Seismic tomography of the Tongariro volcanic centre, New Zealand.

Rowlands, D. P. and White, R. S. and Haines, A. J. (2005) Seismic tomography of the Tongariro volcanic centre, New Zealand. Geophysical Journal International, 163. 1180-1194; doi:10.1111/j.1365. DOI

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Tomographic inversion of local earthquake P- and S-wave traveltime data is used to investigate 3-D P-wave velocity (Vp) and P-wave/S-wave velocity ratio (Vp/Vs) variations at the Tongariro Volcanic Centre (TgVC), New Zealand. P-wave model resolution is generally high throughout the TgVC at depths of around 3–9 km below sea level. Near-surface resolution is lower since rays at shallow depths are predominantly subparallel. Resolution decreases below 12 km depth due to clustering of seismicity at greater depths. The final 3-D Vp model shows low-velocity volumes from 3 to 7 and 8 km depth, respectively beneath the active volcanoes Ruapehu and Ngauruhoe. Smaller low-velocity volumes are observed beneath the active Tongariro volcano and the extinct Tama Lakes vents. Synthetic tests indicate that the resolution of the 3-D Vp/Vs model is insufficient to permit any reliable interpretation. Accurate earthquake depths are determined for the first time within the TgVC. Seismicity is largely restricted to two clusters west of Ruapehu, possibly with origins on eastward striking branches of the normal Raurimu Fault, two lineations near Waiouru in the south-east of the study area and a fault belt between Tongariro and Lake Taupo in the north of the study area. Earthquake depths indicate possible shallowing of the brittle–ductile transition beneath Ruapehu and Ngauruhoe.

Item Type: Article
Uncontrolled Keywords: 2005 P 2005 AREP IA46 IA49
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Geophysical Journal International
Volume: 163
Page Range: 1180-1194; doi:10.1111/j.1365
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 19 Aug 2010 09:19
Last Modified: 23 Jul 2013 09:59

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