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Sea-Floor Sunday #43: Regional context for Hunga Tonga-Hunga Ha’apai volcano

March 29, 2009

Sorry for the lack of posts lately … to be perfectly honest, I’m in a blogging slump of late. Life is catching up with me and I simply haven’t found the time to finish up some posts. But don’t fret … I have numerous posts in ‘draft’ stage waiting to be finished.

This week’s Sea-Floor Sunday shows some regional bathymetric images for the recent eruption of Hunga Tonga-Hunga Ha’apai* volcano along the Tonga volcanic arc. Check out coverage at both Eruptions and The Volcanism Blog for all the details and plenty of links to even more details.

The first image is from GoogleEarth and zoomed way out to give you global context.


Location of Hunga Tonga-Hunga Ha'apai volcano (image made in GoogleEarth)

Hunga Tonga-Hunga Ha’apai is toward the northern end of a subduction zone extending some 3,000 km south through the Kermadec arc and then the north island of New Zealand.

The next image below (from here) zooms in a bit more and has a different color scale (note: for scale, Fiji is about 700 km from Hunga Tonga-Hunga Ha’apai on this map).

Locationof Hunga Tonga-Hunga Ha'apai volcano on Tonga arc (credit:

Locationof Hunga Tonga-Hunga Ha'apai volcano on Tonga arc (credit:

The Pacific Plate  is subducting westward underneath the Australian plate creating this oceanic volcanic arc (check out this slick visualization of the deep seismic data showing the subducting slab). Bathymetry data is absolutely critical for understanding oceanic arc systems becase the vast majority of the area of these prominent features is underwater.

Have a nice Sunday!

* I am glad I’m writing that and not attempting to pronounce it


4 Comments leave one →
  1. March 29, 2009 12:13 pm

    Cool post. I had been more or less assuming that the trench ESE of the volcano was the subduction source of that volcanism, but hadn’t seen it confirmed anywhere. What is the parallel linear feature to the west? And that video is outstanding! Thanks.

  2. March 29, 2009 12:28 pm

    Lockwood says: “What is the parallel linear feature to the west?”

    The Lau Ridge?

    I’m not sure … w/out doing any research, the Lau Basin would be the back-arc basin, so the Lau Ridge is the western boundary of that … but the origin of the ridge itself I’m not sure. One possibility is that it’s the older, now-abandoned arc for the system.


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