The role of fan-shaped volcaniclastic deltas included in the edifice structure is critical to slump formation. This process is more efficient if deltas are associated with another upper LSL, such as weak hyaloclastites or hydrothermally altered rocks. In this Journal of Volcanology and Geothermal Re...
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| Format: | Text |
| Language: | English |
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2004
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.569.9213 http://www.geo.mtu.edu/EHaz/VolcanoInstability_class/wyk_de_vries/pdf/oehler_etal_JVGR_144_2005_LandslidesHotspotLSLs.pdf |
| Summary: | The role of fan-shaped volcaniclastic deltas included in the edifice structure is critical to slump formation. This process is more efficient if deltas are associated with another upper LSL, such as weak hyaloclastites or hydrothermally altered rocks. In this Journal of Volcanology and Geothermal Research 144 (2005) 169–189case, recurrent events generating collapses with increasing width are observed. Gravitational spreading of a volcanic island occurs when it is underlain by a ductile marine substratum, or includes an intra-edifice unconstrained hyaloclastic layer, 1/3 as thick as the height of the subaerial edifice. Spreading is characterized by edifice stretching and subsidence and does not generate major landslides. We also show that gravitational spreading on a marine substratum tends to inhibit slide generation, especially when the thickness of the sedimentary layer is larger than 1/10 of the edifice total height. However, if this value is lower, spreading occurs later and slumps can develop initially. We describe natural examples of oceanic hot-spot or arc shield volcanoes affected by both spreading and landslides, such as Reunion Island, Hawaii Island, James Ross Island (Antarctica) and Martinique Island (Antilles). The main structural features on these volcanoes can be explained solely by deformation on LSLs. We therefore propose a general model for the destabilization of volcanic islands that is applicable to all shield-like edifices. |
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