Crustal structure beneath the Montserrat region of the Lesser Antilles island arc

Winchelle Ian Sevilla, Charles James Ammon, Barry Voight, Silvio De Angelis

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

We use receiver function analysis to estimate the first-order subsurface seismic structure in the vicinity of the island of Montserrat, located in the northern Lesser Antilles arc and home of the active Soufrière Hills Volcano. Near-surface complexity in the island structure inhibits our ability to resolve lateral variations in seismic structure, so we average the signals from eight stations in two directions to produce a first-order regional seismic velocity model. Although we are unable to resolve a precise sharpness of the crust-mantle transition, we can limit its thickness to less than ∼4 km. Lateral variations in shallow structure complicate a receiver function based estimate of Poisson's ratio, but the data indicate that in both directions sampled by the receiver functions, the lower crustal Poisson's ratio is greater than 0.27 and more likely in the range 0.29-0.30. We estimate a mean crustal thickness of ∼30 km, and the observations suggest that the crust may be slightly thinner northwest of the island (∼26-30 km) than it is to the south (∼30-34 km). The high P wave speed and Poisson's ratio indicate a generally mafic lower crust, with rocks of intermediate composition not precluded in the upper part of the lower crust. We did not find evidence for a thick high-speed lower crust (>7.4 km/s) as has been inferred in some other arcs.

Original languageEnglish (US)
Article numberQ06013
JournalGeochemistry, Geophysics, Geosystems
Volume11
Issue number6
DOIs
StatePublished - Jun 1 2010

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Lesser Antilles
island arcs
Poisson ratio
crustal structure
lower crust
island arc
crusts
receivers
crust
Volcanoes
crustal thickness
seismic velocity
estimates
arcs
P-wave
volcano
Rocks
mantle
sharpness
P waves

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Cite this

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abstract = "We use receiver function analysis to estimate the first-order subsurface seismic structure in the vicinity of the island of Montserrat, located in the northern Lesser Antilles arc and home of the active Soufri{\`e}re Hills Volcano. Near-surface complexity in the island structure inhibits our ability to resolve lateral variations in seismic structure, so we average the signals from eight stations in two directions to produce a first-order regional seismic velocity model. Although we are unable to resolve a precise sharpness of the crust-mantle transition, we can limit its thickness to less than ∼4 km. Lateral variations in shallow structure complicate a receiver function based estimate of Poisson's ratio, but the data indicate that in both directions sampled by the receiver functions, the lower crustal Poisson's ratio is greater than 0.27 and more likely in the range 0.29-0.30. We estimate a mean crustal thickness of ∼30 km, and the observations suggest that the crust may be slightly thinner northwest of the island (∼26-30 km) than it is to the south (∼30-34 km). The high P wave speed and Poisson's ratio indicate a generally mafic lower crust, with rocks of intermediate composition not precluded in the upper part of the lower crust. We did not find evidence for a thick high-speed lower crust (>7.4 km/s) as has been inferred in some other arcs.",
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Crustal structure beneath the Montserrat region of the Lesser Antilles island arc. / Sevilla, Winchelle Ian; Ammon, Charles James; Voight, Barry; De Angelis, Silvio.

In: Geochemistry, Geophysics, Geosystems, Vol. 11, No. 6, Q06013, 01.06.2010.

Research output: Contribution to journalArticle

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