The diverging volcanic rift system

Tibaldi, Alessandro; Bonali, Fabio Luca; Corazzato, C.

doi:10.1016/j.tecto.2013.11.023

Cited by 36 publications

(39 citation statements)

References 110 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Longonot, Oldoinyo Lengai, Nyamuragira, and Nyiragongo show evidence of radial dykes and a shallow central magma reservoir. Tibaldi et al (2014) consider Nyiragongo to be an example of a volcano with a divergent rift system based on analysis of scoria cone distribution, but we argue that Nyiragongo does not have the highly elliptical footprint typical of such volcanoes and the splay of the rift fissures is better explained by transfer zone tectonics (Figure 7).…”

Section: Discussionmentioning

confidence: 91%

“…Multiple factors combining to generate such composite fields have been advocated and analyzed: loading due to the edifice (e.g., Dahm, 2000;Pinel and Jaupart, 2000;Maccaferri et al, 2011) and unloading (e.g., Maccaferri et al, 2014), the effects of volcano morphology (e.g., Tibaldi et al, 2014;Corbi et al, 2015), the generation of magma reservoirs and calderas (e.g., Tibaldi, 2015) and the anisotropy of host rocks (Gudmundsson, 2011a). Many dykes do not propagate all the way to the surface, but may be arrested by layers with variable associated stress (Gudmundsson and Philipp, 2006).…”

Section: Factors That Could Affect Stress and Strain In The Earsmentioning

confidence: 99%

See 1 more Smart Citation

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

View full text Add to dashboard Cite

Crustal extension at the East African Rift System (EARS) should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800) and find that 7 match the (approximate) geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic) variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement), transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief) and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes, and evolved and mixed magmas capable of explosive behavior. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g., Kone) and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g., Erta Ale), suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behavior. Eruptions within 7 km of the volcano are of relatively short duration (<100 days), but eruptions with more distal fissures tend to have lesser obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002) due to major along-rift dyking events that effectively changed the Nyamuragira stress field and the intrusion/extrusion ratios of eruptions.

show abstract

Section: Discussionmentioning

confidence: 91%

Section: Factors That Could Affect Stress and Strain In The Earsmentioning

confidence: 99%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The propagation direction of dikes in a volcanic edifice can be also affected by the topographic contrast, especially in an asymmetric edifice (e.g., Tibaldi et al, 2014;Corbi et al, 2015;Rivalta et al, 2015 and references therein).The volcanic edifice of Miyakejima, including its submarine part, has a conical shape without any remarkable bulge along the rift zone ( Figure 1B). The development of the NE-SW rift zone became significant within the last 2800 years.…”

Section: Discussionmentioning

confidence: 99%

“…However, the distribution of dikes and eruption fissures in volcanoes display radial, circumferential, and curvature patterns reflecting the local stress in the volcanic edifice (e.g., Chadwick and Howard, 1991). Local disturbances in the stress field of a volcano are caused by the prominent topography of a volcanic edifice (e.g., Tibaldi et al, 2014), flank instability (e.g., Walter et al, 2005), unloading by collapse (Corbi et al, 2015), active faults near the volcanic system (e.g., Seebeck and Nicol, 2009), mechanical heterogeneity in the volcanic edifice and basement (e.g., Letourneur et al, 2008), and the magmatic activity within the volcano (e.g., Chadwick and Dieterich, 1995;Takada, 1997). Recent observations of the dike intrusion events reveal that the stress field in the host rock is affected by the emplacement of intrusions, and consequently feedbacks to the growth of the next dikes (e.g., Bagnardi et al, 2013;Falsaperla and Neri, 2015).…”

Section: Introductionmentioning

confidence: 99%

Orientation of the Eruption Fissures Controlled by a Shallow Magma Chamber in Miyakejima

Geshi

Oikawa

2016

Front. Earth Sci.

View full text Add to dashboard Cite

Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano is indicative of the competitive processes of the regional tectonic stress and the local stress generated by the activity of a magma plumbing system beneath the volcano. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey and a new dataset of 14 C ages. The dominant orientation of the eruption fissures in the central portion of the volcano was found to be NE-SW, which is perpendicular to the direction of regional maximum horizontal compressive stress (σ Hmax ). Magmas that show evidence of mixing between basaltic and andesitic compositions erupted mainly from the eruption fissures with a higher offset angle from the regional σ Hmax direction. The presence of a dike pattern perpendicular to the direction of maximum compression σ Hmax is an unusual and uncommon feature in volcanoes. Here we investigate the conditions possibly controlling this unexpected dike pattern. The distribution and magmatic compositions of the eruption fissures in Miyakejima volcano highlight the tectonic influence of shallow magma chamber on the development of feeder dikes in a composite volcano. The presence of a shallow dike-shaped magma chamber controls the eccentric distribution of the eruption fissures perpendicular to the present direction of σ Hmax . The injection of basaltic magma into the shallow andesitic magma chamber caused the temporal rise of internal magmatic pressure in the shallow magma chamber which elongates in NE-SW direction. Dikes extending from the andesitic magma chamber intrude along the local stress field which is generated by the internal excess pressure of the andesitic magma chamber. As the result, the eruption fissures trend parallel to the elongation direction of the shallow magma chamber. Some basaltic dikes from the deep-seated magma chamber reach the ground surface without intersection with the andesitic magma chamber. These basaltic dikes develop parallel to the regional compressive stress in NW-SE direction. The patterns of the eruption fissures can be modified in the future as was observed in the case of the destruction of the shallow magma chamber during the 2000 AD eruption.

show abstract

“…These lineaments are located at the north-eastern and south-western flanks of the Capelinhos rift in ∼265 • and ∼320 • directions, respectively (Figure 6). A recent study by Tibaldi et al (2014) has shown that eruptions at the flanks of elongated volcanic edifices may result in locally rotated stress fields which are related to gravity forces and controlled by the topography forming a diverging volcanic rift system. We conclude that the fan-like arrangement of lineaments at Capelinhos rift is the result of a combination of dike emplacement at the flanks of existing volcanic edifices, the shallow rotation of σ 3 and, subsequently, a local change in the orientation of lineaments from the predominant WNW-ESE to a more E-W and NW-SE direction (Figure 6).…”

Section: Discussion the Formation Of The Volcanic Rift Zonesmentioning

confidence: 99%