Volcanoes are formed form magma. Magma is a combination of molten rocks, semi molten rocks, volatiles and solids. Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Volcano formed by the mantle, that pushes magma up to the crust (Magma/Wikipedia.org, Anonymous, 2012)
The hot rocks from mantle rises up to the surface / the Crust by convection so it forces tectonic plates to move apart and so as the pressure of the hot and molten rocks, it formed a volcanoes. As tectonic plates went under the other plates, it is hot enough to melt the rocks from upper mantle, so it could create another Volcanoes and possibly an Earthquakes. (Oregonstate.edu, 2013)
Tectonic Plates - Plate tectonics is a scientific theory that describes the large-scale motions of the Earth's lithosphere. The model builds on the concepts of continental drift developed during the first decades of the 20th century. It was accepted by the scientific community after the concepts of seafloor spreading were developed in the late 1950s and early 1960s. (Macbook's Dictionary, 2013)
Bibliography :
"Wikipedia - Crust." Crust (Geology). N.p., 11 Jan. 2012. Web. 29 Apr. 2013.
Oregonst Ate.edu. "Oregonst Education / Volcano." Volcanoes Facts. N.p., 11 Mar. 2011. Web. 1 May 2013.
Youtube. N.p., 22 June 2011. Web. 28 Apr. 2013.
"Magma." Wikipedia.org. Wikipedia, 12 Feb. 2013. Web. 29 Apr. 2013.
"Wikipedia - Crust." Crust (Geology). N.p., 11 Jan. 2012. Web. 29 Apr. 2013.
Oregonst Ate.edu. "Oregonst Education / Volcano." Volcanoes Facts. N.p., 11 Mar. 2011. Web. 1 May 2013.
Youtube. N.p., 22 June 2011. Web. 28 Apr. 2013.
"Magma." Wikipedia.org. Wikipedia, 12 Feb. 2013. Web. 29 Apr. 2013.