Beginning in 1997, the Division of Geological and Planetary Sciences at Caltech has organized an annual field expedition to areas of particular geologic interest. The 1997 trip, led by Caltech's Professor Jason Saleeby, was to southeast Alaska and the Duke Island ultramafic complex. The 1998 trip, to Alaska's Katmai National Park, was led by Professor John Eichelberger of the University of Alaska at Fairbanks.

Access to Katmai National Park is only by float plane.

Remote Katmai National Park is located on the Alaskan Peninsula, where volcanos of the Aleutian archipelago make their way on to the Alaskan mainland. Katmai Park is located about 300 miles southwest of Anchorage, and is accessible only by float plane. It is best known for its annual salmon run, which attracts large numbers of bears hoping to snatch the salmon as they make their way upstream to spawn. Less well-known, and rarely visited, is the scene of the largest volcanic eruption of the 20th century, the explosive eruption of Novarupta volcano and the associated collapse of Mt. Katmai in 1912. This catastrophic eruption produced amongst the largest ashfalls in recorded history, as well as a large ignimbrite sheet called the Valley of Ten Thousand Smokes. The summer of 1912 was the coolest of the last hundred years as a result of Novarupta's stratospheric loading.



Novarupta dome, a dacite plug , marks the site of the 1912 vent. The over steepened face of Falling Mountain behind it marks the edge of the eruptive crater. Mt. Mageik in the background is an active volcano of the Aleutian arc.

The goal of the expedition was to better appreciate the complex processes associated with explosive volcanic eruptions common to convergent margins around the world. Katmai is an ideal location for such an investigation, because unlike most explosive vents, the Novarupta vent has suffered almost no collapse after evacuation of its magma chamber. This unusual consequence arose because subterranean flow from nearby Mt. Katmai volcano replenished the lost magma. As a consequence, Mt. Katmai itself collapsed (without any substantial eruptive activity at the time), and the Novarupta vent remains only minimally modified from its appearance during the eruption.

Caltech students Magali Billen, Liz Holt, Matt Bachman, Antonin Bouchez, Liz Moyer, Aron Meltzner, and Emily Brodsky (l to r) with Professors John Eichelberger (UAF, 2nd from r) and Ken Farley (Caltech, at r) at an overview of the Novarupta Dome. The remnants of Mt. Katmai are in the background.