Roberts, J., 2007. The Marine Geomorphology of American Samoa: Shapes and Distributions of Deep Sea Volcanics, M.S. thesis, Oregon State University, Corvallis, OR, 92 pp., <http://marinecoastalgis.net/jed07>
ALSO
Wright, D.J., Roberts, J., Fenner, D., Smith, J.R., Koppers, A.A.P., Naar, D., Hirsch, E.R., Clift, L.W., and Hogrefe, K.R., Seamounts, ridges, and reef habitats of American Samoa, in Harris, P.T. and Baker, E.K. (eds.), Seafloor Geomorphology as Benthic Habitat: GeoHab Atlas of Seafloor Geomorphic Features and Benthic Habitats, Elsevier, Amsterdam, 791-806, 2012.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 0.001855
Ordinates (y-coordinates) are specified to the nearest 0.001855
The horizontal datum used is North American Datum of 1927.
Spheroid is Clarke 1866, 6378206.400000, 294.978698, Mean sea level.
Horizontal units are decimal degrees, Zunits are meters, "projection" is "geographic".
Sequential unique whole numbers that are automatically generated.
GMT (Generic Mapping Tools) grdinfo:
grdfile format: cf (# 10)
x_min: 189 x_max: 192.5 x_inc: 0.00185381 name: user_x_unit nx: 1888
y_min: -15.5 y_max: -13.2 y_inc: 0.00180676 name: user_y_unit ny: 1273
z_min: -7156.98 z_max: -5.0029 name: user_z_unit
scale_factor: 1 add_offset: 0
Main contributors were Dawn Wright, Oregon State University; Anthony Koppers, Oregon State University (Scripps Seamount Catalog); Dave Naar, University of South Florida; Joyce Miller and Scott Ferguson, NOAA Coral Reef Ecosystem Division/Pacific Islands Benthic Habitat Mapping Center/Pacific Fisheries Science Center. There were several additional contributors that are acknowledged in the file "multibeam.xls," which also includes a complete list of the bathymetric datasets used to create this regional dataset, as well as information about the sonar data collection systems. This information can also be found in Jed Roberts' thesis.
dawn@dusk.geo.orst.edu
541-737-1200 (FAX)
dawn@dusk.geo.orst.edu
This is a compilation of deepwater (> 250-500 m) multibeam bathymetry in American Samoa, compiled for the purpose of geomorphological analyses as pertaining to seamounts and volcanic lineaments, as well as for regional cartography.
Abstract of the thesis for which the data set was created:
The geologic processes at work in American Samoa have long been a point of scientific debate. Of its numerous volcanic formations, few breach sea level, leaving an enormous proportion of their mass unavailable to traditional observation. This study aims to describe the deep sea geomorphology of American Samoa through compilation, quantitative analysis, and qualitative interpretation of multibeam bathymetry datasets in an effort to contribute a new perspective on volcanic origins. Compilation of multibeam bathymetry datasets collected by various primary sources over the last two and half decades is accomplished using the multibeam processing software package MB‐System by Caress and Chayes (1996). The high‐resolution product is then employed to measure shape parameters of small seamounts (height < 1,000 m). Methods of quantitative analysis established by Jordan et al. (1983) and Smith (1988) are then used to assess the geomorphologic implications of shape parameter relationships. These relationships suggest that morphologies of small seamounts in American Samoa are typical of Pacific seamounts, though infrequent departures show forms indicative of mid‐ocean ridge type magmas. A distribution analysis of small seamounts follows, calculating areal density with the exponential distribution model conceived by Jordan et al. (1983) and modified by Smith and Jordan (1988). Distribution analysis yields a predicted density of 2.8 seamounts per 1,000 km2 and a characteristic height of 139 m, both within expectations for seamounts in the Pacific. Finally, a qualitative interpretation of the entire study area is undertaken that includes mapping of major volcanic features, morphologic descriptions of large seamounts, and considerations of age progression based on arrangements of volcanic lineaments.
MB-System Example
mbgrid -Idatalist.txt -E180/180/m -R189/192.5/-15.5/-13.2 -Oblahblah -L1 -C1 -X0
.1 -A1 -N -V
grdinfo blahblah.grd
grd2xyz blahblah.grd
I: Data list filename.
E: Spatial resolution.
R: Regional bounds.
O: Output file name (".grd" automatically appended).
L: "1" if longitude range is from 0 to 360 (common with SIO data).
C: Number of grid cells splined to edge of grid (for smoothing).
X: Extends the grid for spline interpolation.
A: "1" if depth values are positive. "2" if depth values are negative.
N: Gives empty grid cells a value of "NaN" rather than 99999.9.
V: Shows printout on screen of the mbgrid command executing.
MIRONE color scheme: ML -- hsv
Min Z: 5.0029
Max Z: 7156.98
Hillshade: 135 degrees
Image width: 3488 pixels
Data covered by newer swaths.
PIBSC data not included.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints: Not for navigational purposes. Please cite authors when using the data for your own work in print or on the web.
None required.
| Data format: | ArcGIS grid, GMT grid |
|---|
541-737-8818 (voice)