Arenal Volcano is a 1,633 meter (5,300 feet) high mountain, which is perfectly conically shaped with a crater of 140 meters. It is known as a stratovolcano – a tall, symmetrical volcano that’s built upon successive layers of rock, ash and lava. Arenal’s most recent eruptive period began in 1968 with an explosion that buried three small villages and left 87 people dead. Up until July 2010, the eruptions had been constant, though much less severe—there were effusions of smoke and lava on an almost daily basis.

credit: marianne muegenburg cothern

credit: Jesse Newland 

credit: Isaac Bordas

credit: Isaac Bordas

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credit: Scott Robinson

credit: Scott Robinson

credit: Peter Sheik

credit: Fimb

credit: Scott Robinson

credit: Scott Robinson

Stromboli is a small island in the Tyrrhenian Sea, off the north coast of Sicily, containing one of the three active volcanoes in Italy. It is one of the eight Aeolian Islands, a volcanic arc north of Sicily. A significant geological feature of the volcano is the Sciara del Fuoco, a big horseshoe-shaped depression generated in the last 13,000 years by several collapses on the north western side of the cone. A typical eruption at Stromboli consists of several small gas explosions each hour, ejecting incandescent cinder, lapilli, and bombs to heights of a few tens or hundreds of feet. Tephra is glowing red when it leaves the vent but becomes black and nearly solid before hitting the ground. Occasionally, lava flows may also be produced. Lava flows from Stromboli are typically less fluid than Hawaiian lava flows and thus are somewhat shorter and thicker. Because of the lower fluidity, it is harder for gas to escape from the rising magma. Gas bubbles become pressurized and burst at the top of the magma column, producing small explosions and throwing clots of molten lava into the air. When this type of eruption is observed at other volcanoes, it is referred to as Strombolian.