Almost four years to the day after an unexpected explosion at New Zealand's White Island killed 22 people, tragedy has struck another volcano that is frequented by climbers and tourists. Marapi (not to be confused with Merapi) in Indonesia experienced a small and unexpected explosion on Sunday. The aftermath of the blast appears to be at least 11 hikers dead and a dozen more missing. Sadly, we again have to discuss the dangers of tourism on a potentially active volcano.