New Features in the Subsurface Structure Model of El Hierro Island (Canaries) from Low-Frequency Microseismic Sounding: An Insight into the 2011 Seismo-Volcanic Crisis

Горбатиков, А. В.; Montesinos, Fuensanta G.; Arnoso, José; Stepanova, M. Yu.; Benavent, M.; Цуканов, А. А.

doi:10.1007/s10712-013-9240-4

Cited by 44 publications

(36 citation statements)

References 69 publications

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“…The results obtained with this tomographic study are fully coincident with previous results from gravimetric46 and low-frequency microseismic sounding47. There is coincidence in the position and size of the gravimetric (high density/low density) and seismic (high velocity/low velocity) anomalous bodies, which reveal the location of the main magma intrusion and accumulation zones inside El Hierro, and the accumulation of lighter materials (e.g.…”

Section: Discussionsupporting

confidence: 88%

Stress barriers controlling lateral migration of magma revealed by seismic tomography

Martı́

Villaseñor

Geyer

et al. 2017

Sci Rep

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Understanding how monogenetic volcanic systems work requires full comprehension of the local and regional stresses that govern magma migration inside them and why/how they seem to change from one eruption to another. During the 2011–2012 El Hierro eruption (Canary Islands) the characteristics of unrest, including a continuous change in the location of seismicity, made the location of the future vent unpredictable, so short term hazard assessment was highly imprecise. A 3D P-wave velocity model is obtained using arrival times of the earthquakes occurred during that pre-eruptive unrest and several latter post-eruptive seismic crises not related to further eruptions. This model reveals the rheological and structural complexity of the interior of El Hierro volcanic island. It shows a number of stress barriers corresponding to regional tectonic structures and blocked pathways from previous eruptions, which controlled ascent and lateral migration of magma and, together with the existence of N-S regional compression, reduced its options to find a suitable path to reach the surface and erupt.

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Section: Discussionsupporting

confidence: 88%

Stress barriers controlling lateral migration of magma revealed by seismic tomography

Martı́

Villaseñor

Geyer

et al. 2017

Sci Rep

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“…In fact, Gorbatikov et al [2013] highlight the existence of a reservoir of solidified magma to a depth ranging between 15 and 25 km, located at the northwest of El Hierro and connected with the formation of the younger part of the island. Other subsurface shallow structures identified as well by the density contrast model of Montesinos et al [2006] seem associated to the southward migration of hypocenters along the contact surface of this reservoir and a high-velocity structure, which divides two large low-velocity bodies, one of them containing the solidified magma accumulation zone.…”

Section: Background Information On the Geology Of El Hierro And The 2mentioning

confidence: 89%

Volcanic signatures in time gravity variations during the volcanic unrest on El Hierro (Canary Islands)

et al. 2014

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Gravity changes occurring during the initial stage of the 2011-2012 El Hierro submarine eruption are interpreted in terms of the preeruptive signatures during the episode of unrest. Continuous gravity measurements were made at two sites on the island using the relative spring gravimeter LaCoste and Romberg gPhone-054. On 15 September 2011, an observed gravity decrease of 45 μGal, associated with the southward migration of seismic epicenters, is consistent with a lateral magma migration that occurred beneath the volcanic edifice, an apparently clear precursor of the eruption that took place 25 days later on 10 October 2011. High-frequency gravity signals also appeared on 6-11 October 2011, pointing to an occurring interaction between a magmatic intrusion and the ocean floor. These important gravity changes, with amplitudes varying from 10 to À90 μGal, during the first 3 days following the onset of the eruption are consistent with the northward migration of the eruptive focus along an active eruptive fissure. An apparent correlation of gravity variations with body tide vertical strain was also noted, which could indicate that concurrent tidal triggering occurred during the initial stage of the eruption.

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“…The eruption site is, indeed, located at the edge of the seismogenic region. Montesinos et al [], Gorbatikov et al [], and García‐Yeguas et al [] observed the presence of a high‐velocity block centered underneath El Hierro (up to 15 km depth) whose boundaries are found around the eruption site. In the same area, Blanco‐Montenegro et al [] observed before the 2011 eruption, a highly magnetized vertical structure that had been interpreted as complex deep intrusive bodies.…”

Section: Discussionmentioning

confidence: 99%

Seismic hydraulic fracture migration originated by successive deep magma pulses: The 2011–2013 seismic series associated to the volcanic activity of El Hierro Island

et al. 2015

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In this manuscript we present a new interpretation of the seismic series that accompanied eruptive activity off the coast of El Hierro, Canary Islands, during 2011–2013. We estimated temporal variations of the Gutenberg‐Richter b value throughout the period of analysis, and performed high‐precision relocations of the preeruptive and syneruptive seismicity using a realistic 3‐D velocity model. Our results suggest that eruptive activity and the accompanying seismicity were caused by repeated injections of magma from the mantle into the lower crust. These magma pulses occurred within a small and well‐defined volume resulting in the emplacement of fresh magma along the crust‐mantle boundary underneath El Hierro. We analyzed the distribution of earthquake hypocenters in time and space in order to assess seismic diffusivity in the lower crust. Our results suggest that very high earthquake rates underneath El Hierro represent the response of a stable lower crust to stress perturbations with pulsatory character, linked to the injection of magma from the mantle. Magma input from depth caused large stress perturbations to propagate into the lower crust generating energetic seismic swarms. The absence of any preferential alignment in the spatial pattern of seismicity reinforces our hypothesis that stress perturbation and related seismicity, had diffusive character. We conclude that the temporal and spatial evolution of seismicity was neither tracking the path of magma migration nor it defines the boundaries of magma storage volumes such as a midcrustal sill. Our conceptual model considers pulsatory magma injection from the upper mantle and its propagation along the Moho. We suggest, within this framework, that the spatial and temporal distributions of earthquake hypocenters reflect hydraulic fracturing processes associated with stress propagation due to magma movement.

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New Features in the Subsurface Structure Model of El Hierro Island (Canaries) from Low-Frequency Microseismic Sounding: An Insight into the 2011 Seismo-Volcanic Crisis

Cited by 44 publications

References 69 publications

Stress barriers controlling lateral migration of magma revealed by seismic tomography

Stress barriers controlling lateral migration of magma revealed by seismic tomography

Volcanic signatures in time gravity variations during the volcanic unrest on El Hierro (Canary Islands)

Seismic hydraulic fracture migration originated by successive deep magma pulses: The 2011–2013 seismic series associated to the volcanic activity of El Hierro Island

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