2007-03-14 05:01:17 · 2 answers · asked by mikey 1 in Science & Mathematics ➔ Earth Sciences & Geology
When a plate is subducted into the mantle partial melting of the plate occurs. Molten rock is less dense than solid rock, so the molten rock will migrate towards the surface through cracks and fissures in the rock (and to a lesser degree by melting surrounding rock). This molten material is expanding as it gets closer to the surface due to the decreased pressure. This causes more cracking and greater pressure on the surrounding rock the closer the molten rock gets to the surface. Eventually this leads to a failure of the crust and a volcanic eruption.
Basically, the reason volcanoes form above a subduction zone is because of the partial melting of the subducting plate.
2007-03-14 05:08:12 · answer #1 · answered by brooks b 4 · 2⤊ 0⤋
The crust (oceanic or continental) of one tectonic plate is plunging under the other plate. There is a dehydration, changing in pressure and temperature. This leads to the differential melting of the crust (a part melt another stay solid). The molten fraction is lighter and make kinds of bubles progressing to the surface and later giving volcanoes.
This is very simplified but I guess pretty exact.
2007-03-14 12:11:01 · answer #2 · answered by omalinur 4 · 0⤊ 0⤋