Editing Mount Ruapehu (section)

===1945 eruptions and 1953 lahar===

Ruapehu entered an eruptive phase in March 1945 after several weeks of volcanic tremors. The first indication of an eruption was reported on 8 March, with ashfall seen on the eastern slopes.<ref name="Johnston1997">{{cite book |last1=Johnston |first1=D. M. |title=A Chronology of the 1945 eruption of Ruapehu volcano, New Zealand |date=1997 |publisher=Institute of Geological and Nuclear Sciences science report (97/2)}}</ref> A [[lava dome]] was observed in Crater Lake on 19&nbsp;March but was destroyed in a series of explosive eruptions over the following week. A second, larger lava dome appeared in May, which continued to grow over the following months and had emptied Crater Lake of water by July.<ref name="Johnston1997" />

Eruptions increased from August through November. A particularly powerful eruption in the early hours of 21 August was heard in Hawkes Bay and the [[Tararua District]], loud enough to awaken people from sleep and cause alarm.<ref name="Johnston1997" /> Eruptions began declining in December and had ended by January.

The eruptions dispersed ash across most of the North Island, and [[eruption column]]s could be seen from as far afield as [[Palmerston North]], [[Whanganui]], and [[Hawkes Bay]]. Ash caused disruption to several North Island communities, entering houses, causing eye and throat irritation, and damaging paintwork on cars. Crop damage was reported in Ohakune, and the water supply at [[Taumarunui]] was disrupted.<ref name="Johnston1997" /><ref name="TeAra">{{cite web |title=Ruapehu 1861 – 1945 |url=https://teara.govt.nz/en/historic-volcanic-activity/page-4 |website=Te Ara Encyclopedia of New Zealand |access-date=29 July 2020 |archive-date=14 August 2020 |archive-url=https://web.archive.org/web/20200814034114/https://teara.govt.nz/en/historic-volcanic-activity/page-4 |url-status=live }}</ref>

After eruptions subsided in late December, Crater Lake slowly began refilling, with a "boiling lake" already filling the bottom of the crater by mid-January.<ref name="Johnston1997" /> A tephra dam had formed at the lake's normal outlet during the eruptions, which eventually collapsed on 24&nbsp;December&nbsp;1953 causing a lahar that led to the [[Tangiwai disaster]] with the loss of 151 lives when the Tangiwai railway bridge across the Whangaehu River collapsed while the lahar was in full flood, just before an express train crossed it.