Morphology and Structure of the Southern Part of the New Hebrides Island Arc System

Daniel, Jacques

doi:10.1007/978-94-009-9535-2_11

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…The general submarine morphology is comparable to 216 that observed further south, i.e. west of the islands of Efate and Erromango [20,21 ]. However, the lower part of the trench inner slope seems to be influenced by the structure of the western island chain, which developes from here to the north.…”

Section: Description Of Seismic Profilessupporting

confidence: 51%

d'Entrecasteaux Zone, trench and western chain of the central New Hebrides island arc: Their significance and tectonic relationship

Daniel¹,

Katz

1981

Geo-Marine Letters

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The absence of a trench and the existence of a separate, western chain of islands in the central New Hebrides island arc are a consequence of earlier tectonic evolution, and not the result of subduction of the d'Entrecusteaux Zone as was previously suggested. Because of tectonic consolidation in the western islands prior to present subduction, a resistant block was created opposing subduction, and a trench nevcr did form here. The d'Entrecasteaux Zone is responsible only locally for additional deformation of the subducting plate, in a way that can be regarded as an initial stage of obduction.

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Section: Description Of Seismic Profilessupporting

confidence: 51%

d'Entrecasteaux Zone, trench and western chain of the central New Hebrides island arc: Their significance and tectonic relationship

Daniel¹,

Katz

1981

Geo-Marine Letters

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“…Although there are local variations in slope morphology (Ravenne et al 1977;Daniel 1978), there is no clear tectonic division into lower and upper slope sections as recognized in the larger Tonga of Mariana arcs. Local sedimentary aprons on the upper slope surround the larger active volcanoes but even these are lacking in the Hunter-Matthew section of the arc, where the inner slope is narrower still, and displays irregular, unsedimented benches (Karig & Mammerickx 1972).…”

Section: New Hebrides Arcmentioning

confidence: 99%

Initiation of subduction zones: implications for arc evolution and ophiolite development

Karig

1982

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“…These two adjacent areas of concentrated shallow activity occur in an area of complex bathymetry of the forearc [Daniel, 1978] and might reflect heterogeneities in structure and stress distribution. This may also be reflected by (1) the location of the productive volcanic centers which presumably built Erromango and (2) the persistently high rate of intermediate seismicity beneath Erromango.…”

Section: The Obs 6 Histogram Suggests a Relatively Low Level Of Activmentioning

confidence: 99%

Spatial distribution and mechanisms of earthquakes in the southern New Hebrides arc from a temporary land and ocean bottom seismic network and from worldwide observations

Coudert¹,

Isacks²,

Barazangi³

et al. 1981

J. Geophys. Res.

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In 1977 a wide‐aperture seismic network of land and ocean bottom stations (OBS) was operated for 6 weeks in the southern New Hebrides island arc. Data on the spatial distribution and mechanisms of small events recorded by this local network were integrated with worldwide observations of moderate to large size New Hebrides earthquakes of the past 17 years to study the structure and deformational processes in the New Hebrides subduction zone. Surprisingly, small differences (less than about 10 km) were found between the locations of shallow‐ and intermediate‐depth earthquakes as located by the temporary local network and by the International Seismological Centre using worldwide stations. Analysis of the P wave travel time data from the OBS station closest to the trench shows limited evidence for a high‐velocity zone (about 5% higher than the surrounding mantle) associated with the descending plate. The thrust zone between the descending and upper plates is defined mainly by the spatial distribution and focal mechanisms of moderate to large size events and their aftershocks, but it is not very well defined by the spatial distribution of small size events located in this study. Shallow seismic activity located beneath the trench and beneath the interplate thrust zone indicates a lower limit of about 40 km for the thickness of the seismically active part of the descending plate beneath the thrust zone. Focal mechanisms of moderate to large size earthquakes located within the upper plate and geological observations on the islands suggest that the upper plate in the region of Erromango and Tanna is divided into a series of blocks that are differentially uplifted along mainly NW‐SE striking faults. During the OBS experiment several shallow events were well located beneath the Coriolis trough, a riftlike feature located to the east of the volcanic arc. Well‐determined depths of these events are between 11 and 22 km. The well‐located intermediate‐depth events define a 20‐km‐thick Benioff zone that has a dip of about 70°. The spatial distribution of events within the descending slab is very strongly clustered in a persistent pattern that is seen in both the short‐term sample of small events determined by the local network and the long‐term sample of locations based on worldwide data. Several focal mechanisms of moderate to large size intermediate‐depth events show components of lateral extension along the strike of the arc and some show components of lateral compression, both of which could be interpreted as the result of a lateral bending of the descending plate in the part of the southern New Hebrides arc where the trench begins to curve around to the east.

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Morphology and Structure of the Southern Part of the New Hebrides Island Arc System

Cited by 6 publications

References 8 publications

d'Entrecasteaux Zone, trench and western chain of the central New Hebrides island arc: Their significance and tectonic relationship

d'Entrecasteaux Zone, trench and western chain of the central New Hebrides island arc: Their significance and tectonic relationship

Initiation of subduction zones: implications for arc evolution and ophiolite development

Spatial distribution and mechanisms of earthquakes in the southern New Hebrides arc from a temporary land and ocean bottom seismic network and from worldwide observations

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