Supriya Ghosh (Editor)

1997 Fiji Tonga earthquake

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Date  14 October 1997
Depth  167 km (104 mi)
Magnitude  Mw 7.8
1997 Fiji-Tonga earthquake

The 1997 Fiji-Tonga earthquake occurred south of the Fiji Islands (about 190 km WSW of Nuku'alofa, Tonga, and 255 km SE of Ndoi Island) on 14 October at 09:53 UTC. This earthquake was located in the central part of the Fiji-Tonga subduction zone and it had a magnitude of Mw 7.8. The rupture area was about ~50 km × 25 km, and the average slip was estimated to be 6 m (20 ft). This earthquake could be felt in Wellington, New Zealand.


Tectonic setting

The Pacific Plate is subducting beneath the Australian Plate in the Fiji-Tonga subduction zone. The Tonga Trench is linear, fast converging, and seismically active. Mantle seismicity is active in this area. There is a belt of deep earthquakes in the west of the Tonga Trench. There are more earthquakes with focus depth h ≥ 300 km occurring in the Tonga-Kermadec region than in all other regions combined.


With a depth of 167 km (104 mi), this was an intermediate depth earthquake. Thermo-petrologic models suggest that water may have an important role in the generating process for earthquakes of intermediate depths, as hydrous minerals may exist where intermediate depth seismicity is abundant.


1997 Fiji-Tonga earthquake Wikipedia