GEOLOGY

Detailed explanation-1: -This reduction in overlying pressure, or decompression, enables the mantle rock to melt and form magma. Decompression melting often occurs at divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure.

Detailed explanation-2: -Plates rip apart at a divergent plate boundary, causing volcanic activity and shallow earthquakes; and. At a convergent plate boundary, one plate dives or “subducts” beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate.

Detailed explanation-3: -At divergent plate boundaries hot mantle rock rises into the space where the plates are moving apart. As the hot mantle rock moves upwards, less material is pushing down on it and the pressure decreases. The rock is under lower pressure; this lowers the melting temperature of the rock and so it melts.

Detailed explanation-4: -Melting at divergent plate boundaries is due to release of pressure. Lava erupts through long cracks in the ground, or fissures. Seafloor spreading creates new seafloor in the rift valleys. Rifting in a continent can create a new ocean eventually.

Detailed explanation-5: -Volcanoes called rift volcanoes are formed in spreading centers. In these zones, plates move away from each other, decreasing the pressure on the underlying mantle, allowing it to rise and melt, forming magma. Spreading centers can be found under the sea or on land.