Seismic tomography of Central São Miguel, Azores

Zandomeneghi, D.; Almendros, Javier; Ibáñez, Jesús M.; Saccorotti, Gilberto

doi:10.1016/j.pepi.2008.02.005

Cited by 29 publications

(13 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High b ‐values are often associated with shallow seismicity, in the uppermost 5–8 km of the crust, and elevated ratios of low‐to‐high magnitude events. Several examples of pre‐ and syn‐eruptive earthquake swarms characterized by abundant, low‐magnitude, shallow seismicity have been reported at different volcanoes including Etna (Gresta & Patanè 1983; Centamore et al 1999), Vesuvio (Del Pezzo et al 2003), Krafla (Brandsdóttir & Einarsson 1979), Upptyppingar (Jakobsdóttir et al 2008), Loihi, Hawaii (Klein 1982) and Sao Miguel, Azores (Zandomeneghi et al 2008). As shown in Figs 2 and 3, the El Hierro seismic swarm, with the exception of a minor cluster recorded immediately before the onset of volcanic tremor on October 10, exhibits a severe deficiency in shallow, low‐magnitude, earthquakes.…”

Section: Discussionmentioning

confidence: 99%

Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

Ibáñez

Angelis

Díaz‐Moreno

et al. 2012

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARY The purpose of this work is to gain insights into the 2011–2012 eruption of El Hierro (Canary Islands) by mapping the evolution of the seismic b‐value. The El Hierro seismic sequence offers a rather unique opportunity to investigate the process of reawakening of an oceanic intraplate volcano after a long period of repose. The 2011–2012 eruption is a submarine volcanic event that took place about 2 km off of the southern coast of El Hierro. The eruption was accompanied by an intense seismic swarm and surface manifestations of activity. The earthquake catalogue during the period of unrest includes over 12 000 events, the largest with magnitude 4.6. The seismic sequence can be grouped into three distinct phases, which correspond to well‐separated spatial clusters and distinct earthquake regimes. The estimated b‐value is of 1.18 ± 0.03, and a magnitude of completeness of 1.3, for the entire catalogue. B is very close to 1.0, which indicates completeness of the earthquake catalogue with only minor departures from the linearity of Gutenberg–Richter frequency–magnitude distribution. The most straightforward interpretation of this result is that the seismic swarm reached its final stages, and no additional large magnitude events should be anticipated, similarly to what one would expect for non‐volcanic earthquake sequences. The results, dividing the activity in different phases, illustrate remarkable differences in the estimate of b‐value during the early and late stages of the eruption. The early pre‐eruptive activity was characterized by a b‐value of 2.25. In contrast, the b‐value was 1.25 during the eruptive phase. Based on our analyses, and the results of other studies, we propose a scenario that may account for the observations reported in this work. We infer that the earthquakes that occurred in the first phase reflect magma migration from the upper mantle to crustal depths. The area where magma initially intruded into the crust, because of its transitional nature is characterized by high fracturing, thus favours anomalously high b‐values. The larger magnitude earthquakes recorded in the second phase may reflect relaxation around the magma reservoir that had fed the eruption and, thus, lower b‐values.

show abstract

Section: Discussionmentioning

confidence: 99%

Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

Ibáñez

Angelis

Díaz‐Moreno

et al. 2012

Geophysical Journal International

View full text Add to dashboard Cite

show abstract

“…The detailed structures of crustal magmatic systems below volcanoes have been investigated using seismic tomography in a number of studies for different volcanoes; for example, Etna (Cardaci et al, 1993;Aloisi et al, 2002), Redoubt (Benz et al, 1996), Kilauea (Dawson et al, 1999), Azores (Zandomeneghi et al, 2008), among others. The author of this paper has also contributed to the above list and has taken part in constructing seismic models for the Kluchevskoy volcano group (Koulakov et al, 2011b), the Teide volcano in Canaries (García-Yeguas et al, 2012) and Anak Krakatau (Jaxybulatov et al, 2011).…”

Section: Structure and Dynamics Of The Magmatic Systems Beneath The Vmentioning

confidence: 99%

Studying deep sources of volcanism using multiscale seismic tomography

Koulakov

2013

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

“…VT seismicity provides valuable information to identify magma reservoirs and to track magma migration. VT earthquakes are used in velocity and attenuation tomographic imaging [e.g., Patanè et al, 2003;Martinez-Arevalo et al, 2005;Zandomeneghi et al, 2008Zandomeneghi et al, , 2009García-Yeguas et al, 2012Prudencio et al, 2015aPrudencio et al, , 2015b.…”

Section: Introductionmentioning

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

View full text Add to dashboard Cite

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.

show abstract

Seismic tomography of Central São Miguel, Azores

Abstract: Abstract.We determine the three-dimensional distribution of P-and S-wave veloc- These interpretations are supported by distribution of Vp/Vs, and are consistent with previous geological, geochemical, and geophysical data.

Cited by 29 publications

References 58 publications

Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

Studying deep sources of volcanism using multiscale seismic tomography

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

Contact Info

Product

Resources

About