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Slopes of Western Galapagos volcanoes from airborne interferometric radar
Author(s) -
MouginisMark Peter J.,
Rowland Scott K.,
Garbeil Harold
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl03280
Subject(s) - geology , subaerial , volcano , digital elevation model , caldera , shield volcano , elevation (ballistics) , interferometric synthetic aperture radar , geomorphology , seismology , lava , remote sensing , synthetic aperture radar , geometry , mathematics
The distribution of slopes on the six basaltic shield volcanoes in the Western Galapagos Islands is investigated using a digital elevation model derived from airborne interferometric radar (TOPSAR) data. These measurements have a spatial sampling of 10 m/pixel, a vertical accuracy of 3 to 5 m, and constitute the highest resolution, most complete, topographic data set available for the islands. Volcano heights are determined to range from 1,124 m (Sierra Negra) to 1,710 m (Wolf). Over extensive areas of each volcano, slopes exceed 25°, with the highest slopes being ∼37° on Wolf and ∼36° on Fernandina. We confirm that two morphologic subgroups exist: Cerro Azul, Fernandina, and Wolf, with deep calderas (depth between 40–60% of the subaerial height of the volcano) and steep (>20°) maximum slopes at elevations between ∼60 and 80% of the volcano height; and Alcedo, Darwin, and Sierra Negra, with shallow calderas (depth <25% of subaerial height) and slopes that remain <15° until ∼90% of the total height is reached. Our data show that steep slopes are not uniquely correlated with the occurrence of arcuate fissures at the summit, leaving the origin of the steep slopes unresolved.