Since its eruption stopped about 100,000- 250,000 years ago, the period of eruptive activity was short in time.

Roosevelt had been told that the area was actually extinct in terms of eruptive activity.

Twelve lava domes were built throughout the area and the next period of eruptive activity began.

However rescue officials had to retreat as eruptive activity made their further presence on the slopes too dangerous.

Through early 1990, a total of at least 21 periods of eruptive activity had occurred.

Last eruptive activity is thought to be Pleistocene, about 500,000 years ago.

Since the early Holocene epoch, there has been no eruptive activity.

As with the 1693 earthquake the 1169 event seems to have followed after a major period of eruptive activity.

There is no increased threat of eruptive activity at Yellowstone to cause concern at this time.

During this period, four episodes of magmatic eruptive activity have been recently recognized.