spurr reported activity

Event Name : Spurr 300 yBP

Start: 300 (± 50 Years)

Years BP Tephrochronology

Tephrafall:

Eruption Type:	Explosive
Eruption Product:	andesite
Chem	Yes
Other	mafic

Description: From Beget and others (1994): "The next lower ash in the Skilak cores occurs at a depth of 16-26 cm, and is compositionally much more mafic than the majority of tephras found in the cores (Table 1 [in original text]). Crater Peak, a subsidiary vent of Mt. Spurr, was almost certainly the source of this andesitic tephra. During historic eruptions of Mt. Spurr in 1953 and in 1992, ash from Crater Peak was deposited in Anchorage and other areas around Cook Inlet. The Crater Peak vent is the only Cook Inlet volcano which produces such widely dispersed mafic tephras (Riehle, 1985; Nye, 1990). The ash in Skilak Lake therefore is thought to record a previously unknown eruption of Crater Peak at Mt. Spurr about 300+/-50 years ago, with the age estimate based upon sedimentation rate estimates and interpolation between the historic tephras at the top of the cores and the 500-year-old tephra layer B from Mount St. Augustine found lower in the cores (Fig. 7 [in original text])."