Abstract
AbstractThe 2011–2014 volcanic activity at El Hierro (Canary Islands) was characterized by a 5‐month long submarine eruption as well as a series of magmatic intrusions occurring between 5 months and 2 years after the eruption, as revealed by seismic swarms and ground deformation. We study the temporal evolution of the six post‐eruptive magmatic intrusions, using Global Navigation Satellite System and Interferometric Synthetic Aperture Radar observations complemented with relocated earthquakes. Magma volumes and magma supply rates are determined from inversion of the geodetic data using a Bayesian approach. The intrusions last between ~3 and 20 days and are inferred to be sill‐like, thin compared with their lateral extent and emplaced in the ~13–16 km depth range. Initial magma flow rates of ~300 m3/s decay exponentially with time. The two largest intrusions occurred in June–July 2012 and March–April 2013. During each of these events, magma migrated laterally, and >120 ×106 m3 of magma was intruded beneath the island. The shortest events, <1 week‐long, intruded ~(24hyphen;44) ×106 m3 of magma beneath the volcano. We suggest that all intrusions originated from an overpressure in a deep magma body located beneath the center of El Hierro. The crust/mantle boundary and the previous intrusion that fed the 2011–2012 submarine eruption may have discouraged the ascent of the post‐eruptive intrusions to the surface and forced them to migrate laterally away from the island as sill‐like sources.
Highlights
Magmatic intrusions within the crust typically produce seismicity and ground deformation around them (e.g., Segall, 2013)
The 2011–2014 volcanic activity at El Hierro (Canary Islands) was characterized by a 5‐month long submarine eruption as well as a series of magmatic intrusions occurring between 5 months and 2 years after the eruption, as revealed by seismic swarms and ground deformation
We study the temporal evolution of the six post‐eruptive magmatic intrusions, using Global Navigation Satellite System and Interferometric Synthetic Aperture Radar observations complemented with relocated earthquakes
Summary
Magmatic intrusions within the crust typically produce seismicity and ground deformation around them (e.g., Segall, 2013). Magma intruded beneath the summit of the Miyakejima volcano (Izu Islands, Japan) on 26 June 2000 and migrated for over 30 km with a velocity of ~4.4 km/day before a caldera collapse started 2 weeks later, accompanied by several summit phreatic and phreatomagmatic eruptions during the following 3 months (e.g., Toda et al, 2002). Lateral migration of magma through the crust does not always culminate in an eruption. Lamongan volcano (Java island, Indonesia) showed up to 12 cm of line‐of‐sight (LOS) displacement, mapped by interferometric analysis of synthetic aperture radar satellite images (InSAR) between September and December 2007, suggesting arrival of new magma beneath the volcano. Several seismic swarms occurred below the volcano in 1985, 1988, 2005, and 2012, but no eruption has yet taken place (e.g., Chaussard & Amelung, 2012)
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