This study uses on-land and offshore geological and structural data to demonstrate that a huge lateral collapse involved the SE flank of Nisyros volcano. The collapse beheaded the summit part of the volcano and also involved the submarine portion of the slope, producing a large debris avalanche deposit with a volume of about 1 km<sup>3</sup> which has been recognized on the sea floor. On-land, stratigraphic and structural data indicate that a thick succession of lava flows (Nikia lavas) was emplaced in a huge horseshoe-shaped depression open seaward and extending below the sea. The magma-feeding system in the volcano, pre-dating and following the collapse, was structurally influenced by a dominant NE-SW direction, which is perpendicular to the newly-recognised sector collapse. The NE-SW structural trend is consistent with the regional tectonic structures found offshore around Nisyros and with the related NW-SE extension direction. We suggest that the lateral magma pressure produced by repeated magma injections along tectonic discontinuities contributed to destabilise the volcano flank. The occurrence of a pyroclastic deposit that mantled the scar left by the collapse suggests that a magma batch might have been injected inside the volcano and triggered the collapse. The lavas of the pre-collapse edifice have been deposited in alternating submarine and subaerial environments, suggesting that vertical movements might also be a major triggering mechanism for large lateral collapses. Recognition of this phenomenon is particularly important in recent/active island or coastal volcanoes, as it can trigger tsunamis. © 2008 Elsevier B.V. All rights reserved.

Tibaldi, A., Pasquarè, F., Papanikolaou, D., & Nomikou, P. (2008). Discovery of a huge sector collapse at the resurgent caldera of Nisyros, Greece, by onshore and offshore geological-structural data. JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 177(2), 485-499 [10.1016/j.jvolgeores.2008.06.014].

Discovery of a huge sector collapse at the resurgent caldera of Nisyros, Greece, by onshore and offshore geological-structural data

TIBALDI, ALESSANDRO;
2008

Abstract

This study uses on-land and offshore geological and structural data to demonstrate that a huge lateral collapse involved the SE flank of Nisyros volcano. The collapse beheaded the summit part of the volcano and also involved the submarine portion of the slope, producing a large debris avalanche deposit with a volume of about 1 km3 which has been recognized on the sea floor. On-land, stratigraphic and structural data indicate that a thick succession of lava flows (Nikia lavas) was emplaced in a huge horseshoe-shaped depression open seaward and extending below the sea. The magma-feeding system in the volcano, pre-dating and following the collapse, was structurally influenced by a dominant NE-SW direction, which is perpendicular to the newly-recognised sector collapse. The NE-SW structural trend is consistent with the regional tectonic structures found offshore around Nisyros and with the related NW-SE extension direction. We suggest that the lateral magma pressure produced by repeated magma injections along tectonic discontinuities contributed to destabilise the volcano flank. The occurrence of a pyroclastic deposit that mantled the scar left by the collapse suggests that a magma batch might have been injected inside the volcano and triggered the collapse. The lavas of the pre-collapse edifice have been deposited in alternating submarine and subaerial environments, suggesting that vertical movements might also be a major triggering mechanism for large lateral collapses. Recognition of this phenomenon is particularly important in recent/active island or coastal volcanoes, as it can trigger tsunamis. © 2008 Elsevier B.V. All rights reserved.
Si
Articolo in rivista - Articolo scientifico
Scientifica
Grecia, collassi, vulcani
English
485
499
15
Tibaldi, A., Pasquarè, F., Papanikolaou, D., & Nomikou, P. (2008). Discovery of a huge sector collapse at the resurgent caldera of Nisyros, Greece, by onshore and offshore geological-structural data. JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 177(2), 485-499 [10.1016/j.jvolgeores.2008.06.014].
Tibaldi, A; Pasquarè, F; Papanikolaou, D; Nomikou, P
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10281/7258
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