Available Weekly Reports
FAQ
| Ruapehu |
Google Earth Placemark
- New Zealand
- New Zealand
- Stratovolcano
- 2007
- Country
- Subregion Name
- Volcano Type
- Last Known Eruption
- 2797 m
9174 ft - -39.280°
- 175.570°
- Elevation
- Latitude
- Longitude
6 March-12 March 2013
On 12 March, GeoNet reported that the Volcanic Alert Level for Ruapehu remained at 1 (signs of volcano unrest) and the Aviation Colour Code was lowered to Green based on the analysis of monitoring data and the lack of recent seismic activity.
Sources:
New Zealand GeoNet Project
2013: February | March |
2012: November |
2011: March | April |
2008: September |
2007: March | September | October |
2006: October |
2004: November |
2002: January | December |
2001: February | November |
6 March 2013
Back to TopOn 12 March, GeoNet reported that the Volcanic Alert Level for Ruapehu remained at 1 (signs of volcano unrest) and the Aviation Colour Code was lowered to Green based on the analysis of monitoring data and the lack of recent seismic activity.
Sources: New Zealand GeoNet Project
27 February 2013
Back to TopOn 5 March, GeoNet reported that monitoring of the Ruapehu Crater Lake showed that temperatures at depth remained above background levels but had started a declining trend. Gas data from January and February showed emission rates of 15-25 tonnes per day of sulfur dioxide and around 650 tonnes per day carbon dioxide; these are within the usual range of emissions measured at Ruapehu. Seismicity remained low, characterized by weak volcanic tremor and some shallow earthquakes. Areas of discoloration in the lake, sometimes observed during the previous few weeks, are relatively common and thought to reflect internal lake convection processes. Scientists speculated that there was a partial blockage between the deep and shallow systems causing the lake temperature to remain steady; the relatively low temperature of Crater Lake, 22-25°C since March 2012, is one of the longest periods of low lake temperatures recorded. The Volcanic Alert Level remained at 1 (signs of volcano unrest) and the Aviation Colour Code remained at Yellow.
Sources: New Zealand GeoNet Project
28 November 2012
Back to TopOn 3 December, GeoNet reported that monitoring data suggested that Ruapehu continued in a state of unrest. Scientists aboard an overflight observed that the crater lake was quiet and that the temperature remained steady at 22 degrees Celsius. Seismicity had decreased since the early part of November. The Volcanic Alert Level remained at 1 (signs of volcano unrest) and the Aviation Colour Code remained at Yellow.
Sources: New Zealand GeoNet Project
21 November 2012
Back to TopOn 23 November, GeoNet reported that measurements of Ruapehu's crater lake taken on 21 November suggested that conditions had not changed since the previous week and that Ruapehu was in a state of unrest. The Volcanic Alert Level remained at 1 (signs of volcano unrest) and the Aviation Colour Code remained at Yellow.
Sources: New Zealand GeoNet Project
14 November 2012
Back to TopGeoNet reported that measurements at Ruapehu during the previous few weeks indicated that the likelihood of an eruption had increased. Scientists were concerned that increased heat at depth beneath the crater indicated a partialyl blocked vent and the potential for an eruption due to increased pressure. On 16 November the Volcanic Alert Level remained at 1 (signs of volcano unrest) and the Aviation Colour Code was raised to Yellow.
Sources: New Zealand GeoNet Project
7 November 2012
Back to TopOn 5 November, GeoNet reported that Ruapehu's summit Crater Lake was hot during field visits in December 2011 and January 2012, exhibiting temperatures over 35 degrees Celsius. The lake cooled afterwards, reaching 16 degrees in May and fluctuating between 18-24 degrees during June-October. Scientists visited the lake in late October and reported that the water temperature was 19.5 degrees. During that visit they observed weak convection near the center of the blue-green lake.
GeoNet noted that Ruapehu is often seismically active; during the last month weak volcanic tremor was recorded and more recently several small earthquakes under the volcano had been detected. The largest earthquake was an M 2.
An overflight on 26 October to measure gas flux revealed that sulfur dioxide was 63 tonnes per day and carbon dioxide was 908 tonnes per day. The Aviation Colour Code remained at Green and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Sources: New Zealand GeoNet Project
27 April 2011
Back to TopOn 2 May, GeoNet reported that the temperature of Ruapehu's summit Crater Lake continued to slowly cool and was about 30 degrees Celsius, down from a peak of 41 degrees in March. The lake level remained below the overflow level and no earthquakes had been located within 10 km of the Crater Lake for two weeks. The Aviation Colour Code was lowered to Green and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Sources: New Zealand GeoNet Project
20 April 2011
Back to TopOn 18 April, GeoNet reported that the temperature of Ruapehu's summit Crater Lake was slowly cooling and decreased to 33-34 degrees Celsius from a peak of 41 degrees in March. A general decline of activity had been noted since 4 April, including lower carbon dioxide gas flux, less seismicity, modest change in the Crater Lake water chemistry, and cessation of lake overflow accompanying the start of the cooling trend. The Aviation Colour Code remained at Yellow and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Sources: New Zealand GeoNet Project
30 March 2011
Back to TopOn 5 April, GeoNet reported that the temperature of Ruapehu's summit Crater Lake had been high for a sustained period and was currently between 38 and 39 degrees Celsius. The highest temperature since unrest began in October 2010 was 41 degrees Celsius, measured on 1 March. The report also noted that during the previous few weeks there was an increase in carbon dioxide gas emissions, increased seismicity, and changes in Crater Lake water chemistry. The unrest prompted GeoNet to raise the Aviation Colour Code although the Volcanic Alert Level remained at 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
17 September 2008
Back to TopOn 18 September, GeoNet reported that the temperature of Ruapehu's summit crater lake had increased to 22.5 degrees Celsius, up from 16 degrees Celsius in August. Levels of sulfur dioxide and carbon dioxide also increased. Tremor was detected. GeoNet stated that the cyclic nature of the crater lake temperature and gas flux from Ruapehu was common; the Volcano Alert Level remained at 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
10 October 2007
Back to TopThe Alert Level at Ruapehu was lowered to 1 (on a scale of 0-5) on 9 October because no further eruptions have occurred since the activity on 25 September.
Sources: New Zealand GeoNet Project
19 September 2007
Back to TopAn eruption of Ruapehu that occurred on 25 September prompted GeoNet to raise the Alert level to 2 (on a scale of 0-5). Pilots reported that an eruption plume rose to an altitude below 4.6 km (15,000 ft) a.s.l. Further reports from ski field operators and the Eastern Ruapehu Lahar Alarm and Warning System (ERLAWS) indicated that lahars traveled down the Whakapapa ski field and possibly E in the Whangaehu river valley, and other areas.
On 26 September, aerial observations revealed that the summit area was covered with ash and mud, mostly directed N and reached 2 km from the crater lake. Impact craters caused by falling blocks over 1 m in diameter were also evident.
According to news articles, the eruption prompted evacuations at several ski lodges and caused train service to be temporarily suspended. A boulder crashed through the roof of a hut and injured one person.
Sources: New Zealand GeoNet Project , Agence France-Presse (AFP)
14 March 2007
Back to TopAccording to news articles, a "moderate" lahar from Ruapehu's crater lake traveled E down the Whangaehu River valley on 18 March and reached the sea 140 km away after a soft rock-and-ash dam was breached. The section of dam that failed was about 40 m long and 7 m high. There were no reports of injuries or major damage to infrastructure and only some flooding to farmlands at the base of the volcano. The volume of water and debris was estimated at 1.3 million cubic meters. On 19 March, IGNS confirmed a 6-m drop in the crater lake level and reported an increase in seismicity following the lahar.
Sources: New Zealand GeoNet Project , Associated Press , Stuff , New Zealand Herald
4 October 2006
Back to TopA M 2.8 earthquake centered at Ruapehu was recorded on 4 October. Scientists visited the summit crater lake on 7 October and confirmed that a small hydrothermal eruption had occurred. The lake water level had risen 1 m since a previous measurement, and evidence suggested wave action up to 4-5 m above the surface of the lake. The lake temperature was 22.5°C, up from 15°C. Ruapehu remained at Volcanic Alert Level 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
17 November 2004
Back to TopIGNS reported that a new heating cycle may be under way at Ruapehu volcano. The temperature of Crater Lake has increased three degrees to 18 degrees Celsius, and elevated levels of volcanic tremor have occurred over the last three weeks. Ruapehu remained at Volcanic Alert Level 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
10 November 2004
Back to TopElevated levels of volcanic tremor continue at Ruapehu and may signal the start of another Crater Lake heating cycle. The Volcanic Alert Level remained at 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
3 November 2004
Back to TopOn 2 November, volcanic tremor at Ruapehu increased to the highest level recorded for at least 12 months. The tremor was at moderate levels, but appeared to be declining slowly. The Volcanic Alert Level remained at 1 (some signs of volcano unrest).
Sources: New Zealand GeoNet Project
4 December 2002
Back to TopIGNS reported on 12 December that during the previous 2 months volcanic tremor and earthquakes had been occurring at Ruapehu, but there had been little surface change. However, during 5-12 December the temperature of Crater Lake rose 11°C, to 35°C. Ruapehu remained at Alert Level 1 (signs of volcano unrest).
Sources: New Zealand GeoNet Project
9 January 2002
Back to TopOn 11 and 12 January steam plumes were emitted from Ruapehu. This activity was believed to be associated with hydrothermal activity in the crater lake. Prior to the steam emissions, measurements taken on 8 December revealed that the lake water temperature was at 36-38°C and that it had been heating since late November 2001. Evidence of convection was observed at the S-central vent area including minor sulfur slicks, upwelling, and light steaming. Only minor volcanic tremor was recorded at Ruapehu. The volcano remained at Alert Level 1 ("Initial signs of possible volcano unrest.").
Sources: New Zealand GeoNet Project
28 November 2001
Back to TopSeismicity returned to normal levels on 25 November after a moderate-to-large volcanic earthquake occurred at Ruapehu on 21 November. Observations on 25 November revealed no signs of eruptive activity. Scientists found that upwelling sediment in Ruapehu's crater lake caused the lake to change from its normal blue-green color to dark gray. In addition, the temperature of the lake was relatively low (22°C in comparison to 21°C in September), which further supported the theory that no eruptive activity occurred after the earthquake. The volcano remained at Alert Level 1 (on a scale of 0-5).
Sources: New Zealand GeoNet Project
21 November 2001
Back to TopOn 21 November at 0218 a moderate-to-large volcanic earthquake was recorded at Ruapehu. The earthquake was followed by ~1 hour of moderate-to-strong volcanic tremor. IGNS did not believe an eruption accompanied the earthquake because no air waves were recorded and there were no reports of unusual activity. As of 23 November, seismicity continued to be higher than normal. Ruapehu remained at Alert Level 1 (on a scale of 0-5).
Sources: New Zealand GeoNet Project
21 February 2001
Back to TopThe IGNS reported that an episode of strong volcanic tremor was recorded at Ruapehu. The tremor episode peaked on 16 February and was the strongest tremor recorded since the 1996 eruptions, but direct observations of the crater revealed a lack of unusual activity. By approximately 23 February the tremor had declined to background levels. The volcano remained at Alert Level 1.
Sources: New Zealand GeoNet Project
Summary of eruption dates and Volcanic Explosivity Indices (VEI).
| Start Date | Stop Date | Eruption Certainty | VEI | Evidence | Activity Area or Unit |
|---|---|---|---|---|---|
| 2007 Sep 25 | 2007 Sep 25 | Confirmed | 1 | Historical | |
| 2006 Oct 4 | 2006 Oct 4 | Confirmed | 1 | Historical | |
| 1997 Oct 9 | 1997 Oct 18 | Confirmed | 1 | Historical | |
| 1996 Jun 16 | 1996 Sep 1 | Confirmed | 2 | Historical | |
| [ 1996 Mar 21 (in or before) ] | [ Unknown ] | Uncertain | 0 | ||
| 1995 Jan 11 (?) | 1995 Nov 9 | Confirmed | 0 | Historical | |
| [ 1994 Feb 12 ] | [ 1994 Apr 1 ] | Uncertain | 1 | ||
| 1992 Feb 8 | 1992 Mar 6 | Confirmed | 1 | Historical | |
| 1991 Jul 5 (?) | 1991 Jul 14 (?) | Confirmed | 1 | Historical | |
| 1990 Jun 17 | 1990 Sep 8 (in or before) | Confirmed | 0 | Historical | |
| 1990 Jan 7 | 1990 Jan 26 | Confirmed | 1 | Historical | |
| 1989 Jul 1 | 1989 Sep 20 (?) | Confirmed | 1 | Historical | |
| 1988 Dec 8 | 1989 Mar 5 (?) | Confirmed | 1 | Historical | |
| 1988 Mar 20 | 1988 May 25 ± 3 days | Confirmed | 1 | Historical | |
| 1987 Aug 24 | 1987 Aug 30 | Confirmed | 1 | Historical | |
| 1986 Feb 8 | 1986 Feb 9 (?) | Confirmed | 1 | Historical | |
| 1985 Nov 15 | 1985 Nov 15 | Confirmed | 1 | Historical | |
| 1985 May 21 (in or before) | 1985 Jun 9 (?) | Confirmed | 1 | Historical | |
| 1984 Oct 25 (?) | 1984 Dec | Confirmed | 1 | Historical | |
| 1984 Apr 2 | Unknown | Confirmed | 1 | Historical | |
| 1981 Oct 25 (?) | 1982 Apr 12 ± 3 days | Confirmed | 1 | Historical | |
| 1980 Oct 18 | 1980 Nov 3 | Confirmed | 1 | Historical | |
| 1980 Jan 15 (?) | 1980 Mar 27 (?) | Confirmed | 1 | Historical | |
| 1979 Jun 30 | 1979 Jul 15 | Confirmed | 1 | Historical | |
| 1977 Jul 16 | 1979 Jan 17 | Confirmed | 1 | Historical | |
| 1976 Sep 12 (in or before) | 1976 Nov 22 (?) | Confirmed | 1 | Historical | |
| 1976 Mar 6 | 1976 Mar 6 | Confirmed | 1 | Historical | |
| 1975 Oct 17 (in or before) | 1975 Oct 17 (in or before) | Confirmed | 1 | Historical | |
| 1975 Apr 24 | 1975 Apr 27 | Confirmed | 2 | Historical | |
| 1973 Oct 31 | 1974 Oct 25 | Confirmed | 1 | Historical | |
| 1972 Oct 22 | 1973 Jan 10 | Confirmed | 1 | Historical | |
| 1971 Apr 3 | 1971 Nov 1 | Confirmed | 1 | Historical | |
| 1970 Sep 16 | 1970 Sep 17 | Confirmed | 1 | Historical | |
| 1969 Jun 22 | 1969 Jun 23 | Confirmed | 2 | Historical | |
| 1968 Apr 6 | 1968 Jun 10 | Confirmed | 1 | Historical | |
| 1967 Jul 22 | 1967 Oct 4 (?) | Confirmed | 1 | Historical | |
| 1966 Apr 4 | 1966 Sep 27 | Confirmed | 1 | Historical | |
| 1959 May 21 | 1959 Aug 31 | Confirmed | 1 | Historical | |
| 1956 Nov 18 | 1956 Nov 18 | Confirmed | 1 | Historical | |
| 1952 Jul | Unknown | Confirmed | 1 | Historical | |
| 1951 Mar 19 | Unknown | Confirmed | 1 | Historical | |
| 1950 Jun 26 | 1950 Jun 26 | Confirmed | 1 | Historical | |
| 1948 May 1 | Unknown | Confirmed | 1 | Historical | |
| 1946 Nov 21 | 1947 May 31 | Confirmed | 1 | Historical | |
| 1946 Apr | 1946 Jun | Confirmed | 2 | Historical | |
| 1945 Mar 8 | 1945 Dec | Confirmed | 2 | Historical | |
| 1944 Oct | Unknown | Confirmed | 2 | Historical | |
| 1942 Aug 10 | Unknown | Confirmed | 2 | Historical | |
| 1940 Apr | Unknown | Confirmed | 2 | Historical | |
| 1936 May 9 (?) | 1936 May 13 | Confirmed | 2 | Historical | |
| 1934 Dec | 1935 Feb | Confirmed | 2 | Historical | |
| 1934 Aug 11 | Unknown | Confirmed | 2 | Historical | |
| 1925 Jan 22 | Unknown | Confirmed | 2 | Historical | |
| 1921 Oct | Unknown | Confirmed | 2 | Historical | |
| 1918 Jun 29 | Unknown | Confirmed | 2 | Historical | |
| 1906 Mar 15 | Unknown | Confirmed | 2 | Historical | |
| 1903 | Unknown | Confirmed | 2 | Historical | |
| 1895 Mar 10 | 1895 Mar 14 (in or after) | Confirmed | 2 | Historical | |
| 1889 May 1 | Unknown | Confirmed | 2 | Historical | |
| 1861 May 16 | Unknown | Confirmed | 2 | Historical | |
| 1210 ± 150 years | Unknown | Confirmed | 3 | Radiocarbon (uncorrected) | Tf5 tephra |
| 5550 BCE ± 1000 years | Unknown | Confirmed | Tephrochronology | NE flank (Whakapapa) | |
| 7590 BCE ± 100 years | Unknown | Confirmed | Radiocarbon (uncorrected) | North flank (Whakapapanui Gorge area) | |
| 7840 BCE (in or before) | Unknown | Confirmed | 4 | Radiocarbon (uncorrected) | Upper north flank (Pinnacle Ridge) |
| 9650 BCE (?) | Unknown | Confirmed | Tephrochronology | UT2 tephra | |
| 9850 BCE (?) | Unknown | Confirmed | Radiocarbon (corrected) | UT1 tephra |
Ruapehu, one of New Zealand's most active volcanoes, is a complex stratovolcano constructed during at least 4 cone-building episodes dating back to about 200,000 years ago. The 110 cu km dominantly andesitic volcanic massif is elongated in a NNE-SSW direction and is surrounded by another 100 cu km ring plain of volcaniclastic debris, including the Murimoto debris-avalanche deposit on the NW flank. A series of subplinian eruptions took place at Ruapehu between about 22,600 and 10,000 years ago, but pyroclastic flows have been infrequent at Ruapehu. A single historically active vent, Crater Lake, is located in the broad summit region, but at least five other vents on the summit and flank have been active during the Holocene. Frequent mild-to-moderate explosive eruptions have occurred in historical time from the Crater Lake vent, and tephra characteristics suggest that the crater lake may have formed as early as 3000 years ago. Lahars produced by phreatic eruptions from the summit crater lake are a hazard to a ski area on the upper flanks and to lower river valleys.
