Mount Katmai – Kirk Schleiffarth

100 years ago, the largest volcanic eruption of the 20thcentury occurred on the Alaska Peninsula.  On the 6th to 9th June of 1912, a new vent produced an explosive three day eruption that produced 13.5 cubic kilometers of material (over 3 times larger than the 4 cubic kilometers of the 1980 of Mount St Helens).  Pyroclastic surges produced an ignimbrite deposit over 150 meters thick.  The ignimbrites took years to cool and as a result, fumaroles were present for many years following the eruption.  The area is known as The Valley of 10,000 smokes.
 
As the eruption waned, the viscous magma, now devoid of volatile gases, created a blocky lava plug and dome directly above the vent.  This new vent and dome are now known as Novarupta.
Directly following the eruption, the Katmai composite volcano, 10 km to the east, suddenly collapsed and formed a 1 km deep caldera. This caldera subsequently filled with a crater lake over 240 meters deep.
Katmai Crater Lake in 1980 (by Budd Christman)
Katmai National Park is a spectacular, rugged place that is geologically overwhelming.  A deep, narrow canyon has been carved by snowmelt into the 150-meter ignimbrite deposit.  The Katmai Caldera is now filled with deep blue water.  The Valley of 10,000 smokes has stopped smoking but still illustrates the immense amount of material ejected from Novarupta 100 years ago.  The Novarupta dome stands separate from the nearby cluster of composite volcanic cones as evidence of the unpredictability of volcanic processes.
Katmai Gorge
 

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