FN Archimer Export Format
PT J
TI Vertically extensive magma reservoir revealed from joint inversion and quantitative interpretation of seismic and gravity data
BT 
AF Paulatto, Michele
   Moorkamp, Max
   Hautmann, Stefanie
   Hooft, Emilie
   Morgan, Joanna V.
   Sparks, R. Stephen J.
AS 1:1;2:2;3:3;4:4;5:1;6:5;
FF 1:;2:;3:;4:;5:;6:;
C1 Department of Earth Science and Engineering, Imperial College London London, UK
   Department of Earth and Environmental SciencesLudwig Maximilian University of Munich Munich ,Germany
   Department of Earth Sciences, ETH Zurich Zurich, Switzerland
   Department of Earth Sciences University of Oregon Eugene ,USA
   School of Earth Sciences University of Bristol Bristol ,UK
C2 IMPERIAL COLL LONDON, UK
   UNIV MUNICH, GERMANY
   ETH ZURICH, SWITZERLAND
   UNIV OREGON STATE, USA
   UNIV BRISTOL, UK
IF 3.638
TC 35
UR https://archimer.ifremer.fr/doc/00591/70321/68357.pdf
   https://archimer.ifremer.fr/doc/00591/70321/68358.pdf
LA English
DT Article
CR AGUADOMAR
   CARAVAL
BO L'Atalante
AB Recent advances in our understanding of arc magmatic systems indicate that melt is stored for long periods in low‐melt fraction crystal mushes, and that eruptible magma reservoirs are short‐lived and are assembled rapidly by buoyancy‐induced instabilities and draining of the crystal mush. Many aspects of their architecture remain unclear, particularly in relation to their geometry and shallow melt distribution. We investigate the storage of melt below the active Soufrière Hills Volcano (SHV), Montserrat, using joint geophysical inversion combined with a quantitative interpretation approach based on rock physics. We jointly inverted active‐source P‐wave traveltimes and gravity anomalies to derive coincident 3D models of P‐wave velocity and density to a depth of 8 km. Comparative analysis of the active SHV and extinct Centre Hills volcano and effective elastic medium computations allow us to constrain temperature, melt fraction and melt geometry. A continuous column of partial melt is inferred beneath SHV, at 4‐8 km depth. Melt fraction is ~6% (ranging from 3% to 13% depending on melt geometry) and is maximum at 5‐6 km depth. When under‐recovery of the low‐vP volume is taken into account, the melt fraction is revised to ~17% (ranging from 11 to 28%). Analysis of vP/density cross plots indicates that the melt distribution is best represented by low‐aspect ratio geometries. These likely span a multi‐scale spectrum ranging from grain‐scale inclusions and fractures to 100‐meter‐scale dykes and sills. Our results confirm the concept of vertically extensive crystal mush including one or multiple more melt‐rich layers. Plain Language Summary We use data from the Soufrière Hills Volcano on Montserrat to study the storage of magma in the plumbing system of an active volcano. By measuring the time it takes for seismic waves to travel from artificial sound sources to recording instruments located on the island and on the seabed around it, we can determine the speed of sound in the rocks. By measuring small variations in the gravitational attraction, we can determine the density distribution. We then jointly analyze the speed of sound and density and calculate that the degree of melting of the rocks is between 6% and 17% and the total volume of molten rocks is 1.5 km3 to 4.5 km3. The partially molten region extends from 4 to at least 8 km depth. Some more thoroughly molten layers are likely present but are too small to be imaged with our method. Our findings support a model of the magma storage system comprised mostly of solid crystals with a relatively small amount of molten rocks. Key Points Seismic and gravity data are jointly inverted to produce models of vP and density beneath an active volcano including the magma reservoir Temperature and melt distribution are estimated jointly from vP and are consistent with a mush zone with 6‐17% melt fraction Analysis of vP/density cross‐plot indicates low melt fraction and low‐aspect ratio melt inclusion geometry 
PY 2019
PD NOV
SO Journal Of Geophysical Research-solid Earth
SN 2169-9313
PU American Geophysical Union (AGU)
VL 124
IS 11
UT 000505543800030
BP 11170
EP 11191
DI 10.1029/2019JB018476
ID 70321
ER

EF