Volcanoes and Plate Tectonics. Section 1- Pages 88-91. 1- Where are volcanoes found?. Most volcanoes occur at plate boundaries. Either divergent boundaries like the mid-ocean ridge, Or… Convergent boundaries where subduction occurs.
Section 1- Pages 88-91
As the plates move away from each other, lava pours out the cracks creating volcanoes.
Plumes of magma rise from deep in the mantle and melts through the crust creating volcanoes in the middle of plates.
Lo`ihi Seamount is an active volcano built on the seafloor south of Kilauea about 30 km from shore. The seamount rises to 969 m below sea level and generates frequent earthquake swarms, the most intense of which occurred in 1996.
Section 2- Pages 93-102
Molten material rises forcing its way through the crust.
As pressure increases eventually the magma reaches the surface causing the eruption of lava and gases.
Magma with HIGH silica content makes the magma thicker and clumpy,
Magma with LOW silica content is thin and runny.