Composite volcanoes are the most common type of volcano. They can have violent eruptions and can grow bigger as layers of thick lava and ash harden on top of each ... that flows down the side ...

A note overlaid on the clip says "POV [point of view]: You hike ... you're forced to evacuate down the mountain!" The hiker says in the clip, "We're evacuating the volcano in 20 minutes," as ...

If the magma movement beneath the volcano doesn't settle down, the next sign of an eruption ... showed volcanic tremor for two months before it blew its top. "If we see [tremor]," Haney said ...

Arenal Volcano ... though the quality of the view depends heavily on the weather. One hiker commented that they could see the smoke coming from the top on their clear day visit.