Scientific Investigation Report 2006-5276

Volcano and Earthquake Monitoring

Plan for the Yellowstone Volcano 

Observatory, 2006-2015

U.S. Department of the Interior

U.S. Geological Survey
Volcano and Earthquake Monitoring Plan 

for the Yellowstone Volcano Observatory, 2006-2015

By the Yellowstone Volcano Observatory

Scientific Investigations Report 2006-5276

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

Produced in the Western Region, Menlo Park, California

Manuscript approved for publication, October 18, 2006

Text edited by Peter H. Stauffer

Layout and design by Judy Weathers

U.S. Geological Survey, Reston, Virginia: 2006

This report and any updates to it are available online at:

http://pubs.usgs.gov/sir/2006/5276/

For product and ordering information:

World Wide Web: http//www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information contact:

Yellowstone Volcano Observatory

Mail Stop 910 

U.S.Geological Survey

345 Middlefield Road

Menlo Park, CA 94025

http://volcanoes.usgs.gov/yvo/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement of the U.S. Government.

 

FRONT COVER

The graphic shows the seismic network of Yellowstone National Park. Small black squares and associated letter codes are one-component stations, large dots are three-component stations, and stars 

are broadband stations. The FLWY station is maintained by the USGS/ANSS. Thick black line is the 

boundary of the Yellowstone Caldera. Thin black lines are roads. Gray outline is park boundary. Red 

regions are thermal areas.
iii

Contents

Executive summary........................................................................................................................................1

1. Introduction and scope.............................................................................................................................1

2. Overall goals...............................................................................................................................................3

3. Current status of the Volcano and Earthquake Monitoring System..................................................3

3a. Seismic network .............................................................................................................................3

3b. Ground-deformation network.......................................................................................................4

3c. Gas, water, and thermal monitoring ............................................................................................5

4. Anticipated future volcano and earthquake monitoring needs for the Yellowstone 

volcanic field—a 10-year view ......................................................................................................7

4a. Proposed upgrades to seismic network.....................................................................................7

4b. Proposed upgrades to geodetic network...................................................................................9

4c. Proposed upgrades to gas, water, and thermal monitoring network ....................................9

4d. Data transfer and archiving..........................................................................................................9

4e. Nonpermanent monitoring (temporary experiments).............................................................10

5. Monitoring for hydrothermal explosions .............................................................................................10

5a. Introduction ...................................................................................................................................10

5b. Proposed instrumentation for a hydrothermal monitoring network ....................................10

6. Summary....................................................................................................................................................11

Appendix 1. Locations and names of monitoring stations ....................................................................12

Figures

1. Map of Yellowstone National Park and vicinity....................................................................................2

2. Map showing seismic network of Yellowstone National Park...........................................................4

3. Map showing GPS network of Yellowstone National Park.................................................................6

4. Map showing stream gages of Yellowstone National Park................................................................7

5. Map showing proposed new instruments to be added to the backbone 

volcano-monitoring network................................................................................................................8

6. Map showing potential hydrothermal monitoring network for Norris Geyser Basin...................11
Volcano and Earthquake Monitoring Plan for the 

Yellowstone Volcano Observatory, 2006-2015

By the Yellowstone Volcano Observatory1

Executive Summary

To provide Yellowstone National Park (YNP) and its 

surrounding communities with a modern, comprehensive 

system for volcano and earthquake monitoring, the Yellowstone Volcano Observatory (YVO) has developed a monitoring 

plan for the period 2006–2015. Such a plan is needed so that 

YVO can provide timely information during seismic, volcanic, 

and hydrothermal crises and can anticipate hazardous events 

before they occur. The monitoring network will also provide 

high-quality data for scientific study and interpretation of one 

of the largest active volcanic systems in the world. Among 

the needs of the observatory are to upgrade its seismograph 

network to modern standards and to add five new seismograph 

stations in areas of the park that currently lack adequate station 

density. In cooperation with the National Science Foundation 

(NSF) and its Plate Boundary Observatory Program (PBO), 

YVO seeks to install five borehole strainmeters and two tiltmeters to measure crustal movements. The boreholes would be 

located in developed areas close to existing infrastructure and 

away from sensitive geothermal features. In conjunction with 

the park’s geothermal monitoring program, installation of new 

stream gages, and gas-measuring instruments will allow YVO 

to compare geophysical phenomena, such as earthquakes and 

ground motions, to hydrothermal events, such as anomalous 

water and gas discharge. In addition, YVO seeks to characterize the behavior of geyser basins, both to detect any precursors 

to hydrothermal explosions and to monitor earthquakes related 

to fluid movements that are difficult to detect with the current 

monitoring system. Finally, a monitoring network consists 

not solely of instruments, but requires also a secure system 

for real-time transmission of data. The current telemetry 

system is vulnerable to failures that could jeopardize data 

transmission out of Yellowstone. Future advances in monitoring technologies must be accompanied by improvements in 

1

Attendees at the planning meeting and contributors to this publication 

include Jacob B. Lowenstern, Henry Heasler, Robert B. Smith, W. Arabasz, 

D. Bergfeld, S. Borenstein, R. Burcalu, P. Cervelli, W. Chang, B. Chouet, D. 

Drobeck, D. Dzurisin, W. Evans, J. Ewert, J. Farrell, K. Feaux, R. Fournier, 

C. Gardner, M. Guffanti, D. Hill, S. Hurwitz, C. Jaworowski, K. McGee, A. 

Moeinvaziri, L. Morgan, T. Murray, M. Nathenson, T. Olliff, D. Oppenheimer, 

C. Pankow, C. Puskas, J. Quick, D. Susong, G. Waite, and J. Wynn. J. Power 

and J. Dixon reviewed this plan.

the infrastructure for data transmission. Overall, our strategy 

is to (1) maximize our ability to provide rapid assessments 

of changing conditions to ensure public safety, (2) minimize 

environmental and visual impact, and (3) install instrumentation in developed areas.

1. Introduction and Scope

In 2001, the U.S. Geological Survey (USGS) 

joined forces with Yellowstone National Park (YNP) and 

the University of Utah to form the Yellowstone Volcano 

Observatory (YVO). This organization builds upon a 40-

year program of geologic monitoring and related research at 

Yellowstone by the USGS and the University of Utah. YVO 

provides the park with critical capabilities, acting as a partner 

that can operate modern monitoring facilities, has the expertise 

to scrutinize seismic and ground deformation signals, and 

can rapidly assess the significance of geologic processes that 

may threaten visitors to Yellowstone. YVO gives the park 

the capability to respond rapidly to geologic hazards and a 

mechanism for answering requests for information from park 

management, civil-defense authorities, the media, and the 

public. For YVO to fulfill its promise it must continue to build 

a modern, robust, and reliable monitoring system that provides 

effective and unobtrusive security for the park and its visitors.

Forty years of modern geologic research demonstrate 

the need for vigilant monitoring to observe and interpret 

signals from the Earth and to anticipate hazardous geologic 

events before they occur. In the past two million years, 

Yellowstone (fig. 1) has produced three of the largest volcanic 

eruptions on Earth. Debris from those events spread over 

much of the western and central United States. Since the last 

such eruption, 640,000 years ago, immense but relatively 

nonexplosive lava flows have filled the Yellowstone caldera. 

The hydrothermal system that fuels the park’s geysers can 

produce violent explosions, as it has numerous times in the 

past 15,000 years. Pocket Basin, Mary Bay, Turbid Lake, 

and Indian Pond all owe their origins to catastrophic boiling 

of shallow ground water, causing upheaval and ejection of 

megatons of rocks and debris. Thousands of earthquakes occur 

each year at Yellowstone. In 1959, the magnitude 7.5 Hebgen 

Lake earthquake, the largest historical earthquake in the 
Figure 1. Map of Yellowstone National Park and vicinity. Thick black line is the boundary of the Yellowstone Caldera. Thin 

black lines are roads. Gray outline is park boundary. Red regions are thermal areas. Dashed line shows state boundaries.

interior of the western United States, killed 28 people, caused 

millions of dollars in damage in the park and nearby towns, 

and dramatically changed many of the hydrothermal features.

All of the above geologic events can occur again at Yellowstone, and some likely will within the coming decades. A 

recent volcano hazards assessment by the USGS identified 

Yellowstone as a high-threat volcanic system with a monitoring system that is not commensurate with the potential volcanic 

threat (report available at http://pubs.usgs.gov/of/2005/1164/). 

Similar volcanic systems, such as Long Valley Caldera (California) and Campi Flegrei (Italy), pose similar hazards but are 

monitored by more modern and complete monitoring systems. 

Those systems provide society with insights into the dynamics 

of magma bodies like that beneath Yellowstone. The monitoring 

system at Yellowstone can and should be upgraded to detect the 

subtle precursory changes that are likely to occur before hazardous events so that there can be adequate advance notice to the 

park and the surrounding communities.

On November 9 and 10, 2005, YVO convened a special 

planning meeting to define a series of goals that would ensure 

that Yellowstone, its visitors, and neighboring communities 

are protected by a modern earthquake and volcano monitoring 

system. This document summarizes the results of the meeting, 

including monitoring goals and the equipment needed to attain 

them. Though cost or environmental constraints may preclude 

full implementation of the plan, it is nonetheless important to 

communicate the limitations of the current monitoring system 

and the identified avenues for improvement.

   Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015
3. Current Status of the Volcano and Earthquake Monitoring System   

2. Overall Goals

The Yellowstone volcano and earthquake monitoring 

system should:

a. Detect earth signals that indicate changes in the 

magmatic system that underlies Yellowstone. These 

signals include earthquakes, deforming ground, and 

increased heat, gas, or water flow.

b. Provide rapid notification to park and local 

authorities in the surrounding region about 

the location of damaging earthquakes, their 

magnitudes, and the likely extent of damage at 

different locations within the region.

c. Include the capability to monitor thermal basins so 

that we may detect precursors to hydrothermal 

explosions, which are a major long-term hazard 

within the park.

d. Enable the assessment of earthquake and volcanic 

hazards so that their impacts can be mitigated.

3. Current Status of the Volcano and 

Earthquake Monitoring System

Volcanologists have three principal methods for assessing 

volcanic activity. They evaluate the types, magnitudes, and 

locations of earthquakes; they observe and interpret uplift and 

subsidence of the ground surface; and they detect changes in 

the discharge of heat, water, and gases from volcanic terrain. 

All of these signals, plus others, are used together to assess 

developments at a volcano. The Yellowstone volcanic system 

has the additional characteristic that it is impacted by large 

earthquakes that occur as part of the mountain-building processes in the western United States. Therefore, the YVO monitoring network should also be able to rapidly characterize the 

amount of ground movement (and damage) from large regional 

earthquakes. The following sections provide a summary of the 

current monitoring system and its capabilities and weaknesses.

3a. Seismic Network

Currently, the University of Utah Seismographic Stations 

(UUSS) operates the Yellowstone seismographic network, 

with one additional station maintained by the USGS and its 

Advanced National Seismic System (ANSS). Most of the 

funding for the YVO network comes from the USGS, with 

some additional support through YNP and the National Science Foundation (NSF). There are three types of seismograph 

stations in the network. Single-component stations measure 

short-period (1-10 Hz) vertical ground motion but do not 

measure lateral movement; three-component stations yield 

data from both horizontal and vertical motions; broadband 

seismic stations are a type of three-component station that 

detects short-period energy as well as much longer waves that 

range over periods from one second to hundreds of seconds. 

The YVO network (fig. 2) consists of 26 seismograph stations, 

including 6 modern broadband stations, 3 three-component 

stations, and 17 older single-component stations. Of the 26 

seismometers, 20 are within the boundaries of Yellowstone 

National Park. The data are available in real time through 

the UUSS and YVO websites (http://www.seis.utah.edu/ and 

http://volcanoes.usgs.gov/yvo/.

When ground motions are intense, such as during a 

large earthquake, none of these systems can faithfully record 

the amount of shaking. Earthquake magnitudes can still be 

determined through use of distant seismograph stations, but the 

local effects, detailed locations, and ground accelerations of 

the earthquake cannot be accurately estimated. To address this 

need, seismologists co-locate accelerometers with broadband 

seismometers. These instruments record an additional three 

channels of ground-acceleration data that maintain the fidelity 

of signal size with large earthquakes. Seismic networks with 

accelerometers can determine the intensity of local shaking. If 

there were multiple accelerometers at Yellowstone, the UUSS 

could produce a ShakeMap within seconds of an earthquake 

and make it available to emergency managers, enabling them in 

to predict locations that have suffered the most damage and to 

deploy emergency-response resources appropriately. Currently, 

however, there are no accelerometers deployed at Yellowstone.

One of the key elements of successful volcano monitoring is calculating both the location and depth of the small 

earthquakes that can accompany ascent of magma through the 

crust. A rule of thumb is that instrument spacing for this purpose should be no more than twice the depth of the earthquake. 

In other words, to reliably estimate the depth of an earthquake 

at 2 km, one would need station spacing of less than 4 km. For 

Yellowstone, that would require a 25x25 grid of seismic stations, or 625 seismometers! Clearly, this is not feasible from an 

environmental, economic, or personnel standpoint, but it points 

out the challenge in monitoring a volcano as large as Yellowstone. The actual spacing of seismic stations within the park 

averages about 18 km. Stations are more narrowly spaced in 

northwest portions of the park and are sparser in other regions.

All YVO seismometers are located at the ground surface. 

Modern seismic networks often include several downhole seismometers, instruments placed in boreholes to avoid environmental noise such as wind, traffic, and other signals present at 

the Earth’s surface. 

Because of the reduction of noise, such instruments provide highly improved data relative to surface instruments and 

can detect much smaller earthquakes.

A final consideration is that detection of some types of 

volcanic earthquakes requires modern equipment now only 

partially implemented at Yellowstone. Movement of volcanic 

fluids (magma and hot water and gas) can cause long-wavelength vibrations that are best detected with the newer broadband technology. Though we have not recorded any long-period 

earthquakes in Yellowstone, they may still be occurring, as we 

may not have the proper instrumentation to detect them.
 Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015

Figure 2. Seismic network of Yellowstone National Park. Small black squares and associated letter codes are onecomponent stations, large dots are three-component stations, and stars are broadband stations. The FLWY station is 

maintained by the USGS/ANSS. Thick black line is the boundary of the Yellowstone Caldera. Thin black lines are roads. 

Gray outline is park boundary. Red regions are thermal areas.

3b. Ground-Deformation Network

Ground deformation at Yellowstone is currently 

monitored through four principle techniques:

1. Continuous global positioning system (GPS), a 

satellite-based technique that provides frequent 

(daily or hourly) high-precision locations of 

individual receivers placed on monuments within 

the park (fig. 3); data are telemetered daily to YVO. 

This technique is critical for volcano monitoring 

because it yields high temporal resolution (frequent 

updates) and can therefore alert scientists to 

rapid ground movements that may accompany 

subterranean magma movement.

2. Interferometric synthetic aperture radar (InSAR), 

a satellite-based technique that provides one to 

two synoptic views per year of ground movement 

over the entire park. InSAR data are best collected 

during the summer months because the technique 

does not penetrate snow cover, which prevents 

reproducible measurement of changes in the 

elevation of the ground surface.
3. Current Status of the Volcano and Earthquake Monitoring System   

3. Campaign GPS surveys, in which GPS data are 

collected at many stations on an annual or less 

frequent basis using temporary deployments of GPS 

receivers. This increases the spatial coverage for 

which GPS data are available and provides more 

regional information than leveling.

4. Precise leveling that measures the vertical component 

of ground motion through labor-intensive surveying. 

The technique yields an annual or less frequent, highprecision determination of ground movement over 

one or more surveyed traverses.

InSAR data are processed annually by YVO staff and colleagues. Other YVO staff continue periodic leveling and GPS 

campaigns. Currently, the only permanent equipment required 

for techniques 3 and 4 are the small brass benchmarks, often 

located along roads, which serve as the points for comparison 

of ground movement.

YVO, through the University of Utah, operates six continuous GPS stations at Yellowstone. Recently, the National Science 

Foundation (NSF), through its EarthScope program and with 

help from the University of Utah, installed six new GPS stations on the ground as part of their Plate Boundary Observatory 

(PBO) project, bringing the total number of GPS stations at Yellowstone to 12. PBO has funding for three more GPS stations 

within the park and eight additional stations in areas surrounding the park. These new stations will add critical information to 

the YVO monitoring database. All of the GPS data are available 

in near-real time via the Internet at the UNAVCO data center, a 

nonprofit company partially funded through NSF.

Other techniques for volcano monitoring include downhole strainmeters and tilt-meters, but these are not currently 

deployed at Yellowstone. EarthScope’s PBO has funding to 

install five strainmeters at Yellowstone within the next three 

years (2006-2008). Strainmeters are sensitive instruments that 

are carefully sealed within drill holes and typically located 

300-600 feet beneath the ground surface. They detect very 

slight rock motions that can correspond to regional tectonic 

activity, magma intrusion, or groundwater flow. The instruments are so sensitive that they can detect nanostrain events, 

equivalent to shrinkage or expansion of the United States by 

the thickness of a poker chip (0.5 cm). The instruments excel 

at the detection of transient motion of the Earth at time scales 

intermediate between that of seismometers and GPS receivers. 

For example, ground movements with periods of hours to days 

can easily be seen with strainmeter data. PBO strainmeter 

installations include three-component seismometers, waterlevel gages, and thermometers as well as the actual strainmeter. As such, they can provide highly improved monitoring 

capabilities for YVO.

Like a carpenter’s level, tiltmeters provide information 

on very slight changes in slope angle, such as can occur during episodes of ground deformation. Tiltmeters are typically 

installed in shallow (~10-30 m) boreholes and are useful when 

deformation occurs rapidly. Compared with GPS results, 

which are typically calculated once per day, tilt data provide 

a continuous stream of data sampled every few seconds. The 

instruments are relatively inexpensive and easily deployed. 

In the 1980s (as part of a Ph.D. thesis project) tiltmeters were 

installed at Yellowstone in five shallow (30 m) boreholes near 

park developments. Though the instruments have since been 

removed, new instruments could be re-deployed in the existing 

holes. Tiltmeters are not as sensitive as strainmeters, but are 

simple, reliable, and easy to install.

3c. Gas, Water, and Thermal Monitoring

Volcanic eruptions are typically preceded by increases in 

the amount of heat and gases discharged from the Earth above 

the rising magma. Such changes can occur months, weeks, 

or only days before an eruption. In some cases, the gas may 

indicate the presence of new magma that will never reach the 

surface. Identification of increased discharge of volcanic gases 

is critical in differentiating regional seismic events from those 

involving new magma. Another reason to monitor gas concentrations and fluxes is because volcanic and geothermal gases 

are toxic, and can occasionally accumulate to lethal concentrations at or near the ground surface. Worldwide, there have 

been thousands of deaths from volcanic gases within the past 

30 years, including 1,800 human deaths at Lake Nyos, Cameroon, in 1986. At Yellowstone, although animals occasionally die from toxic-gas inhalation, only one human death (in a 

construction pit) has been clearly related to toxic gases since 

the park’s founding.

The flow of heat and thermal water are two other parameters that can yield insight into the underlying magma system. By 

measuring the discharge of groundwater from Yellowstone, and 

measuring the dissolved components, one can infer the amount 

of thermal water escaping to the surface. Some scientists have 

suggested that the flow of thermal water may be linked to uplift/

subsidence cycles of the Yellowstone Caldera and that the deep 

migration of fluids may actually cause uplift and subsidence.

The following monitoring techniques for gas, water, and 

heat are currently employed at Yellowstone:

1. Gas: As of May 2006, there are no installed sensors 

at Yellowstone to measure either the concentration 

or flux of geothermal gases. The USGS undertakes 

annual to biennial programs of airborne gas 

monitoring, in which low-flying airplanes map the 

concentration of gases within plumes discharged 

from thermal basins. These flights usually take place 

for two days, often in the spring. Other research is 

undertaken by individual researchers with collection 

permits who sample gases, usually on an annual basis.

2. Water: Eleven stream gages are located within 

Yellowstone National Park to measure the flow 

of river water and, in some cases, its temperature 

(fig. 4). Such information is used by biologists and 

climatologists as well as geologists. YNP supports 

the network through its geothermal monitoring 
Figure 3. GPS network of Yellowstone National Park. Black triangles and associated letter codes are existing GPS 

stations. Blue triangles are planned GPS stations. Thick black line is the boundary of the Yellowstone Caldera. Thin 

black lines are roads. Gray outline is park boundary. Red regions are thermal areas.

program. YNP also coordinates a chlorideflux program that combines the stream-gage 

measurements with chemical analysis of the waters 

to determine the amounts of volcanogenic materials 

dissolved in river waters. There are currently no 

sensors installed to provide continuous data on 

any aspect of water chemistry. Other studies of 

Yellowstone waters are undertaken by individual 

researchers with collection permits who sample 

waters, usually on an annual basis. 

3. Heat: Heat flow is estimated through the chloride 

flux program (see discussion above) and through 

occasional airborne missions equipped with infrared 

sensors. The YNP geothermal monitoring program 

has recently initiated annual flights to characterize 

changes in the heat discharge of thermal basins that 

could be due to volcanic, tectonic, or human-caused 

changes. Heat is also estimated at numerous point 

sources with thermistors linked to field data-loggers 

that are regularly downloaded by park staff. The data 

are only retrieved periodically (every few months) 

but provide useful monitoring of changes in the 

temperature of pools and in ground temperature. 

Occasionally, the field loggers fail prior to data 

downloading, resulting in days or weeks of lost data.

   Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015
4. Anticipated Future Volcano and Earthquake Monitoring Needs for the Yellowstone Volcanic Field 

Figure 4. Stream gages of Yellowstone National Park. Numbers correspond to stations in appendix 1. Thick black 

line is the boundary of the Yellowstone Caldera. Thin black lines are roads. Gray outline is park boundary. Red 

regions are thermal areas.

4. Anticipated Future Volcano and 

Earthquake Monitoring Needs for the 

Yellowstone Volcanic Field—A 10-

Year View

In this section we outline proposed additions and 

upgrades to the YVO “backbone” network, which monitors the 

entire park through a distributed network (see fig. 5).

4a. Proposed Upgrades to Seismic Network

1. Upgrade 10 of the single-component seismometers 

to modern broadband stations. The upgrade would 

also include accelerometers and telemetry for six 

channels of data. Such technology would allow 

YVO to locate earthquakes more precisely and to 

provide detailed information about local ground 

movements to emergency responders. The upgraded 

stations would also enable researchers to better 
 Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015

Figure 5. Proposed new instruments to be added to the backbone volcano-monitoring network. See text for details. 

Thick black line is the boundary of the Yellowstone Caldera. Thin black lines are roads. Gray outline is park boundary. 

Red regions are thermal areas.

discriminate between tectonic earthquakes and 

earthquakes that involve significant movements of 

hydrothermal or magmatic fluid.

2. Add as many as five new seismograph stations to 

poorly monitored regions within the park. This would 

permit YVO to locate small earthquakes in remote 

areas. Currently, earthquakes are preferentially 

detected in the northwest part of the park because 

of the greater density of seismic stations in that area 

(potential sites include Thorofare, East Entrance, 

Northeast Entrance, Roaring Mountain, and 

northern west boundary). Both the East and 

Northeast Entrance sites were previously occupied 

by USGS seismic stations.

3. Install five three-component downhole 

seismometers in coordination with PBO’s 

installation of borehole strainmeters with waterlevel indicators. The high signal-to-noise ratio 

of downhole instruments will allow YVO to 

detect seismic signals that may go unnoticed 
4. Anticipated Future Volcano and Earthquake Monitoring Needs for the Yellowstone Volcanic Field 

with the current network. These stations are funded 

through the NSF but require permitting, as well 

as installation. Potential sites are in developed 

areas near Canyon, Norris, Madison Junction, Old 

Faithful, and Lake.

4b. Proposed Upgrades to Geodetic Network

1. Coordinate with PBO to install three continuous 

GPS stations (West Thumb, Roaring Mountain, 

and northern west boundary) and five borehole 

strainmeters, colocated with downhole seismometers. 

The GPS stations are funded through NSF and have 

been permitted by YNP, but they have not been 

installed as of May 2006.

2. Add two tiltmeter stations in existing boreholes in 

developed areas to provide capability of real-time 

monitoring of ground deformation. Such installations 

will be especially useful if strainmeter deployment is 

delayed.

3. Install small (24-inch) radar reflectors at a number 

of sites within the park above the level of the snow 

pack, so that InSAR data can be collected during the 

winter months and compared to previously collected 

data. This would allow monitoring of ground 

movement via satellite at many more locations than 

is possible with the continuous GPS stations. At the 

present time, this technique is still experimental, but 

it is possible that within the next few years a series 

of well-placed radar reflectors could considerably 

aid the YVO monitoring program. The reflectors can 

be camouflaged, and they require neither power nor 

associated telemetry.

4c. Proposed Upgrades to Gas, Water, and 

Thermal Monitoring Network

1. Install three or four continuous gas-monitoring 

stations that measure the concentrations of H2S and 

CO2 at waist-level in the air near active thermal 

areas. The data would ideally be telemetered to YVO 

staff in real time. These stations would serve several 

purposes. They would allow the park to determine 

the frequency with which concentrations of H2S and 

CO2 in the air reach unhealthy levels. They would 

provide information on relations between climatic 

factors (air temperature, wind speed, barometric 

pressure, and precipitation) and gas discharge over 

long periods. These data also would allow YVO to 

assess whether pulses of gas are emitted from the 

Yellowstone hydrothermal system, as opposed to a 

more continuous discharge.

2. Install three or four CO2 gas-flux monitoring stations 

where the rate of gas emission is measured directly. 

This would be done with either a flux chamber that 

periodically pumps CO2 through the soil into a gas 

analyzer or a weather station and CO2-air sensor 

using eddy covariance techniques to calculate 

discharge. Compared with the stations proposed 

in item 1 above, these techniques allow more 

quantifiable evaluation of gas discharge versus time 

and are more useful for volcano monitoring.

3. Add new stream gaging stations at the following 

locations: 

Firehole River above Midway Geyser Basin

Gibbon River near Norris 

Yellowstone River near Mud Volcano

Yellowstone River south of Yellowstone Lake

Boundary Creek

Bechler River 

These stations would collect data on water flow, but 

also on water and air temperature and precipitation. A 

few gages would have sensors to collect information 

on water chemistry, such as conductivity, pH, or 

selected anions. Theses sensors will allow analysis 

of the relative input of thermal fluid from different 

regions into the rivers of Yellowstone and could be 

used to track anomalous pulses of thermal fluids out 

of the subsurface.

4. Install at Norris a small network of temperature 

sensors in thermal pools, stream channels, and soils 

that is capable of data transmission to a central 

node. The data relays will permit YVO personnel to 

recognize when individual sensors are compromised 

and can prevent weeks or months of lost data. If the 

data can be transmitted in real time, they can provide 

insight into new or ongoing thermal events that 

currently are only recognized in hindsight.

In addition to the upgrades and additions described 

above, YVO would continue its current campaign of geochemical and thermal monitoring, including (a) annual gas flights 

with fixed-wing aircraft to calculate the CO2 discharge from 

geyser basins, (b) ground-based flux measurements with portable instruments, (c) geochemical sampling of water and gases 

from selected features, (d) annual infrared monitoring flights 

to detect long-term growth or shrinkage of thermal areas and 

(e) periodic reconnaissance of sub-lake-floor vent systems. 

4d. Data Transfer and Archiving

Most of the monitoring efforts proposed above will 

require real-time data transmission through FM radio, wi-fi, 

cellular, or satellite technologies. Combined with intelligent 
10 Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015

database systems, the data can be queried through the Internet 

by scientists, resource managers, emergency responders, and the 

general public. Without such technology, YVO will be unable to 

add new monitoring techniques or additional stations.

Currently, the YVO monitoring infrastructure is highly 

vulnerable to loss of data-transmission capabilities. For example, an earthquake affecting the integrity of the Mt. Washburn 

relays could cause YVO to lose 75 percent of its seismic and 

GPS data, resulting in loss of information on the nature of the 

event and any potential aftermath scenarios. Public safety at 

Yellowstone will best be ensured if YVO can build a robust 

data-transmission system, allowing multiple pathways for data 

out of the park. Potentially, satellite, radio, and wireless systems could all be used and so provide sufficient flexibility that 

data loss could be minimized during natural and man-made 

disasters. YVO needs to work with YNP, UUSS, the Department of the Interior, and private interests to create a secure, 

efficient and reliable data-delivery system.

4e. Nonpermanent Monitoring (Temporary 

Experiments)

The proposed permanent upgrades listed above will provide a more robust and reliable backbone for geophysical and 

geochemical monitoring of the Yellowstone system. However, 

much can also be learned from temporary deployments of dense, 

portable networks installed in key locations such as the Norris 

Geyser basin or the Firehole River basins. Such deployments 

could include any combination of seismometers, GPS stations, 

tiltmeters, temperature loggers, gas sensors, or other instrumentation. Experiments could last as little as a day or as much as a few 

months. The equipment can be installed with negligible visual 

impact and can be completely removed when the experiment is 

finished. We envision that many of the breakthroughs for understanding the Yellowstone magmatic and hydrothermal system 

may come from these short experimental deployments, done 

in concert with the backbone monitoring system. They may be 

especially useful for understanding short-term changes to thermal 

areas, precursors to hydrothermal explosions, or the links between 

earthquakes and disruption of hydrothermal activity.

5. Monitoring for Hydrothermal 

Explosions 

5a. Introduction

Other than earthquakes and landslides, hydrothermal 

explosions are the most prominent geologic hazard at Yellowstone that threatens park infrastructure and visitor safety. 

At least 20 large (>100 meters) craters owe their origin to catastrophic explosions of Yellowstone’s shallow boiling groundwater system during the past 15,000 years. It is estimated that 

small rock-hurling explosions occur somewhere in the park 

almost every year. Most are not reported or go unnoticed for 

years because they occur in backcountry settings. Others have 

been described in some detail (for example, explosions at the 

Excelsior, Porkchop, Black Opal, Semicentennial, Sapphire, 

and Echinus thermal features). Park visitors may be injured if 

they are present when Yellowstone’s thermal features begin to 

erupt explosively, and park infrastructure can be destroyed.

A variety of mechanisms have been proposed for hydrothermal explosions, including triggering by earthquakes, fluctuations 

in ground-water pressure due to climatic factors, thermal/pressure 

pulses arriving from depth, or a buildup of gas pressures. Whatever 

their cause, the responsible variables can be measured and may 

provide clear indications of increased instability of the geothermal 

system. Unfortunately, YVO’s regional (backbone) monitoring 

system is unlikely to detect localized precursors to hydrothermal 

explosions except at individual stations. A small local network 

of seismic stations and ground-deformation stations, combined 

with thermal and chemical monitoring, might provide sufficient 

data to provide warnings of upcoming hydrothermal explosions. 

Deployment of simple pressure and temperature sensors in existing ground-water wells could also be highly useful. Temperature 

increases were noted before the 1989 explosion of Porkchop 

Geyser, and real-time thermal monitoring might provide critical 

information about such local instabilities. Although there is no 

guarantee that any monitoring system could predict a hydrothermal explosion, the data provided after the explosion would almost 

certainly allow us to ascertain the conditions that contributed to the 

explosive event. Until Yellowstone’s thermal areas are instrumented at a basic level, we shall remain unaware of the conditions 

leading to hydrothermal explosions.

5b. Proposed Instrumentation for a Hydrothermal 

Monitoring Network

1. Add a network of at least three GPS stations in 

one or two selected thermal areas, such as Norris 

(fig. 6) and the Upper Geyser Basin, to assess the 

potential for detecting precursors to hydrothermal 

explosions and to determine the interdependence 

between regional deformation and hydrothermal 

activity. In the same area(s), add a network 

of at least three seismic stations to assess the 

potential for detecting precursory seismic signals 

to hydrothermal explosions and to determine the 

interdependence between regional earthquakes and 

hydrothermal activity.

2. Add a local temperature-sensor network (potentially 

the one proposed above in section 4c, item 4) to 

detect anomalous temperature increases in ground 

and water temperatures).

3. Add three new gas-flux measuring stations to assess 

changes in gas discharge related to disturbances, 

regional deformation, or hydrothermal explosions.

4. Add instrumentation in existing shallow wells to 

detect changes in the pressure and temperature of the 

local ground water (not shown in fig. 6).
6. Summary 11

Figure 6. Potential hydrothermal monitoring network for Norris Geyser Basin. The larger red dot by the Norris 

Museum is a base station for the thermal (temperature-logger) network. Thin black lines are roads. Small black dots 

are place-names.

5. Add two or three shallow tiltmeters to provide 

real-time indicators of crustal strain (not shown in 

fig. 6).

The above list outlines a skeletal monitoring system 

for a hydrothermal basin. No such network exists in the 

world today, and it is virtually certain that it would provide unequalled opportunities to determine the interactions 

between geothermal activity (ground-water flow, boiling, 

mineral reactions), regional tectonism (earthquakes and 

crustal strain), and magmatic processes (intrusion and gas 

discharge). Besides the scientific insights, it would offer a 

real hope of measuring and understanding precursory phenomena to hydrothermal explosions.

6. Summary

This plan outlines a series of steps for YVO to build and 

operate a reliable volcano and earthquake monitoring system 

that meets the expectations of society for public safety and 

allows for improved understanding of the Yellowstone volcano. 

It also recognizes the need to tread lightly on the Yellowstone 

ecosystem, minimizing new monitoring sites and keeping all 

others as unobtrusive as possible. By deploying innovative 

yet unobtrusive instrumentation, YVO strives to protect the 

public while educating it about Yellowstone’s active volcanic 

environment. YVO aims to meet the diverse needs of land and 

city managers, park visitors, scientists, and society.
12 Volcano and Earthquake Monitoring Plan for the Yellowstone Volcano Observatory, 2006-2015

Appendix 1. Locations and Names of Monitoring Stations

Symbol Name, Location Lat Lon

Seismic Stations (DATUM: WGS84)

FLWY Flagg Ranch 44.0830 110.6990

LKWY Yellowstone Lake 44.5652 110.4000

MCID Moose Creek ID 44.1908 111.1838

YDC Denny Creek 44.7090 111.2400

YFT Old Faithful 44.4500 110.8360

YGC Grayling Creek 44.7960 111.1070

YHB Horse Butte 44.7500 111.1920

YHH Holmes Hill 44.7880 110.8510

YJC Josephs Coat 44.7600 110.3490

YLA Lake Butte 44.5130 110.2690

YLT Little Thumb Creek 44.4370 110.5870

YMC Maple Creek 44.7590 111.0060

YML Mary Lake 44.6050 110.6430

YMP Mirror Plateau 44.7400 110.1560

YMR Madison River 44.6690 110.9630

YMS Mt. Sheridan 44.2640 110.5280

YMV Mammoth Vault 44.9740 110.6890

YNR Norris 44.7160 110.6790

YPC Pelican Cone 44.6470 110.1920

YPK Parker Peak 44.7318 109.9214

YPM Purple Mountain 44.6570 110.8670

YPP Pitchstone Plateau 44.2667 110.8000

YSB Soda Butte 44.8840 110.1510

YTP The Promontory 44.3920 110.2850

YUF Upper Falls 44.7126 110.5118

YWB West Boundary 44.6060 111.1010

GPS Stations (DATUM: WGS84)

HVWY Hayden Valley 44.6137 110.5358

LKWY Lake Yellowstone 44.5651 110.4002

MAWY Mammoth Hot Springs 44.9770 110.6850

NRWY Norris 44.7155 110.6792

OFWY2 Old Faithful 44.4525 110.8413

P680 West Yellowstone 44.5984 111.0987

P709 Promontory 44.3914 110.2892

P711 Madison Junction 44.6356 110.8611

P716 Canyon 44.7183 110.5116

P720 Slough Creek 44.9259 110.3089

P721 NE Entrance 45.0030 110.0021

WLWY White Lake 44.6395 110.2866
Stream Gages (DATUM: NAD27)

1 Firehole River near West Yellowstone, MT 44.6202 110.8630

2 Gibbon River at Madison Jct 44.6405 110.8610

3 Madison River near West Yellowstone, MT 44.6569 111.0683

4 Yellowstone River at Yellowstone Lake Outlet 44.5674 110.3808

5 Soda Butte Creek at Park Boundary at Silver Gate 45.0030 110.0019

6 Soda Butte Creek near Lamar Ranger Station, YNP 44.8683 110.1655

7 Lamar River near Tower Falls Ranger Station, YNP 44.9277 110.3938

8 Boiling River at Mammoth 44.9849 110.6891

9 Gardner River near Mammoth, YNP 44.9924 110.6913

10 Yellowstone River at Corwin Springs 45.1119 110.7944

11 Tantalus Creek at Norris Junction, YNP 44.7330 110.7150

12 Falls River above Yellowstone Canal near Squirrel, ID 44.0630 111.1461

13 Snake River above Jackson Lake at Flagg Ranch, WY 44.0891 110.6947

14 Firehole River at Old Faithful, YNP 44.4597 110.8224

Appendix 1 13