Widespread uplift and ‘trapdoor’ faulting on Galápagos volcanoes observed with radar interferometry

Amelung, F.; Jónsson, Sigurjón; Zebker, H. A.; Segall, P.

doi:10.1038/35039604

Cited by 339 publications

(358 citation statements)

References 18 publications

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“…Therefore, the inversion of geodetic data associated with faulting or diking events usually follows a two-step procedure: nonlinear inversion is used to determine the fracture geometry assuming uniform dislocation on a rectangular fracture located in a half-space, followed by kinematic linear inversion to determine the slip or opening distribution on the previously determined fracture [Arnadottir et al, 1991;Amelung et al, 2000]. However, there is no reason for the fracture geometry determined for a uniform dislocation to be the same as the geometry determined for a variable dislocation distribution.…”

Section: Simultaneous Inversion Of Source Geometry Location and Dispmentioning

confidence: 99%

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Wauthier¹,

Cayol²,

Kervyn³

et al. 2012

J. Geophys. Res.

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along a 20 km-long fracture network extending from the volcano to the city of Goma. The event was captured by InSAR data from the ERS-2 and RADARSAT-1 satellites. A combination of 3D numerical modeling and inversions is used to analyze these displacements. Using Akaike Information Criteria, we determine that a model with two subvertical dikes is the most likely explanation for the 2002 InSAR deformation signal. A first, shallow dike, 2 km high, is associated with the eruptive fissure, and a second, deeper dike, 6 km high and 40 km long, lies about 3 km below the city of Goma. As the deep dike extends laterally for 20 km beneath the gas-rich Lake Kivu, the interaction of magma and dissolved gas should be considered as a significant hazard for future eruptions. A likely scenario for the eruption is that the magma supply to a deep reservoir started ten months before the eruption, as indicated by LP events and tremor. Stress analysis indicates that the deep dike could have triggered the injection of magma from the lake and shallow reservoir into the eruptive dike. The deep dike induced the opening of the southern part of this shallow dike, to which it transmitted magma though a narrow dike. This model is consistent with the geochemical analysis, the lava rheology and the pre-and post-eruptive seismicity. We infer low overpressures (1-10 MPa) for the dikes. These values are consistent with lithostatic crustal stresses close to the dikes and low magma pressure. As a consequence, the dike direction is probably not controlled by stresses but rather by a reduced tensile strength, inherited from previous rift intrusions. The lithostatic stresses indicate that magmatic activity is intense enough to relax tensional stresses associated with the rift extension.

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Section: Simultaneous Inversion Of Source Geometry Location and Dispmentioning

confidence: 99%

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Wauthier¹,

Cayol²,

Kervyn³

et al. 2012

J. Geophys. Res.

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“…3). In general, the eruption is accompanied by a clear signal of subsidence due to the discharge of material and release of gas pressure, as occur at the LUSI mud volcano [e.g., 7,8,9] and at magmatic volcanoes [e.g., 25,26]. By contrast, a nearly continuous uplift of the main active zone is observed at the Ayaz-Akhtarma mud volcano, probably because the eruption (associated with subsidence) occurred after the date of the last interferogram (10 November 2005).…”

Section: Discussionmentioning

confidence: 99%

Proceedings of Fringe 2015: Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR Workshop

2015

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Mud volcanism consists in the surface extrusion of gases, saline waters and mud breccias, which produce conical edifices of various sizes with morphology similar to that of magmatic volcanoes. In this work, DInSAR technique has been used to investigate the ground deformation related to the activity of Azerbaijan mud volcanoes during the period October 2003-November 2005. This work focuses on two important deformation events at the Ayaz-Akhtarma and Khara-Zira mud volcanoes. The ground deformations at mud volcanoes are generally originated by fluid pressure and volume variations in the reservoir. The observed deformation pattern is characterized by pre-eruptive inflation that reaches a cumulative value of up to 20 cm at Ayaz-Akhtarma in about two years. Similar pre-eruptive bulging has been observed at magmatic volcanoes, where uplift is typically associated with magma intrusion. We conclude that mud and magmatic volcanoes display some similarities in the behavior of ground deformation during pre-eruptive stages.

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“…In the last decade two-pass InSAR has been extensively applied to volcanoes. Studies include observations of inflation and deflation of inferred magma chambers, e.g., [14]- [17], sill and dike intrusion, e.g., [18]- [20], faulting, e.g., [21] and eruption, e.g., [22], [23]. In the early days of InSAR, it was generally only possible to capture an entire eruption in an interferogram, except in the case of long-lived eruptions, like Kilauea.…”

Section: B Two-pass Insarmentioning

confidence: 99%

Remote Sensing of Volcanic Hazards and Their Precursors

2012

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Ash, tephra and gas ejected during explosive eruptions provides a major far-reaching threat to population, health and air traffic. Lava flows, lahars and floods from ice capped volcanoes can also have a major influence, as well as landslides that have a potential for tsunami generation if they reach into sea or lakes. Remote sensing contributes to the mitigation of these hazards through the use of synthetic aperture radar interferometry (InSAR) and spectroradiometry. In the case of InSAR, displacements of a volcano's surface can be interpreted in terms of magma movement beneath the ground. Thus the technique can be used to identify precursors to eruptions and to track the evolution of eruptions. Recent advances in algorithm development enable relative displacements over many km to be measured with an accuracy of only a few mm. Spectroradiometry on the other hand allows monitoring of a volcanic eruption through the detection of hot-spots, and monitoring and quantification of the ash and SO 2 emitted by volcanoes into the atmosphere. The tracking of ash plumes during eruptions assists in the identification of areas that should be avoided by aircraft. Here we present a review of these two remote sensing techniques, and their application to volcanic hazards.

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Widespread uplift and ‘trapdoor’ faulting on Galápagos volcanoes observed with radar interferometry

Cited by 339 publications

References 18 publications

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Proceedings of Fringe 2015: Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR Workshop

Remote Sensing of Volcanic Hazards and Their Precursors

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