GEOLOGICAL SURVEY PROFESSIONAL PAPER 1022-D 

INFRARED SURVEYS, RADIANT FLUX, 

AND TOTAL HEAT DISCHARGE AT 

MOUNT BAKER VOLCANO, WASHINGTON, 

BETWEEN 1970 AND 1975 
FRONTISPIECE-Mount Baker's Sherman Crater in August 1969, as viewed from the east. Photograph K692- 4 by Austin Post, August 2, 1969. 
Infrared Surveys, Radiant Flux, 

and Total Heat Discharge at 

Mount Baker Volcano, Washington, 

Between 197 0 and 197 5 

By JULES D. FRIEDMAN a'nd DAVID FRANK 

V 0 L C A N I C ACT I V IT Y AT M 0 U N T B A K E R, WAS H I N G T 0 N 

G E 0 L 0 G I CAL S U R V E Y P R 0 FE S S I 0 N A L PAPER 1 0 2 2-D 

A comparison of 1970-1973 and 1975 thermal activity 

using aerial infrared surveys, ground temperatures 

relayed via satellite, and a two-po£nt differential 

geothermal-flux model based on heat balance 

of the ground surface 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1980 
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary 

GEOLOGICAL SURVEY 

H. William Menard, Director 

Library of Congress Cataloging in Publication Data 

Friedman, Jules D 

Infrared surveys, radiant flux, and total heat 

discharge at Mount Baker Volcano, Washington, 

between 1970 and 1975. 

(Volcanic activity at Mount Baker, Washington) 

(Geological Survey professional paper ; 1022-D) 

Bibliography: p. 32-33 

Su.pt. of Docs. no.: I 19.16: 1022-D 

1. Baker, Mount, Wash 2. Earth temperature--

Washington (State)--Baker, Mount. I. Frank, 

David, joint author. II. Title. III. Title. 

IV. Series: United States. Geological Survey. 

Professional paper ; 1022-D. 

QE523.Bl8F74 551.2 80-607072 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 
CONTENTS 

Page 

Abbreviations _ _ ___ _ _ _ _ _ _ _ _ __ _ _ _ _ __ __ _ _ _ _ _ _ ____ __ _ _ _ _ __ _ _ _ VI 

Terminology and conversion factors ------------------------ VII 

Abstract _ _ _ __ _ __ ___ _ _ _ ___ __ __ _ _ _ _ ______ _ _ __ __ __ ___ _ _ _ _ _ _ _ _ D 1 

Introduction _____________________________________ --------- 1 

Acknowledgments ______________________________ ------ 2 

Geologic setting of Mount Baker---------------------------- 2 

Quaternary eruptions _____________________________ --------- 4 

Historic activity ___________________________________ --- 4 

Fumarolic activity between 1970 and 1974 __________________ 8 

Sherman Crater fumarole field ------------------------ 8 

Dorr Fumarole Field ---------------------------------- 8 

Increase in fumarolic activity in 1975 ______________________ 8 

Surveillance and mapping by aerial infrared scanner ________ 8 

Geologic interpretation of infrared images ______________ 8 

Radiant-flux estimation ___________________________ ----_ 10 

Corrections for absorption and emission by atmospheric water vapor, carbon dioxide, and aerosols __ 14 

Temperature corrections for surface emissivity ______ 14 

Thermographic survey of November 20, 1972 ________ 16 

Electronic thermal-sensor array and Landsat data collection 

platform ______________________________________________ -- 18 

Heat-flux estimates ____________________________________ ---- 18 

Differential geothermal flux from Dorr Fumarole Field, 

1972________________________________________________ 23 

Heat-flux estimates-Continued Page 

Differential geothermal flux from Sherman Crater, 1972 

and 197 5 ________________________________________ D 23 

Heat loss from central pit lake, 1975________________ 24 

Evaporation ____ _ __ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ _ ___ __ __ __ _ 24 

Conduction and diffusion to atmosphere ________ 25 

Radiant heat loss______________________________ 26 

Total heat loss -------------------------------- 26 

Differential geothermal flux and comparison of 

heat-loss estimates __________________________ 26 

Heat exchange via mass transfer from fumaroles, 

1975 ____________________________________________ 26 

Advective heat loss via melt-water drainage, 1972 and 

1976 ___ ~---------------------------------------- 26 

Analysis of propagation of error in flux calculations__ 26 

Heat-flux summary_------------------------------- 27 

Inferred energy yield during repose ________________________ 27 

Comparison between 1972 energy yield and 1975 energy 

yield________________________________________________ 27 

Discussion ------------------------------------------------ 30 

Summary and conclusions__________________________________ 31 

References cited _ _ _ _ _ _ _ _ ___ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ ____ __ __ _ 32 

ILLUSTRATIONS 

Page 

FRONTISPIECE. Photograph of Mount Baker's Sherman Crater, August 1969. 

FIGURE 1. Index map of Mount Baker _ __ _ _ _ _ __ _ _ __ __ _ _ _ _ __ __ __ __ _ _ _ _______ _ _ _ _ ____ __ __ _ _ __ _ _ _ _ _ _ ____ __ __ __ _ _ _ _ __ ____ _ D2 

2. Landsat 1 image showing the regional setting of Mount Baker------------------------------------------------ 3 

3-6. Photographs of Mount Baker: 

3. East facade in September 1962, showing Sherman Crater, summit dome, and Sherman Peak ____________ 4 

4. Southwest facade in September 1962 _ _ _ _ _ ____ ___ _ _ _ _ _ __ _ _ __ _ _ __ ____ _ _ _ _ _ _ _ _ _ _ _ _ ___ ___ __ __ _ _ _ _ ______ _ 5 

5. Sherman Crater _ _ _ __ __ _ _ _ _ __ _ _ _ _ _ _ __ _ _ ____ __ __ _ _ _ _ _ _ __ _ _ _ _ _ _ __ ____ __ _ _ _____ _ _ _ _ ___ ____ __ _ _ _ _ _ _ __ __ _ 6 

6. Vertical view of Dorr Fumarole Field on the north slope of Mount Baker, June 1975 ____________________ 9 

7. Schematic diagram of RS-14 aerial infrared scanner -------------------------------------------------------- 10 

8. Infrared images of Sherman Crater, April 1971 to April1973 ------~- ---------------------------------------- 11 

9. Vertical view of Sherman Crater, September 1963 _ ____________ ____________ ________ __ _____________ _________ _ 12 

10. Enlarged infrared image of November 1972 _ _ _ __ ____ ___ _ _ _ _ _ __ __ _ __ _ _ _ ____ ____ __ __ __ _ _ _ _ ___ ___ ___ _ _ _ __ _ _ __ _ 13 

11. Planimetrically corrected distribution of anomalously warm areas of Sherman Crater and Dorr Fumarole Field__ 14 

12. Isodensity scan of infrared image of November 1972 -------------------------------------------------------- 17 

13. Infrared image of Sherman Crater, August 1975 _________ -------------------------------------------------- 20 

14. Differential radiant exitance as a function of ground kinetic temperature at Mount Baker, November 1972 ______ 20 

15. Kinetic temperatures at Dorr Fumarole Field, February 8 through March 17, 1973 ---------------------------- 22 

16. Evaporative heat loss from the central pit lake, Sherman Crater---------------------------------------------- 25 

v 
VI 

TABLE 

a 

B.P. 

oc 

Cp 

cal 

em 

D 

D., 

DCP 

aG 

Fs 

f 

g 

H 

H 

hfu 

hr 

ir 

J 

K 

kg 

km 

kPa 

A 

M 

MW 

m 

m 

mm.s..l. 

mrad 

J.tm 

CONTENTS 

TABLES 

Page 

1. Thermographic surveys over Mount Baker, Wash., before 1975 ---------------------------------------------- DB 

2. Differential radiant flux and nonadvective heat flux at Dorr Fumarole Field and Sherman Crater, Mount Baker, 

Wash ------------------------------------------------------------------------------------------------ 19 

3. Thermal sensor array for Data Collection Platform 6251, Dorr Fumarole Field, Mount Baker, Wash ___________ _ 21 

4. Anomalous nonadvective heat flux from Sherman Crater in 1972 and 1975 ------------------------------------ 24 

27 

28 

29 

29 

5. Estimated total heat discharge from Sherman Crater, Mount Baker, Wash., 1972 and 1975 ___________________ _ 

6. Estimated mean deviation in independent variables in flux calculations -------------------------------------- 7. Analysis of propagation of error in flux calculations _____________________________ , ___________________________ _ 

8. Comparative energy yield of selected volcanoes and geothermal areas ----------------------------------------

ABBREVIATIONS 

half-scan angle of infrared scanner 

years before present 

degree Celsius 

specific heat of air at constant pressure 

calorie 

centimeter 

coefficient of diffusion of water vapor into air 

(transfer velocity) 

value ofD at 273 K (=0.22) 

data collection platform 

differential geothermal flux 

pd 

Ps 

vapor pressure 

effective surface emissivity 

advective heat loss by icemelt, stream runoff, 

and mass transfer to atmosphere from 

fumarole emanations 

differential radiant flux 

heat lost to the atmosphere by evaporation 

net outgoing flux from a water surface via 

eddy diffusion and molecular conduction 

total nonadvective heat loss 

relative humidity of fumarole vapor (=0.95) 

gram 

convective heat flow 

enthalpy of saturated water vapor ( =630.4 cal 

g- 1 at 90°C and 3,000 m m.s.l.) 

heat-flow units (=10-6 cal cm-2 s- 1) 

hour 

infrared 

joule 

kelvin 

kilogram 

kilometer 

kilopascal 

wavelength of radiation 

rate of evaporation in kg m-2 hr- 1 

megawatt 

meter 

cloudiness 

meters above mean sea level 

milliradian 

micrometer 

Pa 

Q 

Ql 

R 

p 

() 

v 

v 

v 

v 

w 

w 

WdA. 

X 

yr 

z 

atmospheric pressure 

atmospheric pressure in mm of Hg (=527.13 

at 3000 m m.s.l.) 

pressure of water vapor in atmosphere, in mm 

of Hg ( =3.6632 for Mount Baker on June 26, 

1975) 

1 atmosphere pressure (101.3 kPa) 

saturated pressure of water vapor in mm of 

Hg ( =39.898 at 34°C) 

pascal 

net geothermal flux 

heat lost to atmosphere by mass transfer 

Bowen ratio (Fh/Fe) 

density of saturated water vapor at 90°C 

(=0.428 x 10-3 g cm-3 ) 

air density in g cm-3 

seconds 

probable error 

variance 

Stefan-Boltzmann constant 

temperature of air above lake surface, in K 

mean temperature of warm surface, in K 

mean temperature of cool reference surface 

( =273 K in this report) 

air temperature ec) 

surface temperature of anomalously warm 

area, in K (in differential geothermal flux 

equation) 

temperature ofwarm water surface (=34°C on 

June 11, 1975) 

surface temperature of anomalously warm 

area, in ac (in differential geothermal flux 

equation) 

ground temperature 

Ps 

pd 

volumetric rate of transfer of fumarole vapor 

( =0.35 m3 s- 1 for 1 percent of fumaroles) 

watts 

wind speed in m s- 1 

differential radiant exitance ( = - F b) 

vertical pathlength of scanner 

year 

average transmission pathlength of scanner 
COi\TENTS VII 

TERMINOLOGY 

[For additional terms see Frank and others, 1977, p. VII.] 

Advective heat loss. Heat transfer from the ground surface by the 

horizontal movement of water or air. 

Aerial infrared scanner. An airborne line-scan system that produces a thermal image, usually in the 8-14 JLm region. 

Bowen ratio. The ratio of convective to evaporative heat transfer. 

Differential geothermal flux. A measure of the change in geothermal flux relative to that of a standard surface. 

Differential radiant exitance (flux). A measure of the change in 

power radiated per unit area, relative to that of a standard surface. 

Emissivity. A measure of the radiant efficiency of a body compared 

to that of a perfect radiator (blackbody). 

Enthalpy. A thermodynamic quantity defined as the sum of a 

body's internal energy plus the product of its volume and pressure. 

Synonymous with heat content. 

Image density. A measure of the transparency or emulsion density of an exposed, processed film or photographic plate. 

Infrared image. An image produced outside the wavelength range 

of photographic sensitivity (which is generally less than 1 JLm) in 

the infrared, using line- or raster-scan systems, typically airborne. 

Infrared survey. An aerial survey technique in which a line-scan 

system collects thermal infrared radiation to produce twodimensional images of the scene. The infrared images produced are 

sually of the Earth's surface. 

Kinetic temperature. The temperature measured by direct contact with a body. 

Landsat. The Landsat 1 satellite system, launched July 3, 1972, by 

the U.S. National Aeronautics and Space Administration (NASAl 

as ERTS-1, was stabilized in a near-polar, sun-synchronous orbit 

approximately 907 km above the Earth. The satellite contains two 

imaging systems, the Multispectral Scanner, a 4-band scanner 

operating in the solar-reflected spectral regions from 0.5 to 1.1 JLm 

wavelength, and the Return Beam Vidicon, which also records 

reflected visible and near-infrared radiation. A third system, the 

Data Collection System, receives and relays data from Earth-based 

monitoring instruments. 

Landsat data collection platform. A ground-based formatting 

and transmitting unit coupled to an instrument station, such as a 

thermistor array; a component of the Landsat Data Collection System (DCSl, which collects, transmits, and disseminates data from 

remotely located Earth-based sensors. The system includes remote 

data collection platforms (DCP's), satellite relay equipment, 

ground receiving site equipment, and a ground data handling system. 

Landsat image. A line-scan image of the Earth's surface recorded 

in several spectral bands simultaneously through the same system, namely, the Multispectral Scanner System (MSS) of Landsat 1. 

Moist adiabatic lapse rate. A measure of the decrease in temperature of saturated air ascending in the atmosphere. Synonymous 

with the pseudo-adiabatic lapse rate. 

Radiometric temperature. The radiation temperature as measured by a radiometer or infrared scanner. 

Radiosonde. An instrument which, when transported through the 

atmosphere, measures pressure, temperature, and humidity and 

transmits these readings to a base station. 

Stefan-Boltzmann constant. The Stefan-Boltzmann constant, a-, 

occurs in the relationship R88 = a-T~, which relates radiant power 

to absolute temperature; a- has the value 5.679 x 10-R W m- 2

• 

Synoptic. Relating to or displaying general atmospheric, weather, 

and terrain conditions as they exist simultaneously over a broad 

area. 

Thermographic image. Synonymous with thermal image. 

Transfer velocity. The coefficient for rate of diffusion of water 

vapor in the air. 

CONVERSION FACTORS 

Multiply 

ft (feet) 

mi (miles) 

ft3 (cubic feet) 

mi2 (square miles) 

Multiply 

cal (gram-calorie) 

J (joule= W -sec) 

Multiply 

1 cal s- 1 cm- 2 

1 cal s- 1 cm- 2 

1 W m-2 

1 erg s- 1 cm- 2 

1 erg s- 1 cm- 2 

For units of length, area, and volume 

By 

3.048x10- 1 

1.609 

2.832x10- 2 

2.590 

For energy units 

By 

4.187 

107 

For energy flux 

By 

4.187x 104 

4.187x 107 

2.388x 10-5 

10-3 

2.388x10-R 

To obtain 

m (meters) 

km (kilometers) 

m3 (cubic meters) 

km2 (square kilometers) 

To obtain 

J (joule) 

erg (dyne-em) 

To obtain 

wm- 2 

erg s- 1 cm- 2 

cal s- 1 cm- 2 

wm- 2 

cal s- 1 cm- 2 

VOLCANIC ACTIVITY AT MOUNT BAKER, WASHINGTON 

INFRARED SURVEYS, RADIANT FLUX, AND TOTAL HEAT DISCHARGE 

AT MOUNT BAKER VOLCANO, WASHINGTON, 

BETWEEN 1970 AND 1975 

By juLES D. FRIEDMAN and DAVID FRANK 

ABSTRACT 

Reconstruction of the 1972 surface thermal regime at Sherman 

Crater and the Dorr Fumarole Field of Mount Baker, based on seven 

aerial infrared surveys (197~73) and on thermistor measurements 

relayed through a Landsat data collection platform, permits an assessment of Mount Baker's heat exchange with the atmosphere before thermal emission increased in 1975. Calibrated infrared images 

obtained in November 1972, contoured for apparent radiometric 

temperature and corrected for atmospheric attenuation and surface 

emissivity, indicate a differential radiant-flux value of 1.0 ± 0.6 

megawatt for Sherman Crater. Total heat discharge from the crater 

was estimated at 11 ± 6 megawatts, which includes less than 8 

megawatts from fumarolic emission and advective loss. Several 

methods were used in combination to produce this estimate, including a modified two-point differential geothermal-flux model based on 

the heat balance of the ground surface and on surface and air temperatures (the model was adapted for use with infrared-scanner output). Similar calculations applied to infrared images and field data 

for 1975 yield a differential radiant flux of 3 ± 1. 7 megawatts and a 

total heat discharge of 80± 44 megawatts, including advective losses 

of about 28 megawatts from ice melt and melt-water drainage and 

direct losses of 38 ± 38 megawatts from fumaroles and vapor plumes. 

Heat loss by radiation represented 9 percent of the total discharge in 

1972 and 4 percent in 1975. The Bowen ratio, R, linking heat loss by 

conduction and turbulence to that by evaporation was 0.3. The estimated net energy yield in 1975 exceeded that in 1972 by 2.1 x 1015 

joules per year. 

INTRODUCTION 

On March 10, 1975, Mount Baker's state of repose 

was interrupted by a sizable thermal event, the magnitude, duration, and cause of which are the subject of 

continuing investigation. This report summarizes the 

results of thermal investigations, including aerial infrared surveys, undertaken at Mount Baker by the 

U.S. Geological Survey between 1970 and 1974, prior 

to the distinct change in pattern of activity that occurred on March 10, 1975, and before the current series 

of investigations was started. Changes at Mount Baker 

attendant upon the 1975 thermal event have been reported by Malone and Frank (1975), Easterbrook 

(1975), Rosenfeld (1976), Eichelberger and others 

(1976), Frank and Post (1976), McLane, Finkelman, 

and Larson (1976a, b), Fretwell (1976), Kiver and 

Steele (1976), Nitsan (1976), Sato and others (1976), 

Malone (1976a, b, 1979), Nolf (1976), Frank, Meier, 

and Swanson (1977), Radke, Hobbs, and Stith (1976), 

and Bortleson, Wilson, and Foxworthy ( 1977). 

Frank, Meier, and Swanson (1977, p. 1) made estimates of that part of the heat flux at Sherman Crater 

that would account for the observed snow and ice loss. 

They found that this component of the total heat flux 

increased by roughly one order of magnitude from 

about 2 MW at 1o~w m- 2 before 1975, to about 30 MW 

at 180 W m-2 during 1975. One object of the present 

investigation is to expand these estimates to encompass a wider range of heat-transfer mechanisms in 

order to approximate the total thermal energy output 

from Mount Baker before and during 1975. To accomplish this, the magnitude of heat transfer via radiation, conduction, diffusion, and evaporation from 

anomalously warm, ice-free ground within Sherman 

Crater is estimated by workup of aerial-infraredsurvey and ground-temperature data; mass transfer to 

the atmosphere from fumaroles and other advective 

heat losses are also estimated. 

Because of the masking effect of geologic, hydrologic, 

and topoographic variations (Banwell, 1970, p. 45-48; 

Watson, 1975, p. 131), heat-flow levels recordable by 

infrared scanner are not equivalent to the minimum 

detectable geothermal flux. Depending on the time of 

day surveys are made, the mean diurnal surface temperature, and the level of error in estimating thermophysical properties of the ground surface, the heatflux equivalent of absolute-temperature error may be 

as much as several thousand heat-flow units (Watson, 

1975, p. 131). However, estimates of the differential 

radiant flux can be made with reasonable accuracy in 

relation to an established ground-temperature reference level. 

D1 
D2 VOLCANIC ACTIVITY AT MOU:\IT BAKER, WASHI;\JGT0:\1 

In the present investigations of Mount Baker, aerial 

infrared images provide .planimetric data on the configuration and size of areas at the surface at incremental, radiometric-temperature levels. Where the thermophysical properties and temperature regime of the 

surface materials are known, the differential radiant 

flux is estimated from the aerial infrared data by application of the Stefan-Boltzmann function and a twopoint method which derives the radiant flux in relation 

to 273-K surfaces. Based on the concept of heat balance 

of the ground surface, several models for estimating 

components of the overall heat-flux density from 

surface-temperature data are compared: namely, the 

two-point model proposed by Sekioka and Yuhara 

(1974); the semi-empirical model of Dawson (1964) for 

convection-dominated systems, built upon the work of 

Angstrom (1920, 1925), Bowen (1926), Brunt (1939), 

and Sutton (1953); and the model of Robson and 

Willmore (1955) for heat lost from warm lake surfaces, 

based on evaporation-pan theory. 

The total energy yield from Sherman Crater for the 

1972 period is then compared with that following the 

increased fumarolic activity of 1975 to assess the magnitude of the increase. Possible geologic causes of the 

increased thermal activity are discussed briefly. 

ACKNOWLEDGMENTS 

The thermal investigations of Mount Baker in 1972 

and 1973 reported herein were funded by the U.S. National Aeronautics and Space Administration and the 

U.S. Geological Survey as part of Landsat 1 experiment SR 251. Six aerial infrared surveys of Mount 

Baker were carried out for the Geological Survey by 

the U.S. Forest Service, and one was conducted by the 

National Aeronautics and Space Administration. In 

addition, Charles L. Rosenfeld, Oregon State University, kindly provided 1975 and 1976 aerial infrared images of Mount Baker and gave permission for their 

publication in this report. The helicopter group of the 

92d Aviation Company, U.S. Army, Paine Field, 

Everett, Wash., provided helicopter support for installation of Data Collection Platform (DCP) 6251. The authors acknowledge with thanks the assistance of S.M. 

Hodge, R. M. Krimmel, and Austin Post in installation 

and removal of DCP 6251. 

Analysis of models for geothermal flux estimation 

from surface manifestations, as applied in the present 

report, was carried out by the senior author in 1975 

and 1976 with funding support of the U.S. Geological 

Survey geothermal program. David V. Fitterman 

kindly prepared an analysis of the propagation of error 

in the flux calculations. 

GEOLOGIC SETTING OF MOUNT BAKER 

Mount Baker (48°47' N., 121°49' W.) is the most 

northerly of a north-south chain of Quaternary volcanoes of the Cascade Range in Washington (fig. 1). It 

consists of porphyritic andesitic lava flows and breccia 

that form a glacier-covered composite cone built upon a 

complex of older rocks (Coombs, 1939; Misch, 1966). 

The summit is 3,285 m above mean sea level and about 

3,000 m above the Skagit River valley, which lies 26 

km to the south (fig. 2). 

The present cone (figs. 3, 4) was formed before the 

last major glaciation 25,000 to 10,000 years ago and 

may be considerably older (Hyde and Crandell, 1975, p. 

1). It abuts extrusive rocks of the Black Buttes, an 

earlier eruptive center (Coombs, 1939, p. 1500). All of 

the higher lava flows on the cone appear to dip away 

from a source area near a broad summit ice dome. On 

the 1952 topographic map (U.S. Geol. Survey, Mount 

Baker quadrangle, 1:62,500), a prominent crater is 

centered 800 m to the south and 300 m lower in altitude than the ice dome and is termed Summit Crater. 

This crater (figs. 5, 9), partly filled with snow and ice 

(crater glacier) which descends from the actual summit 

to the north, is now called Sherman Crater (Frank and 

others, 1975, p. 77). Sherman Peak is a segment of the 

124° 

490·1---,.,"t"c~7~:t=:~~-\i 

0 50 100 KILOMETERS 

FIGURE 1.-Index map of Mount Baker and the area 

covered by portions of Landsat images E1258-18322-7 (fig. 2) and E-420-18303-7 (fig. 3). 
1\'FRARED SLRVEYS, RADIA\IT FLLX, AND TOTAL HEAT DISCHARGE D3 

FIGURE 2.-A portion of Landsat image E- 1258-18322-7 taken April 7, 1973. This image shows the regional setting of Mount Baker, with 

Baker Lake and Lake Shannon reservoirs to the east, the South Fork Nooksack and Skagit River valleys to the south, and the Middle 

Fork and North Fork Nooksack River valleys to the west and north. Intensive cultivation is discernible on the flood plains of the Skagit, 

Nooksack, and Fraser Rivers, to the southwest and northwest, respectively. Major population centers visible from north to south are part 

of the Vancouver, B.C., Canada, area, and Bellingham and Mount Vernon, Wash. The image shows regional snow conditions at about the 

time of the aerial infrared survey of April 29, 1973. 

crater rim on the south side, and Lahar Lookout is a 

remnant of the rim on the east side, just north of a 

breach in the east crater rim. Other eruptive centers 

include the deeply eroded Black Buttes (fig. 4) and a 

small cinder cone at Schriebers Meadow near the south 

base of Mount Baker (Hyde and Crandell, 1975, p. 3). 
D4 \ 'OLCA:\'IC ACTIVITY AT \IOUi\:T BAKER, WASHll\GTON 

FIGURE 3.-Mount Baker, as seen looking west, September 7, 1962. Sherman Crater is to the left of the summit dome (elevation 3,316 m). 

Sherman Peak is the secondary peak on the south rim of the crater. The crater glacier is visible through the east breach in the crater rim; 

above the east breach on the right is Lahar Lookout. Debris-avalanche scars and deposits extend from the east-rim area down the surface 

of Boulder Glacier. In the foreground is Park Glacier; to the right of the head of Park Glacier on the north slope is the Dorr Fumarole 

Field. Photograph Rl- 62-47 by Austin Post. 

QUATERNARY ERUPTIONS 

An early phase of eruptive activity in the Mount 

Baker area was K/Ar-dated by Easterbrook and Rahm 

(1970, p. 20) at 400,000 ± 200,000 yrs B.P. The products of Holocene volcanic activity were studied by Hyde 

and Crandell (1975), who found evidence near Mount 

Baker of four tephra eruptions, three lava eruptions, 

and one period of pyroclastic flows, as well as many 

mudflows, within the last 10,000 years. Hyde and 

Crandell (1975, p. 7) obtaineda radiocarbon date of390 

± 200 yrs B.P. for a mudflow beneath the most recent 

tephra layer, which is thus no more than a few hu ndred 

years old and may have been erupted during historic 

time. 

HISTORIC ACTIVITY 

The first recorded eruption of Mount Baker since the 

beginning of settlement of the Oregon Territory oc-
1:\FRARED SLRVE\'S, RAOIANT FLLX, AND TOTAL HEAT DISCHARGE D5 

FIGURE 4.- Mount Baker, as seen looking northeast, September 7, 1962. Immediately to the right of and below the summit dome are the 

west-rim sector of Sherman Crater and Sherman Peak. The deeply eroded Black Buttes are to the left, and the valley of Deming Glacier 

is in the foreground . Photograph Rl- 62-34 by Austin Post. 

curred in 1843 (Gibbs, 1874, p. 357-358), when a tephrafall was reported. Davidson (1885) was probably the 

first scientist to recognize and describe Sherman Crater as the site of eruptive activity at Mount Baker in 

the 1850's. A short account by Tennant (reported in 

Pioneer-Democrat, 1859) states that two "large and 

bright jects [sic J of flame were seen having the appearance as if issuing from separate fissures or openings" on Mount Baker in 1859. On. the whole, the historical evidence is good for volcanic activity in 1843, 

1854, 1858, and 1859. However, Davidson's (1885) report of "smoke" emission in 1870 suggests a thermal 

event similar to that of 1975. The exact nature of the 

eruptions of the 1850's remains unresolved, but they 

almost surely included large steam emanations from 

Sherman Crater. A photograph of Sherman Crater 

taken in 1900 (Rusk, 1924, p. 309) shows water vapor 

rising from an ice pit in the crater glacier. There are 

many references to steam emanations during the 20th 

century. Frank, Meier, and Swanson (1977, p. 2-8) 

present a detailed review of fumarolic activity in 

Sherman Crater up to the present. 
D6 \"OLCA'\ IC ACTI\'IT\' AT \IOL'\T BAKER, \\'ASHI\!GTO\: 

FIGURE 5. -Photographs of Sherman Crater. A, Oblique view looking west, August 22, 1969. The east breach and clusters of ice-perforation 

features are visible here. In the foreground are debris-avalanche scars on Sherman Peak and Boulder Glacier. Photograph 69 R1- 20 by 

Austin Post. B , Ice pit in west-rim sector of crater glacier, July 2, 1972. Note figure in lower left (circled ) for scale. Photomosaic by Dee 

Molenaar. 
INFRARED SURVEYS, RADIANT FLUX, AND TOTAL HEAT DISCHARGE D7 

FIGURE 5.-Continued. 
D8 VOLCAN IC ACTIVIT Y AT MOUNT BAKER, WASHII\GTON 

Aerial photographs dating back to 1940 reveal the 

presence of ice perforations at fumaroles, and debris 

from geothermally induced avalanches from the south 

rim of Sherman Crater has been noted on Boulder 

Glacier every few years during recent decades (Frank 

and others, 1975, p. 77). These data seem to contradict 

Easterbrook's (1975, p. 681) suggestion that fumarolic 

activity diminished or ceased during the 1940's and 

1950's. Late-summer aerial photographs taken in 1940 

and every year since 1956 show, in fact, that warm, 

snow-free ground has increased from about 5,500 m2 in 

1940 to between 8,000 and 10,000 m2 in the past decade 

(Frank and others, 1977, p. 6). · 

FUMAROLIC ACTIVITY BETWEEN 1970 AND 1974 

SHERMAN CRATER FUMAROLE FIELD 

The Sherman Crater fumarole field, at 2,870-3,050 

m altitude, is the larger of the thermal fields. Here, the 

most active pre-1975 fumaroles (Frank and others, 

1977, p. 6, 8) were located within large ice-perforation 

features (figs. 5A, 9) just inside the east breach, a notch 

200 m deep in the crater rim. Hydrothermal activity 

adjacent to Sherman Crater has effectively 

transformed rock in parts of the crater rim to clay-rich 

alteration products. Hydrothermally altered ground 

also extends beneath the crater glacier. A linear cluster of ice-perforation features (fig. 5B) that was present 

before March 1975 extended northward along the inside of the rim near a low point on the west rim of the 

crater. The area of the crater within the rim is estimated as 167,000 m2 . 

DORR FUMAROLE FIELD 

The Dorr Fumarole Field (fig. 6) lies at 2,350--2,440 

m altitude on the north slope of Mount Baker where 

William Henry Dorr first reported vapor emission in 

1884 (Frank and others, 1977, p. 3- 4). 

The Dorr Fumarole Field was selected for temperature monitoring via a thermistor array and Landsat 

data collection platform for a year-long experiment 

(Landsat-1 expt. SR 251) in 1972. From 1972 through 

1974, this experiment revealed no significant changes 

in activity at the Dorr Fumarole Field, and none was 

observed during ground investigations. Similarly, no 

significant changes in the area of snow-free ground are 

apparent in aerial photographs from 1958 through 

1974. The presence offumaroles suggests that the Dorr 

Field once may have been the site of eruptive activity, 

although no vent has yet been identified there. 

INCREASE IN FUMAROLIC ACTIVITY IN 1975 

The increase in fumarolic activity in 1975 in Sherman Crater, including new areas of heat emission and 

expansion of old areas of heat emission, is well 

documented by Frank, Meier, and Swanson (1977, p. 1, 

8-13, and 28-29). 

SURVEILLANCE AND MAPPING BY AERIAL 

INFRARED SCANNER 

Seven aerial infrared survey missions were undertaken under the auspices of the U .S. Geological Survey 

between 1970 and 1973. Table 1 summarizes these aerial infrared missions, and figure 7 is a block diagram of 

the RS-14 scanner operated over Mount Baker on 

November 20, 1972. These missions were designed to 

map the distribution, size, and geometry of surface 

thermal manifestations, to determine changes in intensity of thermal radiation from the surface, and to 

derive the differential radiant-flux density. For a 

summary of aerial infrared surveys during 1975, see 

Frank, Meier, and Swanson (1977, p. 10-13). 

GEOLOGIC INTERPRETATION OF INFRARED IMAGES 

Thermal infrared images acquired in the aerial surveys show the distribution of pre-1975 surface heatflow anomalies (defined as areas where heat-flux density at the surface is greater than 8.4 W m- 2 or 200 J.LCal 

cm- 2 s- 1

) within Sherman Crater (fig. 8) and Dorr: 

Fumarole Field. The Sherman Crater anomalies (fig. 9) 

formed a semicircle at the inner base of the crater rim 

(fig. 10). These anomalies (fig. llA, llB) included a 

cluster that coincided with the most intensive 

fumarolic activity associated with ice perforations near 

the east breach of the crater. 

Concentration of intense thermal emission in the old 

fumarole clusters of j,he east-breach area is also substantiated by the 1972 isodensity scans. Abundant field 

evidence, supplemented by infrared image analyses 

that show the surface geometry of the east-breach 

anomalies, led to the inference that the east-breach 

area "apparently overlies the most direct permeable 

TABL E 1.-Thermographic surveys over Mount Baker, Wash. , before 1975 

[All missions were fl own on behalf of the U.S. Geological Survey;, t h.e spectral region sensed was 8- l4J.Lm; and RS-7 infrared nne~s were used on a ll miSSIO ns except that of Nov. 20, 1972, :which used an RS- 14 scanner J 

Date 

Nov . 4, 1970 

Apr . 3 , 1971 

Aug. 7 , 1971 

Apr. 22 , 1972 

July 21-22 , 1972 

Nov. 20, 1972 

Apr . 29, 1973 

Time 

0737 - 0806 P . d . t. 

2118-2132 P . d . L. 

0214-0226 P . d.t. 

2020-2047 P . d . t . 

2351-0020 P . d . t . 

0301-0350 P . s . t . 

0432-0457 P . d . t. 

Agency flying miss ion 

U.S . Forest Serv i ce , Boise , Idaho 

Do . 

Do . 

U. S . Forest Serv i ce , Mi ssoula , Montan a 

Do . 

Johnson Space Cente r , Houston, Texas 

U.S. Forest Service , Mi ssoula , Montana 
1:-.JFRAREIJ SURVEYS, RAIJIANT FL UX, AND TOTAL HEAT DISCHARGE D9 

_.,.,..- , .• 

) 

, 

I 

, 

Mazama Glacier 

·. / 

if "'- } 

Mount 

Baker 

I 

FIGURE 6.-Vertical view of the Dorr Fumarole Field on the north slope of Mount Baker, June 10, 1975. The location of Landsat Data 

Collection Platform (DCP) 6251 is shown at the edge of an icemelt feature. Photograph 75 MB1-25 by R. M. Krimmel. 

path from the volcanic heat source" (Frank and others, 

1977, p. 17), as evidenced by the presence of the hottest 

and largest fumaroles, the concentration of activity in 

this area during historic time, and by the presence of 

the east breach itself. 

Aerial infrared images obtained in 1975 (Eichelberger and others, 1976; Rosenfeld, 1976) show a second trend superimposed on the older pattern: an eastwest trend within the crater, which is represented by 

linear alinements of new fumaroles and new thermal 

activity extending downslope from the west rim (Frank 

and others, 1977, p. 17). 

The surface area of anomalously warm ground in 

Sherman Crater, according to the last two infrared 

surveys listed in table 1, ranged from 8,800 m2 in 

November 1972 to 7,500 m2 in April 1973. The 

maximum thermal area exposed at the Dorr Field, as 

recorded in these same surveys, is about 3,020 m2 (fig. 
D10 VOLCA"JIC ACTIVITY AT Y!OUNT BAKER, WASHI NGTON 

MULTICHANNEL 

FM MAGNETIC 

TAPE 

RECORDER 

3 mrad IR 

1.5 mrad IR 

V IS IBLE LIGHT 

SYNCHRONIZATION SYNCHRONIZATION 

SINGLE-CHANNEL 

FILM 

RECORDER 

SIGNAL 

PROCESSING 

AND 

CONTROL 

0.6-1.1 !J.rn 

CHANNEL 

3 mrad 

I R CALIBRATION SOURCE 

INCIDENT RADIATION 

8-14 !J.m 

CHANNEL 

FIGURE 7.-Schematic diagram of airborne scanner used in the aircraft mission over Mount Baker Nov. 20, 1972. A Hg:Ge detector sensitive 

to radiation in the 8-14 /Lm range was used, and both videotape and film coverage were obtained. 

llC). It is significant that the minimum thermal area 

recorded in the surveys of April 1973 was 90 percent of 

the maximum thermal area recorded in July and 

November of the same year. April is the period of 

near-maximum snow cover in the Mount Baker area. 

The relative effect of survey flight altitude is illustrated by the fact that the highest altitude survey 

(3,075 m above the crater on July 21, 1972) recorded 

few thermal details in the major areas, whereas the 

lowest altitude survey (770 m above the crater on April 

29, 1973), which used the same line scanner, recorded 

for the first time two apparent point-source anomalies 

at the base of Lahar Lookout. These two anomalies 

actually correspond to small ice perforations that resulted from subglacial heat emission. The perforations 

are visible in all aerial photographs examined dating 

back to 1940. 

RADIANT-FLUX ESTIMATION 

The radiant flux emitted from one surface can be 

compared to that from another nearby surface, and the 

differential radiant flux can be estimated by application of a two-point thermal model. (See Birnie, 1973; 

Friedman and others, 1976, p. 650.) 

Specifically, the differential radiant exitance WdA. 

(the differential power radiated per unit area from the 

Earth's surface) can be approximated by Stefan's 

fourth-power law, according to which a body at absolute temperature T,, surrounded by a black enclosure 

whose walls are at absolute temperature T~, will lose 
1:\IFRARED SURVEYS, RADIA:">JT FL UX, Af\10 TOT AL IIEAT DISCHARGE Dll 

FIGURE 8.- Infrared images of Sherman Crater from April1971 to April1973 (black, cool; white, warm). A , April3, 1971,2118--2132 P.d.t.; 

B, April 22, 1972, taken 2020--2047 P.d.t.; C, November 20, 1972, 0301-0350 P.s.t.; and D , April29, 1973, 0432-0457 P.d.t. The general 

pattern of thermal activity recorded in these images was similar from 1971 to 1973. The April images of 1971 (A ) and 1972 (B) show less 

apparent thermal activity because of unusually heavy winter snowfall in comparison to that of April1973 (D ). Image C, November 1972, 

represents the time ofleast snowcover during the U.S. Geological Survey infrared surveys. Fumaroles of the east breach indicated by eb. 

Image distortion is variable, but north is toward the top of each frame. 

heat at the rate EO" (T1

1 - T/), where O" is Stefan's 

constant and E is the emissivity of the surface. WdA. 

(=~ , the differential radiant flux (in W m- 2)) is derived from the Stefan-Boltzmann function via the following expression: 

where emissivity E is 0.95 ± 0.04, T1 is the integrated 

kinetic temperature of an individual mapped 

radiometric unit from the infrared images, and T2 is 

273 K, the standard reference surface, equivalent to 

kinetic temperature of the adjacent ground-ice interface . The differential radiant flux above 273 K, for conditions prevailing at Mount Baker on November 20, 
D12 VOLCANIC ACTIVITY AT \<IOU/'IT BAKER, WASIII~CTON 

southwest pit 

central 

depression 

FIGURE 9.-Vertical view of Sherman Crater and crater glacier, September 3, 1963. Photograph 8--V635 by Austin Post. 
INFRARED SCRVEYS, RADIA NT FLUX, AND TOTAL HEAT DISCHARGE D13 

300 METERS 

FIGURE 10.-lnfrared image of November 20, 1972, enlarged to show relationship of thermal features of Sherman Crater to ice perforations 

and fumarole clusters of fig. 9. Note reversal of image polarity-black, warm; white, cool. 
D14 VOI.CANIC ACTIVITY AT \10LNT BAKER, Wi\SIIINGTON 

1972, is plotted as a function of kinetic ground temperature in figure 14. 

CORRECTIONS FOR ABSORPTION AI'\D E'v!ISSION BY 

ATMOSPHERIC WATER VAPOR, CARBON DIOXIDE, 

AND AEROSOLS 

The effective atmospheric absorption of radiation in 

the 8-14 J.Lm region has been plotted by Saunders 

(1970, p. 7598) as a function of water-vapor mixing 

ratio in the air column for a relative humidity of 70 

percent. 

For an atmospheric pathlength of 1 km, under the 

conditions prevailing on November 20, 1972 (mean 

transmission-path air temperature of 265.1 K), 1 absorption in the 8-14 J.Lm region by water vapor would 

be approximately 15 percent, C02 would absorb 

roughly 1 percent, and aerosol absorption would be a 

small fraction of a percent, using a standard model 

atmosphere (McClatchey and others, 1972, p. 60-61, 

62, 68; Gebbie and others, 1951), or Saunders' plot 

(1970, p. 7598). 

The average transmission pathlength z for the 

RS-14 scanner used in the Mount Baker surveys of 

November 20, 1972, approximates a simple function of 

the vertical pathlength x and the half-scan angle a in 

which 

z = x/cos (a/2). (2) 

On November 20, 1972, the vertical path, x, was 

1,040 m between the Sherman Crater fumarole field 

and the survey aircraft traverse altitude of 4,000 m 

m.s.l. The average transmission pathlength z was thus 

1,106 m, equivalent to an overall atmospheric absorption of 17.7 percent. 

TF.MPERATLRE CORRF.CTIOi\S FOR SCRFACF. F.\'IISSIVITY 

Conversion of effective radiometric ground-surface 

temperature derived via the Stefan-Boltzmann function from calibrated infrared (8-14 J.Lm region) images 

to ground kinetic temperature (v) can be approximated 

by the relation 

(3) 

where E is the effective surface emissivity and T is the 

radiometric surface temperature in kelvins. 

1

The integrated temperature of the transmission path was approximated by radiosonde 

data recorded at the Quillayuteweather station, Washington (47' 57 ' N., 124' 33' W.l at 1115 

G.m.t. , November 20, 1972 !U.S. National Climatic Center, Asheville, N.C.). 

Base from U.S.G.S. Advance sheet 

Mt. Baker, Washington, 100 ft. 

7.5' Compiled Menlo Park Base 

Map Section. (10-30) 

0 1 KILOMETER 

FIGURE 11.-Pianimetrically co~rected distribution of anomalously 

warm areas of Sherman Crater and Dorr Fumarole Field, Mount 

Baker, 1972. A is compiled from infrared images and plotted on a 

topographic base; elevations given in feet (100 ft = 30.5 m); B, 

Sherman Crater isothermal map units derived from 10-step calibrated infrared image of November 20, 1972, and image-density 

scans; and C, Dorr Fumarole Field isothermal map units derived 

from 10-step calibrated infrared image of November 20, 1972, and 

image-density scans. 
IN FRARED SU RVEYS, RAD IA:'>/T FL UX, A:\0 TOTAL HEAT DISC H ARGE D15 

N 

1 

0 50 100 METERS 

0 

SHERMAN CRATER 

0 

Estimated Range mean 

288 273-303 

D 307 303-311 

317 311-323 

>323 

B 

Estimated Range mean 

284 269-299 

303 299-307 

313 307-319 

>319 

Area 

in 

m, 

7,700 

1,300 

300 

30 

Zone of 

avalanche 

ice blockage, 

Boulder 

Glacier 

FIGURE 11.- Continued. 

A collection of 38 polished sections of California volcanic rock types, ranging in composition from mafic to 

silicic, was reported to range in E x- 14 JLm from 0.868 to 

0.985, averaging 0.946 (Daniels, 1968, p. 74- 78). For 

rough and natural weathered surfaces the effective 

emissivity of volcanic rock types approaches 1.0 

asymptotically with increased roughening, as implied 

by the work of Gouffe (1945), who showed that the 

change in effective emissivity (in the 8- 14 J.Lm region) 

of a surface is a function of cavity shape and integrated 

emissivity of cavity walls. Vicker and Lyon (1967) have 

also pointed out that for most soils, the effect of reduc-
D16 VOLCANIC ACTIVITY AT MOUNT BAKER, WASHINGTON 

A 

Core-steaming mounds dB 

Surface temperature in kelvins c 

Temperature in kelvins, taken by Co•~-\ d" 

Sample Area PRT-10 Locality in Bimetal thermometer steaming Cores-

''''"~ oco ~::;~: Type m' at surface 

!Scm 

A Solar-heated ---- ---- rock 

B Soil 75 333 

Soil 311 

Steam 4 363 

c Soil ---- 349 

D Soil 

Soil 1,400 ~;s 3 1 

E Soil 300 358 

Soil 323 

Soil margin al to snow 

Shaded ---- ---- Sunlit ---- ---- F Soil ---- ---- G Water pools ---- ---- Steam <SO 364 

<I em Mean 

---- 287 

303 294 

294 303 ---- ----

320 ----

316 308.5 

301 ---- 299 296 

293 293 

---- 276 

---- 283 

---- 305 ---- 314 ---- ----

Range 

----

284-313 

----

----

---- 301-316 

---- 305-319 

----

----

---- 311-317 ----

N 

1 

c 

0 

D 

Cores-boiling 

pools on steep 

slope 

50 METERS 

FIGURE 11.- Continued. 

ing grain size is to diminish the spectral contrast and 

raise the emissivity in the 8-14 f.-till region, producing a 

fairly constant value of 0.95. 

Accordingly, for the fresh and altered andesitic surfaces and hydrothermal alteration products of Mount 

Baker, we assume the effective 14~"m is 0.95 ± 0.04, 

and for water surfaces the effective H~"m is 0.99 ± 

0.01 (Saunders, 1970, p. 7599). 

THERVIOGRAPIIIC SURVEY OF ~OVEMBER 20, 1972 

Calibrated infrared images were obtained from a 

series of traverses flown for this experiment (Landsat-1 

SR 251) by the National Aeronautics and Space Administration NP3-A earth resources aircraft, using a 

dual channel RS- 14 line-scan system (fig. 7) equipped 

with internal blackbody temperature references, 

mercury-doped germanium detectors, and a 10-step 
INFRARED SU RVEYS. RADIANT FLU X, AND TOTAL HEAT DISCHARGE 

:.:~~ .. :.~f;.:;....;t. 

::..~.1 ... 

, .£.,. 

D17 

FIGURE 12.-Isodensity scan of infrared image shown in fig. 10, taken November 20, 1972. Magnification of film image 5x; density-scan 

interval 0.12-0.20 of the total density range of the image. 

gray-scale calibration strip. One channel was operated tures ranging from 294 K to 373 K were recorded on 

in a display mode, producing an intensity-modulated film, and uncalibrated images that encompassed the 

trace on a 5-inch cathode-ray tube in a recording unit total temperature range of the system were recorded on 

that was optically coupled to a film magazine unit. The videotape. 

thermographic images that gave a two-dimensional The infrared images were compared with the 10-step 

representation of uncorrected radiometric tempera- gray scale by means of an image-density scan (fig. 12) 
DIS \'OLCA'\IC i\CTI\'ITY AT \IOL \!T BAKER, WAS I-11\!GTO:\' 

and were thus contoured for radiometric surfacetemperature levels. The scan was prepared on an EDP~ 

scanning microscope, at magnifications of 1.8, 5, 10, 

and 50x, at apertures from 100 to 200 J.Lm, and at 

density-scan intervals of 0.12 to 0.20 of the total density range of the image. Estimates of differential 

radiant-flux density of the east breach area, the entire 

Sherman Crater, and the Dorr Fumarole Field, given 

in table 2, were derived from these scans, converted to 

ground kinetic temperature, and corrected for 

planimetric distortion of the area of the anomalies on 

the video-processed images. Planimetric corrections for 

linear image distortion were made in plotting 

figure 11. 

Of the total8,800 m~ of anomalously warm ground in 

Sherman Crater, as measured by this method, 3,600 m2 

is included in the east-breach cluster of anomalies and 

much of the remainder is in the west-rim sector. Table 

2 gives the kinetic ground temperatures and areas of 

the infrared anomalies. The integrated background 

radiometric temperature for adjacent cold, high-albedo 

ice surfaces averaged 255 K, as measured from the 

NP3-A aircraft by a Barnes PRT-5 infrared radiome-

. ter on November 20, 1972. However, for purposes of 

radiometric comparison with adjacent nonthermal 

ground, which is essential in application of the twopoint thermal model, the relatively constant kinetic 

ground temperature of 273 K at the ground-ice interface approaches the mean annual temperature and was 

used in the present investigation as the standard reference.3 

The inference that 273 K is very close to the constant 

ground-ice interface temperature at the periphery of 

the ice perforations in the crater glacier is supported by 

temperature measurements by E. P. Kiver (oral commun., 1976) and by data reviewed by Robin (1976, p. 

186) for ground and air temperature below temperate 

glaciers. Theakstone (1967), for example, reported that 

air temperature in a tunnel beneath 50 m of ice near 

the margin of 0sterdalsisen in Norway remained almost constant at -1.0°C, and Vivian and Bocquet 

(1 973, p. 441) reported air temperatures which vary a 

little around +0.5oC in ice tunnels they studied 

beneath Glacier d'Argentiere at Mount Blanc, France. 

Table 2 gives the radiant-flux density in relation to 

adjacent 273-K surfaces at Mount Baker. 

!Use of trade names in this report is for descriptive purposes only and does not constitute 

endorsement by the U.S. Geological Survey. 

:vr he mean a nnual air temperature at Sherman Crater (at 2,960 m m.s.i.) is close to 272.6 

K based on the mean annual temperature of277.65 K (1m above ground) recorded at an 

~vat n of 1,277 m m.s.L at Heather Meadows Recreational Area (data .from U.S. Nationa l 

Climatic Center, Asheville, N.C., 1976) and a n interpolated moist adiab8tic lapse rate ~cc 

Brunt, 1939, p. 66 ) of0.003 K m- 1

, which roughly corresponds to a relative humidity of72 

percent. Radiosonde data for 1115 G.m.t. , November 20 , 1972, at 47"57' N., 124' 33 ' W. 

indicated a lapse ra te of 0.0035 K m 1 a nd an air temperature of268.2 K at 2,960 m m.s. l. 

Aerial infrared surveys similar to those reported 

here were carried out in 1975 and 1976 by Rosenfeld 

(1976) (fig. 13). We have derived radiant-flux estima~es 

from Rosenfeld's data, using the same two-pomt 

method that was used for the 1972 infrared data; these 

are given in table 2. (See also fig. 14.) 

ELECTRONIC THERMAL-SENSOR ARRAY 

AND LANDSAT DATA COLLECTION PLATFORM 

The Landsat-! Data Collection Platform 6251, designed specifically for kinetic temperature monitoring 

at Mount Baker, was installed at the Dorr Fumarole 

Field at approximately 48°45' N., 121°40' W. at 2,400 

m m.s.l.; it transmitted data successfully from February 8, 1973, to March 15, 1974. A brief description of 

the typical thermistor-array DCP system and 

simplified schematic diagrams are given in Friedman, 

Preble, and Jakobsson (1976); a detailed description of 

the electronic thermal-sensor system and related 

data-collection-platform technology is given in Preble, 

Friedman, and Frank (1977). 

Sensor-probe sites, specifications for DCP 6251, and 

mean kinetic temperatures between February 8 and 

March 17, 1973, are given in table 3, and kinetic temperature variations for this same period are plotted in 

figure 15. 

HEAT-FLUX ESTIMATES 

The geothermal flux in the vegetation-free anomalous temperature zones at Mount Baker is considered to 

be related to the other major components of the heat 

budget of the ground surface by the following equation: 

(4) 

where Q is the net geothermal flux ; F b is the differential radiant flux relative to 273 K (that is, F b approximates the outgoing radiant flux minus the absorbed 

solar flux , minus nondirectional or diffuse sky radiation minus heat flux in the ground that results from 

sola~ radiation); F h is the outgoing flux of energy from 

the surface by eddy diffusion and molecular conduction; Fe is the heat flux lost to the atmosphere by evaporation· and Fad is the heat flux carried out of the area 

advecti~ely by ice melt, by stream runoff, and by mass 

transfer to the atmosphere via fumarole and vaporplume emanations. 

In the present investigation, the differential geothermal flux (that flux corresponding to kinetic temperatures higher than 273 K, the ground-ice inte~face 

temperature at Mount Baker's Sherman Crater) IS estimated by use of a two-point physical model (similar to 
TABLE 2.-Diff"erential radiant flux and nonadvective heat flux at Dorr Fumarole Field and Sherman Crater, Mount Baker, Wash. 

[Based on density analysis of ca librated aerial infrared (8--14 ~-tm l images. Radiant flux calculated using the Stefan~ Boltzmann function. Heat flux calculated using a two-point thermal mOOel adapted from that of Sekioka and Yuhara 

(1974 ); excludes flux components from plume and fumarole em ission and other advective heat losses. ------ · not calculated] 

Integrated 

temperature 

of ground 1 

y (kelvins) 

288 

307 

317 

Total (or mean) 

288 

307 

317 

Total (or mean) 

288 

307 

317 

322 

Total (or mean) 

Area 

(m2) 

2 ,520 

460 

40 

3,020 

3,370 

200 

30 

3,600 

7,170 

1,300 

300 

30 

8,800 

285 22,600 

295 9,900 

307 (Central 

pit lake ) 2,700 

Total (or mean) 35 ,200 

Total (or mean) 

excluding central 

pit lake---------- 32,500 

Radiantflux 

density 

(\-/ m- 2) 

391 

505 

574 

( 411) 

391 

505 

574 

(400) 

391 

505 

574 

611 

(415) 

375 

431 

505 

(403) 

(394) 

Radiant 

flux 

(MH) 

2.06 

.23 

.02 

2 . 31 

Differential 

radiant-flux 

density2 

(W m- 2 ) 

Differential 

radiant 

flux 

(MH) 

Dorr Fumarole Field, 1972 3 

91 

205 

274 

(109) 

0.23 

.09 

. 01 

.33 

East breach area of Sherman Crater, 1972 3 

l. 32 

.10 

.02 

l. 44 

2 .80 

.66 

. 17 

.02 

3.65 

8.5 

4.7 

1.4 

14.2 

12.8 

91 

205 

274 

(100) 

0.31 

. 04 

.01 

.36 

Entire Sherman Crater, 1972 3 

91 

205 

274 

31 1 

(ll5) 

0.65 

.27 

.08 

. 01 

l. 01 

Entire Sherman Crater, 1975 5 

75 

131 

205 

(101) 

(92) 

l. 70 

l. 30 

.55 

3.55 

3.00 

1Includes corrections fo r surface emissivity (0.95+0.04) and atmospheric attenuation. 

2Rela tive to an adjacent 273-K reference surface which has a radiant-flux density of 300 \-/ m- 2 . 

Differential 

heat- flux 

density 

(W m- 2) 

321, 

745 

972 

(397) 

324 

745 

972 

1,093 

(410) 

259 

>478 

741 

(357) 

(326) 

To tal 

anoma lous 

heat flux 

(MW) 

0.82 

. 34 

.04 

l. 20 

2.32 

.97 

.29 

.03 

3 .61 

5.85 

4.73 

6 2. 0 

12.58 

10. 58 

Nonradiant 

anomalous 

heat flux 

(MH) 

0.59 

.25 

.03 

.87 

l. 67 

.80 

. 21 

.02 

2.60 

4.15 

3.43 

l. 45 

9.03 

7. 58 

3Mission flown 030 1-0350 P.s.t., Nov. 20, 1972, in NP3-A aircraft by Natl. Aeronautics and Space Adm. Johnson Space Center using RS - 14 infrared 

line scanner. 4Model of Dawson (1964) for convection-dominated systems gives average flux density of 287 W rr,- 2 for DCP-thermistor locations 6, 7, and 8, bas ed 

on 15-cm-d ept h t emperatures of 355 to 364 K. 5Mission flown Aug. 24, 1975, in CV-1C aircraft by Oregon Army Natl. Guard on behalf of Oregon State Un iv., using an AN/AAS-14A infrared line 

scanner (Rosenfeld, 1977, p. 12-16). 

6Compare with othe r estimates of total heat flow for central pit lake shown in table 4. 

z 

..,., 

:;>::l 

)> 

:;>::l 

~ 

V> 

c: 

:;>::l 

< 

~ ..,. 

.~ 

:;>::l 

)> 

0 

)> 

z 

..,., 

r 

c: 

X 

)> 

z 

0 

....: 

c 

)> 

:r 

71 

>: 

..., 

0 

V> 

n 

:r 

)> 

;:o 

c; 

tTl 

t::J 

"'"' (!) 
D20 VOLCANIC,ACTIVITY AT VIOUNT BAKER, WASHINGTON 

FIGURE 13.-Infrared image (8-14 ,..,.m range) of Sherman Crater, August 1975. Polarity: white, warm; black, cool. Note thermal emission 

from ice-perforation features. Part of west-facing slope of Sherman Crater appears warm as a result of direct solar irradiance late in the 

day. Image by Oregon National Guard. 

:.! 340 

~ 

w- 330 a: 

::J 

I-

<( 320 

a: 

w 

ll. 310 :2 

w 

IFIGURE 14.- The differential radiant exitance (Wd.\) in relation to a 

standard reference surface of 273 K plotted as a function of ground 

kinetic temperature for radiation conditions prevailing at Mount 

Baker, November 20, 1972. The differential geothermal flux 

(excluding advective heat loss) in relation to the same standard 

reference surface is also given as a function of ground kinetic temperature. 

the two-point differential radiance model) in which the 

two points selected are sufficiently close to have similar topography (slope), emissivity, albedo, and thermophysical properties of the ground surface. Following 

Sekioka and Yuhara (1974, p. 2055), we can express 

the difference between the geothermal fluxes at two 

adjacent places as a function of the difference between 

their corresponding surface temperatures, which can 

be measured simultaneously by an aerial infrared 

scanner as radiometric temperatures and converted to 

kinetic temperatures. The error introduced by assuming that emissivity, albedo, topography, and thermophysical properties of the surface are identical at 

the two points selected is considered to be less than the 

experimental error inherent in estimating the mean 

geothermal flux at the moderately high levels investigated. (See fig. 15 and table 6.) 

The two-point model for heat balance of the ground 

surface for estimating moderate to high volcanogenic 

heat flows considers the following factors: (1) the net 

outgoing radiant flux (by subtracting the reflected 

shortwave radiation from the sum of the direct solar 

radiation and the nondirectional sky radiation), (2) the 
TABLE 3.-Thermal sensor array for Data Collection Platform 6251, Dorr Fumarole Field, Mount Baker, Wash. 

[Data collected from Feb. 8, 1973, to Mar. 15, 1974, at 48°45' N., 121°40' W.; elevation 2,400 m m.s.l.] 

Distance Distance 

(m) and above (+) Sensor He an 

direction or helmv teTiperature Relationship of temperature 

DCP from (-) ground range and temperature, T Feb. 8 to 

analog Sensor type instrument surface accuracy (OC)' to output Mar. 17' 1973 

channel and number Medium tested station (em) (OC) voltage, V (OC) 

-

IA YSI 44203 Air inside instrument 0 + so -40 to 60+2 T=20(V)-40 0.10+2.11 

station 

2 IB YSI 44203 Ambient air (in 0 +100 -40 to 60+2 T=20(V)-40 -3.04+2.83 

shade) 

3 IC YSI 44203 Harginally thermal 2 E. 0 -10 to 40+1 T=lO(V)-10 3.10+0. 46 

ground (under snow). 

4 ID 104MB Fumarole vent-------- 6 w. - lS 30 to 130+2 T=20(V)+30 90.41+0.30 

s liA 104B ----do--------------- 2 s. - lS 30 to 130+2 T=20(V)+30 91.20+0.14 

6 liB 104 MB Geothermal ground---- 6 E. - 30 30 to 130+2 T=20(V)+30 80.77+1.00 

7 liC YSI 44201 ----do--------------- 6 E. 0 18 to S8+1 T= 8(V)+l8 33.94+7.26 

8 liD 104MB ----do--------------- 6 E. - so 30 to 130+2 T=20(V)+30 89.S7+0.30 

Coefficient 

of 

variation 

(on Celsius 

Variance scale) 

4.4S 21.10 

8.01 .93 

. 21 .lS 

.09 < • 01 

.02 < • 01 

l. 00 .01 

S2.6S . 21 

.09 < • 01 

z 

...., 

::0 

> 

::0 

M 

0 

\JJ 

c-: 

::0 

< M 

........ 

.ciJ 

::0 

> 

u 

> z 

---l 

...., 

t"" 

c 

?< 

> 

z 

0 

---l 

0 

---l 

> t"" 

::r:: 

M 

> ---l 

0 

c;; 

(") 

::r:: 

> 

~ 

C"l 

M 

u 

~ 

1-' 
D22 VOLCANIC ~CTIVITY AT MOUNT BAKER, WASHINGTON 

92.5r--,r--.l---.l---,-1--.-l--.-l--l.--,lr--.l--~l---~l~ 

90.0 f- -

87.5 f- -

A 

85.0 r---------------------------------------------~ 

82.5 f80.0 f77.5-

75.0-

72.5-

B 

. 

-. -. ·-.. -· . . 

--. . . 

---. . -----· -· --.. -. . ·-· . . 

-

-

-

7o.or-----------------------------------------~ 

~ 5o.or-------------------------------------------~ 

en 

~ 47.5 -

u 

~ 45.0 w 

a: 

0 42.5- w 

0 

z 40.0-

~ 37.5-

::> 

1-

<( 

a: 

w 

a.. 

~ 

w 

1-

u 

1-

w 

z 

35.0 f32.5 f30.0 f27.5 f-

::.! 25.0 f22.5 f20.0 ,_. 

17.5 '--

c 

.. 

.. . . 

·~ .. 

.. 

.. 

. · . . 

.. 

. .. 

. 

• I • (~ 

.... 

. . 

... 

. . . . 

. : 

. . :. ·. 

·. . . . 

.. 

1!. 

. 

·. 

I!·. 

.. 

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-

-

-

-

-

-

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15.or-------------------------------------------~ 

12.5-

10.0 

7.5 -

5.0-

"' 

2.5- a ~---------------"'... I 

0.0 D ~·· I I 1 I I I 

400 410 420 430 440 

LANDSAT 1 ORBITAL DAY 

(DAY 1 =JULY 23, 1972) 

-

-

-

-

-

I I 

450 460 

87.5 

E 

85.0 1----------------------------------------------~ 

10.0 1--------------------------------------------~ 

7.5 f- • 

5.0 -

2.5 - •• 

0.0 -

-2.5 

-5.0 -

-7.5 -

-10.0 -

-12.5 -

... ... . . ... 

... . . 

.. 

.:. 

. . . 

. . . . . .. . . . 

. . -. -. ... 

. 

... . . . . . . . . . . .. . . . .... "! ••• 

. . . -.. . . . . ·- ··· . ... ... .. 

. . . . . . . 

-15.0 F I I I I I I I I 

400 410 420 430 440 450 

LANDSAT 1 ORBITAL DAY 

EXPLANATION 

A DCP ANALOG CHANNEL 8: 50-cm DEPTH 

IN WARM GROUND 

B DCP ANALOG CHANNEL 6: 30-cm DEPTH 

IN WARM GROUND 

-

-

-

-

-

-

-

460 

C DCP ANALOG CHANNEL 7: WARM GROUND SURFACE 

D DCPANALOG CHANNEL 3: MARGINALLY COOL GROUND 

UNDER SNOW 

E Upper: DCP ANALOG CHANNEL 5: 

Lower: DCP ANALOG CHANNEL 4: 

FUMAROLE VENT 

FUMAROLE VENT 

F DCP ANALOG CHANNEL 2: AMBIENT AIR 1 m 

ABOVE GROUND 

FIGURE 15.-Kinetic temperatures recorded by Landsat-1 Data Collection Platform 6251 at the Dorr Fumarole Field between February 8 and 

March 17, 1973. Electronic thermal probes recorded temperatures at (A) 50-cm depth and (B) 30-cm depth in the fumarole field, on a 

geothermally warmed surface (C) (note scatter of temperature points caused by diurnal variations in micrometeorological conditions), 

and on a marginally warmed surface beneath a snowbank (D). Nearly constant vapor-vent temperatures are also given for the same 

period (E), as are ambient-air temperatures 1 m above the ground surface (F). 
l;\;FRARED Sl'R\'EYS. RADIANT FLUX, AND TOTAL HEAT DISCHARGE D23 

nocturnal radiation, (3) heat flow in the ground (positive or negative) due to solar radiation, (4) heat flow to 

the atmosphere via eddy diffusion, (5) evaporative heat 

exchange with the atmosphere, and (6) the geothermal 

flux. The two-point model permits the following 

simplified relationship (Sekioka and Yuhara, 1974, p. 

2056): 

~G = ECl-0.09m) [ 0.52+0.065Cew)~,,] u(~Tc,)~ 

+ PaCvDC1 +.A) ~8 (5) 

in which the differential geothermal flux ~G is expressed in terms of effective surface emissivity E 

(0.95±0.04), cloudiness m (1 during the infrared surveys), vapor pressure ew (4.1 mbar), surface temperature To (in kelvins) and 8 (°C), air density Pa (0.909 X 

10-3 g cm-3 at 3,000 m m.s.l.), the specific heat of air at 

constant pressure cv (1.00 J g- 1 K- 1), the transfer velocity D~ (1.59 em s-I, following Budyko, 1956, p. 46-57, 

and Sekioka and Yuhara, 1974, p. 2057), and the 

Bowen ratio R (Bowen, 1926) 0.3, determined for 

Mount Baker by calculating the ratio of heat loss from 

the surface by eddy diffusion and conduction to heat 

lost by evaporation in still air. 

The present writers have made several modifications 

in the Sekioka and Yuhara (1974) model to reduce 

error in the geothermal-flux estimates. These 

modifications can be summarized as follows: 

(1) An aerial infrared scanner has been used as the 

sensing system in preference to a land-based radiation 

thermometer to ensure virtual simultaneity in measurement. 

(2) Atmospheric transmission-path corrections have 

been incorporated. 

(3) A method has been introduced to assess the 

Bowen ratio. 

(4) Local conditions at Mount Baker were taken into 

account in determining values for air density, vapor 

pressure, enthalpy of saturated water vapor, and the 

standard reference surface kinetic temperature. 

(5) Estimates for advective heat loss via icemelt 

fumarole emanations and vapor plumes, and melt~ water drainage from the thermal area have been added 

to the heat budget of the ground surface. 

DIFFERENTIAL GEOTHERMAL FLUX FROM DORR 

FUMAROLE FIELD, 1972 

The subsurface temperature data (from depths of 

15-100 em) obtained by DCP 6251 'in 1972 and 1973 

complement those data derived from density scans of 

the calibrated infrared images of November 20, 1972. 

Together, these data sets permit application of the empirical Dawson (1964) model for heat flow through soils 

that have heat-flux densities of less than 400 W m-2 

and comparison of the Dawson model with the twopoint geothermal-flux model of Sekioka and Yuhara 

(1974). 

An adaptation of the Dawson model (1964, p. 160) for 

calculation of convective heat flow (H) to the surface 

from depth is given by 

(6) 

where T 15 is the mean kinetic temperature (in °C) at a 

depth of 15 em. 

This relation was determined from temperature and 

heat-flow observations in the Wairakei area, New Zealand. The corresponding heat-flow relation between 

T too and T t5 has been established by Robertson and 

Dawson (1964). 

The application of the Dawson model to DCP thermal probes 6, 7, and 8 in the Dorr Fumarole Field is 

given in table 2 (footnote 4). 

The differential geothermal-flux densities generated 

by the Sekioka and Yuhara model for integrated kinetic temperature units of the Dorr Field are given in 

table 2 and are plotted against the differential radiant 

flux in figure 14. The average flux density thus derived 

was 397 W m- 2 , compared to 287 W m-2 obtained by 

use of the Dawson model. The mean for the two models 

is 342 W m- 2 and the mean standard deviation is 78 W 

m-2, which corresponds to a coefficient of variation of 

23 percent. 

DIFFERENTIAL GEOTHERMAL FLUX FROM 

SHERMAN CRATER, 1972 AND 1975 

Table 2 contains figures for the differential geothermal flux from Sherman Crater on November 20, 1972, 

based on the heat balance of the ground surface estimated from density analysis of aerial infrared images 

and on our adaptation of the Sekioka and Yuhara 

(197 4) model given in the previous section. This estimate excludes flux components from vapor plumes and 

fumarole emission to the atmosphere, ice melt, and 

other advective heat losses. 

Also in table 2 is a similar differential geothermal 

flux estimate for the period following the increase in 

'The transfer velocity, D, is the coefficient of diffusion of water vapor in the air. It is given 

by D = D,IT/T, 11 "tP,/PI where D, is the value ofD at 273 K 1 =0.22; Washburn, 1929, p. 621, 

Tis air temperature lin Ki, T, = 273 K, Pis air pressure, and P, = 1 atmosphere 1101.3 kPal 

!Brunt, 1939, p. 4211. 
D24 VOLCANIC ACTIVITY AT l\IOLJNT BAKER. WASHI:'-JGTON 

thermal emission that began March 10, 1975. Integrated kinetic temperature zones are based on infrared 

images obtained by Rosenfeld (1976, 1977). This estimate excludes the same flux components left out of the 

1972 estimate, and it also excludes heat lost from the 

central pit lake that developed in mid-1975. This heat 

loss is analyzed in the next section. 

HEAT LOSS FR0,\1 CENTRAL PIT LAKE. 1975 

After thermal activity increased in March 1975, a 

large ice pit developed near the center of Sherman Crater. The central pit was occupied by a warm lake, 

which had a surface area of 2,700 m2 by July of that 

year. Vertical ice walls rose about 40 m above the lake 

surface. The pit developed on the site of a saucershaped depression in the crater glacier, which had been 

noted in pre-197 5 photographs and illustrated by 

Frank, Post, and Friedman (1975, p. 86, fig. 8), who 

speculated that a subglacial lake might exist under the 

crater glacier at that point. The water-equivalent 

thickness of the ice that melted out of the central pit is 

estimated at 25 m. The near-surface kinetic temperature of the lake, 34 oc, was measured by thermometer 

on June 11, 1975. An infrared survey on June 30, 1975, 

reported by Eichelberger and others (1976, p. 42), gave 

a water-surface temperature range of 33-40°C, but the 

average lake-surface temperature as estimated from 

this survey was approximately 33oC (J. E. Eichelberger, oral commun., June 1976). For the following 

heat-loss estimates, a mean surface kinetic temperature of 34 oc was used. 

The total nonadvective heat loss (F 5 ) from a calm 

lake surface is given by the expression (Sutton, 1953) 

(7) 

where the Bowen ratio, R = F h/F e· 

The synonymy and definition of terms used in this 

and the following subsections on heat loss from the 

central pit lake are as follows: 

F h = net outgoing flux from the surface via eddy diffusion and molecular conduction 

F b = differential radiant flux 

Fe = heat lost to the atmosphere by evaporation 

Ps = e5 = V = saturated pressure of water vapor [at 

34°C in mm Hg, Ps = 39.898 (Weast, 1970, 

p. D143)] 

Pct = ea = v =pressure ofwater vapor in atmosphere 

in mm of Hg [June 26, 1975, at ooc, P ct = 

4.579 x 0.80 (relative humidity) = 3.6632] 

P1 =atmospheric pressure in mm of Hg [at 3,000 m 

m.s.l. = 527.13 J 

W =wind speed in m·s-1 [W = 0 to 1] 

Ts = temperature of water surface in oc [ = 34 J 

T a = temperature of air in oc [ = 0 J 

M =rate of evaporation in kg m- 2hr-1 

In the following subsections, the Fe and F h components are estimated using two semiempirical equations 

(Washburn, 1929; and Robson and Willmore, 1955) 

based on evaporation-pan theory. (See table 4.) The 

overall heat loss from the lake surface estimated from 

equation 7 is then compared with that derived from 

equation 5. 

EVAPORATION 

The Fe component in equation 7 can be estimated 

using the following relationship (Washburn, 1929, p. 

54, and Dawson, 1964, p. 162): 

M = (0.031 + 0.0135W) <Ps - Pct) (760/P1). (8) 

Where W = 0, M = 1.6195 kg m-2 hr-1. Since the area 

of the lake is 2,700 m2 , and the enthalpy of water vapor 

at 34°C = 622.3 cal g-I, 

Fe = 3.2 X 106 W. 

Where W = 1 m s-t, M = 2.3248 kg m-2 hr-t, and 

Fe = 4.5 X 106 W. 

An alternative equation for calculation of evaporation from a heated water surface is given by Robson 

and Willmore (1955, p. 21): 

TABLE 4.-Anomalous nonadvective heat flux from Sherman Crater 

in 1972 and 1975, including calculations for central pit lake based on two different models 

[Excludes plume, icemelt, and other advective heat loss. Area of lake, 2, 700m2

; emissivity, 

0.99; lake temperature, 34aC (as measured by Frank, June 11, 19751] 

Component 

Anomalous heat flux, exclusive of 

central pit lake 1 (from table 2)-----

Central pit lake: 

Differential radiant flux (from 

table 2) ---------------------------

Nonradiant transfer (where _li = 0): 

Evaporation------------------------

Conduction and diffusion-----------

Total for lake-----------------------

Total anomalous heat flux from crater--

Hean nonadvective heat-flux density: 

In thermal areas---------------------

Averaged over entire Sherman Crater 

( 16 7, 000 m;') -----------------------

1 Lake was 'not present in 197 2. 

19n 

3.6 MW 

3.6 MW 

197 5 

10.6 MW 

.6 MW 

: 1. 8-3.2 MW 

c 0.8-l.O MW 

." 3.2-4. 7 HW 

l3 . 8- 1 5 . 4 MW 

395-4"7 2 W m-2 

2Lower estimate was calculated using model of Robson and Willmore ( 1955); 

higher estimate was derived from model of Sutton. (1953) and Dawson (1964). 

Figure shown in table 3 for total heat flux from lake (2. 0 MW) was derived from model of Sekioka and Yuhara (1974). 
INFRARED SURVEYS, RADIANT FLUX, AND TOTAL HEAT DISCHARGE D25 

Fe = (1 + T/150) (1 + 0.33W) (V - v) 

x 0.33 x 10-3 cal cm-2 s- 1 • 

ing atmospheric conditions, Bowen arrived at the ex-

(9) pression 

Where W = 0, Fe= 1.7 X 106 W; where W = 1, Fe= 2.3 

X 106 W. 

These alternative semiempirical methods thus yield 

results that differ by 25 percent, which is less than the 

combined probable error in the overall estimate. 

Evaporative heat loss from the central pit lake surface 

is plotted in figure 16 as a function of temperature and 

windspeed for prevailing conditions at Sherman Crater. 

CONDUCTION AND DIFFUSION TO ATMOSPHERE 

Bowen (1926, p. 779), following the work of 

Angstrom (1920) and others, showed that the process of 

evaporation and diffusion of water vapor (Fe) from any 

water surface into the body of air above it replicates 

that of the conduction or diffusion of specific heat energy (Fh) from the water surface into the same body of 

air. Because of this relationship, it is possible to represent the heat loss by conduction and turbulence to that 

by evaporation by a specified ratio, R, which Bowen 

introduced, in which R = Fh/Fe. By considering limit-

(10) 

Bowen's limiting conditions assume molecular diffusion and conduction and therefore apply only to laminar motion, but Bowen inferred that the ratio of heat 

losses would be much the same in turbulent motion 

(Sutton, 1953, p. 314-315). Bowen's inference was investigated by Cummings and Richardson, who found 

that Bowen's theoretical conclusions were supported by 

their own empirical observations. Cummings and 

Richardson conclude (1927, p. 534) that it" is worthwhile to assess the value of Rat various places and 

various times of the year. Substituting the variables 

listed above into equation 10, R = 0.30 for the central 

pit lake in Sherman Crater in July 1975. And since Fe 

ranges from 3.2 x 106 to 4.5 x 106 W, as shown by 

equation 9, F h would range from 1.0 x 106 to 1.4 x 106 

w. 

An alternate expression for heat flow from a surface 

into a convecting vapor is given by Robson and 

Willmore (1955, p. 21): 

F h = (1 + .0069 Llt) x 2.04 x 10-~ cal cm- 2 s- 1

, (11) 

where Llt is the difference in oc between the surface 

HEAT LOSS BY EVAPORATION, IN 103 W m- 2 

370° 2 3 4 5 6 7 8 9 18 

~ 

~ 

w 

a: 

::> 

1-

<( 

a: 

w 

a.. 

~ 

w 

1-

w 

u 

<( 

LL 

a: 

::> 

en 

w 

~ 310 <( 

...J 

1-

a: 

...J 

<( 

a: 

1-

z 

w 

u 

280 

6.5 7.8 9.1 10.4 11.7 13.0 14.3 15.6 16.9 18.2 19.5 20.8 22.1 23.4 

COMBINED HEAT LOSS BY EVAPORATION, CONDUCTION, AND CONVECTION, IN 103 W m- 2 (BOWEN RATIO= 0.30) 

FIGURE 16.-Evaporative heat loss from the surface of the central pit lake, Sherman Crater, as a function of kinetic water-surface temperature and windspeed, at 273 K air temperature. 
D26 VOLCANIC ACTIVITY AT .\IOU~T BAKER, WASHI~GTOI\' 

and the atmosphere (Ts - Ta). Substituting the variables listed above F 11 = 292 W m- 2 or 0.8 x 106 W. 

RADIANT HEAT LOSS 

The net radiant loss to the atmosphere is estimated 

from equation 1 and the area of the lake where 

Tt 34°C, the main temperature of the 

lake surface, 

Tz 0°C, the adjacent, nonanomalously 

warm ground surface, 

and E 0.99 ± 0.01, 

Fh 186 W m-2 or 0.50 x 106 W. 

TOTAL HEAT LOSS 

If the values for Fe, R, and F b from the foregoing 

analysis are substituted into equation 7, Fs = 1700 to 

2370 W ·m- 2 , or 4.6 x 106 to 6.4 x 106 W. This range in 

values reflects the variation in wind speed and the differing values for Fe obtained from equations 8 and 9. 

DIFFERENTIAL GEOTHERMAL FLUX AND COMPARISON OF 

HEAT-LOSS ESTIMATES 

Total heat loss from the lake surface can also be approximated using equation 5 and the area of the lake, 

from which the differential geothermal flux, LlG = 7 45 

W m- 2 for a total heat loss of 2.0 x 106 W. 

Deviations from mean heat-flow estimates were calculated for the central pit lake, where three heatbalance models were applied. Heat-flow estimates for 

the central pit lake ranged from 2.0 x 10n to 4.6 x 10n 

W (table 6). The mean is 3.2 ± 1.4 x 106 , equivalent to 

a coefficient of variation of 57 percent. 

Equation 7, as applied here, yields a Bowen ratio 

(Fh/Fel, R, = 0.30; application of the Robson-Willmore 

model yields R = 0.31. 

HEAT EXCHANGE VIA l\IASS TRA~SFER FROl\I FUMAROLES, 

1975 

With the exception of data on temperature variations, little quantitative information is available on 

fumarole emanations from Sherman Crater for the 

1972-73 period. Fumaroles of the Dorr Field, 

monitored by the DCP system, averaged 90.8oC in 1973 

(table 3). In March 1975, however, Kiver and Steele 

(1976) measured the velocities of fumarole gases in the 

west-rim sector of Sherman Crater and along the edge 

of the newly formed crater lake in the central pit. The 

much larger fumaroles in the east-breach sector were 

not measured. The volumetric rate of fumarolic gas 

emission reported by Kiver and Steele (1976) was 0.35 

m3 s- 1, somewhat less than 1 percent of the total from 

Sherman Crater at that time (E. P. Kiver, oral commun., July 21, 1976). We infer here, based on field 

reconnaissance, that fumarolic gas emission of 0.35 m3 

s- 1 is approximately 1 percent of the total gas emission 

at 90°C. 

The heat lost to the atmosphere via mass transfer 

CQt) from fumarolic vapor emission in Sherman Crater 

(neglecting nonaqueous constituents of the vapor) can 

be estimated by using an expression of the form 

Qt = v f pH, (12) 

where v = volumetric rate of transfer of fumarole 

vapor ( = 0.35 m=l s- 1 for 1 percent of the fumaroles), f = 

relative humidity of the ascending vapor ( = 0.95), p = 

density of saturated water vapor at 90oC ( = 0.428 x 

10-3 g cm-a; Perry and others, 1969, p. 3-191 ), H = 

enthalpy of saturated water vapor at 90oC and 

barometric pressure equivalent to 3,000 m m.s.l. ( = 

630.4 cal g- 1

; Keenan and Keyes, 1936; Burnham and 

others, 1969, p. 14). From equation 12, Q1 = 0.37 x 106 

W for the fumaroles investigated by Kiver and Steele. 

For the entire Sherman Crater, heat lost via mass 

transfer from all fumaroles in March 1975 would then 

have been about 37 x 106 W. However, the uncertainty 

in this value is estimated at 100 percent. 

ADVECTIVE HEAT LOSS VIA .\1ELT-WATER DRAINAGE, 

1972 A~D 1976 

The volumetric outflow of the melt-water stream 

(Crater Creek) draining the entire Sherman Crater 

was estimated on July 14, 1976, by Frank to be 0.2 m3 

s- 1• The water temperature was 22°C. The estimated 

advective heat loss by snowmelt and icemelt given by 

Frank, Meier, and Swanson (1977, p. 17) and shown in 

revised form in table 5 does not include the heat content of melt water above 0°C. The enthalpy of water at 

22oc and 3,000 m m.s.l. is 91.62 J g- 1

, hence the heat 

content of the melt-water stream is ~ 18 x 106 W. 

The estimated outflow in 1972 was 0.1 m=l s- 1 at 7 to 

soc (as measured by Frank), equivalent to an advective 

heat loss of 3 x 106 W. 

ANALYSIS OF PROPAGATION OF ERROR IN FLUX 

CALCULATIONS 

Table 6 gives the estimated mean standard deviation 

and variance for significant independent variables for 

four categories of flux calculations reported in this 

paper: differential radiant flux density (F b), outgoing 

net flux to the atmosphere by diffusion and conduction 

(F11 ), outgoing flux to the atmosphere via evaporation 

(Fe), and rate of advective heat loss via mass transfer 
INFRARED SURVEYS. RADIANT FLllX. A~D TOTAL HEAT DISCHARGE D27 

TABLE 5.-Estimated total heat discharge from Sherman Crater, Mount Baker, Washington, 1972 and 1975, from all major sources 

Component 

Infrared radiation loss above 0°cl _____________ _ 

Heat loss by evaporation, molecular conduction, 

and diffusion to atmospherel _________________ _ 

Total heat loss from central pit lake 2 ----------

Direct heat loss by mass transfer from 

fumaroles and vapor plumes--------------------

Advective heat loss from geothermal melting 

of snow and ice 3------------------------------

Advective heat loss via melt-water drainage-----

Total heat discharge----------------------------

11975 figures exclude loss from central pit lake. 

November 

Heat flux 

(MW) 

1.0 

2.6 

0 

4.0 

0.6 

3.0 

4 11.2 

1972 

Percent 

of total 

9 

23 

0 

36 

5 

27 

100 

Summer 197 5 

Heat flux Percent 

(MW) of total 

3.0 4 

7.6 9 

4.6 6 

37.5 47 

9.8 12 

18.0 22 

5 80.5 100 

2Los·s from calm water surface by radiation, evaporation, conduction, and diffusion. 

3Anomalous heat flux in those geothermal areas covered by snow and ice at the time of the infrared 

surveys. Data are derived from Frank, Meier, and Swanson (1977, p. A17, table 4, sec. Band C) 

and include an adjustment of value B to account for heat loss already considered here under other 

headings. 

4Equivalent to a heat-flux density of 67 W m- 2 through the entire crater (167,000 m2 ). 

5Equivalent to a heat-flux density of 482 W m- 2 through the entire crater, a sevenfold increase over 

1972. 

from fumaroles (F adl. From these estimates, the propagation of error in flux calculations for the major components of power output is analyzed (table 7) using the 

method of Bevington (1969, p. 56-65). Percentages of 

error accumulated in calculating Fh, Fh, Fe, Fad 

(fumaroles only), and .:lG (differential geothermal flux 

using the Sekioka and Yuhara model) are tabulated. 

The combined error for overall power output for the 

two basic models tested in this investigation, Qa = 

Fb+Fh+Fe+Fad (eq. 4) and Qb = .:lG+Fad (eqs. 5 and 

12), is also given. The lower combined error was obtained using the Sekioka and Yuhara model (Qb) and is 

55 percent. The largest uncertainty, the volumetric 

rate of transfer of fumarole vapor (Fad), is inherent in 

Qa and Qh models. If Fad were known at 50 percent 

error, the overall error in Qb would be only 29 percent. 

HEAT-FLl'X Sl'\l\IARY 

The estimated heat discharge and energy partition 

at Sherman Crater in November 1972 is compared to 

that of 1975 in table 5. In terms of energy partition, 

heat loss from Mount Baker was dominated, both before and after the thermal event of 1975, by mass 

transfer from fumaroles, which increased in significance in 1975. The second largest mode of heat transfer in 1972 was advection through melt-water drainage, and it remained so in 1975. Although all modes of 

heat transfer increased in 1975, the percentage of loss 

by evaporation, diffusion, and conduction to the atmosphere declined to fourth most important. Radiation 

loss, although increasing quantitatively, declined in 

percentage of total heat loss between 1972 and 1975. 

INFERRED ENERGY YIELD DURING REPOSE 

The 1972 heat-flux density in Sherman Crater (table 

5, footnote 4) is estimated at 67±37 W m- 2 for the 

entire crater, compared to a heat-flux density of 20 W 

m - 2 for thermal areas in the vast Torfajokull silicic 

volcanic center (PaJmason and others, 1970) of Iceland 

(table 8), based on Boovarsson (1961), and 45-50 W 

m_ 2 for thermal zones in the Grimsvotn caldera in the 

ice sheet Vatnajokull (Bjornsson, 1974, p. 18). From a 

review of historical data and photographs of thermal 

ground and fumaroles, we infer that the 1972 energy 

yield of Sherman Crater represents a maximum of 

near-steady-state conditions that prevailed for the past 

century. The average energy yield would then have 

been somewhat less than 11.2±6.2 MW or 3.5±1.9 x 

1014 J yr- 1. 

COMPARISON BETWEEN 1972 ENERGY YIELD AND 1975 

ENERGY YIELD 

The total heat discharge from Sherman Crater increased in 1975 to about 80.5±44.3 MW (about 2.5± 1.4 
D28 VOLCANIC ACTIVITY AT MOUNT BAKER, WASHINGTON 

TABLE 6.-Estimated mean deviation in independent variables in flux calculations 

Independent variable Symbol Mean value 

Estimated 

mean 

deviation (s) 

Differential radiant flux density (Fb) 

Effective surface emissivity-- e: 0.95 + 0.04 

Mean temperature of warm 

surface, in K--------------- Tl 300 + 9.0 

Mean temperature of cool 

reference surface, in K----- T2 273 + <2. 7 

Outgoing flux by diffusion and conduction (Fp) 

Increment in temperature of 

warm lake surface in °c----- 27 + 6. 75 

Outgoing flux via evaporation (Fe) 

Temperature of air above warm 

lake surface in oc----------

Saturated pressure of water 

T 

vapor in mm of Hg----------- Vi (Ps) 

Pressure of water vapor in 

atmosphere in mm of Hg------ v (Pd) Wind speed in m s-1___________ W 

Advective heat loss 

Volumetric rate of transfer 

of fumarole vapor in m3·s-l- v 

Relative humidity of 

fumarole vapor-------------- f 

Density of saturated water 

vapor in g cm-3------------- p 

Enthalpy of saturated water 

vapor in cal g-1 ____________ H 

Differential 

Effective surface emissivity-- e: 

Cloudiness-------------------- m 

Vapor pressure in mbars------- ew 

Increment in surface 

temperature above 273 K----- 6T0 Air density in g cm-3 _________ p~ 

Enthalpy of air in J g-1 deg-1 Cp 

Transfer velocity in air em s-1 D 

Increment in surface 

temperature in °C 69 

Bowen ratio R 

34 

39.898 

3.663 

0 

+ 0.34 

+ 3.9 

+ .037 

0 

via fumarole emanations (Fqd) 

0.35 + 0.35 

.95 + .05 

.428x1o- 3 + .043x1o- 3 

630.4 + 12.6 

geothermal flux (6G) 

0.95 + 0.04 

1.0 + .10 

4.1 + .62 

27 + 2.2 

.909x1o- 3 - .009x1o- 3 + 

1.00 + .02 

1.59 + .24 

27 + 2.2 

.31 + .009 

Variance 

(s2) 

0.0016 

81 

<7.5 

45.6 

0.12 

15.2 

.0013 

0 

0.12 

.0025 

.0018x1o- 6 

159. 

0.0016 

.01 

.38 

4.7 

.00008x10- 3 

.0004 

.057 

4.7 

.000086 
INFRARED SURVEYS, RADIANT FLUX, A::-.lD TOTAL HEAT DISCHARGE 

TABLE 7.-Analysis of propagation of error in flux calculations 

[Following the method of Bevington (1969, p. 56-651 and assuming that variables are independent and not correlated] 

Reference Mean Standard 

Model Component of power output Symbol equation (cal cm- 2 s- 1) deviation 

Differential radiant flux------- Fb 0.0033 +0.0013 

Net outgoing flux via diffusion 

and conduction to atmosphere-- F 11 2.4x1o- 4 + .095x1o- 4 

Flux to the atmosphere via h 

Qa evaporation------------------- F 9 .015 + .0016 

Advective heat loss via mass e 

transfer to atmosphere from 

fumaroles, etc.--------------- F 12 .090 + .090 

Qb Differential geothermal flux via ad 

method of Sekioka and Yuhara 

Part 1---------------------- llG 5 .026 + .0083 

Part 2---------------------- llG 5 .051 + .015 

Qa = F +F +F +F ------------------------------------ 4 .108 + .090 b h e ad 

Q = llG+F ------------------------------------------- 5, 12 .167 + .092 b ad 

TABLE B.-Comparative energy yield of selected volcanoes and geothermal areas 

Surface thermal 

manifestations 

[- ____ indicates no data available] 

Anomalous 

geothermal 

flux over 

Area Heat-flux 

(km2 ) density 

D29 

Percentage 

error 

39 

4 

11 

100 

32 

29 

83 

55 

Volcano or 

geothermal area (W m- 2 ) 

Equivalent 

100-yr rate 

of energy 

release 

(x10 18 J) 

assumed 400-km2 

volcanic domain 

(W m- 2) (hfu) Reference 

Kilauea-Mauna Loa, 

Hawaii 1-------------

Grfmsvotn, Iceland 1 , 2 - 100 

Nyiragongo, Zaire----- .13 

Torfaj~kull, Iceland 2- 100 

Kverkfjoll, Iceland2 --

Hekla, Icelandl ______ _ 

Vesuvius, Italyl _____ _ 

Oshima, Japanl _______ _ 

Tikitere, New Zealand 2 

Mount Baker, 

Washington, 1975----

Mount Baker, 

Washington, 1972----

. 25 

.17 

.17 

47.5 

300,000 

20 

485 

482 

67 

40 

15 

13 

6.5 

>4 

3 

1 

. 6 

. 4 

.25 

.04 

32.5 775 

12 285 

10.5 250 

5 120 

>3 >90 

2.5 60 

.8 20 

. 5 12 

. 3 7 

.20 4.6 

.03 . 8 

Swanson (1972). 

Bjornsson (1974, p. 18). 

Bonnet (1960, p. 713); Delsemme 

(1960, p. 705-6). 

Bjornsson (1974' p. 17). 

Friedman and others (1972, 

P· 40-41). 

Friedman and others (1970). 

Yokoyama (1972, p. 167). 

Yokoyama (1972, p. 166) . 

Dickinson, 1973, p. 1) . 

This report. 

This report. 

1Volcanoes for which steady-state energy yields are inferred. 

2Geothermal field for which steady-state heat flows are inferred. 

3Projected to 100-year rate for comparative purposes only. 

x 1015 J yr - 1 ) from 11.2±6.2 MW in 1972. Thus, the 

heat-flux density averaged over the entire Sherman 

Crater increased from about 67±37 W m- 2 in 1972 to 

about 482±265 W m~2 in 1975. 

The thermal-balance method used to arrive at these 

conclusions is essentially different from the method 

used by Frank, Meier, and Swanson (1977) to make 

their icemelt heat-flow estimate. The two results are 
D30 VOLCANIC ACTIVITY AT MOCNT BAKER, WASHINGTON 

not strictly comparable because a wider, more comprehensive range of heat-loss mechanisms was considered in the thermal-balance method and because the 

icemelt estimate averages heat flow over long periods. 

Yet even with the sparse data available on critical 

components such as mass transfer from fumaroles, the 

thermal-balance method yielded estimates suggesting 

an increase in heat flow in 1975 of about the same 

order of magnitude as that shown by the snow-andice-melt method. For that part of the total heat flow 

that could account for the observed snow and ice loss, 

Frank, Meier, and Swanson (1977, p. A16) calculated a 

heat-flux change from 2 MW to about 30 MW during 

1975, or an increase factor of about 15. The thermalbalance method in the present report yielded an overall 

heat-flux change from 11 MW in 1972 to 80 MW in 

1975, an increase factor of about 7, after including that 

part of the snow-and-ice-melt estimates that is not 

duplicated by the present methods (table 5 ). It is not 

surprising that a greater part of the total heat flow 

should go into melting snow and ice in 1975, considering that much of the new thermal activity had a subglacial origin. 

DISCUSSION 

F h/Fs ratios obtained for the central pit lake, the Dorr 

Fumarole Field, and the entire Sherman Crater by application of the three heat-balance models in the preceding sections range from 0.11 to 0.28; the mean Fh/Fs, 

0.21 ± 0.09, is close to that obtained (0.24 ± 0.02) using 

the Sekioka-Yuhara model alone. 

If we examine the literature for the relationship between radiant and total heat loss from volcanic and 

geothermal manifestations, two examples may be readily cited: (1) Decker and Peck (1967, p. D175) found 

that at the crustified Alae lava lake, Hawaii, the net 

radiant heat loss was 10 percent of the total heat loss, 

and (2) Friedman and others (1969) calculated that at 

Surtsey, Iceland, radiant heat loss (as detected by the 

Nimbus 2 high-resolution infrared radiometer) from an 

incandescent lava eruption in 1966 was 3.4 percent of 

the total volcanogenic heat loss. Comparable estimates 

from the present experiment indicate the differential 

radiant flux was 8.9 percent of the total volcanogenic 

flux (Fh/Q) at Mount Baker in 1972 and 3. 7 percent in 

1975. 

If the 1972 energy transfer from the Sherman Crater 

represents a maximum of near-quiescent conditions, as 

suggested by the historical evidence presented and 

analyzed in previous sections, the sevenfold increase in 

energy transfer that began in March 1975 and continued through 1976 requires a specific geologic explanation rooted in a process or event. 

Tiltmeter and seismic records are not adequate for 

the period before 1975 (because of the lack of instrument stations) to establish the nature of the event or 

process that culminated in the increase in thermal 

emission on about March 10, 1975. Subsequent tiltmeter and seismic records show virtually no evidence for 

magma movement or infusion since March 10, 1975, 

along conduits beneath Sherman Crater. 

The net increase in energy yield from 1972 to 1975 

(80.5 MW - 11.2 MW = 69.3 MW) is equivalent to 

2.2 ± 1.2 x 1015 J yr- 1• The rate of energy transfer in 

1976 remained at about the same level. Without endorsing a magmatic hypothesis, we may estimate the 

mass-transfer equivalent of volcanic energy yield in 

the manner of Yokoyama (1972, p. 165), Swanson, 

Wright, and Helz (1975, p. 900), and Blackwell (1978, 

p. 182), who have shown that volcanic thermal energy 

yield, based on the specific and latent heat content of 

lava and assuming cooling of an effusive lava to ambient temperature levels, ranges between 1,360 and 

1,507 J g- 1. Thus, the net increase in thermal energy 

yield at Sherman Crater in 1975 would correspond to a 

magma mass of 1.6±0.8 x 109 kg (about 0.62 x 106 m3). 

A larger mass of magma would be required to account for the energy output of Mount Baker if devolatilization of magma occurred at depth. Assuming 

that 5 percent of the mass of a magma body was 

transported to the surface in the form of hydrothermal 

vapor, we can estimate the magnitude of the hypothetical body from the energy output of the system. 

If we assume an enthalpy of2,680 J g- 1, which would 

reflect the temperature and pressure conditions at the 

surface at Sherman Crater, the hydrothermal vapor 

equivalent of the annual heat discharge at Sherman 

Crater in 1975 and 1976 would be 9±5 x 108 kg yr-I, 

equivalent to the devolatilization of 2±1 x 1010. kg of 

magma per year. The volume of magma involved would 

be 0.008 km3 , or, in the most compact form, a sphere of 

124m radius. Interestingly, Frank, Meier, and Swanson (1977, p. A17) found that the surface distribution of 

hydrothermal activity in Sherman Crater can be summarized as having a central core of heat emission 

60-80 min diameter, near the east breach, on which is 

superposed a semicircular zone of activity 400 m in 

diameter, along the inside crater rim. 

Although an increase in activity in the Mount Baker 

hydrothermal system might be associated with the devolatilization or cooling of a small magma body at 

depth, the sevenfold increase in fumarolic activity in 

1975 at Sherman Crater could as well be accounted for 

by an influx and subsequent loss of high-temperature 

fluids as the result of an independent abyssal process. 

The lack of direct geophysical evidence for the intrusion or devolatilization of a magma body or chamber in 
INFRARED SURVEYS, RADIANT FLUX, AND TOTAL HEAT DISCHARGE D31 

the conduit system beneath Sherman Crater suggests 

that a nonmagmatic hypothesis would be better. It is 

not unusual for energy yields of the magnitude reported here for Mount Baker to occur during repose or 

dormant periods of a volcanic system. In this connection, we note that more than 34 percent of the total 

energy release in Quaternary time in the Kamchatka 

volcanic province (Polak, 1967, p. 136) has occurred as 

a result of fumarolic activity at individual volcanoes 

during dormant periods rather than during eruptions. 

Moreover, the level of energy output from Mount 

Baker, even after the increase of 1975, suggests that in 

heat-flux density and rate of energy release, the Mount 

Baker system more closely resembles a small hydrothermal field of the Tikitere, New Zealand, type 

(table 8) than the moderate to large geothermal fields 

associated with volcanic systems like Nyiragongo, 

Zaire, or Kilauea-Mauna Loa, Hawaii, where the 

high-level energy yield can be attributed to recurrent 

influx of magma into the volcanic system. 

Thus, the heat-flow evidence at hand establishes the 

magnitude of the 1975 thermal event at Mount Baker, 

but is not yet adequate to demonstrate conclusively 

whether the additional supply of heat can be attributed 

to devolatilization of a magma body or, more likely, to 

influx of high-temperature fluids from depth. 

SUMMARY AND CONCLUSIONS 

(1) Seven aerial infrared scanner missiOns were 

flown over Mount Baker, Wash., between 1970 and 

1973, including one survey on November 20, 1972, in 

which an RS-14 scanner produced calibrated, taped 

infrared images. Data from these missions were used to 

reconstruct the 1972 surface thermal regime of Sherman Crater and the Dorr Fumarole Field of Mount 

Baker by mapping radiometric surface temperatures of 

anomalously warm zones associated with ice perforations and fumarole clusters. An assessment of Mount 

Baker's heat exchange with the atmosphere before and 

after the March 1975 increase ill thermal emission was 

built up from the surface thermal regime. 

(2) The scanner temperature readout was corrected 

for atmospheric attenuation due to H20 and C02 along 

the transmission path by use of radiosonde data, standard model atmospheres, and transmissivity curves for 

the 8-14 JLm region. 

(3) A planimetrically corrected map plot of 

radiometric surface-temperature zones was derived 

from a film readout of the scanner tapes via imagedensity slicing using an emulsion-density scanning 

microscope. 

( 4) Ground kinetic temperature units were established for the anomalous zones by applying surface 

emissivity corrections to the radiometric temperature 

map plot. 

(5) A two-point differential radiant-flux (or 

radiant-exitance) model, based on the StefanBoltzmann function, provided an estimate of radiantflux density for each kinetic temperature unit in relation to a selected reference surface at 273 K. 

(6) A two-point model (requiring synchronous 

surface-temperature records) for heat balance of the 

ground surface was modified by the writers for use with 

temperature data derived from synoptic aerial infrared 

scanner images under conditions prevailing at Mount 

Baker. In addition to the corrections listed above, 

evaporation from the warm crater-lake surface was estimated independently using evaporation-pan theory, 

and the Bowen ratio (R = ~ 0.3) was calculated and 

used to derive heat loss to the atmosphere via diffusion 

and conduction from the figures for evaporation. The 

differential geothermal flux was then calculated in relation to the 273-K reference surface. 

(7) An electronic thermal sensor system integrated 

with a Landsat data collection platform provided repetitive near-surface (30-50 em), surface, fumarole-vapor, 

and ambient-air temperatures over a period of several 

months in 1973 and 1974 for a site within the Dorr 

Fumarole Field, yielding data for an independent estimate of near-surface flux density. 

(8) The differential radiant flux from Sherman 

Crater for the 1972 period was estimated at 1.0±0.4 

MW and the total heat discharge at 11.2±6.2 MW including advective heat loss from icemelt and surface 

drainage and direct heat loss via mass transfer from 

fumarole emanations. 

(9) Application of the same procedure to infrared 

scanner images made in 1975 indicated a differential 

radiant flux o( 3.0±1.6 MW and a total heat discharge 

(as defined above) of 80.5±44.3 MW. 

(10) The annual energy yield from Sherman Crater 

in 1972 was estimated as 3.5±1.9 x 1014 J yr- 1 and in 

1975 as 2.5±1.4 x 1015 J yr- 1• A sevenfold increase in 

heat discharge was thus associated with the thermal 

events that began in March 1975. 

(11) The hydrothermal vapor equivalent of the annual heat discharge would be 9.0±5.0 x 108 kg yr- 1 at 

an enthalpy of 2,680 J g- 1• Although there is no independent evidence of emplacement of a magma body in 

the conduit system beneath Sherman Crater, the annual level of hydrothermal emission would be equivalent to the devolatilization of 2.0± 1.0 x 1010 kg of 

magma per year at depth, or to the influx and subsequent loss of equivalent hydrothermal fluids as the 

result of an independent abyssal process. 
D32 VOLCANIC ACTIVITY AT MOUNT BAKER, WASHINGTON 

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