Intrusive Mechanisms at Mt. Etna Forerunning the July-August 2001 Eruption from Seismic and Ground Deformation Data

Bonaccorso, Alessandro; D’Amico, S.; Mattia, M.; Patané, Domenico

doi:10.1007/s00024-004-2515-4

Cited by 42 publications

(17 citation statements)

References 25 publications

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“…A second process is related to the inflation of the volcano due to magma storage, as from 1994 to 2000, when ∼1 km 3 of magma was inferred to have accumulated [ Neri et al , 2009] at depths greater than 5 km below sea level (Figure 12b) [ Bonaccorso et al , 2004b; Puglisi and Bonforte , 2004; Palano et al , 2008, 2009; Bonforte et al , 2008]. Magma accumulation at depth uplifts the edifice and displaces the western and eastern flanks westward and eastward, respectively.…”

Section: Discussionmentioning

confidence: 99%

Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008

et al. 2010

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Volcano deformation may occur under different conditions. To understand how a volcano deforms, as well as relations with magmatic activity, we studied Mt. Etna in detail using interferometric synthetic aperture radar (InSAR) data from 1994 to 2008. From 1994 to 2000, the volcano inflated with a linear behavior. The inflation was accompanied by eastward and westward slip on the eastern and western flanks, respectively. The portions proximal to the summit showed higher inflation rates, whereas the distal portions showed several sectors bounded by faults, in some cases behaving as rigid blocks. From 2000 to 2003, the deformation became nonlinear, especially on the proximal eastern and western flanks, showing marked eastward and westward displacements, respectively. This behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002–2003 eruptions. From 2003 to 2008, the deformation approached linearity again, even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002. The eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those (largely inactive) to the south. In addition, from 1994 to 2008 part of the volcano base (south, west, and north lower slopes) experienced a consistent trend of uplift on the order of ∼0.5 cm/yr. This study reveals that the flanks of Etna have undergone a complex instability resulting from three main processes. In the long term (103–104 years), the load of the volcano is responsible for the development of a peripheral bulge. In the intermediate term (≤101 years, observed from 1994 to 2000), inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks. In the short term (≤1 year, observed from 2001 to 2002), the emplacement of feeder dikes along the NE and south rifts results in a nonlinear, focused, and asymmetric deformation on the eastern and western flanks. Deformation due to flank instability is widespread at Mt. Etna, regardless of volcanic activity, and remains by far the predominant type of deformation on the volcano.

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Section: Discussionmentioning

confidence: 99%

Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008

et al. 2010

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“…However, it should be considered that the faults with morphological evidence may represent only a part of the tectonic structures present in the Etnean area and hidden fault segments could be covered by the huge pile of volcanic products [e.g., Azzaro , 1999]. Indeed, most recent seismic studies [ Bonaccorso and Patanè , 2001; Bonaccorso et al , 2004; Patanè et al , 2005] show the existence of several notable segments of unknown faults, ca. NE‐SW and ENE‐WSW oriented, both on the western [6–8 km length, Bonaccorso et al , 2004; Bonanno et al , 2011] and on the east‐northeastern [up to 10 km length, Patanè et al , 2005] flanks of the volcano.…”

Section: Mt Etna: Geological Settingmentioning

confidence: 99%

Ground deformations and volcanic processes as imaged by CGPS data at Mt. Etna (Italy) between 2003 and 2008

et al. 2012

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“…Conversely, the low‐density anomalies observed at different depths (Figure 7; late 1997 to late 1999 and early 2001 to mid‐2006 periods), rather than being associated only with the subsurface magma migration, could reflect also the passive mechanical response of the eastern and southern flanks of the volcano to tectonic stresses leading to a bulk density decrease. Accordingly, seismic data pointed out a progressive renewal of tectonic stresses during the first months of 2001 with hundreds of events clustering on the southeastern sector of the volcano, mainly along a NNW‐SSE alignment at a depth of 1–5 km, which coincides with the inferred low‐density anomalies [ Bonaccorso et al , 2004; Carbone et al , 2007]. The instability of the eastern and southern flanks of the volcano is recognized as one of the main dynamic processes on Etna [ Borgia et al , 2000; Neri et al , 2004; Rust et al , 2005] and has been emphasized to be a triggering mechanism for some of the recent flank eruptions [ Burton et al , 2005; Bonaccorso et al , 2006].…”

Section: Discussionmentioning

confidence: 82%

Spatiotemporal gravity variations to look deep into the southern flank of Etna volcano

et al. 2010

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A 14‐year‐long microgravity data set (October 1994 to September 2007) collected along a 24‐km east‐west trending profile of 19 stations was analyzed to detect underground mass redistributions related to the volcanic activity involving the southern flank of Mt Etna (Italy). A multiresolution wavelet analysis was applied to separate the volcano‐related anomalies from the unwanted components. The residual image having both spatial extension and temporal duration evidenced two complete gravity increase/decrease cycles mainly affecting the central and eastern stations of the profile. The first gravity increase (early 1995 to the end of 1996) and decrease (end of 1996 to late in 1998) cycle reached a maximum amplitude of approximately 90 μGal. The second gravity increase (mid‐1999 to mid‐2000) and decrease (mid‐2000 to early‐2004) cycle attained an amplitude of about 80 μGal. After about 5 years of a persistent negative gravity anomaly, a new semicycle started at the end of 2006 and continued during the last survey carried out in September 2007. The density changes, modeled over time since 1994 using a Quadratic Programming algorithm, are mainly located at a depth of 2–4 km bsl in a region recognized to be a preferential pathway of magma rising and an intermediate zone of magma storage/withdrawal. The computed positive mass variations of about 105 × 109 kg were interpreted as magma accumulation, while negative mass changes of about −120 × 109 kg were associated with either magma drainage or opening of new voids by tectonic stresses within a source volume, where tensional earthquakes occurred.

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Intrusive Mechanisms at Mt. Etna Forerunning the July-August 2001 Eruption from Seismic and Ground Deformation Data

Cited by 42 publications

References 25 publications

Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008

Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008

Ground deformations and volcanic processes as imaged by CGPS data at Mt. Etna (Italy) between 2003 and 2008

Spatiotemporal gravity variations to look deep into the southern flank of Etna volcano

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