U.S. Geological Survey 2018 1.0 vector digital data data release DOI:10.5066/F7X929K6 Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts U.S. Geological Survey, Coastal and Marine Geology Program https://doi.org/10.5066/F7X929K6 https://www.sciencebase.gov/catalog/item/5a9593c9e4b06990606a7df5 Wayne E. Baldwin Seth D. Ackerman Charles R. Worley William W. Danforth Jason D. Chaytor 2018 1.0 data release DOI:10.5066/F7X929K6 Reston, VA U.S. Geological Survey Suggested citation: Baldwin, W.E., Ackerman, S.D., Worley, C.R., Danforth, W.W., and Chaytor, J.D, 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7X929K6. https://doi.org/10.5066/F7X929K6 https://www.sciencebase.gov/catalog/item/5a8c4bcbe4b00f54eb44044c High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic gas in the shallow subsurface). Approximately 675 kilometers (km) of multibeam bathymetry and backscatter data, 420 km of towed chirp data, and 550 km of multichannel seismic data were collected. Varied mudflow (gully, lobe), prodelta morphologies, and structural features were imaged in selected survey areas from Pass a Loutre to Southwest Pass. This dataset contains common midpoint navigation for approximately 550 km of multi-channel streamer seismic-reflection profiles collected by the U.S. Geological Survey during cruise 2017-003-FA along theMississippi River Delta front offshore of southeastern Louisiana. This information allows for spatial correlation of brute stack seismic-reflection profiles images with other geophysical and sample data for investigating sea-floor morphology and geologic framework in the area. Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-003-FA. 20170521 20170526 ground condition Complete None planned. -89.552178 -88.881535 29.161339 28.781718 USGS Metadata Identifier USGS:5a9593c9e4b06990606a7df5 None U.S. Geological Survey USGS Woods Hole Coastal and Marine Science Center WHCMSC Coastal and Marine Geology Program CMGP Bureau of Ocean Energy Management BOEM field activity number 2017-003-FA shapefile common midpoint navigation seismic navigation seismic reflection seismic profile boomer Applied Acoustics S-boom sparker SIG multi-channel streamer Geometrics GeoEel Marine Geology ISO 19115 Topic Category oceans location USGS Thesaurus seismic reflection methods marine geophysics marine geology navigational data None Gulf of Mexico Southeast Louisiana Mississippi River Delta front Southwest Pass South Pass Pass a Loutre None sea floor seafloor none 2017 none Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset. U.S. Geological Survey Wayne E. Baldwin Geologist mailing and physical

384 Woods Hole Road

Woods Hole Massachusetts 02543-1598 US 508-548-8700 x2226 508-457-2310 wbaldwin@usgs.gov https://www.sciencebase.gov/catalog/file/get/5a9593c9e4b06990606a7df5/?name=2017-003-FA_MCS_100cmp_browse.jpg Thumbnail image of multi-channel seismic-reflection common midpoint locations from the Mississippi River Delta front offshore of southeastern Louisiana. JPEG Multichannel seismic-reflection profile data were collected continuously throughout the cruise except during a survey hiatus between 19:19 (UTC) 5/21/2017 (JD141) and 02:17 5/22/2017 (JD142), a period of inclement weather, rough sea state, and system malfunction between 10:45 5/23/17 (JD 143) and 00:20 5/24/17 (JD144), and within Louisiana state waters, where the cruise was not permitted to use the seismic sources. Sparker and boomer sources were used with the multichannel streamer during the cruise to test their relative effectiveness in the delta front setting, and some lines were reoccupied with each source to provide comparative results over common sections of sea floor. Substantial flux of freshwater from the Mississippi River caused rather low at several locations during the cruise, which reduced the effectiveness of the sparker source, which is predicated on operation in sea water conditions. During these periods, the boomer source was deployed instead. Line numbering begins at FA2017003_transit4 and ends at FA2017003_bonus3. This feature class contains common midpoint (CMP) locations for each trackline, at the start (1000 or 1600), end (x), and even 100-CMP intervals in between. The CSV file contains unique CMP navigation. No duplicates exist. The attribute field 'imagename' lists the PNG brute stack image that corresponds to each line (see MCS.zip folder accompanying 2017-003-FA_MCS_Images_meta.xml available from the larger work citation). Sections of tracklines where navigation was recorded but no seismic data were logged are not included such as some turns and transits (e.g. FA2017003_sw13a, from which the CMPs prior to 1600 are not included because many of the raw traces contain no data). There are no lines FA2017003_transit1, FA2017003_transit2, FA2017003_transit3, or FA2017003_dw13. Troubleshooting of the seismic power source during line FA2017003_sw9 caused shots 3003 - 4343 to not be logged. As a result, there is a gap in the CMP navigation for FA2017003_sw9 (see 2017-003-FA_MCS_cmp-nav.csv), as well as a conspicuous artifact in the form of an abrupt vertical sea floor offset in the PNG brute stack image corresponding to those CMPs (contained in the MCS.zip folder accompanying 2017-003-FA_MCS_Images_meta.xml available from the larger work citation). Similarly, the power source was briefly suspended and restarted during line FA2017003_sw25 causing shots 1014 - 1146 to not be logged. While the resulting gap is evident in the CMP navigation, the effect is less conspicuous in the PNG brute stack image. Multichannel seismic-reflection data were navigated using a Wide Area Augmentation System (WAAS) enabled Hemisphere Differential GPS (DGPS) receiver, with an antenna mounted on an 01 deck port side rail 7.35 m from the stern of the R/V Point Sur. The seismic sources were towed from the center of the stern approximately 17 m (lines FA2017003_transit4 - FA2017003_sw8) and 22 m (lines FA2017003_sw9 - FA2017003_bonus3) aft and approximately 4 m starboard of the DGPS antenna. The 150-m long GeoEel 32-channel (50 m active section) streamer was towed approximately 3 m outboard of the port side of the vessel from a boom crane, with the center of the first and last active groups approximately 73 m and 123 m aft of the DGPS antenna, respectively. The Geometrics CNT-1 seismic acquisition software (version 5.361) logged the shot navigation coordinates to the to the SEG-D external header. Layback distance between the GPS antenna and the acoustic source and receivers were calculated in post processing (described in the processing steps). Although horizontal accuracy of WAAS enabled DGPS is estimated to be within 2 m, the actual accuracy is assumed to be coarser due to the additional uncertainty added from calculation of source/receiver layback and common midpoint positions. U.S. Geological Survey Unpublished Material digital data disc 20170521 20170526 ground condition raw MCS data Multichannel seismic-reflection data were shot using Applied Acoustics S-Boom or SIG mini sparker (ELC 1050 and 1200) sources powered by Applied Acoustics CSP-D (700 and 2400) power supplies. Both sparker and boomer sources were used to test their relative effectiveness in the delta front setting, and some lines were reoccupied with each source to provide comparative results over common sections of sea floor. Shots were recorded using a 150-m long 32-channel (50 m active section) solid-state Geometrics GeoEel streamer with 1.5625-m spaced groups connected to a Geometrics Streamer Power Supply Unit (SPSU). The seismic sources were towed from the center of the stern approximately 17 m (lines FA2017003_transit4 - FA2017003_sw8) and 22 m (lines FA2017003_sw9 - FA2017003_bonus3) aft and approximately 4 m starboard of the DGPS antenna, and the GeoEel streamer was towed approximately 3 m outboard of the port side of the vessel from a boom crane, with the center of the first and last active groups approximately 73 and 123 meters aft of the DGPS antenna, respectively. The S-Boom source was powered at 600 joules (200 J per plate) and deployed from the start of surveying up to 19:19 (UTC) 5/21/2017 (JD141), between 02:17 and 15:31 5/22/2017 (JD142), and between 20:06 5/22/2017 (JD142) and 10:08 5/23/2017 (JD143). SIG mini sparker sources were supplied between 200 and 500 joules and deployed between 15:31 and 20:04 5/22/2017 (JD142), and between 00:20 5/24/2017 (JD144) and 00:44 5/26/2017 (JD146). Geometrics CNT-1 seismic acquisition software (version 5.361) running on a Windows PC was used to control the multichannel system and digitally log traces in the Geometrics SEG-D format, and record GPS navigation coordinates to the SEG-D external headers. Data were acquired at shot rates of 0.5 and 1 s, record lengths between 400 and 800 milliseconds (ms), and a sample interval of 0.25 ms. A SIOSEIS (version 2015.3.1) seismic processing software script (sio_segd2segy) was used to read Geometrics SEG-D formatted (SIOSEIS process SEGDDIN) traces and write them (SIOSEIS process DISKOX) to SEG-Y Rev. 1 format (IEEE floating point) for each line. This process step and all subsequent process steps were conducted by the same person - Wayne Baldwin. 201705 U.S. Geological Survey Wayne E. Baldwin Geologist mailing and physical

384 Woods Hole Rd.

Woods Hole MA 02543-1598 (508) 548-8700 x2226 (508) 457-2310 wbaldwin@usgs.gov OpenCPS (version 3.3.0) seismic processing software was used to perform the following series of processing flows: 1. read_segy.flow - SegyTapeRead read the traces. HeaderMath and UTMLatLong were used to convert the source lat/lon positions from seconds of arc to decimal degrees, project them to UTM Zone 16N WGS 84 meters, and write each to new header words (NRP_LAT, NRP_LON, NRP_X, and NRP_Y). DBWrite wrote the UTM positions for the first channel of each FFID to an internal OpenCPS database table. Finally, Output wrote the traces to a new file "*.sht-raw.seis" in the internal OpenCPS format. 2. geom.flow - Input read the "*.sht-raw.seis" file and sorted the traces to FFID/CHANNEL. The custom Python module ShotlineLayback (developed by Nathan Miller of USGS-WHCMSC) was used to define the source shot and streamer geometry based on measured horizontal offsets from the DGPS antenna to the source (-17.35 or -22.35) and the centers of the first (1) and last (32) channel groups (-73.43/-112.8) of the active streamer section. The algorithm interpolated a sail line from the source shot positions (NRP_X and NRP_Y), then computed layback positions for the source shot and 32 channel groups for each FFID by translating them back along the sail line by their respective measured offsets. Midpoint positions along the sail line were also computed for each shot/receiver pair, allowing the traces to be binned by common midpoints (CMPs) spaced evenly (by 0.781 m) along the sail line. Output wrote the traces to a new file "*.sht-raw_geom.seis" in which the trace header words SRC_X, SRC_Y, REC_X, REC_Y, MPT_X, MPT_Y, BIN_X, BIN_Y, and OFFSET were populated to reflect the layback Source X and Y, layback Receiver X and Y, layback Source/Receiver Midpoint X and Y, and CMP BIN X and Y positions, as well as the offset value (computed by sqrt((REC_X - SRC_X) * (REC_X - SRC_X) + (REC_Y - SRC_Y) * (REC_Y - SRC_Y))) for each trace in the resulting CMPs. *A limitation of the ShotlineLayback module is the inability to layback source shot/receiver locations that would have occurred prior to the start of the interpolated sail line (i.e. it does not project the sail line backward). This results in erroneous computation of those shot/receiver locations and their respective midpoints, making them unable to be stacked by bin location in the subsequent step. Consequently, up to 40 dead traces exist at the start of each common midpoint stack profile.* 3. brute_stack.flow - Input read the "*.sht-raw_geom.seis" file and sorted the traces to CMP/OFFSET. The Python module Butterworth applied an Obspy version (modified from Scipy version 0.17.1) of a zero-phase, four corner Butterworth bandpass filter to the traces, between 450 and 1800 Hz for data shot with the S-Boom, or between 350 and 1400 Hz for those shot with the mini sparker. NormalMoveout applied a travel time correction to each trace based on offset and a constant velocity of 1530 m/s (water column sound speed), as well as a 60 percent stretch mute with a 30 ms taper. Stack summed the traces within each CMP, computed the average amplitude for each trace sample, and wrote the computed samples to a single CMP trace, as well as averaging the Midpoint positions of the input traces and updating the header words MPT_X and MPT_Y with the resulting averaged values. Output wrote the stacked traces to a new file "*.stk-brute.seis" in the internal OpenCPS format. 4. geom2geojson.flow - Input read the "*.stk-brute.seis" file and sorted the traces to CMP. The custom Python module Header2GeoJSON (developed by Nathan Miller of USGS-WHCMSC) exported the stacked trace navigation (using coordinates from the BIN_X and BIN_Y headers) as point features in the GeoJSON format. Attributes for CMP, BIN_X, BIN_Y, linename, surveyid, vehicleid, and deviceid were also included in the GeoJSON output. 201711 A batch shell script, MCSGeojson2SQL, was executed on the output GeoJSON file from the previous step. First, ogr2ogr (version 2.1.1) was used to import the GeoJSON formatted CMP navigation point geometries into a Spatialite (version 4.3.0) enabled SQLite (version 3.21.0) database table, and in the process add fields for the coordinates converted from UTM Zone 16N WGS 84 meters to GCS WGS 84 decimal degrees. Second, GJpts2lines.py created two new database tables, one containing line geometries generated from the CMP point navigation (with sort order defined by the linename and CMP fields), and another containing CMP navigation filtered to maintain the first and last CMPs, and CMPs at multiples of 100. 201711 The MCS first, last, and multiple of 100 CMP features were added (Add Data) into ArcGIS desktop (version 10.3.1) from the SQLite database, and then exported (Right click on database feature class > Data > Export Data) to the new Esri point shapefile 2017-003-FA_MCS_100cmp. 201712 Added keywords section with USGS persistent identifier as theme keyword (20200807). Removed the web services distribution formats in preparation for ScienceBase moving platforms and those services will no longer be available (20260407). 20260407 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543-1598 508-548-8700 x2251 508-457-2310 vatnipp@usgs.gov Vector Point 7132 0.000001 0.000001 Decimal degrees D_WGS_1984 WGS_1984 6378137.000000 298.257224 2017-003-FA_MCS_100cmp Multichannel seismic-reflection common midpoint locations for survey 2017-003-FA along the Mississippi River Delta front. U.S. Geological Survey FID Internal feature number. Esri Sequential unique whole numbers that are automatically generated. Shape Feature geometry. Esri Coordinates defining the features. bin_x Easting coordinate in UTM Zone 16 N meters, WGS 84 U.S. Geological Survey 251046.09 316989.33 meters 1 bin_y Northing coordinate in UTM Zone 16 N meters, WGS 84 U.S. Geological Survey 3185620.26 3227334.75 meters 1 lon Longitude coordinate in decimal degrees, WGS 84 U.S. Geological Survey -89.552178 -88.881535 degrees .000001 lat Latitude coordinate in decimal degrees, WGS 84 U.S. Geological Survey 28.781718 29.161339 degrees .000001 linename Name of the trackline along which MCS data were collected in the format: survey ID (i.e. 2017003FA_) + file name (i.e. transit4). U.S. Geological Survey Character set imagename Name of the PNG image file associated with the MCS survey line. The appended '.stk-brute' in the file name indicates that that the image represents a constant velocity, common midpoint stack version of the multi-channel seismic data. U.S. Geological Survey Character set cmp Common midpoint number (values are first, last, and every 100 CMPs between). U.S. Geological Survey 1000 45122 common midpoint 1 year Year the survey was conducted (YYYY). U.S. Geological Survey 2017 2017 year 1 surveyid WHCMSC field activity identifier (e.g. "2017-003-FA" where 2017 is the survey year, 003 is survey number of that year, and FA is Field Activity). U.S. Geological Survey Character set vehicleid Survey vessel name. U.S. Geological Survey Character set deviceid Sonar device used to collect MCS data in the format: source (AA S-Boom or SIG mini sparker)/receiver (GeoEel). U.S. Geological Survey Character set The CMP locations can be hyperlinked to the PNG brute stack seismic-reflection image corresponding to line name in a GIS (see the 2017-003-FA_MCS_Images.zip archive accompanying 2017-003-FA_MCS_Images_meta.xml available from the larger work citation). The fist, last, and multiple of 100 common midpoint features in "2017-003-FA_MCS_100cmp.shp" correspond to the x-axis ticks on the PNG images. The unique common midpoint CSV file has the following column headings: bin_x, bin_y, lon, lat, linename, cmp, year, surveyid, vehicleid, and deviceid. All columns correspond to the attributes of the shapefile, except "imagename" and the shapefile specific attributes. U.S. Geological Survey U.S. Geological Survey - ScienceBase mailing and physical address

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Denver CO 80225 1-888-275-8747 USGS data release 2017-003-FA MCS data from the Mississippi River Delta front area: includes the shapefile 2017-003-FA_MCS_100cmp.shp, the browse graphic 2017-003-FA_MCS_100cmp_browse.jpg, a CSV file of common midpoint locations (2017-003-FA_MCS_cmp-nav.csv), and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2017-003-FA_MCS_100cmp_meta.xml. Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Shapefile ArcMap 10.3.1 Shapefile Shapefile of MCS common midpoint locations collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center along the Mississippi River Delta front and the associated metadata. none 9.5 https://www.sciencebase.gov/catalog/item/5a9593c9e4b06990606a7df5 https://www.sciencebase.gov/catalog/file/get/5a9593c9e4b06990606a7df5 https://doi.org/10.5066/F7X929K6 The first link is to the page containing the data, the second link downloads all data available from the page as a zip file, and the third link is to the publication landing page. CSV None Comma-Separated Values (CSV) CSV file of MCS common midpoint locations locations collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center along the along the Mississippi River Delta front and the associated metadata. none 82 https://www.sciencebase.gov/catalog/item/5a9593c9e4b06990606a7df5 https://www.sciencebase.gov/catalog/file/get/5a9593c9e4b06990606a7df5 https://doi.org/10.5066/F7X929K6 The first link is to the page containing the data, the second link downloads all data available from the page as a zip file, and the third link is to the publication landing page. none To utilize these data, the user must have software capable of reading shapefile format, or GIS software capable of utilizing web mapping or feature services. The CSV file can be read with a text editor. 20260407 U.S. Geological Survey Wayne E. Baldwin Geologist mailing and physical

384 Woods Hole Rd.

Woods Hole MA 02543-1598 (508) 548-8700 x2226 (508) 457-2310 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319) FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time