North of Cantwell and east of the Parks Highway stands Panorama Mountain, a hulk of pointy black spires. Look on the west side of the mountain, Beget said, and you see a gash from a prehistoric rock avalanche that traveled across the Nenana River. Just across the river and visible from the highway are former chunks of Panorama Mountain as large as houses.
Panorama Mountain sits on the western end of the Denali fault. The eastern portion of the fault ruptured in the magnitude 7.9 earthquake of 2002, the largest earthquake on the planet that year. Scientists are trying to find out when the fault last ripped at its western end, the part that runs beneath the Parks Highway and near Cantwell.
Beget and research partner Mary Keskinen looked at the lichens clinging to the rocks that fell during the Panorama Mountain slide. The oldest lichens on the rocks date back to 400 years, making the geologists think that the last great earthquake on the western portion of the fault may have happened about the year 1600 or so. Since then, the fault has been building up stress, perhaps similar to the energy that the great 2002 earthquake released.
Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. Ned Rozell is a science writer for the Geophysical Institute. A version of this column ran in 2006.