Hangaroa Mud Eruption 1931

At the time of the magnitude 7.8 Hawkes Bay earthquake on the 3rd of February 1931, a mud blowout occurred many kilomteres north at Hangaroa, inland from Gisborne.

A loud report which was accompanied by a flash of flame as escaping gas ignited was followed by the eruption of an estimated 20,000 tons of mud at a property owned by Mr J. Barnes-Graham. The mud, which was finely crushed Lower Tertiary mudstone and sandstone, covered an area of approximately two and a quarter acres, and temporarily blocked the Hangaroa River as it flowed over the lip of the vent.

The report of the event in the New Zealand Department of Scientific and Industrial Research Bulletin No. 43 (p 78) stated that there were numerous examples of extinct and active mud volcanoes in the Gisborne district.

Earlier, in May 1930, an extensive blowout occurred at the cold mud springs in Waimata Valley, near Gisborne. J. A. MacKay in “Historic Poverty Bay and the East Coast, N.I. N.Z.” (p 370) states that they had erupted on previous occasions but the 1930 event was more extensive. “Explosions of gas brought up sufficient mud to raise the height of an area of some acres by, in places, as much as from 10 to 15 feet [3 to 4.5 metres]. The gas produced a steady flame when ignited.”

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