Posted by: magmatist | February 27, 2012

Aerial views into Sherman Crater- bare ground around the fumaroles

View NW into Sherman Crater over Sherman Peak (foreground). The West Rim and NW rim fumaroles are prominent below the lava cliffs. The Main Fumarole spews gases in the East Breach Pit, lower right. Crater width is about 430 m (1400'). (C) Steph Abegg. Click to enlarge any image.

Steph Abegg sent us several aerial views into Sherman Crater taken on February 26. John Scurlock piloted the plane. The photos show once again that even in the depths of winter, fumarolic heat flow is sufficient to keep a fair amount of the talus and rock in the fumarole fields bare of snow.

Closer view of Northwest Fumarole Field. The single large fumarole at right is at the foot of the glacier on the north wall of the crater, below the summit. (C) Steph Abegg.

Sherman Crater has a number of distinct fumarole fields, each containing dozens of separate gas vents. The fumarole fields have moved about, coalesced, or separated over the past few decades.

Here’s a link to Steph’s photo website.

Bare ground around he NW fumarole field is evident. Wind swirls around in the crater, so the direction plumes drift are not a good indicator of where ash could fall in an eruption. (C) Steph Abegg.

Melissa mapped Sherman Crater fumaroles for her 2011 MS thesis.

Melissa Park mapped the fumarole for her Masters thesis at WWU. These photos by Steph bear out Melissa’s designation of three levels of heat intensity in the Sherman fumarole fields. She designated these types (see map below):

Type A, snow free year-round, type B: snow free in the summer and type C: snow-covered year-round. We estimate the approximate size and location of these thermal grounds based on aerial photographs and the above background orthographic imagery from July 2009 in ArcGIS. Background photo by NAIP, digital orthographic imagery, 2009

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