1947 Gisborne earthquakes and tsunami

Earthquakes in New Zealand October 2024 December 2016 15 km Yes New Zealand Hikurangi Margin 7.7 w yes 7.6 w iscgem897790 iscgem897857 897790 897857 1947-03-25 20:32:20 1947-05-17 07:06:41 New Zealand -38.676 178.533 inline, title None thumb|Run-up for the 25 March tsunami thumb|Run-up for the 17 May tsunami The 1947 Gisborne earthquakes and tsunami occurred east of Gisborne and offshore from New Zealand's North Island. Both earthquakes measured 7.7 and 7.6 on the moment magnitude scale,http://info.geonet.org.nz/display/tsunami/Gisborne+tsunami,+25+March+and+17+May+1947 Gisborne tsunami, 25 March and 17 May 1947 – Tsunami – GeoNet GeoNet 7 February 2016 and generated large tsunamis, although there were no casualties. Tectonic setting New Zealand lies along the boundary between the Indo-Australian and Pacific plates. In the North Island the displacement is mainly taken up along the Hikurangi Subduction Zone, although the remaining dextral strike-slip component of the relative plate motion is accommodated by the North Island Fault System. Both earthquakes are believed to have occurred along the Hikurangi Subduction Zone, in close proximity to each other. Both earthquakes generated tsunami caused by the sudden release of energy from the Earth's crust. Due to the unusually large tsunami that accompanied the earthquake, and the lack of damage due to weak shaking, this event has been identified as a rare "tsunami earthquake".M 7.0 Gisborne, Wed Mar 26 1947 https://www.geonet.org.nz/tsunami/story/1542993 GeoNet 5 March 2021 Earthquakes The first earthquake, which struck offshore Poverty Bay on 26 March 1947 at 8:32am NZST, measured 7.7 w y.ISC-GEM Global Instrumental Earthquake Catalogue Version 11.0 International Seismological Centre 25 June 2024 10.31905/D808B825 Data set free It generated a tsunami with a maximum measured run-up height of 10 metres that struck the coast from Māhia Peninsula to Tokomaru Bay, swamping the coast between Muriwai and Tolaga Bay 30 minutes after the quake. The tsunami was not observed outside of New Zealand. Four people at the Tatapouri Hotel, 13 kilometres by road north of Gisborne, saw the tsunami coming and rushed up a hill. Two waves swept through the ground floor of the hotel up to window sill height, and retreating water then washed small buildings out to sea. A little further north at Turihaua, a 10-metre high wave hit a cottage, sweeping two men who were outside it inland onto the coast road. Three other people were trapped in the kitchen, which filled with water to head height. Retreating water then destroyed the cottage, leaving only the kitchen. The Pouawa River bridge, a little further north, was swept 800 metres inland. Seaweed was later found in telegraph wires 12 metres above sea level at Pouawa Beach.https://www.geonet.org.nz/tsunami/story/1542993 M 7.0 Gisborne, Wed Mar 26 1947: Tsunami GeoNet 14 November 2020 A house at Mahanga Beach, just north of Māhia Peninsula, was moved off its piles.Tsunamis – 20th-century and recent tsunamis Eileen McSaveney https://teara.govt.nz/en/tsunamis/page-3 Te Ara – the Encyclopedia of New Zealand 17 February 2017 14 November 2020 Seven weeks later, a second earthquake struck offshore Tolaga Bay on 17 May, and was estimated at 7.6 w. It also generated a tsunami, which had a maximum measured run-up height of 6 metres. Despite occurring at low tide and being less powerful than the first, the tsunami caused small amounts of damage along the east coast and is noted for washing away construction materials being used to repair damage from the earlier tsunami. No one died in either of the tsunamis, but there could have been a high toll had they struck when beaches were crowded during summer holidays. See also List of earthquakes in 1947 List of earthquakes in New Zealand References External links 897790 (25 March 1947) 897857 (17 May 1947) Gisborne Gisborne earthquakes Category:Earthquakes in New Zealand Category:History of the Gisborne District Category:Tsunamis in New Zealand Category:1940s tsunamis Category:Tsunami earthquakes Category:March 1947 in Oceania Category:May 1947 in Oceania Category:1947 disasters in New Zealand