For the first time since a new eruptive phase began back in September 2004, Mount St. Helens will again be open to climbers starting July 21.

Federal officials will allow as many as 100 climbers per day to tackle the south-side route that leads to the edge of the summit crater.

There climbers can get a look at an active – albeit relatively peaceful – eruption of magma that has been continually making its way to the surface.

The movement of the magma sets off small earthquakes. Rockfalls inside the crater occasionally kick up ash and steam. And on dry days, shimmers of heat move off the crater rocks. “It really is quite impressive,” said Peter Frenzen, a scientist with the Mount St. Helens National Volcanic Monument.

Federal officials closed the climbing route after swarms of earthquakes and ash and steam releases raised the volcano’s threat level. Since then, the magma has continued to ooze out of the mountain, but it does not contain much explosive gas. That indicates there’s not likely to be a dangerous eruption in the near future, Frenzen said.

Scientists for the U.S. Geological Survey and the University of Washington will continue to closely monitor the mountain. If conditions change, and it appears to be building toward a violent eruption, the mountain could again be put off-limits to climbers.

The trip up the mountain is not a highly technical climb, but it requires good physical conditioning to climb 4,500 feet to reach the summit at 8,325 feet elevation. Most climbers take between seven and 12 hours to make the round trip.

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