The GeoNet project, which monitors quakes in New Zealand, recorded a Magnitude 6.0 Earthquake at a depth of 11 km, about 43 km to the west of the town of Geraldine in the Canterbury Region of South Island, New Zealand, slightly before 9.15 am local time on Wednesday 20 September 2023 (slightly before 9.15 pm on Tuesday 19 September GMT). No damage or casualties have been reported following this event, but people have reported feeling it across much of New Zealand.
New Zealand is located on the boundary beneath the Australian and Pacific Plates. Beneath the islands the Pacific Plate is being subducted beneath the Australian Plate. This causes a great deal of friction which causes Earthquakes where the boundary between the two plates is close to the surface; this is to the east of North Island, but onshore on South Island, where it can lead to strong Earthquakes. Technically such quakes also occur where the plate margin is deeper, but these are felt less strongly as the rocks between the boundary and the surface absorb much of the energy, making strong tremors much less frequent on North Island. As the Pacific Plate sinks deeper into the Earth it is partially melted by the friction and the heat of the planet's interior. Some of the melted material then rises through the overlying Australian Plate, fuelling the volcanoes of New Zealand.
Witness reports of Earthquakes can help scientists to understand these events, and the underlying geologic processes that cause them. If you this quake then you can report it to the GeoNet here.
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