Multibeam acoustic-backscatter data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA
These metadata describe acoustic-backscatter collected during a 2015 multibeam echosounder survey near Cross Sound, southeast Alaska. Data were collected by the U.S. Geological Survey (USGS) and the Alaska Department of Fish and Game (ADFG) aboard the ADFG R/V Solstice during USGS field activity 2015-629-FA. The acoustic-backscatter data are provided as a GeoTIFF.
Additional information about the field activities from which these data were derived is available online at:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
Dartnell, Peter, Brothers, Daniel S., and Haeussler, Peter J., 20220919, Multibeam acoustic-backscatter data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA: data release DOI:10.5066/F7JH3KG6, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.
Dartnell, Peter, Brothers, Daniel S., and Haeussler, Peter J., 2022, Multibeam bathymetry and acoustic-backscatter data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA: data release DOI:10.5066/F7JH3KG6, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 10.0
Ordinates (y-coordinates) are specified to the nearest 10.0
Planar coordinates are specified in Meters
The horizontal datum used is WGS84.
The ellipsoid used is WGS84.
The semi-major axis of the ellipsoid used is 6378137.00.
The flattening of the ellipsoid used is 1/298.257223563.
backscatter intensity as a digital value
(Source: Producer defined)
The complete 10-m resolution 2015 Cross Sound acoustic-backscatter grid was originally archived as a GeoTIFF image with the following attributes.
Cell size = 10.0
Number of rows = 6741
Number of columns = 5632
Data type = floating point
Xmin = 371360
Xmax = 427680
Ymin = 6409440
Ymax = 6476850
Minimum value = 0
Maximum value = 254
Mean = 26.98
Standard deviation = 51.4
Coordinate system description
These metadata describe the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC) 2015 acoustic-backscatter data collected near Cross Sound, southeast Alaska that is provided as a 10-m resolution TIFF image. In 2015 the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC) in cooperation with the Alaska Department of Fish and Game (ADFG) collected bathymetry and acoustic-backscatter data near Cross Sound in southeast Alaska using an Reson 7111 multibeam echosounder mounded to the ADFG R/V Solstice. The survey was conducted to map the offshore expression of the Queen Charlotte fault system that runs for approximately 500 kilometers off the coast of southeast Alaska and British Columbia. This was the first in a series of surveys to map the entire offshore component of the fault. The fault system has generated numerous powerful earthquakes in the magnitude 7 and 8 range. This new mapping will help understand the fault's slip rate, earthquake recurrence intervals, and paleoseismic history. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify bathymetric features. These data are not intended to be used for navigation.
In May 2015 the USGS, PCMSC mapped offshore Cross Sound in southeast Alaska over the northern section of the Queen Charlotte fault. A Reson 7111 multibeam echosounder was pole-mounted to the Alaska Department of Fish and Game R/V Solstice. The survey line files were imported into PDS2000 software for backscatter processing. Backscatter images were generated for each survey day. Each days backscatter image was exported as a ASCIIRaster file and imported into a Geographic Information Systems (GIS). The brightness and contrast of some of the images were adjusted to better match the surrounding images. All of the individual day images were merged into one overall backscatter image. The image was exported as a GeoTIFF file in UTM zone 8, WGS84 coordinates.
Where are the gaps in the data? What is missing?
Errors occurred processing backscatter imagery for a few lines and are not included in this dataset. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey and the Alaska Department of Fish and Game as the originators of the dataset and in products derived from these data. This information is not intended for navigation purposes.
Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
The downloadable data file has been compressed with the "zip" command and can be unzipped with Winzip (or other tool) on Windows systems. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing a GeoTIFF file.