High-Resolution Seismic Reflection and Marine Magnetic Data Along the Hosgri Fault Zone--Cayucos to Pismo Beach, California

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Frequently anticipated questions:


What does this data set describe?

Title:
High-Resolution Seismic Reflection and Marine Magnetic Data Along the Hosgri Fault Zone--Cayucos to Pismo Beach, California
Abstract:
This report consists of high-resolution chirp and single-channel mini-sparker seismic-reflection profile data from the offshore San Luis Obispo County, California. These data were acquired in 2008 and 2009 using the Research Vessel Parke Snavely (USGS Field Activity IDs: S-6-08-SC, S-6-09-SC). The data are available in binary, TIFF and JPEG image formats. Binary data are in Society of Exploration Geologists (SEG) SEG-Y format and may be downloaded for further processing or display. Reference maps and JPEG images of the profiles may be viewed with your Web browser.
Supplemental_Information:
Chirp seismic-reflection profiles are acquired by means of an acoustic source and a hydrophone array, both contained in a single unit towed in the water behind a survey vessel approximately 4 meters below the water surface. The sound source emits a short (30 ms) swept-frequency (500 to 7,200 Hz) acoustic pulse, which propagates through the water and sediment columns. The acoustic energy is reflected at density boundaries (such as the sea floor or sediment layers beneath the sea floor), and detected by the hydrophone array, and digitally recorded by the onboard PC-based acquisition system. As the vessel moves, this process is repeated multiple times per second, producing a two-dimensional image of the shallow geologic structure beneath the ship track. Mini-sparker profiles are collected with a 500 Joule sparker source and 15-m single-channel streamer towed at the sea surface and using the same acquisition system.
Marine magnetic data were collected using a Geometrics G882 cesium vapor magnetometer that was towed approximately 30 m behind the vessel. Data were recorded using Geometrics MagLog acquisition software. A magnetic base station was setup onshore to record continuous measurements of the local magnetic field. A proton precession magnetometer was used for the base station.
Additional information about the USGS field activity S-6-08-SC is available at <http://walrus.wr.usgs.gov/infobank/s/s608sc/html/s-6-08-sc.meta.html>.
Additional information about the USGS field activity S-6-09-SC is available at <http://walrus.wr.usgs.gov/infobank/s/s609sc/html/s-6-09-sc.meta.html>.
  1. How might this data set be cited?
    Sliter, Ray W., Triezenberg, Peter J., Hart, Patrick E., Watt, Janet T., Johnson, Samuel Y., and Scheirer, Daniel S., 2009, High-Resolution Seismic Reflection and Marine Magnetic Data Along the Hosgri Fault Zone--Cayucos to Pismo Beach, California: U.S. Geological Survey Open-File Report 2009-1100, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.3756
    East_Bounding_Coordinate: -120.6368
    North_Bounding_Coordinate: 35.6843
    South_Bounding_Coordinate: 34.8424
  3. What does it look like?
    <https://pubs.usgs.gov/of/2009/1100/tracklines/sparker2008/jpg/PBS-07.jpg> (JPEG)
    Example of single-channel mini-sparker seismic data accessible via this report.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Jun-2008
    Ending_Date: 08-Aug-2009
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: seismic reflection profile section
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Horizontal X and Y locations for the seimic profiles location are provided in ASCII position files and are also stored in the SEG-Y data trace headers in the standard header locations.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -119.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 3
      Ordinates (y-coordinates) are specified to the nearest 3
      Planar coordinates are specified in seconds
      The horizontal datum used is World Geodetic System 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Ascii data sets s-6-08-sc.410_sparker, s-6-08-sc.410_chirp, s-6-09-sc.410_sparker have initial header records followed by data records with these fields - 4-digit year, 3-digit day of year, 2-digit hour, 2-digit minute, 2-digit second, 1-digit tenth of second, decimal degree latitude, decimal degree longitude, alpha-numeric line ID, FFID number, Shot number, and CDP number. Example:
    ! 08/22/2008 ray s-6-08-sc.410_chirp
    ! /infobank/programs/edit/mergeit/mergeit
    ! merged nav with times from SEG-Y headers -RS
    !
    20081641603410  35.38477 -120.88194       PBC-05         1         1         1
    20081641604090  35.38448 -120.88248       PBC-05         2         2         2
    20081641604100  35.38447 -120.88250       PBC-05         4         4         4
    20081641604110  35.38445 -120.88252       PBC-05         6         6         6
    20081641604120  35.38444 -120.88254       PBC-05         9         9         9
    20081641604130  35.38443 -120.88256       PBC-05        11        11        11
    
    Entity_and_Attribute_Detail_Citation:
    U.S. Geological Survey, USGS CMG InfoBank format for Seismic FFID/Shot/CDP data, 2009, <http://walrus.wr.usgs.gov/infobank/programs/html/dictionary2html/format_410.html>.
    Entity_and_Attribute_Overview:
    Ascii data set s-6-09-sc.mag.csv.zip, exported from Oasis montaj as a .csv file, has initial header records followed by data records with these fields - date yr/mo/day, day of June 2008 in Pacific Daylight Time, time hr:mn:sc, decimal degree latitude, decimal degree longitude, ship speed-knots, magnetometer signal level, raw magnetic data-nanotesla, magnetic data with IGRF correction-nanotesla, base station magnetic data-nanotesla, magnetic data with IGRF and base station correction-nanotesla, magnetic data with IGRF/base station/leveling correction-nanotesla. The data are separated by line number. Example:
    /Date,Day_of_Jun2008_PDT_,Time,LatMag,LonMag,Speed_kts,SignalLevel,Mag_raw,Mag_IGRF,Basemag,Mag_corr_basemag,Mag_level
    //Flight 0
    //Date 2008/09/17
    Line  0
    2008/06/10,10.587384,14:05:50,35.2820680,-121.0099651,3.67,1605.4,47800.243,-174.0,-24.4,-149.7,-143.6
    2008/06/10,10.587442,14:05:55,35.2821117,-121.0098761,4.57,1601.7,47800.509,-173.7,-24.4,-149.3,-143.2
    2008/06/10,10.587500,14:06:00,35.2821745,-121.0097416,5.33,1617.0,47801.237,-173.1,-24.4,-148.7,-142.6
    2008/06/10,10.587558,14:06:05,35.2822343,-121.0096140,5.38,1630.7,47800.939,-173.4,-24.4,-149.0,-142.9
    2008/06/10,10.587616,14:06:10,35.2822985,-121.0094773,5.41,1633.6,47800.897,-173.5,-24.4,-149.1,-143.0
    2008/06/10,10.587674,14:06:15,35.2823586,-121.0093479,5.32,1635.4,47802.066,-172.4,-24.5,-147.9,-141.8
    
    Entity_and_Attribute_Detail_Citation:
    Geosoft, Oasis montaj, 2009, <http://www.geosoft.com/pinfo/oasismontaj/index.asp>.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Ray W. Sliter
    • Peter J. Triezenberg
    • Patrick E. Hart
    • Janet T. Watt
    • Samuel Y. Johnson
    • Daniel S. Scheirer
  2. Who also contributed to the data set?
    U.S. Geological Survey
  3. To whom should users address questions about the data?
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Ray W. Sliter
    Geophysicist
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5194 (voice)
    (650) 329-5190 (FAX)
    rsliter@usgs.gov

Why was the data set created?

Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data were acquired in in the offshore areas between Cayucos and Pismo Beach from the nearshore (~6 m depth) to just west of the Hosgri Fault Zone, in support of the California State Waters Mapping Program and the Cooperative Research and Development Agreement (CRADA) between Pacific Gas & Electric Company and the U.S. Geological Survey. The specific objective of this seismic survey is to provide seismic reflection images and magnetic anomaly maps of the depositional geometry of the upper 50 m of subbottom stratigraphy in order to better understand the mechanisms of sediment transport and deposition. Another objective of the survey is to identify offsets in sedimentary strata and basement rocks to characterize important fault properties. These seismic profiles provide high-quality images with approximately 1 m of vertical resolution and up to 120 m of subbottom penetration.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2009 (process 1 of 11)
    Refer to report sections "Data Acquisition and Processing" for details of geophysical data acquisition and processing sequence used for data in this report. - Ray W. Sliter
    Date: 2009 (process 2 of 11)
    Created bathymetry overlay using GMT <http://gmt.soest.hawaii.edu/>. - Peter J. Triezenberg
    Date: 2010 (process 3 of 11)
    Created interactive trackline map using Google Maps API <http://code.google.com/apis/maps/>. - Peter J. Triezenberg
    Date: 2010 (process 4 of 11)
    Created downloadable Google Earth "kmz" file <http://code.google.com/apis/kml/>. - Peter J. Triezenberg
    Date: 2009 (process 5 of 11)
    Created seismic profile images using Seismic Unix <http://www.cwp.mines.edu/cwpcodes/> to provide format options for downloading data. - Ray W. Sliter Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Ray W. Sliter
    Geophysicist
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5194 (voice)
    (650) 329-5190 (FAX)
    rsliter@usgs.gov
    Date: 2009 (process 6 of 11)
    Converted profiles to TIFF and JPEG files using ImageMagick <http://www.imagemagick.org/>. - Peter J. Triezenberg
    Date: 2009 (process 7 of 11)
    Used GEODAS (GEOphysical DAta System) to create a custom bathymetric and topographic grid for the southern California region covered by the cruise maps. The website is: <http://www.ngdc.noaa.gov/mgg/geodas/geodas.html>. The parameters used are as follows: Grid Database: US Coastal Relief Model Grids Grid Area in degrees and minutes: 34:30 N to 33:48 N, 119:00 W to 120:24 W Grid Cell Size: 3 seconds Grid Format: XYZ (lon, lat, depth), no header, space-delimited, omit empty grid cells. Cell Parameters: 4-byte floating point, tenths of meters Land/Sea Coverage: Sea cells only. - Peter J. Triezenberg Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Peter J. Triezenberg
    Geologist
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5207 (voice)
    (650) 329-5190 (FAX)
    ptriezenberg@usgs.gov
    Date: 2009 (process 8 of 11)
    Processed raw magnetic data using GMT <http://gmt.soest.hawaii.edu/>. Also used several Unix utilities and some home-grown programs to convert the raw ship and base-station magnetic data into the corrected form for import into Oasis montaj. - Daniel S. Scheirer Person who carried out this activity:
    U.S. Geological Survey (USGS)
    Attn: Daniel S. Scheirer
    USGS, MailStop 989, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-4127 (voice)
    dscheirer@usgs.gov
    Date: 2009 (process 9 of 11)
    Performed magnetic survey leving using Oasis montaj <http://www.geosoft.com/pinfo/oasismontaj/index.asp>. - Janet T. Watt
    Date: 2009 (process 10 of 11)
    Gridded preliminary magnetic data and exported TIFF files using Oasis montaj <http://www.geosoft.com/pinfo/oasismontaj/index.asp>. - Janet T. Watt Person who carried out this activity:
    U.S. Geological Survey (USGS)
    Attn: Janet T. Watt
    USGS, MailStop 989, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5307 (voice)
    jwatt@usgs.gov
    Date: 29-Mar-2019 (process 11 of 11)
    Separated authors' names onto individual originator lines/tags. -Susan Cochran scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG), 2009, USGS CMG S-6-09-SC Metadata.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Data have not been independently verified.
  2. How accurate are the geographic locations?
    Shot point numbers in the data files correspond to those in the navigation files. The horizontal positional accuracy of the seismic data thus linked to ship's position is estimated to be within 30 meters.
  3. How accurate are the heights or depths?
    Depths shown in the seismic data files are in milliseconds (round trip travel time) and are referenced to sea level.
  4. Where are the gaps in the data? What is missing?
    Reference the full report for a description of data coverage. All seismic-reflection data collected on the referenced cruises have been included in this report. Some seismic profiles have gaps in them due to system crashes, mammal shutdowns or hardware maintenance.
  5. How consistent are the relationships among the observations, including topology?
    Undetermined

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
Information presented in this publication is considered public information and may be distributed or copied.
Use_Constraints:
Please recognize the U.S. Geological Survey (USGS) as the source of this information.
This information is not intended for navigational purposes.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Some USGS information accessed through this means may be preliminary in nature and presented without the approval of the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the responsibility of the user.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Ray W. Sliter
    Geophysicist
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5194 (voice)
    (650) 329-5190 (FAX)
    rsliter@usgs.gov
    Contact_Instructions:
    Data may be available off-line only by special arrangement with the distributor above. Please use the on-line download option unless precluded by download times or access difficulties.
  2. What's the catalog number I need to order this data set? U.S. Geological Suvey Open-File Report 2009-1100
  3. What legal disclaimers am I supposed to read?
    Information presented in this publication is considered public information and may be distributed or copied. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
    This information is not intended for navigational purposes.
    Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    Some USGS information accessed through this means may be preliminary in nature and presented without the approval of the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the responsibility of the user.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: SEG-Y, JPEG, TIFF, ASCII Size: 2500
      Network links: https://pubs.usgs.gov/of/2009/1100/
      Media you can order: none (format ISO 9660)
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized software, such as ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX by Paradigm Geophysical; SPW by Parallel Geoscience; or VISTA by Seismic Image Software.

Who wrote the metadata?

Dates:
Last modified: 29-Mar-2019
Metadata author:
U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
Attn: Ray W. Sliter
Geophysicist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA
USA

(650) 329-5194 (voice)
(650) 329-5190 (FAX)
rsliter@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/10.faq.html>
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