NOVA Online | Deadly Shadow of Vesuvius

This series of photos shows the landslide and lateral blast that happened within the first few minutes.

Yes, this eruption has a VEI of 5.
The observations you just read describe Mount St. Helens when it erupted on May 18, 1980. This "very large" eruption was the worst volcanic eruption in the recorded history of the U.S. It's also the most extensively studied eruption of any in the world to date.

What's in the Future?
Will an eruption similar to the May 18, 1980 one take place in the next decade or century? Scientists glean clues to the volcano's future behavior by analyzing the past. Mount St. Helens alternates between eruptive periods and dormant periods. During its most recent eruptive period in the 1800's, a major explosive eruption was followed by relatively smaller eruptions over the next 57 years. Assuming that Mount St. Helens behaves in the same way, the present eruptive period could continue for years. The chance of another eruption like that of May 18, 1980 happening anytime soon is very low. However, the volcano's past history suggests that a similar eruption might occur before the volcano returns to a dormant period.

Photos: Gary Rosenquist. Source: "Eruptions of Mount St. Helens: Past, Present, and Future." (USGS)