that's called the magma chamber , and if the pressure continues to increase on the magma in the magma chamber, it will result in an eruption . Websites used: http://wiki.answers.com/Q/Why_do_volcanoes_erupt&isLookUp=1 http://answers.yahoo.com/question/index?qid=20100216071935AA2o0O5 2. Why is lava red? Lava is red because anything that's 1200 to 1400 degrees Fahrenheit will turn red. The