Formed some 7,000 years ago from the adjacent (and now extinct) Chato Volcano, 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.
Since 2010, however, the volcano’s seismicity, explosions and lava flows have decreased significantly. It is, scientists assure us, still alive; it’s just sleeping. At present, visitors will be unable to see lava flowing down its sides or find plumes of ash rising from its top. Still, there is much to see and do here – including rainforest hikes, whitewater rafting, horseback riding and more – that visitors will undoubtedly enjoy.
Arenal is what is known as a stratovolcano – a tall, symmetrical volcano that’s built upon successive layers of rock, ash and lava. Due to the convergence of oceanic and continental tectonic plates, magma (the molten or partially molten rock that forms beneath earth’s surface) rises into Arenal’s volcanic chamber and can eventually erupt from its top.
