point; measure field - shot. Rest of the option left at default values.
Source_Used_Citation_Abbreviation: ir_Routes_Calib.shp
Source_Used_Citation_Abbreviation: ir_100shot_LocateFeatures.dbf
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_100shot_LocateFeatures Events
Process_Step:
Process_Description:
Convert the event layer to a shapefile in ArcMap 9.2 by exporting the data (right mouse click on event layer, Data, Export Data). Output: ir_shot100tmp.shp
Source_Used_Citation_Abbreviation: ir_100shot_LocateFeatures Events
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_shot100tmp.shp
Process_Step:
Process_Description:
Within ArcMap 9.2 use VAC Extras version 2.1 (an extension written by the USGS in Woods Hole) to sort the shapefile. VAC Extras - FeatConv - Table Sort with the shot file sorted based on linename and shot. Linename was set as the primary sort field, ascending order. Shot was set as the secondary sort field - ascending order. Output to ir_100shot_sort.shp.
Source_Used_Citation_Abbreviation: ir_shot100tmp.shp
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_100shot_sort.shp
Process_Step:
Process_Description:
Because there are instances where the seismic acquisition automatically switched files, there are instance where the end shot of one line is in the same location as the start shot of the next line. An example of this are the lines l1f2 and l1f2.001. This issue leads to a duplicate shot #1 at these boundaries. The first shot #1 as it appears in the table should reflect the linename of the previous line, and it's ending shot number. For example, the first occurrence of l1f2.001 had the linename edited to be l1f2, and the shot value changed from 1 to 8959. The ending shot number was determined by displaying the hatch labels on the calibrated polyline generated earlier in the process steps.
On line l5f2 there are 3 points with the shot number 1500. The problem with this line is they did a loop. Because the line crossed itself, the confusion as to the location of shot 1500 arose. Using the editor, I deleted the 2 shot 1500's that don't belong, and manually moved the location of the remaining shot 1500 to correspond to the calibrated polyline position of that shot number combined with the information from the shapefile containing all the original shot point navigation. Users will have to be careful if using the calibrated shot measures for this looped line in the loop area.
Source_Used_Citation_Abbreviation: ir_100shot_sort.shp
Process_Date: 201101
Source_Produced_Citation_Abbreviation: ir_100shot_sort.shp
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.). Attempted to modify http to https where appropriate. Moved the minimal source information provided to make it the first process step. 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: 20171002
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
