As the oceanic crust subducts
, it experiences a very high pressure but relatively low temperature style of regional metamorphism, and the basalt and gabbro are transformed to blueschist (or glaucophane schist) and then to eclogite (Figure 5).
For central Costa Rica, where the seamount segment of the Cocos plate subducts
, local earthquake seismic tomography data by Husen et al.
Coastal mountain ranges from Northern California up to Alaska were formed by the scraping off of fragment of the ancient Farallon plate as it subducted
beneath the North American continent.
Also shown are the predicted former positions of mid-oceanic ridges (thin red lines), with the areas where these are subducted
being highlighted in solid black.
Sigloch and Mihalynuk noticed that the shape of one slab, previously interpreted from fuzzier images as the eastern section of the Farallon plate, doesn't match what you'd expect to find if it had simply subducted
beneath North America.
Ringwood, "Phase transformations in subducted
oceanic crust and buoyancy relationships at depths of 600-800 km in the mantle," Earth and Planetary Science Letters, vol.
Notably, the Pacific plate subducts
below (is pushed underneath) northern Honshu along the Japan trench at a rate of 93 mm/yr., while the Philippine plate subducts
beneath southern Honshu along the Nankai trough at a rate of 58 mm/yr.
"The 1992 Nicaragua earthquake: A slow tsunami earthquake associated with subducted
sediments," Nature, 361, 714-716.
Most earthquakes of this kind are produced at subduction zones where an oceanic plate slides beneath another plate, known as the upper plate, and the down-going plate descends into the interior of the Earth as a subducted
But Sentry had already been committed to another expedition in March, so ABE was brought back into service for a mission to explore the Chile Triple Junction, the only place on Earth where a mid-ocean ridge is being subducted
(or pushed beneath) a continent (South America) in a deep ocean trench.
The Chilean quake occurred where the Nazca tectonic plate was squeezed under, or "subducted
," below the adjacent South American plate.
Rather, the worldwide success of traditional Irish music has indeed paralleled the political and economic success of the Republic, and the music in Northern Ireland--not as well championed or promoted--has been subducted
in the process.