Monowai Seamount

Monowai Seamount
Summit depth 132 metres (433 ft)[1]
Location North of the Kermadec Islands; south of Tonga
Coordinates 25°53′13″S 177°11′17″W / 25.887°S 177.188°W / -25.887; -177.188
Country New Zealand
Last eruption August 2012

Monowai is a volcanic seamount to the north of New Zealand. It is one of the most active volcanoes in the Kermadec volcanic arc and has erupted many times since 1977.[2][3] Coordinates: 25°53′13″S 177°11′17″W / 25.887°S 177.188°W / -25.887; -177.188


The summit of Monowai is approximately 132 metres (433 ft)[1] below sea level, considerably above the level of the nearby Tonga and Kermadec Trenches. The summit's position and depth changed between 1998 and 2004, due to a landslide and eruptive regrowth. A 1,500 metres (4,900 ft) deep caldera, 13 by 8 km (8.1 by 5.0 mi), lies 5 to 15 km (3.1–9.3 mi) NNE of the seamount's main cone.

Monowai was discovered by an aerial survey in 1944. Subsequent surveys showed evidence of significant change - sea discolouration and seismic activity. Studies between 1978 and 2007 showed the summit repeatedly rising and falling.[4]


Sonar data from the research ship R/V Sonne showed that between May 14 and June 1–2, 2011 the summit collapsed by as much as 18.8 m (62 ft) and lava flows had raised another area by 79.1 m (260 ft). Additionally a new volcanic cone was created. The R/V Sonne also observed the sea to be a yellowy-green with gas bubbles. Researchers believe that only Vesuvius and Mount St Helens have recorded larger growth rates.[4]

In August 2012, a 25,000 km2 (9,700 sq mi) floating raft of pumice was found offshore from New Zealand. It was initially believed to be from Monowai,[5][6] but Monowai was later ruled out as a possible source.[7]

See also


This article is issued from Wikipedia - version of the 6/29/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.