Global distribution of seamounts from Seasat profiles

Abstract

Bathymetrie profiles and contour charts have been used to study the distribution of seamounts in the deep ocean basins, but only a small fraction of the seafloor has been sampled by ships. At the present exploration rate it will take several centuries to map significant portions of the seafloor topography. Satellite altimetry, which maps the topography of the equipotential sea surface, is a promising tool for studying the gravity fields of seamounts because all ocean basins can be sampled in a couple of years. Using a model of a Gaussian‐shaped seamount loading a thin elastic lithosphere, we develop a new technique for measuring basic characteristics of a seamount from a single satellite altimeter profile. The model predicts that the seamount diameter is equal to the peak‐to‐trough distance along the vertical deflection profile and that the overall diameter of the signature reveals the age of the lithosphere when the seamount formed. Moreover, the model suggests that these two measurements are relatively insensitive to the cross‐track location of the seamount. We confirm these model predictions using Seasat altimeter profiles crossing 14 well surveyed seamounts in the Pacific. We then apply the measurement technique to 26 × 106 million kilometers of Seasat profiles resulting in a new global set of seamount locations. Approximately one quarter of the seamounts identified in Seasat profiles were previously uncharted. Modeling suggests that there is no direct relationship between the size of a seamount and its signature in the geoid; therefore the set of locations is not a straightforward sampling of the total seamount population, but is weighted toward seamounts which are poorly compensated. A preliminary analysis indicates considerable variations in population density and type across the oceans; most notable among them are the absence of seamounts in the Atlantic, variations in population density across large age‐offset fracture zones in the Pacific, the prevalence of small signatures in the Indian Ocean, and the existence of linear trends in the large seamounts of the west Pacific.

Turbulent 3-D thermal convection in an infinite Prandtl number, volumetrically heated fluid: implications for mantle dynamics

“…Plates represent horizontal motion on scales of several thousands of kilometres that are persistent on 100-200 Myr time scales. Intraplate volcanism, ranging from small seamounts abundant on the sea-floor (Batiza 1982;Craig & Sandwell 1988;Smith & Jordan 1988) to hotspots (Morgan 1971) of larger scale and longer duration, correspond to spatially smaller and temporally shorter scales of convective motion. Mantle plumes that generate hot spots are thought to originate by the instability of a thermal-boundary layer at depth in the mantle (Parmentier, Turcotte & Torrance 1975), perhaps at the core-mantle boundary.…”

The tectonic evolution of the South Atlantic from Late Jurassic to present

“…Ma~~~ti~ anomaly pick locations for Chron 34 to 3 correspond to the young end of tbe normal polarity interval Shaw, 1987;Cande et al. 1988;Shaw and Cande, 1990;Craig and Sandwell, 1988;MiilIer et al,, in press MacArthur et al, 19871, 2.9 times better than the 10 cm accuracy of Seasat data for wave heights less than 20 m (Tapley et al, 1982). Geosat has an ~q~~~torial track spacing of 164 km (McConathy and Kilgus, 1987).…”

A Synoptic Review on Deriving Bathymetry Information Using Remote Sensing Technologies: Models, Methods and Comparisons

“…Several algorithms are developed to derive bathymetric predictions from satellite altimeter. The most popular methods are: 1) the one-dimensional inversion of satellite tracks using linear approximation of the transfer function [9] [48] [49], 2) the one-dimensional adjustment of synthetic and satellite tracks [50], 3) the geometrical analysis of satellite tracks [51], 4) the two-dimensional inversion of geoid anomalies [52], and 5) the two-dimensional inversion of satellite data and the merging with conventional geophysical measurements [10] [53] [54].…”