The British Parliament passed a law granting independence in July 1947. The law gave people only one month to decide which country they wanted to live in and to move there. As millions of people began to move, more violence broke out.
Calderas form when an enormous magma chamber under, what was probably a pretty ginormous volcano, empties and collapses, causing the land above it to collapse as well. An explosive caldera-forming eruption has never been witnessed first hand, but we know that they should pretty fearsome spectacles. Much smaller calderas atop effusive volcanoes (hawaiian style) have been observed. So, formation: maars form when a vent intersects groundwater and blasts out the overlying material.
On July 29, 1968, for the first time in recorded history, Arenal Volcano erupted. Lava and magma exploded from the volcano, turning its once-green slopes to dots of red and gray ash. Eighty people and approximately 45,000 cattle, in addition to countless wild animals, were killed in the eruption.