scholarly journals Origins of oblique-slip faulting during caldera subsidence

2013 ◽  
Vol 118 (4) ◽  
pp. 1778-1794 ◽  
Author(s):  
Eoghan P. Holohan ◽  
Thomas R. Walter ◽  
Martin P.J. Schöpfer ◽  
John J. Walsh ◽  
Benjamin van Wyk de Vries ◽  
...  
Keyword(s):  
Caldera Subsidence

Submarine flank eruption preceding caldera subsidence during the 2000 eruption of Miyakejima Volcano, Japan

2005 ◽  
Vol 67 (3) ◽  
pp. 243-253 ◽  
Author(s):  
Takayuki Kaneko ◽  
Atsushi Yasuda ◽  
Taketo Shimano ◽  
Setsuya Nakada ◽  
Toshitsugu Fujii ◽  
...  
Keyword(s):  
Flank Eruption ◽  
Miyakejima Volcano ◽  
Caldera Subsidence

Coupled caldera subsidence and stirring inferred from analogue models

2008 ◽  
Vol 1 (6) ◽  
pp. 385-389 ◽  
Author(s):  
Ben M. Kennedy ◽  
A. Mark Jellinek ◽  
John Stix
Keyword(s):  
Analogue Models ◽  
Caldera Subsidence

Is Efate (Vanuatu, SW Pacific) a result of subaerial or submarine eruption? An alternative model for the 1 Ma Efate Pumice Formation

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Robert Stewart ◽  
Karoly Németh ◽  
Shane Cronin
Keyword(s):  
Fault Scarp ◽  
Pyroclastic Rock ◽  
Shallow Marine ◽  
The North ◽  
Sw Pacific ◽  
Volcanic Succession ◽  
Volcaniclastic Deposits ◽  
Caldera Subsidence ◽  
Volcaniclastic Succession ◽  
Explosive Event

AbstractThe Efate Pumice Formation (EPF) is a trachydacitic volcaniclastic succession widespread in the central part of Efate Island and also present on Hat and Lelepa islands to the north. The volcanic succession has been inferred to result from a major, entirely subaqueous explosive event north of Efate Island. The accumulated pumice-rich units were previously interpreted to be subaqueous pyroclastic density current deposits on the basis of their bedding, componentry and stratigraphic characteristics. Here we suggest an alternative eruptive scenario for this widespread succession. The major part of the EPF is distributed in central Efate, where pumiceous pyroclastic rock units several hundred meters thick are found within fault scarp cliffs elevated about 800 m above sea level. The basal 200 m of the pumiceous succession is composed of massive to weakly bedded pumiceous lapilli units, each 2-3 m thick. This succession is interbedded with wavy, undulatory and dune bedded pumiceous ash and fine lapilli units with characteristics of co-ignimbrite surges and ground surges. The presence of the surge beds implies that the intervening units comprise a subaerial ignimbrite-dominated succession. There are no sedimentary indicators in the basal units examined that are consistent with water-supported transportation and/or deposition. The subaerial ignimbrite sequence of the EPF is overlain by a shallow marine volcaniclastic Rentanbau Tuffs. The EPF is topped by reef limestone, which presumably preserved the underlying EPF from erosion. We here propose that the EPF was formed by a combination of initial subaerial ignimbrite-forming eruptions, followed by caldera subsidence. The upper volcaniclastic successions in our model represent intra-caldera pumiceous volcaniclastic deposits accumulated in a shallow marine environment in the resultant caldera. The present day elevated position of the succession is a result of a combination of possible caldera resurgence and ongoing arc-related uplift in the region.

Caldera subsidence in extensional tectonics

2014 ◽  
Vol 76 (10) ◽  
Author(s):  
Stefano Carlino ◽  
Anna Tramelli ◽  
Renato Somma
Keyword(s):  
Extensional Tectonics ◽  
Caldera Subsidence

scholarly journals Geodetic data shed light on ongoing caldera subsidence at Askja, Iceland

2013 ◽  
Vol 75 (5) ◽  
Author(s):  
Elske de Zeeuw-van Dalfsen ◽  
Hazel Rymer ◽  
Erik Sturkell ◽  
Rikke Pedersen ◽  
Andy Hooper ◽  
...  
Keyword(s):  
Geodetic Data ◽  
Shed Light ◽  
Caldera Subsidence

L'evolution volcano-tectonique du massif du Mont-Dore (Auvergne) pendant le Mio-Pliocene

1958 ◽  
Vol S6-VIII (7) ◽  
pp. 797-804
Author(s):  
Louis Glangeaud ◽  
J. C. Lemonnier
Keyword(s):  
Aerial Photographs ◽  
Tectonic Activity ◽  
Tectonic Processes ◽  
Caldera Subsidence

Abstract New surveys based on aerial photographs of the Mont-Dore massif (Auvergne, France) show the position of the network of dikes and their relation to faults, and thus throw light on the evolution of the Bourboule-Mont-Dore caldera and its magmas (trachyandesites). Volcanic-tectonic activity began in the Pontian and terminated in the lower Pliocene. Extrusion of lavas was simultaneous with caldera subsidence, which was contemporaneous with the tectonic processes responsible for orogenic activity in numerous areas borderingthe Alps.

scholarly journals From prodigious volcanic degassing to caldera subsidence and quiescence at Ambrym (Vanuatu): the influence of regional tectonics

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tara Shreve ◽  
Raphaël Grandin ◽  
Marie Boichu ◽  
Esline Garaebiti ◽  
Yves Moussallam ◽  
...  
Keyword(s):  
Satellite Remote Sensing ◽  
Rift Zone ◽  
Lateral Migration ◽  
Submarine Eruption ◽  
Pyroclastic Deposits ◽  
Thermal Anomalies ◽  
New Hebrides ◽  
Lava Lakes ◽  
Caldera Subsidence ◽  
Regional Tectonics

AbstractEruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide caldera and several intensely-degassing lava lakes confined to intra-caldera cones. Using satellite remote sensing of deformation, gas emissions and thermal anomalies, combined with seismicity and ground observations, we show that in December 2018 an intra-caldera eruption at Ambrym preceded normal faulting with >2 m of associated uplift along the eastern rift zone and 2.5 m of caldera-wide subsidence. Deformation was caused by lateral migration of >0.4 cubic kilometers of magma into the rift zone, extinguishing the lava lakes, and feeding a submarine eruption in the rift edge. Recurring rifting episodes, favored by stress induced by the D’Entrecasteaux Ridge collision against the New Hebrides arc, lead to progressive subsidence of Ambrym’s caldera and concurrent draining of the lava lakes. Although counterintuitive, convergent margin systems can induce rift zone volcanism and subsequent caldera subsidence.

scholarly journals Explosive caldera-forming eruptions and debris-filled vents: Gargle dynamics

Geology ◽  
2021 ◽  
Author(s):  
Greg A. Valentine ◽  
Meredith A. Cole
Keyword(s):  
Grain Size ◽  
Numerical Modeling ◽  
Volcanic Eruptions ◽  
Low Energy ◽  
Buoyant Plume ◽  
Entire Height ◽  
The World ◽  
Jet Behavior ◽  
Explosive Volcanic Eruptions ◽  
Caldera Subsidence

Large explosive volcanic eruptions are commonly associated with caldera subsidence and ignimbrites deposited by pyroclastic currents. Volumes and thicknesses of intracaldera and outflow ignimbrites at 76 explosive calderas around the world indicate that subsidence is commonly simultaneous with eruption, such that large proportions of the pyroclastic currents are trapped within the developing basins. As a result, much of an eruption must penetrate its own deposits, a process that also occurs in large, debris-filled vent structures even in the absence of caldera formation and that has been termed “gargling eruption.” Numerical modeling of the resulting dynamics shows that the interaction of preexisting deposits (fill) with an erupting (juvenile) mixture causes a dense sheath of fill material to be lifted along the margins of the erupting jet. This can cause an eruption that would otherwise produce a buoyant plume and fallout deposits to instead form pyroclastic currents as the dense sheath drives pulsing jet behavior. Increasing thickness of fill amplifies the time variation in jet height. Increasing the fill grain size relative to that of the juvenile particles can result in a much higher jet due to poorer mixing between the dense sheath and the dilute jet core. In all cases, material collapses along the entire height of the dense sheath rather than from the top of a simple fountain. These gargle dynamics provide strong backing for processes that have been inferred to result in intraplinian ignimbrites and simultaneous deposition from high- and low-energy pyroclastic currents.

The Southern Mountains Zone, Isle of Rum, Scotland: volcanic and sedimentary processes upon an uplifted and subsided magma chamber roof

2009 ◽  
Vol 146 (3) ◽  
pp. 400-418 ◽  
Author(s):  
E. P. HOLOHAN ◽  
V. R. TROLL ◽  
M. ERRINGTON ◽  
C. H. DONALDSON ◽  
G. R. NICOLL ◽  
...  
Keyword(s):  
Debris Flow ◽  
Stream Flow ◽  
Country Rock ◽  
Mass Movement ◽  
Central Complex ◽  
Caldera Collapse ◽  
Precambrian Basement ◽  
Rock Outcrops ◽  
Caldera Floor ◽  
Caldera Subsidence

AbstractThe Southern Mountains Zone of the Rum Central Complex lies inside a major ring fault and comprises an intricate association of country-rock outcrops, breccias and rhyodacite. The breccias and rhyodacite were long thought to be products of subterranean explosion and intrusion, respectively. Here, we report new observations that support re-interpretation of these units as mass movement deposits and ignimbrites. The most abundant breccias (Coire Dubh-type) consist mainly of country-rock clasts <1 m in diameter in a sand or silt matrix. Internally bedded and graded, and interlayered with sandstones and lithic tuffs, these breccias are interpreted as debris flow and stream flow deposits. Rhyodacite sheets show gradational or sharp, concordant contacts with Coire Dubh-type breccias, and display graded basal lithic tuffs and graded fiamme swarms. These sheets are interpreted as moderately to densely welded rhyodacite ignimbrites (25–100 m thick). A steep body of fragmented (fiamme-bearing) rhyodacite with intrusive non-fragmented contacts is interpreted as an ignimbrite vent system. The rhyodacite and breccia succession is over 200 m thick and unconformably overlies a structurally uplifted Precambrian basement, within which there is also evidence of later subsidence. Outcrops of potential caldera-collapse ‘megabreccia’ are more structurally consistent than previously thought, and are re-interpreted here as coherent segments of Precambrian country rock (caldera floor). The Southern Mountains Zone breccias and rhyodacites respectively reflect sedimentary and pyroclastic processes acting in response to a complex tectonic interplay of intrusion-related uplift and caldera subsidence.

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