SV_SeismicShot500 - Shot Points at 500 shot intervals for seismic data collected aboard R/V RAFAEL (field activities 05001 and 06001) in Apalachicola Bay and St. George Sound, FL

These data were collected under a cooperative mapping program between the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration Office for Coastal Management (NOAA\OCM), and the Apalachicola National Estuarine Research Reserve (NERR). The primary objectives of this program were to collect marine geophysical data to develop a suite of seafloor maps to better define the extent of oyster habitats, the overall seafloor geology of the bay and provide updated information for management of this resource. In addition to their value for management of the bay's oyster resources, the maps also provide a geologic framework for scientific research and the public.

High-resolution bathymetry, backscatter intensity, and seismic profile data were collected over 230 square kilometers of the floor of the bay. The study focused on the Apalachicola Bay and Western St. George Sound portions of the estuary in mostly in depths > 2.0 meters.

Original contact information:

Contact Name: Brian Andrews

Contact Org: U.S. Geological Survey

Title: Geographer

Phone: 508-548-8700 x2348

Email: bandrews@usgs.gov

These data represent shot navigation at 500 shot intervals for seismic profile data collected during USGS field activities 05001, and 06001 in Apalachicola Bay and the western part of St. George Sound, Florida. These data are used to locate the 500 shot index markers on each seismic profile in geographic space.

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Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. 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.

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Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350

RTK GPS was used to navigate the survey platform from which the seismic-reflection data were collected. The GPS antenna was mounted over the bathymetric sonar and a layback of 4 meters was used for the seismic systems.

Navigation was recorded to all data acquisition systems using Real Time Kinematic GPS at a one second interval.

Horizontal accuracy of the navigation is assumed to be +/- 1 meter. The shot point file and survey line file for the

seismic data are both derived from the same navigation file that was logged by the seismic acquisition system, but

because the two were processed differently, the shot points do not always fall directly on the survey line. To create

the shot point file, the navigation was queried to extract every 500th point starting with shot point 500. By

contrast, to create the survey line file, the navigation was queried at a one minute interval (every 60th point), and

then a line was drawn using these points. Because of the different processing approaches, many of the shot points,

although close, do not fall exactly on the survey line. If meter accuracy is truely needed, it would be best to

extract the navigation from the archived SEG-Y seismic files.

Navigation tracklines for which there was no valid data were deleted.

Data was compared to sediment grabs and was collected following standard best practices for recording sub-bottom profile data.