scholarly journals The 2008–2010 Subsidence of Dallol Volcano on the Spreading Erta Ale Ridge: InSAR Observations and Source Models

2021 ◽  
Vol 13 (10) ◽  
pp. 1991
Author(s):  
Maurizio Battaglia ◽  
Carolina Pagli ◽  
Stefano Meuti
Keyword(s):  
Magma Chamber ◽  
Hydrothermal System ◽  
Shallow Depth ◽  
Volcanic Area ◽  
Subsidence Analysis ◽  
Source Models ◽  
Crustal Magma ◽  
Volume Decrease

In this work, we study the subsidence of Dallol, an explosive crater and hydrothermal area along the spreading Erta Ale ridge of Afar (Ethiopia). No volcanic products exist at the surface. However, a diking episode in 2004, accompanied by dike-induced faulting, indicates that Dallol is an active volcanic area. The 2004 diking episode was followed by quiescence until subsidence started in 2008. We use InSAR to measure the deformation, and inverse, thermoelastic and poroelastic modelling to understand the possible causes of the subsidence. Analysis of InSAR data from 2004–2010 shows that subsidence, centered at Dallol, initiated in October 2008, and continued at least until February 2010 at an approximately regular rate of up to 10 cm/year. The inversion of InSAR average velocities finds that the source causing the subsidence is shallow (depth between 0.5 and 1.5 km), located under Dallol and with a volume decrease between −0.63 and −0.26 × 106 km3/year. The most likely explanation for the subsidence of Dallol volcano is a combination of outgassing (depressurization), cooling and contraction of the roof of a shallow crustal magma chamber or of the hydrothermal system.

Chemistry and Differentiation of Mafic Dikes in an area near Fiskenaesset, West Greenland

1975 ◽  
Vol 12 (5) ◽  
pp. 721-730 ◽  
Author(s):  
Giorgio Rivalenti
Keyword(s):  
Trace Element ◽  
Magma Chamber ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
Olivine Tholeiite ◽  
Three Generations ◽  
Upward Displacement ◽  
Crustal Magma

In the Fiskenaesset region (West Greenland), there are three generations of postorogenic doleritic dikes of tholeiitic affinity. Two types of differentiation are evident: (a) laterally from the contacts to center and vertically, with the upper centres of the youngest generation of dikes attaining an andesitic or rhyolitic composition; and (b) between the different generations of dikes.Major and trace element geochemistry and calculations of the cumulus composition indicate that the differentiation within dikes is due not to flow, but to a shallow crustal fractionation of an olivine tholeiite magma. The differentiation between the various generations is attributed to fractionation of an olivine tholeiite magma during its upward displacement from a deep crustal magma chamber.

A Modeling of the Magma Chamber Beneath the Changbai Mountains Volcanic Area Constrained by Insar and GPS Derived Deformation

2008 ◽  
Vol 51 (4) ◽  
pp. 765-773 ◽  
Author(s):  
Guo-Hu CHEN ◽  
Xin-Jian SHAN ◽  
Wooil M. Moon ◽  
Kyung-Ryul Kim
Keyword(s):  
Magma Chamber ◽  
Changbai Mountains ◽  
Volcanic Area

2D thermo-mechanical-chemical coupled numerical models of interactions between a cooling magma chamber and a visco-elastic host rock

2020 ◽  
Author(s):  
Dániel Kiss ◽  
Evangelos Moulas ◽  
Lisa Rummel ◽  
Boris Kaus
Keyword(s):  
Magma Chamber ◽  
Host Rock ◽  
Numerical Models ◽  
Bulk Composition ◽  
Inertial Forces ◽  
Volume Changes ◽  
Consistent System ◽  
Host Rocks ◽  
2D Numerical Model ◽  
Crustal Magma

<p>A recent focus of studies in geodynamic modeling and magmatic petrology is to understand the coupled behavior between deformation and magmatic processes. Here, we present a 2D numerical model of an upper crustal magma (or mush) chamber in a visco-elastic host rock, with coupled thermal, mechanical and chemical (TMC) processes. The magma chamber is isolated from deeper sources of magma and it is cooling, and thus shrinking. We quantify the mechanical interaction between the shrinking magma chamber and the surrounding host rock, using a compressible visco-elastic formulation, considering several geometries of the magma chamber.</p><p>We present a self-consistent system of the conservation equations for coupled TMC processes, under the assumptions of slow (negligible inertial forces), visco-elastic deformation and constant chemical bulk composition. The thermodynamic melting/crystallization model is based on a pelitic melting model calculated with Perple_X, assuming a granitic composition and is incorporated as a look-up table. We will discuss the numerical implementation, show the results of systematic numerical simulations, and illustrate the effect of volume changes due to crystallization on stresses in the host rocks.</p>

scholarly journals Thermodynamic Model for Energy-Constrained Open-System Evolution of Crustal Magma Bodies Undergoing Simultaneous Recharge, Assimilation and Crystallization: the Magma Chamber Simulator

2014 ◽  
Vol 55 (9) ◽  
pp. 1685-1717 ◽  
Author(s):  
Wendy A. Bohrson ◽  
Frank J. Spera ◽  
Mark S. Ghiorso ◽  
Guy A. Brown ◽  
Jeffrey B. Creamer ◽  
...  
Keyword(s):  
Magma Chamber ◽  
Open System ◽  
Thermodynamic Model ◽  
System Evolution ◽  
Energy Constrained ◽  
Crustal Magma

scholarly journals Igneous stratigraphy and internal structure of the Little Minch Sill Complex, Trotternish Peninsula, northern Skye, Scotland

1991 ◽  
Vol 128 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Sally A. Gibson ◽  
Adrian P. Jones
Keyword(s):  
Internal Structure ◽  
Magma Chamber ◽  
Thermal Gradient ◽  
Olivine Basalt ◽  
Small Scale ◽  
Basalt Magma ◽  
Alkali Olivine Basalt ◽  
Modal Layering ◽  
Crustal Magma

AbstractDetailed sampling of the Little Minch Sill Complex reveals that it is composed of both single and multiple sills. These are formed of three main, genetically related units: picrite, picrodolerite and crinanite, which are the result of differentiation of an alkali-olivine basalt magma (approximately 10% MgO) in an upper-crustal magma chamber. Variations in igneous stratigraphy and the presence of internal chills in the Trotternish sills suggest that they were emplaced by multiple intrusion and subsequently differentiated in situ. Changes in petrography adjacent to pegmatite veins and textures within picrite units indicate compaction and filter-pressing were important processes after emplacement. Rhythmic layering (1 cm to 1 m thick) is conspicuous in the sills near contacts but does not involve cryptic mineral variation. Such modal layering may be more common than realised in relatively small-scale intrusions and maybe modelled in terms of in situ differentiation under conditions of significant undercooling in a changing thermal gradient at the synthetic for-sterite-diopside-anorthite eutectic.

Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise

Nature ◽  
1987 ◽  
Vol 326 (6108) ◽  
pp. 35-41 ◽  
Author(s):  
R. S. Detrick ◽  
P. Buhl ◽  
E. Vera ◽  
J. Mutter ◽  
J. Orcutt ◽  
...  
Keyword(s):  
Magma Chamber ◽  
Seismic Imaging ◽  
East Pacific Rise ◽  
East Pacific ◽  
Crustal Magma

Innovative boat-towed transient electromagnetics — Investigation of the Furnas volcanic lake hydrothermal system, Azores

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. E41-E56 ◽  
Author(s):  
Pritam Yogeshwar ◽  
Mira Küpper ◽  
Bülent Tezkan ◽  
Volker Rath ◽  
Duygu Kiyan ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Field Survey ◽  
Fault Zones ◽  
Volcanic Area ◽  
Noise Sources ◽  
Volcanic Lake ◽  
Time Domain Electromagnetic ◽  
A Minor ◽  
Central Loop ◽  
Standard Instrumentation

Water-covered areas may lead to gaps in surface electromagnetic surveys, causing reduced resolution and, as a consequence, increased uncertainty in derived subsurface models. We have evaluated a boat-towed floating central loop time-domain electromagnetic technique that mitigates this problem. It facilitates obtaining data with a spatial sampling density, which is rarely possible with standard instrumentation on land, and it only requires moderate logistical effort. A unique field study on a shallow volcanic lake demonstrated that this method is feasible with only a minor loss of accuracy when compared to anchored and land soundings. We found that the noise sources arising from the moving instrument and the boat engine can be neglected. The field survey was performed on the Lagoa das Furnas (São Miguel, Azores Islands, Portugal), which is located within an active volcanic area and is characterized by fumarolic fields and [Formula: see text] degassing. Thus, the associated hydrothermal system is expected to extend below the lake. However, the character, geometry, and extent of this system are unknown because of the lack of boreholes and geophysical studies. In total, 600 soundings, combining towed profiles with anchored and land-based soundings, were acquired with an aim of imaging the hydrothermal system beneath the lake down to 200 m. The results from all three types of measurements compare well and thus led to consistent 1D inversion models. The inversion results delineate a highly conductive, smectite-rich cap layer dipping below the lake away from the main fumarole zone. Near this zone, the extent of the conductor agrees well with an area of intense dispersed [Formula: see text] degassing, which appears to be controlled by at least two electrically distinctive fault zones in which the conductor is found at greater depths.

The continued 2008-2010 subsidence of Dallol on the spreading Erta Ale ridge: InSAR observations and source models

2021 ◽  
Author(s):  
Maurizio Battaglia ◽  
Carolina Pagli ◽  
Stefano Meuti
Keyword(s):  
Volume Change ◽  
Surface Deformation ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Line Of Sight ◽  
Central Volcano ◽  
Pore Fluid Pressure ◽  
Source Models ◽  
Magma Plumbing ◽  
Crustal Magma

<p>Volcanoes commonly subside during eruptions as magma flows out of a chamber, but continued subsidence during non-eruptive episodes is not easy to explain. In this work, we use InSAR and source modelling to understand the causes of the continued subsidence of Dallol, a nascent volcano along the spreading Erta Ale ridge of Afar (Ethiopia). The Dallol volcano never erupted and no volcanic deposits originating from the volcano exists at the surface. Recent seismicity, diking and continuous deformation of a crustal magma chamber indicate the Dallol is a nascent central volcano with its own rift segment. An active magma plumbing exists and the injection of a dike beneath the volcano was imaged in 2004 from InSAR data. This unrest episode was followed by complete quiescence until subsidence started in 2008. We analysed InSAR data from 2004-2010 to create time-series of line-of-sight (LOS) surface deformation. Average velocity maps show that subsidence centred at Dallol initiated in October 2008 and continued as far as February 2010 at an approximately regular rate of up to 10 cm/yr. The inversion of InSAR average velocities found that a sill-like source, located a depth between 1.2 and 1.5 km under Dallol with a mean volume change of  -0.62 to -0.53 10<sup>6</sup> km<sup>3</sup>/yr and a radius of approximately 1.6 km, best fits the InSAR observations. The observed volume change could be explained by changes in pore fluid pressure in a confined hydrothermal aquifer or by thermoelastic deformation caused by changes in temperature in a volume of rock. Simple models of poro-elastic and thermo-elastic contraction indicates that the observed deformation would require either a decrease in pore fluid pressure of the order of 10<sup>-2</sup>G, where G is the rock shear modulus, or a decrease in temperature between 60 °C and 80 °C.  </p>

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