Only to be approached under extreme circumstances with a good reason to be there.
Only enter with a suitably qualified guide.
This location is subject to intra crater earthquakes, extreme temperatures, choking and toxic gases, falling projectiles, and unstable terrain.
An eruption may give 30 seconds warning at most.
Limit your time there to minutes.
Volcanoes can eject rocks 3 km out of the vent.
Don't approach the vents.
High Risk Zone (100 m to 300 m)
This is the area on the edge of the crater.
You have a 50:50 chance of survival here in a larger than normal eruption.
Limit your time in this area.
This is the closest you should approach an active volcano under ideal conditions.
Medium Risk Zone (300 m to 3 km)
Spending hours in this zone may be OK.
Keep a careful watch on activity and follow the instructions of guides.
Any closer requires experience and knowledge of volcanic conditions.
Low Risk Zone (3 km to 10 km)
Low risk of injury from an eruption in this zone.
Safe Zone (Beyond 10 km)
Only a large eruption will affect this area.
Chances of being killed by a volcano are 1 in 80,000 over a lifetime.
You would have to live 5 million years on average before you would be killed in this zone.
Living 10 km from a volcano is no more dangerous than facing risks such as wild fires, hurricanes, floods, and earthquakes for other people around the world.
Butler, John, C. "Project 1." Exercise 1 : Searching for Specific Information.
John C. Butler, n.d. Web. 20 Jan. 2015.