This spectacular video of an erupting undersea volcano recently came through the geoscience grapevine, and thought I would share it here. Enjoy!
According to the anonymous voice accompanying the video, the volcano is Kavachi (9.02° S 157.95° E), near the Solomon Islands. The eruptive history of Kavachi has been recorded since 1939 and numerous periods of volcanism have been documented in that time. Although the date of this video is uncertain, the most recent known eruption occurred in early April 2007 following a magnitude 8.1 earthquake. Kavachi has emerged above the ocean surface to form an island on nine occasions, only to subside again due to erosion.
Kavachi is a forearc volcano located about 30 km northeast of the convergent boundary between two oceanic plates--the Pacific plate (on which Kavachi sits) and the Indo-Australian (IA) plate. The IA plate is being subducted (i.e., recycled into the mantle) to the northeast below the Pacific plate at a rate of about five centimeters per year.
In the map below (courtesy of Google), Kavachi is indicated by the green marker. Just southwest of Kavachi, the San Cristobal trench, which marks the plate boundary, can be seen running northwest/southeast.
The Solomon Islands form an island arc, a characteristic feature of ocean-ocean subduction zones. Other examples of island arcs include the Aleutians extending west from Alaska, the Mariana Islands in the western pacific, and the Antilles in the Caribbean.
On the worthy-of-patent-status-but-not-actually-patented +/- Science Awesomeness Meter, I rate this video as…
References and more information:
Baker, E.T. et al. (2002) Observations and sampling of an ongoing subsurface eruption of Kavachi volcano, Solomon Islands, May 2000, Geology, 30, 975-978.
Tregoning, P. et al. (1998) Present-day crustal motion in the Solomon Islands from GPS observations, Geophys. Res. Letters, 25, 3627-3630.
Update (added 1 February 2011, 11:30 am)
A nice graphic from the National Science Foundation showing the basic process of island-building by a submarine volcano:
|(image by Zina Deretsky, National Science Foundation)|
It illustrates pretty well how an island formed in this way is typically just the top-most portion of the volcano. A prominent example is Mauna Kea, on the big island of Hawaii, which peaks at almost 14,000 feet above sea level. This represents only about 40 percent of the total height of the volcano, though, with the rest rising from the sea floor to the surface.