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Marthelot et al. 1985
Marthelot, J.-M., Chatelain, J.-L., Isacks, B.L., Cardwell, R.K. and Coudert, E. (1985). Seismicity and attenuation in the central vanuatu (New Hebrides) islands: A new interpretation of the effect of subduction of the D’Entrecasteaux fracture zone. Journal of Geophysical Research 90. doi: 10.1029/JB080i010p08641. issn: 0148-0227.

The spatial distribution of the intermediate-depth earthquakes in the central Vanuatu (New Hebrides) islands includes a remarkable gap in seismic activity located between depths of 100 and 200 km and having a lateral extent of about 150 km. No well-located earthquakes determined from teleseismic data during a 16-year period nor any microearthquakes located by a local seismograph network during a 5-year period have occurred in the gap. A zone of attenuation of high-frequency shear waves overlaps the seismicity gap. No contortion of the Benioff zone in the region of the gap indicative of major disruption of the subducted plate is apparent. However, the gap is close to the extrapolated location of the subducted part of the D'Entrecasteaux Fracture Zone (DFZ). The DFZ is a ridgelike bathymetric feature on the oceanic plate being subducted beneath the island arc. A positive thermal anomaly associated with the DFZ may cause the gap of intermediate-depth seismicity and produce anomalous absorption of high-frequency shear waves. Alternatively, a zone of strong scattering associated with the subducted part of the DFZ may also account for the anomalous attenuation.

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Journal of Geophysical Research
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American Geophysical Union
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