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Raoul Island

Google Earth Placemark
  • Country
  • Subregion Name
  • Volcano Type
  • Last Known Eruption
  • 516 m
    1692 ft
  • -29.270°
  • -177.920°
  • Elevation
  •  
  • Latitude
  • Longitude

13 September-19 September 2006

The Alert Level at Raoul Island was lowered to 0 (on a scale of 0-5) on 18 September due to a general decline in activity. Since April 2006, no significant earthquake activity had occurred within ~30 km of the island, the water in Green Lake dropped to the pre-eruption level, and on-going hydrothermal activity returned to normal.

Sources: New Zealand GeoNet Project



 Available Weekly Reports




2006: March | April | September |

13 September 2006              Back to Top

The Alert Level at Raoul Island was lowered to 0 (on a scale of 0-5) on 18 September due to a general decline in activity. Since April 2006, no significant earthquake activity had occurred within ~30 km of the island, the water in Green Lake dropped to the pre-eruption level, and on-going hydrothermal activity returned to normal.

Sources: New Zealand GeoNet Project

26 April 2006              Back to Top

Hydrothermal activity at Raoul Island's Green Lake crater had declined significantly as of 28 April and the lake water level continued to fall. The Alert Level at Raoul Island was reduced from 2 to 1 (some signs of volcano unrest), on a scale of 0-5.

Sources: New Zealand GeoNet Project

19 April 2006              Back to Top

As of 21 April, hydrothermal activity at Raoul Island's Green Lake crater declined significantly and the lake level continued to fall. Recent earthquakes at or near the island were smaller and occurred less often than during the previous 3 weeks. Raoul Island remained at Alert Level 2 (minor eruptive activity).

Sources: New Zealand GeoNet Project

12 April 2006              Back to Top

As of 13 April, seismicity at Raoul Island had returned to normal and Green Lake's water level was dropping. Raoul Island remained at Alert Level 2 (minor eruptive activity).

Sources: New Zealand GeoNet Project

5 April 2006              Back to Top

Seismicity continued to decline at Raoul Island through 7 April. In addition, Green Lake's water level began to recede, ending the water-level increase that had occurred in response to the 17 March eruption. Raoul Island remained at Alert Level 2 (minor eruptive activity).

Sources: New Zealand GeoNet Project

29 March 2006              Back to Top

As of 31 March, no new eruptive activity had occurred at Raoul Island after the 17 March eruption. Seismicity continued to decline and Green Lake's water level continued to rise in response to the eruption. Raoul Island remained at Alert Level 2 (minor eruptive activity).

Sources: New Zealand GeoNet Project

22 March 2006              Back to Top

After a 17 March eruption at Green Lake on Raoul Island, no new eruptions occurred and seismicity declined through 24 March. GNS observed the volcano via photographs and video on the afternoon of the 17th, and noted that many new craters had formed in and around Green Lake and that pre-existing 1964 craters had reactivated. The main steam columns were derived from Crater I, Marker Bay, and Crater XI. The eruption blew over mature trees as far as 200 m from the eruption site and deposited dark gray hydrothermal mud and ballistic blocks.

An aerial inspection on 21 March revealed that steam discharge from vents had declined significantly owing to a dramatic (6-8 m) rise in Green Lake's water level, and consequent drowning of most of the active vents. There was no evidence of further eruptions after 17 March. There was also no evidence that any activity occurred at the 1964 craters NW of crater gully, but many new craters had formed at the mouth of the gully where hot, bare ground was present. GNS reported that as the hydrothermal system adjusts to the increased fluid pressure, further eruptions remain possible. They recommended that access to the active crater area should be restricted to the margins of the areas affected to date and the Green Lake area should not be entered. According to news reports, the search for a missing person on the island ceased around 22 March. Raoul Island remained at Alert Level 2 (minor eruptive activity).

Sources: New Zealand GeoNet Project , Associated Press

15 March 2006              Back to Top

An eruption began in the Green Lake area of Raoul Island volcano on 17 March around 0821. Based on interpretations of seismic data, the eruption appeared to have lasted for 30 minutes, with the most intense activity lasting 5-10 minutes. The eruption consisted of the ejection of mud and rocks, and a steam plume. A strong sequence of earthquakes began during the evening of the 12th that declined in number and size a few days before the 17th. According to GNS, the eruption appeared to have occurred with no immediate warning. New Zealand Department of Conservation officials evacuated a dozen staff on the island. News articles reported that one person remained missing on the island as of 22 March. The last eruption from the Green Lake area occurred during November 1964-April 1965.

Sources: New Zealand GeoNet Project , Wellington Volcanic Ash Advisory Center (VAAC) , Associated Press



Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2006 Mar 17 2006 Mar 17 Confirmed 1 Historical Green Lake crater
[ 1987 Mar 25 ] [ 1987 Mar 25 ] Uncertain 0   NNE flank (7 km from Raoul Island)
1964 Nov 19 1965 Apr 25 (?) Confirmed 0 Historical West side of Green Lake, Denham caldera
1886 Mar Unknown Confirmed 0 Historical NNE flank (7.5 km from Raoul Island)
[ 1872 Feb 1 ± 60 days ] [ Unknown ] Discredited    
1870 Jun 20 ± 4 days 1870 Oct 3 Confirmed 3 Historical Denham caldera, Green Lake
1814 Mar 9 Unknown Confirmed 3 Historical Denham caldera and Smith Crater
1720 ± 50 years Unknown Confirmed 4 Radiocarbon (uncorrected) Denham Bay?, Tui Lake Crater
1630 ± 50 years Unknown Confirmed 4 Radiocarbon (uncorrected) Rangitahua Crater
1450 (?) Unknown Confirmed   Tephrochronology NE of Raoul Island (Meyer Islands)
850 (?) Unknown Confirmed 4 Tephrochronology Expedition Crater
700 (?) Unknown Confirmed 3 Tephrochronology Pukekohu Crater
550 (?) Unknown Confirmed 4 Radiocarbon (uncorrected) Green Lake Pumice Crater
400 (?) Unknown Confirmed 4 Tephrochronology S part Raoul Caldera, Raynor tephra
100 (?) Unknown Confirmed 4 Tephrochronology N flank Moumoukai volcano, Judith tephra
50 BCE (?) Unknown Confirmed 3 Tephrochronology Denham caldera?, Bell tephra
250 BCE ± 75 years Unknown Confirmed 6 Radiocarbon (uncorrected) Denham caldera, Fleetwood tephra
1200 BCE ± 150 years Unknown Confirmed 4 Radiocarbon (uncorrected) SW part of Raoul caldera, Oneraki tephra
2000 BCE ± 100 years Unknown Confirmed 4 Radiocarbon (uncorrected) SE Raoul caldera, Matatirohia tephra

Anvil-shaped Raoul Island is the largest and northernmost of the Kermadec Islands. During the past several thousand years volcanism has been dominated by dacitic explosive eruptions. Two Holocene calderas are found at Raoul. The older caldera cuts the center of Raoul Island and is about 2.5 x 3.5 km wide. Denham caldera, formed during a major dacitic explosive eruption about 2200 years ago, truncated the western side of the island and is 6.5 x 4 km wide. Its long axis is parallel to the tectonic fabric of the Havre Trough that lies west of the volcanic arc. Historical eruptions at Raoul during the 19th and 20th centuries have sometimes occurred simultaneously from both calderas, and have consisted of small-to-moderate phreatic eruptions, some of which formed ephemeral islands in Denham caldera. A 240-m-high unnamed submarine cone, one of several located along a fissure on the lower NNE flank of Raoul volcano, has also erupted during historical time, and satellitic vents at Raoul are concentrated along two parallel NNE-trending lineaments.