Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano

Bonforte, Alessandro; Gambino, Salvatore; Neri, Marco

doi:10.1016/j.tecto.2008.09.028

Cited by 62 publications

(54 citation statements)

References 51 publications

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“…However, the involvement of the Hyblean Plateau with the magmatic plumbing system at Mt. Etna volcano does not end there, as new heat sources, in the form of eccentric reservoirs or peripheral dykes that have fed recent flank eruptions, are also inferred to populate these depth intervals Andronico et al, 2005;Carbone et al, 2009;Bonforte et al, 2009), thus possibly exposing fresh, unaltered carbonate rock to high temperatures. Volcanic activity at the flanks of Mt.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…Etna will be exposed to high temperatures as a result of their proximity to large, long-lived magmatic bodies (Murru et al, 1999;Chiarabba et al, 2000;Bonaccorso et al, 2010), and lateral growth of the reservoir via eccentric dyking and ponding (Carrigan et al, 1992;Behncke and Neri, 2003;Andronico et al, 2005;Carbone et al, 2009;Bonforte et al, 2009), as well as circulating hot fluids (Siniscalchi et al, 2010): "proximity without intimacy". Indeed, accelerated flank movements are commonly observed to follow magmatic events within the sedimentary substratum (Walter et al, 2005), highlighting the intimate link between basement deformation and flank instability.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…However, as explained above, magmatic activity at Mt. Etna is constantly evolving and recent flank eruptions were sourced from new reservoirs and new pathways emplaced within the carbonatic basement Andronico et al, 2005;Carbone et al, 2009;Bonforte et al, 2009); therefore new volumes of carbonate rock may well be readily available for decarbonation.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

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Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

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Mollo

Vinciguerra

et al. 2013

Journal of Volcanology and Geothermal Research

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The physical integrity of a sub-volcanic basement is crucial in controlling the stability of a volcanic edifice. For many volcanoes, this basement can comprise thick sequences of carbonates that are prone to significant thermally-induced alteration. These debilitating thermal reactions, facilitated by heat from proximal magma storage volumes, promote the weakening of the rock mass and likely therefore encourage edifice instability. Such instability can result in slow, gravitational spreading and episodic to continuous slippage of unstable flanks, and may also facilitate catastrophic flank collapse. Understanding the propensity of a particular sub-volcanic basement to such instability requires a detailed understanding of the influence of high temperatures on the chemical, physical, and mechanical properties of the rocks involved. The juxtaposition of a thick carbonate substratum and magmatic heat sources makes Mt. Etna volcano an ideal candidate for our study. We investigated experimentally the effect of temperature on two carbonate rocks that have been chosen to represent the deep, heterogeneous sedimentary substratum under Mt. Etna volcano. This study has demonstrated that thermalstressing resulted in a progressive and significant change in the physical properties of the two rocks. Porosity, wet (i.e., water-saturated) dynamic Poisson's ratio and wet Vp/Vs ratio all increased, whilst P-and S-wave velocities, bulk sample density, dynamic and static Young's modulus, dry Vp/Vs ratio, and dry dynamic Poisson's ratio all decreased. At temperatures of 800 °C, the carbonate in these rocks completely dissociated, resulting in a total mass loss of about 45% and the release of about 44 wt.% of CO 2 . Uniaxial deformation experiments showed that high in-situ temperatures (> 500°C) significantly reduced the strength of the carbonates and altered their deformation behaviour. Above 500 °C the rocks deformed in a ductile manner and A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTthe output of acoustic emissions was greatly reduced. We speculate that thermally-induced weakening and the ductile behaviour of the carbonate substratum could be a key factor in explaining the large-scale deformation observed at Mt. Etna volcano. Our findings are consistent with several field observations at Mt. Etna volcano and can quantitatively support the interpretation of (1) the irregularly low seismic velocity zones present within the sub-volcanic sedimentary basement, (2) the anomalously high CO 2 degassing observed, (3) the anomalously high Vp/Vs ratios and the rapid migration of fluids, and (4) the increasing instability of volcanic edifices in the lifespan of a magmatic system. We speculate that carbonate sub-volcanic basement may emerge as one of the decisive fundamentals in controlling volcanic stability.

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

See 1 more Smart Citation

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Heap

Mollo

Vinciguerra

et al. 2013

Journal of Volcanology and Geothermal Research

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“…GPS data collected during the surveys, passing through a N-S profile crossing the volcano summit Bonforte et al, 2009), allowed strain calculation. Geodetic measurements on the summit part of Etna are possible only in the summer, due to the snow cover during the rest of the year that prevents the access to the highest GPS points.…”

Section: Geodetic Datamentioning

confidence: 99%

Why Does a Mature Volcano Need New Vents? The Case of the New Southeast Crater at Etna

et al. 2016

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Mature volcanoes usually erupt from a persistent summit crater. Permanent shifts in vent location are expected to occur after significant structural variations and are seldom documented. Here, we provide such an example that recently occurred at Etna. Eruptive activity at Mount Etna during 2007 focused at the Southeast Crater (SEC), the youngest (formed in 1971) and most active of the four summit craters, and consisted of six paroxysmal episodes. The related erupted volumes, determined by field-based measurements and radiant heat flux curves measured by satellite, totalled 8.67 × 10 6 m 3 . The first four episodes occurred, between late-March and early-May, from the summit of the SEC and short fissures on its flanks. The last two episodes occurred, in September and November, from a new vent ("pit crater" or "proto-NSEC") at the SE base of the SEC cone; this marked the definitive demise of the old SEC and the shift to the new vent. The latter, fed by NW-SE striking dikes propagating from the SEC conduit, formed since early 2011 an independent cone (the New Southeast Crater, or "NSEC") at the base of the SEC. Detailed geodetic reconstruction and structural field observations allow defining the surface deformation pattern of Mount Etna in the last decade. These suggest that the NSEC developed under the NE-SW trending tensile stresses on the volcano summit promoted by accelerated instability of the NE flank of the volcano during inflation periods. The development of the NSEC is not only important from a structural point of view, as its formation may also lead to an increase in volcanic hazard. The case of the NSEC at Etna here reported shows how flank instability may control the distribution and impact of volcanism, including the prolonged shift of the summit vent activity in a mature volcano.

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“…It occurred from seven eruptive fissures, showed high levels of explosivity and produced 5-10 × 10 6 m 3 of ash and 25 × 10 6 m 3 of lava [28]. The final accelerated intrusive process of the 2001 eruption and the opening of the eruptive fractures was accompanied by important seismic activity and marked ground deformation was recorded on the 12-17 of July [29,30].…”

Section: Introductionmentioning

confidence: 99%

Tilt offset associated with local seismicity: the Mt. Etna January 9, 2001 seismic swarm.

Gambino

2016

Open Geosciences

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On the 9 th of January 2001 a seismic swarm on the southeastern flank of Mt. Etna at 3.5 km beside sea level (b.s.l.), caused co-seismic variations on short and long baseline tiltmeters of the Mt. Etna permanent tilt network. Taking account of the geometry and mechanism of the active tectonic structure obtained by seismological studies, the theoretical tilt linked to the faulting source was calculated at multiple different recording stations. It was found that the amount of measured deformation exceeded that which was generated seismically, indicating that much of the deformation along the fault was aseismic. The 9 January 2001 episode represents a shear response to a local stress caused by a volcanic source that acted in the period preceding the 2001 eruption. Tilt data also suggest a marked slip of 70-140 cm along the fault, probably due to the presence of fluids.

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Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano

Cited by 62 publications

References 51 publications

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Why Does a Mature Volcano Need New Vents? The Case of the New Southeast Crater at Etna

Tilt offset associated with local seismicity: the Mt. Etna January 9, 2001 seismic swarm.

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