Two tidbits from New Zealand:
- A recent survey of volcanoes in the Kermadec Arc north of New Zealand suggest that there is abundant - and recent - undersea volcanism. Scientists from University of Washington (one of my former homes) and Southhampton University (UK) explored a number of submarines volcanoes including Rumble II West, Rumble III and Brothers, which are all located along the same arc of volcanoes as New Zealand's own White Island and Mt. Edgecumbe. What they found was a change in the shape of Rumble III (1.4 km below the sea surface) since the last survey in 2007 - the summit crater has been filled and the height of the summit cone is almost 100 m shorter! Sounds like that would have been a significant eruption for that sort of physiographic changes to the volcanic edifice. Previous to this, the last known eruption at Rumble III was in 1986, but the only known eruptions are based on hydrophone evidence. They also found abundant "black smokers" on Brothers Volcano. The map of Rumble II West (above) also shows what appears to be a caldera-like feature with a new cone growing in the center. Studies like this always make me wonder how many eruptions occur under the surface of the ocean that go unnoticed.
- If you're into historical accounts of volcanic eruptions (and who isn't?), you might enjoy the snippet posted in the Otaga Daily Times from 1909 entitled "Little to fear from Ngauruhoe's eruption". Mt. Ngauruhoe (which is really just the youngest vent of Mt. Tongariro) erupted 100 years ago on March 11 (see above), the original articles reports that the eruption was "the finest seen in New Zealand for years." The eruption in 1909 was one of many of the volcano in the 20th century, explosive eruptions of ash and debris with moderate intensity (VEI 2).
//Below are the comments from the original posting of this article. doug Says: March 12, 2009 at 1:33 am e given the relative proportion of the earth that is covered by water compared to land and the various plate boundaries, should one assume that there are many more underwater volcanoes than those that reach above sea level (continental and island arc)?
gg Says: March 12, 2009 at 4:50 am e Do tell, Dr. K! Just want to say that I check the world earthquakes and volcanoes. We have underwater vents in Canada, even. If it's on the Ring of Fire, and in water, I'd guess there's a pretty good chance of underwater volcanoes.
New Zealand undersea volcanism at the Eruptions blog « The Volcanism Blog Says: March 12, 2009 at 8:13 am e [...] New Zealand undersea volcanism at the Eruptions blog 12 March 2009 Posted by volcanism in New Zealand, current research, geoscience, submarine volcanism. Tags: Kermadec Arc, New Zealand, undersea volcanism, volcano research trackback Dr Klemetti has an interesting post at his Eruptions blog today on undersea volcanism in the Kermadec Arc, north of New Zealand. A study by the University of Southampton and the University of Washington found evidence of a high level of volcanic activity in this area, with the delightfully-named Rumble III volcano having apparently filled in its crater and lost 100m in height since 2007. Eruptions has all the information and relevant links: Volcanoes old and new in New Zealand. [...]
Bruce Says: March 12, 2009 at 1:54 pm e Wow! that's almost like Indonesia!
Erik, I just had a thought, do you think the volume of rhyolite produced by the TVZ has something to do with the fact that the plate boundary is actually dissecting (or trying to) the submerged continent of Zealandia? I read one report a couple of years ago that theorized that melt from the plate boundary was being transferred north from the south of the North Island to be pooled under Taupo .. (this was also to explain the absence of volcanism south of Ruapehu) but couldn't the volume of rhyolite simply be a product of the thickness of the Zealandia continent itself? Does anyone know of any other regions where plate boundaries are actually dissecting a continent (and no, I don't mean rift scenarios).. Is there any comparable volcanism?
Thomas Donlon Says: March 13, 2009 at 8:26 am e Erik,
I'd be interested to link the location of these volcanoes with current earthquakes so that maybe we could get a sense ahead of time which volcanoes may continue to be active - or be in danger of erupting.
Now are all these volcanoes that you are talking about underwater? And how close are they to breaking through to the surface and how dangerous would that be? So if any breaks through to the surface would it pose any threat for worldwide climate? I am thinking anything that might be Pinatubo size or larger. We have gone a number of months with a dearth of meaningful sunspot activity. Even the occasional sunspot now is often tied in with the last sunspot cycle. A few degrees cooler - like what Pinatubo generated on top of a presently cooling off earth may translate into meaningful or substantial cooling.
Bruce Stout Says: March 13, 2009 at 11:23 am e To Thomas!
first thanks for your feedback on my post the other day.
The best way to trace the correlation between the earthquakes and these volcanoes is probably still via the USGS earthquakes site and then when one happens click on the link to Google Earth. I know there are plans to put the seabed into Google earth but I haven't seen anything yet.
There has been a lot of earthquake activity along the Kermadec trench but from what I have seen most of it has been in the subducting Pacific plate rather than volcano related.
I'd like to see comparable studies for up near Tonga because they have positively huge rates of subduction up there and all that material must result in some volcanism someday, me thinks.
NZ is kind of strange because the axis of subduction flips completely along the Southern Alps and this seems to be holding up plate movement. The TVZ is actually a zone of attenuated crust (ie. extensional) like a rift zone but with a subducting plate underneath it providing the oomph. As far as I know this scenario extends up into the Havre trough NNE of NZ: