Sherman crater sampling trip

The West Rim fumarole field lies just inside Sherman Crater. J. Scurlock photo. CLICK to enlarge any photo.

MBVRC volunteer mountaineers climbed into Sherman Crater for the volcano’s annual ‘check-up’, on July 14, 2013. Fumarole gases were sampled and  fumarole temperatures were recorded. Three HOBO temperature recorders installed last year were retrieved, and replaced with three others. These devices record ground and fumaroles temperature for one year. Data is downloaded in the lab. Soil and water samples were collected for pH determination back in town. Temperature profiles into the soil were made. This work is on behalf of the US Geological Survey’s hydrothermal monitoring program at Mount Baker.

MBVRC climbers rope up at the Easton Glacier.

This year’s volunteers were Doug McKeever, Lora Beatty, Dick Tucker, Mike Crowley, Matheau Corris, and Dave Tucker. We were joined by Sean McShane and Al Leader who were making video for an eventual Daily Planet (Discovery Channel) TV program on MBVRC’s work at Sherman Crater.  Two American Alpine Institute guides, Britt Ruegger and Jared Drapala, accompanied Al and Sean. Charlie Linneman and Josh Schacht hauled loads to our base camp.

Purpose:

Lora Beatty collects Sherman Crater fumarole gases for chemical analysis.

Fumaroles at Mount Baker’s active Sherman Crater are sampled annually to indirectly monitor changes in chemistry and temperature in the hot magma body at an unknown depth below the volcano. This program is explained here on the MBVRC blog. The other projects aim to obtain basic information about conditions in the crater. We know that parts of the crater remain snow free even in the howling winter at 9700 feet.  How hot is the ground in the fumarole areas year round? We also know that the bare ground in the crater is acidic and can damage clothing and gear. How acidic is it? All sampling this year was just inside the west rim of Sherman Crater, near the snow-covered crater floor. Location is 48° 46.187’N, 121° 49.169’W.

Data and Observations:

One of the HOBOs installed in 2012…

Fumarole temperatures were between 89.3 and 90.8 C. This is the boiling point at the elevation of the crater (2655m  9700′). There has been no change in temperatures of the fumaroles we sample since we began this work in 2006.

…and as they appeared after a year in the tough acidic environment of Sherman Crater.

The plastic casings of last year’s three HOBOs were severely damaged. They have been sent to Steve Ingebritsen’s USGS  lab in Menlo Park in the hope that a full year’s temperature data can be retrieved.

pH test. The two colors of soil can be seen at bottom. The pH meter is at left. Distilled water (pH 7) is added to the samples.

Soil pH- Two soil samples were collected in the West Rim Fumarole Field. Soil consists of hydrothermally altered clay and stones. Alteration is the effect of acidic water and heat percolating through andesite lava rock or loose tephra. The ground is generally wet from snow melt or fumarole fluids. One sample was highly altered and pale yellow-brown clay; pH was 1.88- 1.90 (between gastric fluid and lemon juice). The other was less altered and medium gray, with pH of 2.55-2.65 (about the same as carbonated soft drinks).

Gas samples are sent to a USGS gas chemistry lab in Menlo Park, California. Composition from previous years is available at the MBVRC gas data webpage.

Telephoto view of the Sherman team (5 small dots) exiting the crater.

Three soil temperature profiles were taken, with measurements at 10 cm intervals.

#1 depth (cm)   T (C)

10           25.3

20           36.2

30           40.0

40           61.4

50           64.9

60           76.8

70           82.4

rock

#2 depth (cm)  T (C)

10           48.0

20           48.0

30           74

40           81

50           90.4

60           91.0

rock

#3 depth (cm) T (C)

10           29.4

20           84.9

30           86.1

40           90.2

50           89.2

60           90.8

rock

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