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Morphometric analysis of the submarine arc volcano Monowai (Tofua – Kermadec Arc) to decipher tectono-magmatic interactions

Record type: Article

Morphometric analysis of multibeam bathymetry and backscatter data is applied to Monowai, a submarine volcano of the active Tofua–Kermadec Arc to map and document the structure and evolution of the volcanic centre. Low rates of erosion and sedimentation, and pervasive tectonic and magmatic processes, allow quantification through detailed structural analysis and measurement of deformation. The Slope, Aspect, Curvature, Rugosity, and Hydrology (flow) tools of ArcGIS provide a robust structural interpretation and the development of a model of Monowai evolution.

A nested caldera structure with a volume of ~ 31 km3 and a stratovolcano of ~ 18 km3 dominate the magmatic constructs. The outer caldera is elongate along 125°, and the inner caldera along 135°. Numerous parasitic cones and fissure ridges are also observed, oriented at 039° and 041°, respectively. Northeast trending faults (with a regional average strike of 031°) are widespread within this part of the backarc, forming a nascent rift graben to the west of the Monowai caldera complex. The distribution of throw varies spatially, reaching a maximum total along-rift of 320 m and across rift of 120 m, with greater throw values measured in the west.

Elongation directions of the two nested calderas are near-perpendicular to the trends of faults and fissure ridges. The inner caldera is more orthogonal to the magmatic constructs (fissure ridges and aligned vent cones) and the outer caldera is approximately orthogonal to the regional fault fabric, suggesting a strong interaction between magmatic and tectonic processes, and the directions of the horizontal principal stress. We present a detailed morphometric analysis of these relationships and the data are used to interpret the spatial and temporal evolution of the tectono-magmatic system at Monowai, and classify the type of rifting as transtensional. Similar analysis is possible elsewhere in the Kermadec backarc and within other regions of submarine volcanism.

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Citation

Wormald, Sarah C, Wright, Ian C., Bull, Jonathan M., Lamarche, Geoffroy and Sanderson, David J. (2012) Morphometric analysis of the submarine arc volcano Monowai (Tofua – Kermadec Arc) to decipher tectono-magmatic interactions Journal of Volcanology and Geothermal Research, 239-240, pp. 69-82. (doi:10.1016/j.jvolgeores.2012.06.004).

More information

Published date: 15 September 2012
Keywords: Morphology, Multibeam analysis, Backarc, Caldera, Horizontal stress, Kermadec, Monowai, Tectono-magmatic
Organisations: Geology & Geophysics, Marine Geoscience, Civil Maritime & Env. Eng & Sci Unit

Identifiers

Local EPrints ID: 340799
URI: http://eprints.soton.ac.uk/id/eprint/340799
ISSN: 0377-0273
PURE UUID: c94fad76-9805-40ab-b473-c8d1e8408d65
ORCID for David J. Sanderson: ORCID iD orcid.org/0000-0002-2144-3527

Catalogue record

Date deposited: 03 Jul 2012 09:38
Last modified: 18 Jul 2017 05:41

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Contributors

Author: Sarah C Wormald
Author: Ian C. Wright
Author: Geoffroy Lamarche

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