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Tomographic image of melt storage beneath Askja Volcano, Iceland using local microseismicity
Author(s) -
Mitchell Michael A.,
White Robert S.,
Roecker Steve,
Greenfield Tim
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50899
Subject(s) - geology , sill , volcano , seismology , magma , magma chamber , anomaly (physics) , caldera , microseism , petrology , geophysics , physics , condensed matter physics
We use P wave and S wave arrivals from microseismic earthquakes to construct 3‐D tomographic V p and V s images of the magma storage region beneath Askja's central volcano in the Northern Volcanic Zone of Iceland. A distinctive ellipsoidal low‐velocity anomaly, with both V p and V s velocities 8‐12% below the background, is imaged at 6‐11 km depth beneath the caldera. The presence of a shallow magma chamber is corroborated by geodetic and gravity studies. The small V p / V s anomaly suggests a lack of pervasive melt. We interpret this anomaly as a region of multiple sills, some frozen but hot, others containing partial melt. A second, smaller low‐velocity anomaly beneath the main magma storage region may represent a magma migration pathway. This interpretation is supported by the close proximity to the anomaly of clusters of deep, magmatically induced earthquakes. However, the location and shape of this deep anomaly are poorly constrained by the current data set.