Gisborne New Zealand Earthquake

Gisborne New Zealand Earthquake

The New Zealand Gisborne Earthquake occurred on 2016-09-01 16:37:57 (UTC), located at 37.359°S 179.146°E with a depth of 19.0 Km. “The Hikurangi subduction zone is potentially the largest source of earthquake and tsunami hazard in New Zealand, but there is still much to learn about it. We know that the Hikurangi subduction zone can produce large earthquakes and tsunamis and that these events have occurred in the past. However, we don’t know how often these earthquakes tend to happen, nor do we know how large they can be. Understanding what hazard this poses for East Coast communities is a key outcome of this research project. It is also the best place to study slow slip events (also referred to as “slow earthquakes” as they happen slowly for weeks to months, rather than suddenly in one massive earthquake). The world’s shallowest slow slip events occur just offshore Gisborne, and offer a globally unique opportunity to understand why slow slip events happen.” (Science).

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Tectonic Settings

“The September 1, 2016, M 7.1 earthquake northeast of Gisborne, New Zealand occurred as the result of shallow oblique-normal faulting near the plate boundary between the Pacific and Australia plates. Preliminary focal mechanism solutions indicate oblique rupture occurred on either a steep dipping, southwest striking normal fault, or on a shallow dipping, north-northeast striking fault. The Pacific plate begins its westward subduction beneath the Australia plate at the Kermadec and Hikurangi trenches, 65 km to the east of this event, with a velocity of about 47 mm/yr. The depth, location, and focal mechanism of the earthquake all indicate this is most likely an intraplate event within the subducting Pacific slab, rather than being an interplate thrust earthquake on the overlying subduction zone interface. The Australia-Pacific plate boundary region east of the North Island of New Zealand has a history of large earthquakes both along the plate boundary proper, within the subducting Pacific Plate, and in the overlying Australia plate. Seismic activity is especially high in the Kermadec Islands region to the north. Within 250 km of the September 1, 2016 event, 28 other M 6 and larger earthquakes have occurred over the preceding century. The largest was a M 7.1 event in February 1995, about 45 km to the southwest of the September 1, 2016 earthquake. The 1995 event also occurred as a result of shallow oblique-normal faulting, and is not known to have caused any fatalities or damage. The 1995 M 7.1 earthquake was followed by a M 6.5 aftershock five days later. The September 1, 2016 event was preceded by a M 5.8 foreshock, approximately 18 hours earlier and 30 km to the north, at a similar depth and with the same faulting mechanism as the subsequent M 7.1 earthquake.” (USGS Earthquake Hazards Program).

Effects of the Earthquake

“With very limited road access to Kaikoura after the earthquake, tourism expenditure in the Kaikoura District decreased the most compared to other regions. International tourism spend dropped to zero for the first 5 weeks after the earthquake. , and the domestic tourism dropped approximately 85%. In weeks 6 and 7, after road access from the south was partially restored, the tourism spend has started to increase, but is still well below the usual spend at this time of year. Based on the forecast MRTE data, conservative estimates put the estimated loss in tourism spend at $2016NZ 21 million (made up of $2016NZ 15 million international and $2016NZ 6 million domestic for the Kaikoura District for the 7 weeks after the earthquake. This contributes to the bulk of the impact for North Canterbury.” (Economic Impact of the 2016 Kaikoura earthquake).

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How did the New Zealand Government respond to the 2016 Earthquake?

Were there any related predictions on the 2016 New Zealand Earthquake?

Works Cited

Economic Impact of the 2016 Kaikoura Earthquake. www.transport.govt.nz/assets/Uploads/Our-

Work/Documents/5df0bac69b/Kaikoura-Earthquake-MERIT-Report.pdf.

Science, GNS. “Hikurangi Subduction Earthquakes and Slip Behaviour.” New Zealands Largest

Fault / Earthquakes / Science Topics / Learning / Home – GNS Science, www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/New-Zealands-Largest-Fault.

USGS Earthquake Hazards Program,

earthquake.usgs.gov/earthquakes/eventpage/us10006jbi/executive.