Great challenges in volcanology: how does the volcano factory work?

Acocella, Valerio

doi:10.3389/feart.2014.00004

Cited by 18 publications

(13 citation statements)

References 89 publications

(96 reference statements)

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“…Fortunately, almost all eruptions are preceded by anomalous, usually elevated seismicity, deformation, and gas emission of the volcano—called unrest and usually lasting from a few hours to several years. Commonly reported forms of unrest are local earthquake swarms, uplift, subsidence, tilt, ground fissuring, changes in the gravity field, changes in the temperature of soil, water or gas, and changes in fumarolic activity (Figure ) [ Newhall and Dzurisin , , and references therein; Sandri et al , ; Moran et al , ; Acocella , ]. All eruptions are thus preceded by unrest, which may show variable features from volcano to volcano and even within the same volcano.…”

Section: Introductionmentioning

confidence: 99%

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Acocella

Lorenzo

Newhall³

et al. 2015

Reviews of Geophysics

152

165

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Calderas are among the most active and dangerous volcanoes. Caldera unrest is defined by enhanced seismicity, gravity changes, surface deformation, and degassing. Although much caldera unrest does not lead to an eruption, every eruption is preceded by an unrest episode. Therefore, the proper description of unrest and the forecast of its possible outcome is a timely and challenging task. Here we review the best known unrest at calderas from 1988 to 2014, building on previous work and proposing an updated database. Where established, the root cause for unrest is always magmatic; none was purely hydrothermal or tectonic. An interpretive classification of unrest invokes two spectra-compositional (mafic to felsic) and the state of magma conduits feeding from the magma reservoir(s) to the surface (from fully plugged, through semiplugged, to open). Magma and gas in open conduits can rise and erupt freely; magma in semiplugged conduits erupts less frequently yet still allows some gas to escape; plugged conduits allow neither magma nor gas to escape. Unrest in mafic calderas is subtler, less pronounced, and repeated, especially with open systems, ensuring the continuous, aseismic, and moderate release of magma. Plugged felsic calderas erupt infrequently, anticipated by isolated, short and seismically active unrest. Semiplugged felsic calderas also erupt infrequently and are restless over decades or centuries, with uplift, seismicity, and degassing and, on the longer-term, resurgence, suggesting repeated stalled intrusions. Finally, the expected advances in better understanding caldera unrest are discussed.

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Section: Introductionmentioning

confidence: 99%

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Acocella

Lorenzo

Newhall³

et al. 2015

Reviews of Geophysics

152

165

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“…The ultimate challenge for volcanology is to forecast eruptions; this task requires a probabilistic approach, which, given our current knowledge, is more effective than any determinist attempt [ Sparks , ]. The difficulty in forecasting eruptions is somehow mitigated by the fact that almost all eruptions are preceded by anomalous seismicity, deformation, and gas emission of the volcano, called unrest and usually lasting from a few hours to several years [ Newhall and Dzurisin , , and references therein; Sandri et al ., ; Moran et al ., ; Acocella , ]. All eruptions are thus preceded by unrest, which may show variable features from time to time.…”

Section: Introductionmentioning

confidence: 99%

Searching for patterns in caldera unrest

Sandri

Acocella

Newhall³

2017

Geochem Geophys Geosyst

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The ultimate goal of volcanology is forecasting eruptions. This task is particularly challenging at calderas, where unrest is frequent, affects wider areas and its evidence is often masked by the activity of hydrothermal systems. A recent study has compiled a database on caldera unrest, derived from seismicity, geodetic, gravity, and geochemical monitoring data at calderas worldwide, from 1988 to 2014. Here we exploit this database, searching for the most recurring features of unrest and, in turn, its possible dynamics. In particular, we focus on (a) the duration of unrest at calderas; (b) recurring patterns in unrest; (c) unrest episodes culminating in eruptions, including time‐predictability or size‐predictability and a multivariate regression analysis. Our analysis indicates that preeruptive unrest is shorter than noneruptive unrest, particularly with open or semiplugged calderas, calderas with mafic or mixed composition of past eruptive products, or unrest driven by mafic magma; conversely, lack of data on preeruptive unrest driven by felsic magma and/or at felsic or plugged calderas prevents an analysis of these specific subsets. In addition, 72% of preeruptive unrest lasts <10 months and shows high seismicity and degassing. The remaining 28% (a) is essentially aseismic in calderas with open‐conduit (17%), or (b) lasts between 10 and 18 months, with seismicity and degassing, constituting a longer‐duration tail of the preeruptive unrest with seismicity and degassing (11%). Surface deformation is not always reliable to characterize preeruptive unrest. Our analysis suggests that magma may withstand only a limited period of “eruptability,” before becoming stored in the upper crust.

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“…Nonetheless, this is a rather simplified overview. The internal plumbing system of an active volcano can be quite intricate, though recent monitoring efforts involving geodetic, seismic and geochemical measurements are helping at improving the estimations of size, depth, and activity of magma chambers under active volcanoes 2 3 4 .…”

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On a Possible Unified Scaling Law for Volcanic Eruption Durations

Cannavò

Nunnari

2016

Sci Rep

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Volcanoes constitute dissipative systems with many degrees of freedom. Their eruptions are the result of complex processes that involve interacting chemical-physical systems. At present, due to the complexity of involved phenomena and to the lack of precise measurements, both analytical and numerical models are unable to simultaneously include the main processes involved in eruptions thus making forecasts of volcanic dynamics rather unreliable. On the other hand, accurate forecasts of some eruption parameters, such as the duration, could be a key factor in natural hazard estimation and mitigation. Analyzing a large database with most of all the known volcanic eruptions, we have determined that the duration of eruptions seems to be described by a universal distribution which characterizes eruption duration dynamics. In particular, this paper presents a plausible global power-law distribution of durations of volcanic eruptions that holds worldwide for different volcanic environments. We also introduce a new, simple and realistic pipe model that can follow the same found empirical distribution. Since the proposed model belongs to the family of the self-organized systems it may support the hypothesis that simple mechanisms can lead naturally to the emergent complexity in volcanic behaviour.

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Great challenges in volcanology: how does the volcano factory work?

Cited by 18 publications

References 89 publications

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Searching for patterns in caldera unrest

On a Possible Unified Scaling Law for Volcanic Eruption Durations

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