Deep long period volcanic earthquakes generated by degassing of volatile-rich basaltic magmas

Melnik, Oleg; Lyakhovsky, Vladimir; Shapiro, N. M.; Galina, Natalia; Bergal‐Kuvikas, Olga

doi:10.1038/s41467-020-17759-4

Cited by 40 publications

(26 citation statements)

References 46 publications

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“…Deep long-period earthquakes (DLPs) associated with volcanoes have been observed in the mid-lower crust or mantle (Aso and Tsai 2014;Melnik et al 2020;Wech et al 2020). Although their origin is enigmatic, some studies have linked DLPs to an exsolved MVP.…”

Section: Seismicity and Strain Signals Related To The Migration Of Vo...mentioning

confidence: 99%

“…These events are not linked to eruptions but have been ascribed to the second boiling of deep (near-Moho) magma intrusions. Other interpretations of DLPs include thermal stresses set up by cooling magmas (Aso and Tsai 2014) and rapid changes of magmatic pressure in the lower crust caused by rapid nucleation and growth of gas bubbles in response to the slow upwelling of volatile-saturated magma (Melnik et al 2020). The latter explanation for the Klyuchevskoy volcanic group relates to primary melts that may contain ≤ 4 wt% H 2 O and 0.6 wt% CO 2 , which would cause volatile saturation at 800 MPa (~ 30 km).…”

Section: Seismicity and Strain Signals Related To The Migration Of Vo...mentioning

confidence: 99%

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Open-vent volcanoes fuelled by depth-integrated magma degassing

2022

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Open-vent, persistently degassing volcanoes—such as Stromboli and Etna (Italy), Villarrica (Chile), Bagana and Manam (Papua New Guinea), Fuego and Pacaya (Guatemala) volcanoes—produce high gas fluxes and infrequent violent strombolian or ‘paroxysmal’ eruptions that erupt very little magma. Here we draw on examples of open-vent volcanic systems to highlight the principal characteristics of their degassing regimes and develop a generic model to explain open-vent degassing in both high and low viscosity magmas and across a range of tectonic settings. Importantly, gas fluxes from open-vent volcanoes are far higher than can be supplied by erupting magma and independent migration of exsolved volatiles is integral to the dynamics of such systems. The composition of volcanic gases emitted from open-vent volcanoes is consistent with its derivation from magma stored over a range of crustal depths that in general requires contributions from both magma decompression (magma ascent and/or convection) and iso- and polybaric second boiling processes. Prolonged crystallisation of water-rich basalts in crustal reservoirs produces a segregated exsolved hydrous volatile phase that may flux through overlying shallow magma reservoirs, modulating heat flux and generating overpressure in the shallow conduit. Small fraction water-rich melts generated in the lower and mid-crust may play an important role in advecting volatiles to subvolcanic reservoirs. Excessive gas fluxes at the surface are linked to extensive intrusive magmatic activity and endogenous crustal growth, aided in many cases by extensional tectonics in the crust, which may control the longevity and activity of open-vent volcanoes. There is emerging abundant geophysical evidence for the existence of a segregated exsolved magmatic volatile phase in magma storage regions in the crust. Here we provide a conceptual picture of gas-dominated volcanoes driven by magmatic intrusion and degassing throughout the crust.

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Section: Seismicity and Strain Signals Related To The Migration Of Vo...mentioning

confidence: 99%

Section: Seismicity and Strain Signals Related To The Migration Of Vo...mentioning

confidence: 99%

Open-vent volcanoes fuelled by depth-integrated magma degassing

2022

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“…S-wave dominated signals can arise from volumetric sources with non-spherical geometries (e.g. Melnik et al, 2020) or from singleforce sources associated with fast local pressure variations (Shapiro et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Episodicity and Migration of Low Frequency Earthquakes Modeled With Fast Fluid Pressure Transients in the Permeable Subduction Interface

2021

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We model fluid pressure diffusion in a channel along the subduction interface in which the permeability varies through a valving mechanism• Tremor is generated as valves break open and interactions between valves through fluid pressure transients shape realistic event patterns• The input fluid flux in the fault controls seismic activity, opening possibilities to diagnose hydraulic conditions using LFE patterns

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“…One should finally note that the predominance of S-waves in the seismic signals does not necessarily establish a shear rupture mechanism. S-wave dominated signals can arise from volumetric sources with non-spherical geometries [e.g., 66] or from single-force sources associated with fast local pressure variations [85].…”

Section: Introductionmentioning

confidence: 99%

Episodicity and Migration of Low Frequency Earthquakes modeled with Fast Fluid Pressure Transients in the Permeable Subduction Interface

Farge¹,

Jaupart²,

Shapiro³

2021

Preprint

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In many subduction zones, the plate interface hosts intermittent, low-frequency, low-magnitude seismic tremor and low-frequency earthquakes (LFEs). Seismic activity clusters in episodic bursts that migrate along the fault zone in complex ways. Geological structures in fossil tremor source regions testify to large and pervasive variations of fluid pressure and permeability. Here, we explore the potential of fluid pressure transients in a permeable subduction interface to trigger seismic sources and induce interactions between them. We show how variations of pore pressure and permeability can act in tandem to generate tremor-like patterns. The core feature of the model is that lowpermeability plugs behave as elementary fault-valves. In a mechanism akin to erosive bursts and deposition events documented in porous media, valve permeability opens and closes in response to the local fluid pressure distribution. The rapid pressure release and/or mechanical fracturing associated with valve opening acts as the source of an LFE-like event. Valves interact constructively, leading to realistic, tremor-like patterns: cascades, synchronized bursts and migrations of activity along the channel, on both short and long time and space scales. Our model predicts that the input fluid flux is a key control on activity occurrence and behavior. Depending on its value, the subduction interface can be seismically quiescent or active, and seismicity can be strongly time-clustered, quasi-periodic or almost random in time. This model allows new interpretations of low frequency seismic activity in terms of effective fluid flux and fault-zone permeability.

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Deep long period volcanic earthquakes generated by degassing of volatile-rich basaltic magmas

Cited by 40 publications

References 46 publications

Open-vent volcanoes fuelled by depth-integrated magma degassing

Open-vent volcanoes fuelled by depth-integrated magma degassing

Episodicity and Migration of Low Frequency Earthquakes Modeled With Fast Fluid Pressure Transients in the Permeable Subduction Interface

Episodicity and Migration of Low Frequency Earthquakes modeled with Fast Fluid Pressure Transients in the Permeable Subduction Interface

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