High-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California
Frequently-Anticipated Questions
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Frequently-anticipated questions:
- 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>.
- How should this data set be cited?
Ray W. Sliter, Peter J. Triezenberg, Patrick E. Hart, 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:
- 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
- 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.
- 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
- What is the general form of this data set?
- Geospatial_Data_Presentation_Form: seismic reflection profile section
- How does the data set represent geographic features?
- 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.
- 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.
- 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 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, and Daniel S. Scheirer
- Who also contributed to the data set?
U.S. Geological Survey
- To whom should users address questions about the data?
U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
c/o Ray W. Sliter
Geophysicist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA
(650) 329-5194 (voice)
(650) 329-5190 (FAX)
rsliter@usgs.gov
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.
- From what previous works were the data drawn?
- How were the data generated, processed, and modified?
- Date: 2009 (process 1 of 10)
-
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 10)
-
Created bathymetry overlay using GMT
<http://gmt.soest.hawaii.edu/>.
- Peter J. Triezenberg
- Date: 2010 (process 3 of 10)
-
Created interactive trackline map using Google Maps API
<http://code.google.com/apis/maps/>.
- Peter J. Triezenberg
- Date: 2010 (process 4 of 10)
-
Created downloadable Google Earth "kmz" file
<http://code.google.com/apis/kml/>.
- Peter J. Triezenberg
- Date: 2009 (process 5 of 10)
-
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)
c/o Ray W. Sliter
Geophysicist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA
(650) 329-5194 (voice)
(650) 329-5190 (FAX)
rsliter@usgs.gov
- Date: 2009 (process 6 of 10)
-
Converted profiles to TIFF and JPEG files using ImageMagick
<http://www.imagemagick.org/>.
- Peter J. Triezenberg
- Date: 2009 (process 7 of 10)
-
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)
c/o Peter J. Triezenberg
Geologist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA
(650) 329-5207 (voice)
(650) 329-5190 (FAX)
ptriezenberg@usgs.gov
- Date: 2009 (process 8 of 10)
-
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)
c/o Daniel S. Scheirer
USGS, MailStop 989, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA
(650) 329-4127 (voice)
dscheirer@usgs.gov
- Date: 2009 (process 9 of 10)
-
Performed magnetic survey leving using Oasis montaj
<http://www.geosoft.com/pinfo/oasismontaj/index.asp>.
- Janet T. Watt
- Date: 2009 (process 10 of 10)
-
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)
c/o Janet T. Watt
USGS, MailStop 989, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA
(650) 329-5307 (voice)
jwatt@usgs.gov
- 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 well have the observations been checked?
Data have not been independently verified.
- 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.
- 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.
- 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.
- How consistent are the relationships among the observations, including topology?
Undetermined
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.
- Who distributes the data set? (Distributor 1 of 1)
U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
c/o Ray W. Sliter
Geophysicist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
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.
- What's the catalog number I need to order this data set?
U.S. Geological Suvey Open-File Report 2009-1100
- 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.
- How can I download or order the data?
- Availability in digital form:
- Cost to order the data: None
- 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.
- Dates:
- Last modified: 19-Feb-2009
- Metadata author:
-
U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
c/o Ray W. Sliter
Geophysicist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
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)
Generated by mp version 2.9.8 on Tue Mar 2 10:29:23 2010
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U.S. Geological Survey
