According to Institute of Geological & Nuclear Sciences Limited (GNS) in a media release on 11 August, the Laboratoire de Géophysique (Papeete, Tahiti) reported that seismographs in Rarotonga recorded eruptive activity at Monowai seamount on 3 August. The activity then stopped overnight.

8 August 2012              Back to Top

According to Institute of Geological & Nuclear Sciences Limited (GNS) in a media release on 11 August, the Laboratoire de Géophysique (Papeete, Tahiti) reported that seismographs in Rarotonga recorded eruptive activity at Monowai seamount on 3 August. The activity then stopped overnight.

Sources: New Zealand GeoNet Project

Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Brothers R N, Heming R F, Hawke M M, Davey F J, 1980. Tholeiitic basalt from the Monowai seamount, Tonga-Kermadec ridge (Note). {New Zeal J Geol Geophys}, 23: 537-539

Davey F J, 1980. The Monowai Seamount: an active submarine volcanic centre on the Tonga-Kermadec Ridge (note). {New Zeal J Geol Geophys}, 23: 533-536

Latter J H, 1978. Submarine eruption south of Tonga. {New Zeal Volc Rec}, 7: 61

Latter J H, Lloyd E F, Smith I E M, Nathan S, 1992. Volcanic hazards in the Kermadec Islands, and at submarine volcanoes between southern Tonga and New Zealand. {New Zeal Ministry Civil Defense, Volc Hazards Inf Ser}, 4: 1-45

Smithsonian Institution-SEAN, 1975-89. [Monthly event reports]. {Bull Scientific Event Alert Network (SEAN)}, v 1-14

Wright I C, Chadwick W W Jr, de Ronde C E J, Reymond D, Hyvernaud O, Gennerich H-H, Stoffers, P, Mackay K, Dunkin M A, Bannister S C, 2008. Collapse and reconstruction of Monowai submarine volcano, Kermadec arc, 1990-2004. {J Geophys Res}, doi:10.1029/2007JB005138

Monowai seamount, also known as Orion seamount, rises to within 100 m of the sea surface about halfway between the Kermadec and Tonga island groups. The volcano lies at the southern end of the Tonga Ridge and is slightly offset from the Kermadec volcanoes. Small parasitic cones occur on the north and west flanks of the basaltic submarine volcano, which rises from a depth of about 1500 m and was named for one of the New Zealand Navy bathymetric survey ships that documented its morphology. A large 8.5 x 11 km wide submarine caldera with a depth of more than 1500 m lies to the NNE. Numerous eruptions from Monowai have been detected from submarine acoustic signals since it was first recognized as a volcano in 1977. A shoal that had been reported in 1944 may have been a pumice raft or water disturbance due to degassing. Surface observations have included water discoloration, vigorous gas bubbling, and areas of upwelling water, sometimes accompanied by rumbling noises.