The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

Chadwick, William W.; Howard, Keith A.

doi:10.1007/bf00414523

Cited by 145 publications

(98 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…7 becomes out of plane; therefore fissures are expected to be primarily circumferential, with minor deviations e.g. the 1958 fissure at Fernandina (Chadwick and Howard, 1991).…”

Section: Resultsmentioning

confidence: 99%

“…Burchardt and Gudmundsson, 2009). Their surface expression as circumferential eruptive fissures is, on the other hand, relatively rare, and has only been observed around calderas in the western Gal ‡pagos Archipelago (Fernandina, Wolf, Darwin, Alcedo, Sierra Negra and Cerro Azul; Chadwick and Howard, 1991) and, to lesser extent, in Iceland at Krafla, Grimsvotn (Thordarson and Self, 1993) suggests that most inclined sheets stall at depth, without reaching the surface, and that formation of these fissures is favored, but not guaranteed, by the presence of a caldera. This may imply a specific stressing mechanism active at volcanoes with a caldera, competing with other stressing factors.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the best-developed circumferential fissures are found at Fernandina (Gal ‡pagos; Fig1; Chadwick and Howard, 1991), which hosts a ~1 km deep and ~6.5 x 4 km wide caldera resulting from several collapses testified by old benches and a ~350 m drop of the SE caldera floor in the formation of circumferential fissures at Fernandina, considering the effect of: a) caldera faults capturing and channeling magma to the caldera rim (Nordlie, 1973, Browning andGudmundsson, 2015); b) caldera walls unbuttressing re-orienting the minimum compressive stress perpendicular to them (Simkin, 1984;Munro and Rowland 1996); c) stress perturbations due to the pressurization of a magma chamber (Chadwick and Dieterich, 1995;Chestler and Grosfils, 2013) or d) a previous intrusion (Bagnardi et al, 2013). The caldera fault model was excluded based on observing: i) no displacement in layers adjacent to circumferential dikes; ii) circumferential dikes crosscutting caldera faults; and iii) circumferential fissures located well downslope from the caldera rim (Chadwick and Dieterich, 1995).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

Corbi

Rivalta

Pinel

et al. 2015

Earth and Planetary Science Letters

View full text Add to dashboard Cite

Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Gal ‡pagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with ! 1 calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

show abstract

“…7 becomes out of plane; therefore fissures are expected to be primarily circumferential, with minor deviations e.g. the 1958 fissure at Fernandina (Chadwick and Howard, 1991).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

Corbi

Rivalta

Pinel

et al. 2015

Earth and Planetary Science Letters

View full text Add to dashboard Cite

show abstract

“…Such radial dyke swarms are typically emplaced during the volcano inflating step at the beginning of an eruptive phase (Chadwick and Howard, 1991;Walker, 1999). The dominant breccia products of the Platzkegel agglomerate might have filled the former eruptive vent of Shira during this final eruptive event.…”

Section: The Shira Stagementioning

confidence: 99%

New K–Ar age determinations of Kilimanjaro volcano in the North Tanzanian diverging rift, East Africa

Nonnotte

Guillou

Gall

et al. 2008

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

The Kilimanjaro is the African highest mountain and culminates at 5895 m high. This huge volcanic edifice is composed of three main centres along a N110°E-striking axis (Shira, Kibo and Mawenzi from W to E), and emplaced in a key area where a major N80°E-oriented volcanic lineament intersects a first-order NW-SE basement fault-like discontinuity.Seventeen K-Ar ages (on microcrystalline groundmass) acquired on lavas and intrusive facies from the three eruptive centres confirm that the Plio-Quaternary volcanicity of Kilimanjaro is clearly polyphased. The oldest phases of volcanic activity begun at ~2.5 Ma in the Shira vent and our data suggest that the latest important phases occurred around 1.9 Ma, just before the collapse of the Northern part of the edifice. Magmatic activity then shifted eastwards in the

show abstract

“…The islands are a cluster of about 20 basaltic volcanoes that typically have large summit calderas. Unlike Hawaiian basaltic volcanoes, they do not have well-developed rift zones, but instead have a pattern of arcuate vents near the caldera rim and radial vents further away on the flanks [Chadwick and Howard, 1991].…”

Section: Introductionmentioning

confidence: 99%

A shallow‐dipping dike fed the 1995 flank eruption at Fernandina Volcano, Galápagos, observed by satellite radar interferometry

Jónsson

Zebker

Cervelli

et al. 1999

Geophysical Research Letters

View full text Add to dashboard Cite

Abstract. Satellite radar interferometry data reveal strong localized uplift in a semi-circular pattern on the southwest flank of Fernandina volcano, Gal&pagos, where an eruption took place in January to April, 1995. The observations show a maximum decrease in radar range of 0.75 m, and they are consistent with a model of a shallow-dipping dike intrusion feeding this fissure eruption. We solve for the best-fit single rectangular dislocation dike source using non-linear inversion techniques where simulated annealing searching' algorithm is used to avoid local minima.The best-fit dike is 3.8 km long, 2.3 km high, 0.86 m thick and with a 34 ø dip.The total dike volume (7.5 x 10 -3 km 3) is ,--40% of the volume of extrusive materials estimated to have been produced during the eruption. The data do not permit a sub-vertical dike, implying that the least principal stress direction is not horizontal as is usually assumed.

show abstract

The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

Cited by 145 publications

References 42 publications

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

New K–Ar age determinations of Kilimanjaro volcano in the North Tanzanian diverging rift, East Africa

A shallow‐dipping dike fed the 1995 flank eruption at Fernandina Volcano, Galápagos, observed by satellite radar interferometry

Contact Info

Product

Resources

About