title: Magma plumbing system and seismicity of an active mid-ocean ridge volcano.
abstract: At mid-ocean ridges volcanism generally decreases with spreading rate but surprisingly massive volcanic centres occur at the slowest spreading ridges. These volcanoes can host unexpectedly strong earthquakes and vigorous, explosive submarine eruptions. Our understanding of the geodynamic processes forming these volcanic centres is still incomplete due to a lack of geophysical data and the difficulty to capture their rare phases of magmatic activity. We present a local earthquake tomographic image of the magma plumbing system beneath the Segment 8 volcano at the ultraslow-spreading Southwest Indian Ridge. The tomography shows a confined domain of partial melt under the volcano. We infer that from there melt is horizontally transported to a neighbouring ridge segment at 35 km distance where microearthquake swarms and intrusion tremor occur that suggest ongoing magmatic activity. Teleseismic earthquakes around the Segment 8 volcano, prior to our study, indicate that the current magmatic spreading episode may already have lasted over a decade and hence its temporal extent greatly exceeds the frequent short-lived spreading episodes at faster opening mid-ocean ridges.
authors.affiliation: Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schmid
authors.affiliation: Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Schlindwein
authors.affiliation: Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia Novosibirsk State University, Pirogova 2, 630090, Novosibirsk, Russia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Koulakov
authors.affiliation: Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.|Institue of Geophysics and Geology, University of Leipzig, Germany.
authors.forename: Aline
authors.initials: A
authors.lastname: Plötz
authors.affiliation: Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
authors.forename: John-Robert
authors.initials: JR
authors.lastname: Scholz