This report describes venting of ash and gas that continued at White Island during November 2000 through May 2001. As previously reported, on 27 July 2000, strong seismicity accompanied a short-lived magmatic eruption and produced a new explosion crater. Following the event, the two active vents at White Island emitted an ash plume. The ash content of the plume declined significantly during late August-early September 2000 (BGVN 25:08).

On 9 November 2000 scientists visiting White Island found weak-to-moderate fumarole activity, with the two active vents producing a white steam-and-gas plume. By 16 November, a small new vent SE of the active MH was also steaming. Around that time, the noise from the MH vent was so loud that it could be heard from the beach in still conditions. By mid-December, the steam-and-gas plume rose to an altitude of ~1,250 m, and occasional bursts of low-level tremor occurred. The level of gas emission seemed to have stabilized after the increase that occurred during the previous month.

On 3 January 2001 a volcanologist visiting the site reported that the lake within the 78/90 Crater Complex had enlarged and had a yellowish-brown discoloration with surface slicks and noticeable areas of convection. Fumaroles appeared to be more extensive within the complex. A strong haze of sulphur dioxide gas was evident within the crater. By mid-January the water level near the vents had risen.

Based on reports from White Island tour operators, the Institute of Geological and Nuclear Sciences (IGNS) stated that on 19 February minor ash eruptions resumed. A light gray plume of fine ash rose ~2 km above the MH vent and drifted towards the mainland. Fine ash was deposited on and near White Island, but only an acid aerosol cloud reached the mainland near the town of Matata (~55 km SW).

During mid-March the steam-and-gas plume was not nearly as noisy as it had been, but it was still very hot, as indicated by the transparency of the bottom of the plume as it exited from the vent. The IGNS received reports from the public of an unusually large gas plume extending over White Island. This large plume, however, was attributed to still wind conditions and cooler air temperatures.

On 19 April a team from IGNS visited White Island and found no significant change from previous visits. The lake was still a yellow/green color, but was somewhat cooler at 28°C. The MH vent was still emitting a considerable volume of steam, but was not as noisy as it had previously been. Steam emerged from the vent at a temperature of 145°C, and reached a height of about 20 m before condensing. No ash was produced.

Heavy rain affected the area around the vents during May 2001 and changed the lake color to gray, but the volcanic activity was essentially unchanged. On 28 May, air waves were recorded by the seismometer, indicating a small surface explosion. Fumaroles continued to be active and produced a high level of water vapor in the crater area.

By July the gas pressure at White Island had decreased. A few isolated, small, low-frequency events were recorded in August. Weak volcanic tremor was recorded in September, but no changes occurred at the surface.

Geological Summary. The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

Information Contacts: Brad Scott and Tony Hurst, Wairakei Research Center, Institute of Geological and Nuclear Sciences (IGNS), Private Bag 2000, Wairakei, New Zealand (URL: http://www.gns.cri.nz/).