ISSN:
1573-0581
Keywords:
Marquesas
;
Hawaii
;
mass wasting
;
archipelagic aprons
;
landslides
;
island volcanism
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract Geophysical observations demonstrate that the archipelagic apron surrounding the Marquesan hot-spot volcanoes is derived almost entirely from mass wasting processes. Seismic reflection and refraction data constrain the volume of the apron sediments to approximately 200,000 km3, with thicknesses reaching over 2 km in the deep portions of the moat near the edge of the volcanic edifice. Seismic velocities average 4 to 5 km s−1 in the sediments, and 6 km s−1 at the top of the underlying basement. Single channel seismic profiles show acoustically chaotic cores in the sediments of the apron, which are interpreted as debris flows from mass wasting events. We deduce that the apron is formed by catastrophic collapses that may involve volumes over 100 km3 tens to hundreds of times during the lifetime of a volcano. Comparison with similar data from the Hawaiian Islands yields the result that the total volume of volcanics and their derived sediments along the strike of the chains is only slightly smaller for the Marquesas, implying comparable eruption rates. However, the ratio of sediment to surface volcanic load is much larger for the latter, leading to an overfilled moat in the Marquesas and an underfilled moat at Hawaii. The much larger size of the Hawaiian islands can be explained as the combined effects of a higher thermal swell, loading a stiffer elastic plate, and proportionately less mass wasting.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01203974
Permalink
