Location and orientation of eruptive fissures and feederdykes at Mount Etna; influence of gravitational and regional tectonic stress regimes

McGuire, William; Pullen, A. D.

doi:10.1016/0377-0273(89)90046-2

Cited by 169 publications

(81 citation statements)

References 26 publications

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“…In the concept of volcano spreading (see Borgia et al, 2000 for a review), the gravity field of a volcano directs the paths of individual dike intrusions and entire rift zones (Nakamura 1980;Dieterich 1988). On the eastern flank of Mount Etna, for instance, dikes intrude along the topographic crest around the deep and several km-wide 'Valle del Bove ' (McGuire and Pullen 1989;Borgia et al 2000). There too, strengths and inclination of the subvolcanic strata may significantly influence the development of rift zones and unstable flanks.…”

Section: Discussionmentioning

confidence: 99%

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Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands

et al. 2004

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The relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented. Our field data, aerial image analysis, and 40 Ar/ 39 Ar chronology from Anaga basaltic shield volcano on Tenerife, Canary Islands, support a rift zoneflank instability relationship. A single rift zone dominated the early stage of the Anaga edifice (~6-4.5 Ma). Destabilization of the northern sector led to partial seaward collapse at about~4.5 Ma, resulting in a giant landslide. The remnant highly fractured northern flank is part of the destabilized sector. A curved rift zone developed within and around this unstable sector between 4.5 and 3.5 Ma. Induced by the dilatation of the curved rift, a further rift-arm developed to the south, generating a threearmed rift system. This evolutionary sequence is supported by elastic dislocation models that illustrate how a curved rift zone accelerates flank instability on one side of a rift, and facilitates dike intrusions on the opposite side. Our study demonstrates a feedback relationship between flank instability and intrusive development, a scenario probably common in ocean island volcanoes. We therefore propose that ocean island rift zones represent geologically unsteady structures that migrate and reorganize in response to volcano flank instability.

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Section: Discussionmentioning

confidence: 99%

“…Lipman 1980;McGuire and Pullen 1989;Walter and Schmincke 2002;Walter and Troll 2003). Rift curvature takes place due to the stress field reorientation near an unstable volcano flank.…”

Section: Development Of a Triaxial Rift Zonementioning

confidence: 99%

Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands

et al. 2004

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“…Historical activity is marked by eruptions from the summit vents and also by effusive eruptions lower down on the flanks that are fed by laterally propagating dykes. These follow preferential routes that define rift zones, the most important of which trend north and south from the summit (McGuire & Pullen 1989). The volcano's most notable topographic feature is the Valle del Bove (figure 1), a large (5 × 8 km) amphitheatre cut into the eastern flank, bounded by cliffs up to 1 km high and opening towards the Ionian Sea.…”

Section: Volcano Lateral Collapse At Mount Etnamentioning

confidence: 99%

“…The volcano's most notable topographic feature is the Valle del Bove (figure 1), a large (5 × 8 km) amphitheatre cut into the eastern flank, bounded by cliffs up to 1 km high and opening towards the Ionian Sea. More than 100 exposed dykes in the cliff walls mark the positions of east-northeast (ENE) and southeast (SE) trending defunct rift zones (McGuire & Pullen 1989), whose intersection is bisected by the long axis of the collapse amphitheatre (figure 1). While an origin owing to prehistoric lateral collapse is now corroborated by subaerial and offshore stürtzstrom deposits adjacent to the amphitheatre's open, downslope, outlet (e.g.…”

Section: Volcano Lateral Collapse At Mount Etnamentioning

confidence: 99%

Climate forcing of volcano lateral collapse: evidence from Mount Etna, Sicily

Deeming

McGuire

Harrop

2010

Phil. Trans. R. Soc. A.

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In this study, we present evidence for early Holocene climatic conditions providing circumstances favourable to major lateral collapse at Mount Etna, Sicily. The volcano's most notable topographic feature is the Valle del Bove, a 5 × 8 km cliff-bounded amphitheatre excavated from the eastern flank of the volcano. Its origin due to prehistoric lateral collapse is corroborated by stürtzstrom deposits adjacent to the amphitheatre's downslope outlet, but the age, nature and cause of amphitheatre excavation remain matters for debate. Cosmogenic 3 He exposure ages determined for eroded surfaces within an abandoned watershed flanking the Valle del Bove support channel abandonment ca 7.5 ka BP, as a consequence of its excavation in a catastrophic collapse event. Watershed development was largely dictated by pluvial conditions during the early Holocene, which are also implicated in slope failure. A viable trigger is magma emplacement into rift zones in the eastern flank of a water-saturated edifice, leading to the development of excess pore pressures, consequent reduction in sliding resistance, detachment and collapse. Such a mechanism is presented as one potential driver of future lateral collapse in volcanic landscapes forecast to experience increased precipitation or melting of ice cover as a consequence of anthropogenic warming.

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“…[4] Tectonics of Mount Etna is the result of the interaction between the regional tectonics and local-scale volcanorelated processes [McGuire and Pullen, 1989]. The western flank of the volcano is affected by a modest tectonic activity, the Ragalna and Calcerana faults [Azzaro, 1999] being the main structures ( Figure 1a).…”

Section: Local Geology and Structural Settingmentioning

confidence: 99%

Evidence for ground motion polarization on fault zones of Mount Etna volcano

et al. 2008

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[1] During local and regional earthquakes, an evident amplification of horizontal ground motion is observed at two seismological stations near the Tremestieri fault, on the southeastern flank of Mount Etna volcano. Rotated component spectral ratios show a narrow spectral peak around 4 Hz along a N40°E direction. A conventional polarization analysis using the eigenvectors of the covariance matrix confirms the very stable directional effect enhancing the approximately NE-SW elongation of the horizontal ground motion in the fault zone. The effect is evident during the entire seismogram and independent of source back azimuth as well as distance and depth of earthquakes. The same polarization is observed in ambient noise as well. This consistency allowed us to use microtremors for checking ground motion polarization along and across the Tremestieri fault zone with a high spatial resolution. The result is a stable polarization of horizontal motion in the entire area that can be observed in a broad frequency band. To check whether this ground motion property is recurrent and to understand a possible relationship with fault strike, faulting style, or orientation of fractures, ambient noise was recorded on other mapped faults of the Mount Etna area, the Moscarello, Acicatena, and Pernicana faults. The latter, in particular, is characterized by different strike and faulting style. A systematic tendency of ambient noise to be polarized is found in all of the faults. A picture emerges where normal faults of the eastern flank show an E-W to NE-SW polarization that changes on the Pernicana fault, which develops approximately E-W and is characterized by a prevailing NW-SE to N-S polarization. Directions of polarization were never parallel to the fault strike. Moreover, polarization persists too far away from the fault trace, excluding an effect limited to a narrow low-velocity zone hosted between harder wall rocks. Both these observations rule out an interpretation in terms of faulttrapped waves. The cause of observed polarizations will be the subject of future studies. However, the consistency with recent results of velocity anisotropy in a part of the investigated area suggests a possible role of attenuation anisotropy on horizontal amplitude variations versus azimuth.

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Location and orientation of eruptive fissures and feederdykes at Mount Etna; influence of gravitational and regional tectonic stress regimes

Cited by 169 publications

References 26 publications

Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands

Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands

Climate forcing of volcano lateral collapse: evidence from Mount Etna, Sicily

Evidence for ground motion polarization on fault zones of Mount Etna volcano

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