OPEN-FILE REPORT 2005-1164 

An Assessment of Volcanic Threat and Monitoring

Capabilities in the United States:

Framework for a NNational VVolcano EEarly WWarning SSystem 

NVEWS

John W. Ewert, Marianne Guffanti, and Thomas L. Murray

U.S. Geological Survey 

April 2005 
TABLE OF CONTENTS 

Executive Summary........................................................................................... 3 

Introduction...................................................................................................... 6 

• Table 1. Eruptions and notable unrest since 1980 

• Figure 1. Map of U.S. volcanoes, observatories, and CUSVO partners 

• Figure 2. Volcano monitoring schematic 

• Sidebar 1. Mount St. Helens Reawakens 

Volcanic Threat Assessment: Analysis of Hazard and Risk Factors......................... 14 

• Table 2. List of hazard and exposure factors used in the NVEWS 

 threat assessment 

• Figure 3. Distribution of overall threat scores for U.S. volcanoes 

with unrest scores superimposed 

• Figure 4. Distribution of overall threat scores for U.S. volcanoes 

with aviation-threat scores superimposed 

• Table 3. Summary of volcanic threat by state 

• Table 4. Volcanoes, listed by state, in 5 threat groups with required 

level of monitoring indicated 

Gap Analysis for a National Volcanic Early Warning System.................................... 22 

• Table 5. Summary of current overall monitoring levels at U.S. volcanoes 

• Table 6. Results of monitoring-gap analysis 

• Figure 5. Map showing locations of NVEWS priority volcanic targets 

Implementation Framework.................................................................................. 30 

• Products and Outcomes of NVEWS 

• NVEWS Organizational Structure 

• General Equipment Needs of NVEWS 

• NVEWS Information Technology 

• 24X7 National Volcano Watch Office 

• NVEWS Coordination Mechanisms 

• Role of Research in NVEWS 

• External Grants Program 

• Next Steps for NVEWS 

• Figure 6. Proposed NVEWS model for data and information flow 

References Cited................................................................................................ 36 

Appendices 

1. Charter of the Consortium of U.S. Volcano Observatories and 

list of participants in meetings to formulate NVEWS, page........................................ 37

2. Explanation of hazard and exposure factors for NVEWS threat assessment........... 39

3. Scoring of NVEWS hazard and exposure factors for U.S. volcanoes....................... 48 

4. Guidelines for rating the current level of monitoring at U.S. volcanoes................... 56 

5. Ratings of current monitoring capabilities at for U.S. volcanoes............................ 59 

Cover photo: Mount St. Helens, Washington, reawakens on October 1, 2004. USGS photo.

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EXECUTIVE SUMMARY 

NVEWS – a National Volcano Early Warning System – is being formulated by the Consortium 

of U.S. Volcano Observatories (CUSVO) to establish a proactive, fully integrated, national-scale 

monitoring effort that ensures the most threatening volcanoes in the United States are properly 

monitored in advance of the onset of unrest and at levels commensurate with the threats posed. 

Volcanic threat is the combination of hazards (the destructive natural phenomena produced by a 

volcano) and exposure (people and property at risk from the hazards). 

The United States has abundant volcanoes, and over the past 25 years the Nation has 

experienced a diverse range of the destructive phenomena that volcanoes can produce. 

Hazardous volcanic activity will continue to occur, and – because of increasing population, 

increasing development, and expanding national and international air traffic over volcanic 

regions – the exposure of human life and enterprise to volcano hazards is increasing. 

Fortunately, volcanoes exhibit precursory unrest that if detected and analyzed in time allows 

eruptions to be anticipated and communities at risk to be forewarned with reliable information in 

sufficient time to implement response plans and mitigation measures. 

In the 25 years since the cataclysmic eruption of Mount St. Helens, scientific and technological 

advances in volcanology have been used to develop and test models of volcanic behavior and 

to make reliable forecasts of expected activity a reality. Until now, these technologies and 

methods have been applied on an ad hoc basis to volcanoes showing signs of activity. 

However, waiting to deploy a robust, modern monitoring effort until a hazardous volcano 

awakens and an unrest crisis begins is socially and scientifically unsatisfactory because it forces

scientists, civil authorities, citizens, and businesses into “playing catch up” with the volcano, 

trying to get instruments and civil-defense measures in place before the unrest escalates and 

the situation worsens. Inevitably, this manner of response results in our missing crucial early 

stages of the volcanic unrest and hampers our ability to accurately forecast events. Restless 

volcanoes do not always progress to eruption; nevertheless, monitoring is necessary in such 

cases to minimize either over-reacting, which costs money, or under-reacting, which may cost 

lives. 

Volcano monitoring in the U.S. is conducted by five volcano observatories, supported primarily 

by the USGS Volcano Hazards Program. Under the Stafford Act, the USGS is responsible for 

issuing timely warnings of potential volcanic disasters to the affected populace and civil 

authorities. To make maximum use of the Nation’s scientific resources, the USGS operates the 

observatories with the help of universities and other governmental agencies, through formal 

partnerships. At present, about half of the most threatening U.S. volcanoes are monitored at a 

basic level with real-time sensors (primarily seismic arrays), and a few are well monitored with a 

suite of modern instrument types and methods. However, monitoring capabilities at many 

hazardous volcanoes are known to be sparse or antiquated, and some hazardous volcanoes 

have no ground-based monitoring whatsoever. 

Recognizing that there are potentially dangerous volcanoes within the United States and its 

Territories that have inadequate or no ground-based monitoring, the USGS Volcano Hazards 

Program, with CUSVO, is preparing a plan for a National Volcano Early Warning System 

(NVEWS). NVEWS is based on a systematic assessment of various hazard and exposure (risk) 

factors that are used to calculate a threat score for each U.S. volcano. The resultant scores 

permit a relative ranking of U.S. volcanoes into five threat groups from very high to very low. 

(The threat scores presented in this report are subject to change as new data on past eruptive 

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activity appear and/or as unrest develops and exposure factors change.) The level of 

monitoring called for by the threat assessment is compared to the current monitoring coverage 

at each volcano to identify those volcanoes with significant monitoring gaps that require 

improvements. The improvements should be implemented well in advance of the escalation of 

unrest with the aim of providing early detection of unrest and reliable forecasting of likely 

hazards. 

Based on the NVEWS analysis and volcanic activity as of April 2005, the highest priority targets 

for monitoring improvements are: 

• 5 volcanoes that currently are erupting (Mount St. Helens in Washington, Anatahan in 

the Mariana Islands, Kilauea in Hawaii) or exhibiting precursory unrest (Mauna Loa in 

Hawaii, Mount Spurr in Alaska). 

• 13 very-high-threat volcanoes with inadequate monitoring (9 in the Cascade Range and 

4 in Alaska).

• 19 volcanoes in Alaska and the Mariana Islands that have high aviation-threat scores 

and no real-time ground-based monitoring to detect precursory unrest or eruption onset. 

An additional 21 under-monitored volcanoes in Washington, Oregon, California, Hawaii, Alaska, 

the CNMI, and Wyoming also are priority NVEWS targets. The physical aspects of NVEWS 

involve installation of modern instrumentation arrays with data links to the volcano observatories 

and facilities of the CUSVO partners. Monitoring improvements at these volcanoes would entail 

new capital costs for equipment as well as recurring expenses for operation and maintenance 

and take several years to implement, requiring a substantial investment beyond the current 

resources of the USGS Volcano Hazards Program and its affiliated partners. 

Along with enhancing instrumentation capabilities, NVEWS proposes to institute a National 24x7 

Volcano Watch Office to improve alerting and forecasting capabilities and provide authoritative 

information on volcanic activity. Duties at the Watch Office would be shared among all the 

observatories in a distributed fashion. Implementing NVEWS and a National Volcano Watch 

Office will require significant investment in IT hardware and software to handle continuous 

archiving and sharing of data from monitoring networks. The IT system would increase interoperability among observatories and permit all data streams from monitored volcanoes to be 

accessed in real time at multiple locations. 

A fully implemented NVEWS, when combined with current monitoring capabilities, will provide: 

• A much richer body of observations and data on volcanic activity, as the basis for more 

reliable eruption forecasts and a range of derived information products from real-time 

graphical and map depictions of data to peer-reviewed research papers. 

• Minimized risk of a surprise eruption at a dangerous volcano. 

• Real-time hazard analysis and rapid event notification during periods of escalating

unrest and eruption at well-monitored volcanoes, aiming for 5-minute notification by 

volcano observatories to the FAA of major explosive eruptions. 

• The hardware, software, and networking infrastructure to enable scientists to view and 

analyze all data streams from monitored volcanoes in real time at multiple locations. 

• A National 24X7 Volcano Watch Office for full alerting capabilities and authoritative 

information about unrest and eruptive activity throughout the U.S. and more general 

situational awareness of volcanic activity globally. 

• A National Volcano Data Center to archive all the diverse kinds of NVEWS data. 

• An NVEWS web site with a daily status report covering all monitored volcanoes. 

• Efficient coordination of volcano-monitoring resources across agencies and institutions. 

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As a next step, the USGS Volcano Hazards Program will convene workshops to review and 

refine the proposed implementation framework. A workshop will be held with the full CUSVO 

membership and other scientific stakeholders to establish data and operational policies and 

launch topical working groups. At another workshop, a broader group including other Federal 

agencies, State and County emergency management agencies, and business and private 

organizations, will be consulted about their specific information requirements. 

One ought never to turn one's back on a threatened danger and 

try to run away from it. If you do that, you will double the danger.

But if you meet it promptly and without flinching, you will reduce 

the danger by half. 

Sir Winston Churchill

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INTRODUCTION 

This report presents an assessment of the Nation’s volcano monitoring needs based on the 

threats posed by the 169 geologically active U.S. volcanic centers listed in the global volcanism 

database of the Smithsonian Institution (Simkin and Siebert, 1994). In the past, the Volcano 

Hazards Program has measured its progress in volcano monitoring and hazard assessment 

against an estimate of 70 volcanoes that represent significant hazards to people and property. 

Results of this report constitute a major improvement to that earlier estimate by providing a 

comprehensive analysis of all U.S. volcanoes and determining the appropriate level of 

monitoring based on a systematic measure of the threats posed to lives and property. Although 

the total number of volcanoes representing the most significant hazards remains similar to the 

earlier estimate, this report identifies critical gaps in the Nation’s monitoring capability that 

should be used as a basis for charting the course and measuring the performance of the 

Volcano Hazards Program. 

Volcanoes produce many kinds of destructive phenomena. In the U.S. over the past 25 years, 

communities have been invaded by lava flows, a powerful explosion has devastated huge tracts 

of forest and killed people miles from the volcanic source, debris avalanches and mudflows 

have choked major river ways, destroyed bridges, and swept people to their deaths, noxious 

gas emissions have given rise to widespread lung ailments, airborne ash clouds have caused 

hundreds of millions of dollars of damage to aircraft and nearly brought down passengers jets in

flight, and ash falls have disrupted the lives and businesses of hundreds of thousands of people. 

The growing potential for such severe threats to communities, property, and infrastructure down 

stream and down wind of volcanoes drives the need to decipher the past eruptive behavior, 

monitor the current activity, and mitigate the damaging effects of these forces of nature. 

Volcanic eruptions can be anticipated in time to take preparatory actions. Unlike most other 

natural hazards, eruptions herald their coming over periods of days to years with various 

physical and chemical indicators (called “unrest”) related to the rise of magma toward the 

surface of the Earth. Modern instrumentation and data-processing techniques, combined with 

an understanding of the previous eruptive activity of a volcano, provide a means to monitor and 

interpret precursory signals – seismicity, ground deformation, gaseous emissions, thermal 

changes, and hydrothermal flux – and make forecasts of the expected hazards. Moreover, 

because the locations of volcanoes are known, the sources of the hazardous events can be 

anticipated well ahead of time. 

If a hazardous volcano is properly monitored with a diverse suite of instruments and methods in 

advance of the onset of unrest, it is possible to forewarn communities at risk of an impending 

eruption with reliable information and in sufficient time to implement specific response plans and 

mitigation measures. Waiting to deploy a proper monitoring effort until a hazardous volcano 

awakens and an unrest crisis begins means that scientists, civil authorities, businesses, and 

citizens are caught in a reactive mode of “playing catch up” with the volcano, trying to get 

instruments and civil-defense measures in place before the unrest escalates and the situation 

worsens. Precious time and data are lost in the weeks it can take to deploy a response to a 

reawakening volcano – time and data that the public needs and should have to prepare for the 

hazards they may be confronted with. A worst-case example of a failed “catch-up” scenario 

occurred in 1985 during the response to the unrest and eruption of Nevado del Ruiz in 

Colombia. At Ruiz, volcanologists were scrambling to install monitoring systems on the 

volcano, prepare hazards assessments, and educate the authorities and public about the 

looming danger. Ultimately, there was public notification that an eruption was in progress, yet 

over the course of the next several hours more than 23,000 people lost their lives, needlessly, 

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because adequate pre-event monitoring did not exist and linkage had not been established 

between scientists, public officials, and the community at risk (Voight, 1996). 

Volcanoes operate on individual time scales, some progressing to eruption very quickly (days to 

weeks), others needing months to a year or more. Not all unrest leads to eruptions, and 

interpreting the significance of unrest on a sustained basis is important so that communities and 

businesses can make informed choices without being either too apprehensive or too 

complacent about potential volcanic hazards. A fundamental benefit of long-term volcano 

monitoring is that by providing sound, long-baseline, scientific information to the public and 

emergency managers throughout unrest episodes, the twin problems of either over-reacting or 

under-reacting are minimized. 

The United States has abundant volcanism, both in terms of recent eruptions and episodes of 

unrest (Table 1). Based on the global volcanism database of the Smithsonian Institution 

(Simkin and Siebert, 1994; modified where new data are available), the U.S. is home to 169 

geologically active volcanoes – i.e., those that are erupting, have erupted recently or, if dormant, 

are young enough to be capable of reawakening (Figure 1). U.S. volcanoes occur in diverse 

tectonic settings and present a range of potential dangers depending on the manner in which 

they erupt and the communities and infrastructure within their reach. 

Volcano monitoring in the U.S. is conducted by five volcano observatories, supported primarily 

by the USGS Volcano Hazards Program (Figure 1). The observatories are located in distinct 

volcano-tectonic areas of the U.S., but staff and resources are shared among them. Under the 

Stafford Act (Public Law 93-288), the USGS has the responsibility to issue timely warnings of 

potential volcanic disasters to the affected populace and civil authorities. As part of this 

responsibility, the volcano observatories issue notices and warnings of conditions at monitored 

U.S. volcanoes on a regular basis or as often as warranted during eruptive periods (see 

http://volcanoes.usgs.gov/update.html). 

To make maximum use of the Nation’s scientific resources, the observatories partner with 

academia and other governmental agencies through various formal agreements. The 

Consortium of U.S. Volcano Observatories (CUSVO) was established in 2001 to promote 

scientific cooperation among the Federal, academic, and State agencies involved in observatory 

operations. The principal CUSVO members are the USGS, University of Washington, 

University of Alaska, University of Utah, University of Hawaii, Advanced National Seismic 

System, National Science Foundation's Plate Boundary Observatory, Alaska Division of 

Geology and Geophysics, and Yellowstone National Park. (Details of CUSVO’s charter and 

membership are given in Appendix 1). 

Other agencies contribute to volcano studies. NSF funds installation of geophysical instruments 

at some volcanoes for research projects, through its EarthScope Initiative as well as through its 

regular geoscience proposal process. Meteorological satellites operated by the National 

Oceanic and Atmospheric Administration (NOAA) provide important, near-real-time, remotesensing data used by the volcano observatories, and NOAA operates two Volcanic Ash 

Advisory Centers – in Washington DC and in Anchorage, Alaska – to track the dispersion of 

volcanic-ash clouds hazardous to aircraft. The Smithsonian Institution’s Global Volcanism 

Program supports volcano monitoring activities by maintaining a comprehensive database on 

the eruptive histories of volcanoes throughout the world, providing data that are critical input to 

forecasting the likely future activity of restless volcanoes. 

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Table 1. 45 eruptions and 15 cases of notable volcanic unrest have occurred at 33 U.S. volcanoes since 

1980. 

VOLCANO ERUPTION YEAR UNREST EPISODE 

Kilauea, Hawaii 1983-present 

Mauna Loa, Hawaii 

1984 2002-2004, inflation and deep 

seismicity 

Mt. St. Helens, 

Washington 

1980-1986, 2004-2005 1989-2003, occasional earthquake 

bursts, minor phreatic explosions, small 

mudflows 

Mt. Hood, Oregon Occasional earthquake swarms 

Three Sisters, Oregon Uplift began 1997; earthquake swarm 

March 2004 

Long Valley, California 

Recurrent earthquake swarms and uplift 

since 1980, CO2 emission from ground 

since 1989. 

Medicine Lake, California 1988-1989 earthquake swarm 

Yellowstone National Park 

Recurrent earthquake swarms and 

ground deformation (uplift & 

subsidence), changes in hydrothermal 

features 

Redoubt, Alaska 1989-1990 

Spurr, Alaska

1992 2004-2005 earthquake swarms and 

melt pit at summit 

Augustine, Alaska 1986 

Iliamna, Alaska

1996 earthquake swarm and elevated 

gas emission 

Veniaminof, Alaska 1983-1984, 1993-1995, 2004-2005 

Pavlof, Alaska

1980, 1981, 1983, 1986-1988, 1996-

1997 

Shishaldin, Alaska 1986-1987, 1995-1996, 1999 2004-2005 earthquakes and tremor, 

thermal anomalies 

Westdahl, Alaska 1991-1992 

Dutton, Alaska

1984 earthquake swarm; 1988 

earthquake swarm and intrusion 

Shrub Mud Volcano, 

Alaska 

1996-1999 carbon dioxide/mud eruption

Becharof Lake, Alaska 1998 earthquake swarm 

Chiginigak, Alaska 1997-1998 fumarolic activity

Akutan, Alaska 1980, 1987, 1988, 1992 Intense earthquake swarm and intrusion 

with ground cracks in 1996. 

Makushin, Alaska 1980 

Bogoslof, Alaska 1992 

Okmok, Alaska 1981, 1983, 1986-1988, 1997 

Cleveland, Alaska 1986, 1987, 1994, 2001 

Amukta, Alaska 1987, 1996? 

Seguam, Alaska 1992, 1993 

Korovin, Alaska 1987, 1998 

Kanaga, Alaska 1993-1995 

Gareloi, Alaska 1980, 1982 

Kiska, Alaska 1987? 

Pagan, Mariana Islands 1981-1996 

Anatahan, Mariana 

Islands 

2003-2005

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 Figure 1: Locations of volcanoes (red triangles), volcano observatories (gray stars), and affiliated 

cooperators (gray squares). Eruption styles, hazards, and risk vary greatly from place to place, and 

communication of natural hazards information to the public and local civil authorities is most effective

when it comes from locally accessible scientists with credible expertise. The observatory concept works 

well because it is at this regional or local level that volcanic systems can be adequately monitored and the

complex issues attendant to hazards mitigation can be addressed. The nation’s first volcano observatory, 

the Hawaiian Volcano Observatory (HVO), was founded in 1912 atop Kilauea Volcano on the island of

Hawaii; currently, HVO and its affiliated partner the University of Hawaii are tracking Kilauea’s 22-yearlong eruption. After the devastating eruption of Mount St. Helens in 1980, the USGS Cascades Volcano

Observatory (CVO) in Vancouver, Washington, was established in 1982 to continue long-term monitoring

and hazard assessment for Cascade Range volcanoes, in partnership with the University of Washington 

Geophysics Program and the USGS Northern California Seismic Network. Recurring unrest began in

1980 at the large Long Valley caldera in east-central California, and research and monitoring conducted

by the USGS and university community eventually led to formal organization of the Long Valley

Observatory (LVO) in 1999. After the 1986 eruption of Augustine Volcano, near Alaska’s major 

population center in the Cook Inlet, the Alaska Volcano Observatory was created as a partnership of the 

USGS, University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and 

Geophysical Surveys. Beginning in 1996, with new Congressional funding, AVO began an ambitious and

unprecedented effort to increase the number of monitored volcanoes in the remote Aleutian volcanic 

islands so that the aviation sector can be quickly informed of potential ash-cloud hazards. The 

Yellowstone Volcano Observatory (YVO) was established in 2001 by the USGS, University of Utah, and

Yellowstone National Park. YVO formalizes the long-term monitoring and geologic mapping of 

Yellowstone caldera, the largest volcanic system in North America and the world's first National Park. 

Since the eruption in 2003 of Anatahan Volcano in the Mariana Islands (a U.S. Commonwealth), 

monitoring of data telemetered from the volcano is shared by CVO, HVO, and LVO. 

9
At present, about half of the most threatening U.S. volcanoes are monitored at a basic level with 

real-time sensors (primarily seismic arrays), and a few are well monitored with denser networks 

involving a variety of instrument types. However, monitoring capabilities at many hazardous 

volcanoes are known to be sparse or antiquated, and some hazardous volcanoes have no 

ground-based monitoring whatsoever. 

Optimum volcano monitoring is achieved by integrating a combination of approaches employing 

ground-based, airborne, and remote-sensing techniques, rather than relying on any single 

method or class of methods. Real-time data from ground-based geophysical sensors, 

telemetered to a regional observatory, provide the continuous all-weather data required to 

correctly interpret volcanic unrest and accurately forecast the consequences. Satellite-based 

remote sensing can be useful in detecting long-term changes in conditions at a volcano and 

confirming eruptive activity. Integrating the various data streams that pertain to detecting and 

diagnosing volcanic activity nationally is one of the goals of this framework. 

Globally, institutions with the responsibility to monitor volcanic hazards and mitigate impacts 

face growing demand for rapid hazard analysis and real-time eruption reporting. This demand 

is exemplified by the aviation sector’s stated need that air traffic control centers be notified by a 

volcano observatory of an ash-producing eruption within five minutes of the start of the eruptive 

event (Salinas and Watt, 2004). This ambitious goal was met by the Cascades Volcano 

Observatory when Mount St. Helens reawakened in October 2004 because sufficient monitoring 

infrastructure was in place at the volcano (see Sidebar 1). In contrast, at Anatahan volcano in 

the Mariana Islands no real-time monitoring capability existed when the volcano unexpectedly 

erupted in 2003, and a distressingly long period of several hours elapsed before the eruption 

could be confirmed using images from meteorological satellite (Guffanti and others, 2005). 

Recognizing that there are potentially dangerous volcanoes within the United States and its 

Territories that have inadequate or no ground-based monitoring, the USGS Volcano Hazards 

Program and its CUSVO partners are preparing a plan for a National Volcano Early Warning 

System (NVEWS) to move beyond a reactive mode of mitigating volcanic risk and toward a 

proactive, fully integrated approach. NVEWS is based on a systematic assessment of the 

threats posed by each volcano coupled with an evaluation of its current monitoring capability. 

The assessment has identified which volcanoes in the U.S. need monitoring improvements. 

The improvements should be commensurate with the risks posed by a particular volcano and 

should be implemented well in advance of precursory unrest with the aim of providing early 

detection of unrest and reliable forecasting of likely hazards. 

Twenty-five years of scientific and technical accomplishments provide us with a solid base for 

such an assessment: 

• We have established five volcano observatories (Figure 1) in the U.S. to carry out a 

partnered program of long-term monitoring, and we have worked with USAID’s Office of 

Foreign Disaster Assistance to respond to numerous volcanic crises and build monitoring 

capabilities in other countries. 

• We have gained scientific experience with numerous episodes of volcanic unrest both 

foreign and domestic, many culminating in eruption, some not. We also have gained 

practical experience by interacting with emergency-management agencies as they make 

decisions affecting their constituencies. 

• Through detailed geologic field investigations, we have greatly expanded our knowledge 

about eruptive histories of major volcanoes in Alaska, Hawaii, and the Cascade Range. 

10
• We have identified new, acutely hazardous phenomena – such as the airborne-ash hazard 

to aviation, carbon-dioxide degassing from soils and lakes, far-reaching lateral blasts – and 

we have documented the full catastrophic scope of volcanic mudflows. 

• With this broader understanding of eruptive hazards, we have improved our ability to 

evaluate volcanic risk at different kinds of volcanoes in a variety of settings. 

• Technological advances, developed and proven at erupting volcanoes in the U.S. and 

abroad, have provided us with a rich variety of new volcano monitoring tools. Also, 

improvements in telemetry now permit large amounts of data to flow in real time from remote 

volcanoes to observatories for analysis and interpretation (Figure 2). 

This combination of diverse programmatic partnerships, greatly enhanced knowledge about the 

hazards and eruptive histories of U.S. volcanoes, global experience with volcanic unrest and 

eruptions, and technological advancements have set the stage for a more effective, proactive 

approach to living with volcanic hazards. In the following sections of this report, we explain our 

methodology for assessing volcanic threat, for rating the adequacy of monitoring currently in 

place at U.S. volcanoes, and for identifying the most serious monitoring gaps that should be 

filled as part of an effective National Volcano Early Warning System. 

The NVEWS methodology was developed at a series of meetings in 2004, convened by the 

USGS mostly as CUSVO meetings (Appendix 1). Non-USGS participants who reviewed the 

methodology in its formative stages are John Eichelberger (Univeristy of Alaska Fairbanks), 

Michael Jackson (UNAVCO), Steven Malone (University of Washington), Christopher Nye 

(Alaska Division of Geological and Geophysical Surveys), David Schmidt (University of Oregon), 

Robert B. Smith (University of Utah), and Donald Thomas (University of Hawaii).

. 

Figure 2: Volcano-monitoring methods are designed to detect changes in the state of a volcano caused

by magma movement beneath the volcano. Rising magma typically triggers swarms of earthquakes and 

other types of seismicity, causes swelling or subsidence of a volcano's edifice, and leads to the emission

of volcanic gases. By monitoring these and related phenomena, scientists can anticipate an eruption days 

to weeks ahead of time. Transmission of monitoring data occurs via radios, phone lines, internet, and/or

satellites from instruments installed at volcanoes to scientific facilities for processing and analysis. 

Automatic, computer-based data processing systems make most data available in real to near-real time

for analysis by scientists that may be located in different facilities. Interpreting monitoring data and

assessing the future behavior and eruptive potential of a restless volcano, however, is far from automatic

and requires complex analysis by a variety of volcanological experts as soon as the data are received. 

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SIDEBAR 1

MOUNT ST. HELENS REAWAKENS

 Scientists prepare to fly into the crater of Mount St. Helens (background, right), 3 Jan. 2005. 

 (USGS photo) 

 8 March 2005 eruption of Mount St.Helens, Washington. (USGS photo)

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After lying in repose for 18 years, Mount St. Helens volcano reactivated on 23 September 2004 with

a swarm of earthquakes and rapid deformation of the crater floor. Within days the volcano was

producing small steam and ash eruptions that led to the closure of a popular U.S. Forest Service

visitor center, and after only 18 days the first lava reached the surface. Although sufficient 

monitoring was in place to detect the obvious onset of unrest, much of the instrumentation and

telemetry infrastructure had been installed more than 20 years previously, and their limitations soon

became evident. For example, as earthquake activity increased many seismic signals went off

scale, which limited their diagnostic capabilities. Broadband seismometers for use at other restless

volcanoes were borrowed and hurriedly installed; however, data from these instruments was not

available in real time because the telemetry infrastructure for these new instruments was lacking. A 

single telemetered GPS station located 8 km north of Mount St. Helens recorded far-field

deformation that accompanied the onset of the initial earthquake swarm. Although additional

instruments were installed in cooperation with the NSF-EarthScope program, they could not be 

installed quickly enough to catch the deformation event, precluding our ability to determine with 

confidence the volume of magma potentaily involved with the current eruptive event. 

As additional instrumentation was installed at Mount St. Helens, the Cascades Volcano Observatory 

and CUSVO-partner University of Washington were in the position of playing catch up with the

volcano while a potentially hazardous situation unfolded under the scrutiny of the National media.

Even though working in a largely reactive mode at Mount St. Helens, scientists still had the 

advantages of responding to initial mildly explosive activity at a well-characterized volcanic system

with basic instrumentation already in place and in mild, early fall weather. These advantages cannot

be counted on should other U.S. volcanoes awaken, particularly in deepest winter. In those cases,

playing catch up will be very difficult. 

Two seismograms from the same earthquake measured by different instruments. Top panel is a clipped 

seismogram from a traditional short-period instrument where the amount of ground shaking has exceeded

the range of the instrument. Bottom panel is from a modern broadband instrument (at a slightly greater 

distance from the earthquake) which is responsive to a much larger range of shaking and thus less likely 

to clip. The broadband also can sense ground tremors that are too fast or too slow for the older shortperiod instruments. While short-period instruments are capable of locating earthquakes, broadbands are 

required to understand the physical processes at the source of the seismic signal. 

13
VOLCANIC-THREAT ASSESSMENT: 

ANALYSIS OF HAZARD AND RISK FACTORS

An underlying principle of NVEWS is that the degree and type of early-warning monitoring at a 

particular volcano should be commensurate with the threat it poses. Volcanic threat is the 

combination of hazards (the dangerous or destructive natural phenomena produced by a 

volcano) and exposure (the people and property at risk from the volcanic phenomena). 

Accordingly, our first step is a systematic assessment of various hazard and exposure factors – 

defined herein – at each U.S. volcano in order to have a consistent, objective basis for 

prioritizing an early warning system on a national scale. We calculate an overall threat score for 

each volcano by first assigning numerical values to the hazard and exposure factors; the 

individual factors are summed into a hazard score and an exposure score which are then 

multiplied to generate the volcano’s overall threat score. The resultant scores produce a 

relative ranking of U.S. volcanoes that we use to group them into five threat categories from 

very high to very low. 

A total of 169 US volcanic systems are evaluated. We have used the Smithsonian’s Global 

Volcanism Program’s (GVP) volcano reference file, which is the on-line successor to Simkin and 

Siebert (1994), as the source listing of geologically active volcanic centers in the United States. 

(http://www.volcano.si.edu/gvp/world/index.cfm). The GVP file includes volcanoes that currently 

are in an eruptive phase, have erupted in historical time, and those that have not erupted 

recently but are young enough (eruptions within the past 10,000 years) to be capable of 

reawakening. Among exceptions to the 10,000-year criterion in the GVP file is the large 

Yellowstone caldera system, which has not produced a purely magmatic eruption in the past 

10,000 years but shows obvious signs of unrest, has had geologically recent large steam 

explosions in areas that now have high visitor density, and has a large magmatic source at 

depth. 

Based on some recent radiometric dating results, we have omitted several volcanoes from the 

Smithsonian list. The omitted volcanoes are Ko`olao and Kaho`olawe, Hawaii, and Saddle 

Buttes, Oregon. Also omitted from our consideration are four deep submarine volcanoes off the 

Washington and Oregon coast and Loihi Volcano, Hawaii, whose great depths of more than 900 

m (3000 ft) below sea level negate most potential threats. Of these submarine volcanoes, Loihi 

which lies close by the Big Island of Hawaii is the subject of cooperative research endeavors by 

numerous groups; the USGS will continue to inform the broader research community of notable 

seismic activity at Loihi when detected by the HVO monitoring network. 

The NVEWS threat assessment is not a formal risk assessment of U.S. volcanoes. The latter 

requires that probabilities of particular hazards occurring at individual volcanoes within a set 

time period be calculated and that the vulnerability of people and property to the hazards be 

estimated as expected losses in dollars. Such an analysis for so many volcanoes is beyond the 

scope of this work, especially because our knowledge of eruptive histories of many U.S. 

volcanoes is not sufficient to determine solid probabilities of eruption-recurrence intervals. 

The approach taken in this report uses hazard and exposure factors that are general enough to 

be applied easily to most of the volcanoes. Also, there are sufficient factors such that the 

absence of data for one or two factors will not have an inordinately large effect on final individual 

scores. Table 2 lists the hazard and exposure factors used in the NVEWS threat assessment. 

The 15 hazard factors include volcano type, occurrence of unrest, the general frequency of past 

eruptions, and the tendency toward explosivity. Unrest factors include seismicity within 20 km 

14
of a volcano, deformation in response to magma intrusion or gross changes to an existing 

hydrothermal system, and degassing (e.g., fumaroles, thermal features, cold degassing of 

magmatic gases). The 10 exposure factors include population (both permanent and transient; 

Ewert and Harpel, 2004), aviation exposure, power generation/transmission, etc. A more 

detailed explanation of the factors is given in Appendix 2. 

Table 2. List of the 15 hazard and 10 exposure factors used in the NVEWS threat 

assessment and their scoring ranges. Detailed explanation of the factors is 

given in Appendix 2. 

Hazard Factors Scoring Ranges 

Volcano type 0 or 1 

Maximum Volcanic Explosivity Index 0 to 3 

Explosive activity in past 500 years? 0 or 1 

Major explosive activity in past 5000 years? 0 or 1 

Eruption recurrence 0 to 4 

Holocene pyroclastic flows? 0 or 1 

Holocene lahars? 0 or 1 

Holocene lava flow? 0 or 1 

Hydrothermal explosion potential? 0 or 1 

Holocene tsunami? 0 or 1 

Sector collapse potential? 0 or 1 

Primary lahar source? 0 or 1 

Observed seismic activity 0 or 1 

Observed ground deformation 0 or 1 

Observed fumarolic or magmatic degassing 0 or 1 

Total of Hazard Factors

Exposure Factors 

Log10 of Volcano Population Index (VPI) at 30 km 0 to 5.4 

Log10 of approximate population downstream or

downslope 

0 to 5.1 

Historical fatalities? 0 or 1 

Historical evacuations? 0 or 1 

Local aviation exposure 0 to 2 

Regional aviation exposure 0 to 5.15 

Power infrastructure 0 or 1 

Transportation infrastructure 0 or 1 

Major development or sensitive areas 0 or 1 

Volcano is a significant part of a populated island 0 or 1 

Total of Exposure Factors

Sum of all hazard factors X Sum of all exposure 

factors = Relative Threat Ranking

Scoring of hazard and exposure factors used to generate the threat scores is tabulated in 

Appendix 3. In addition to the overall threat score, the factors also are subtotaled to give a 

hazard score, exposure score, and an aviation-threat score for each volcano. The aviation 

score, which we use to help define threat groups, is the product of four hazard factors 

(maximum VEI, explosive activity in the past 500 years, major explosive activity in the past 5000 

years, and eruption recurrence) and the local and regional aviation exposure factors.

15
The overall threat score for each volcano is given in Table 6 in a later section of this report. The 

threat scores presented here are subject to revision as more information becomes available. 

How much we know about individual volcanoes varies greatly from one to another. The 

individual scores and hence the overall ranking are subject to change as new data on past 

eruptive activity appear and/or as unrest develops and exposure factors change. The ranking 

represents minimum scores for many volcanoes where past behavior and ages of explosive 

eruptions are poorly known. It also is important to keep in mind that the NVEWS threat ranking 

is a tool to guide long-term monitoring plans and is not a prediction of which volcano is most 

likely to awaken or erupt next. 

The distribution of overall threat scores, shown in Figure 3, is more informative than any 

individual score alone. The distribution exhibits a generally exponential decrease, from a value 

of 324 to 0. In Figure 3, the corresponding unrest score for each volcano is superimposed on 

the overall threat sequence. The maximum score possible for unrest at a volcano is 3; scores 

less than 3 may be the result of no data at un-instrumented volcanoes. The distribution of 

overall scores with aviation-threat scores superimposed is shown in Figure 4. Using these 

figures, we divide the distribution into five threat groups, from very high to very low: 

• 18 volcanoes comprise a group having VERY HIGH overall threat scores (324 to 123

points, volcanoes 1 through 18 in the ranking sequence). This segment of the 

distribution has a steep exponential rise in scores from point 18 to point 1. Two 

volcanoes in this group are erupting (Mount St. Helens in Washington and Kilauea in 

Hawaii), and all others have shown some signs of unrest since last erupting. 

• 37 volcanoes comprise a group having HIGH scores (113 to 64 points, volcanoes 19

through 55 in the sequence). At point 19 in the sequence, there is a step decrease in 

scores from the very-high group. In the high group, all but two volcanoes have shown 

signs of unrest since last erupting, and most of them have high aviation-threat scores. 

The lower bound of the group is defined by a change in slope of the distribution (less 

steep) after point 55 and an overall drop in aviation scores. 

• A group of 48 volcanoes comprise a group having MODERATE scores (63 to 30 points, 

volcanoes 56 through 103 in the sequence). The aviation threat scores remain 

significant on the whole; the lower bound of the group is defined by a marked decline in 

aviation-threat scores after number 103 in the sequence. 

• A group of 34 volcanoes comprise a group having LOW scores (30 to 6, volcanoes 104 

to 137 in the sequence); this is a transitional group between Moderate and Very Low 

scores. Aviation-threat scores continue to decline in this group. A few volcanoes in this 

group show one component of unrest (score of 1). 

• A group of 32 volcanoes comprise a tail of VERY LOW scores (6 to 0, volcanoes 138 

through 169 in the sequence. No unrest is observed in this group, and aviation scores 

are zero. 

16
Figure 3. Distribution of overall threat scores for 169 U.S. volcanoes (red) with unrest scores (blue) 

superimposed. See text for explanation of scoring and threat groupings. 

Figure 4. Distribution of overall threat scores for 169 U.S. volcanoes (red) with aviation scores 

(open diamonds) superimposed. See text for explanation of scoring and threat groupings. 

17
Table 3 gives an analysis of threat scores by state. The volcanic threat in the U.S. is generated 

by volcanoes in 12 states and the Commonwealth of the Northern Mariana Islands (CNMI). All 

the volcanoes in the very high and high threat groups are found in Alaska, California, 

Washington, Oregon, Hawaii, the CNMI, and Wyoming. Hawaii, Washington, and Wyoming are 

further noteworthy for having volcanoes that predominantly fall in the very high and high threat 

groups; some of these volcanoes lie in heavily visited National Parks (Hawaii Volcanoes 

National Park, Mt. Rainier National Park, and Yellowstone National Park). Alaska is notable for 

being home to about half of U.S. volcanoes, including the most volcanoes that erupt frequently 

and explosively. 

Table 3. Summary of volcanic threat by state. N is number of volcanoes; %N is 

percentage of the total of 169 volcanoes.. For each state, the number of 

volcanoes in each of the five threat groups (very high, high, moderate, low, very 

low) is given; the percentage of a state’s volcanoes that have a very high (VH) 

or high (H) threat level also is calculated. Recur=4 is the code for an eruptionrecurrence interval of 1-99 years and indicates the most frequently erupting 

volcanoes. Number of volcanoes in each state with eruptions having a volcanic 

explosivity index (VEI) greater than 3 in the past 500 years is tabulated in the 

last column.

STATE N %N VERY 

HIGH

HIGH (VH+H)/N 

as %

MOD LOW VERY 

LOW

RECUR 

=4

VEI>3/500 YR

 AK 90 53.3 5 26 34 31 22 6 22 29 

 CA 19 11.2 3 4 37 4 0 8 0 2 

 WA 7 4.1 4 1 71 0 2 0 1 1

 CNMI 13 7.7 0 4 31 4 3 2 4 2 

 OR 19 11.2 4 0 21 2 2 11 0 0

 HI 5 3.0 2 1 60 2 0 0 2 1 

 WY 1 0.6 0 1 100 0 0 0 0 0 

 UT 4 2.4 0 0 0 1 1 2 0 0 

 ID 4 2.4 0 0 0 0 4 0 0 0 

 NM 3 1.8 0 0 0 1 0 2 0 0 

 AZ 2 1.2 0 0 0 1 0 1 0 0 

 NV 1 0.6 0 0 0 1 0 0 0 0 

 CO 1 0.6 0 0 0 1 0 0 0 0 

Total 169 100 18 37 N/A 48 34 32 29 35

Table 4 lists volcanoes alphabetically by state, in the five threat groups. The very high threat 

group includes 10 Cascade Range volcanoes in Washington, Oregon, and California – Baker, 

Crater Lake, Glacier Peak, Hood, Lassen, Newberry, Rainier, Shasta, South Sister, St. Helens – 

whose explosive behavior and lahar potential can impact both large populations and extensive 

development on the ground as well as heavily traveled air-traffic corridors. In Alaska, the 

highest threat volcanoes are represented by Augustine, Redoubt and Spurr, which are located 

near the state’s major population center of Anchorage and its international airport, and

Makushin and Akutan, which are near towns, regional airports, and important fishing ports in the 

Aleutian Islands; all five volcanoes pose major hazards to busy air-traffic routes in the North 

Pacific. Kilauea and Mauna Loa on the Island of Hawaii, which are frequently active and 

18
capable of producing far-reaching and damaging lava flows, rate as very-high-threat volcanoes; 

Kilauea’s hazards also include the potential for explosive eruptions. The large Long Valley 

caldera system, which has exhibited recurring signs of unrest for more than two decades and is 

close to major resort development and transportation infrastructure, also falls in the very-highthreat group. 

The high-threat group includes numerous Alaskan volcanoes located throughout the State. 

Most pose a significant threat to aviation because of their frequent explosive behavior; many are 

also near smaller population centers and power or transportation infrastructures. The high 

threat group also includes four volcanoes in the Mariana Islands; one of those, Anatahan 

volcano, has been erupting intermittently since 2003. Yellowstone caldera also falls in the highthreat group, as do Hualalai volcano in Hawaii, Mount Adams in Washington, and Clear Lake, 

Medicine Lake, and Inyo Craters and Mono Craters in California. 

Volcanoes in the moderate threat group are spread throughout nine states and the Mariana 

Islands. Again, numerous Alaskan volcanoes fall in this group, primarily because of the ashcloud hazard to aviation. Volcanoes in the low- and very-low-threat groups are also are 

dispersed among several states; although eruptions at these volcanoes would not constitute a 

significant threat to people and property, the reawakening of any of them would present a 

valuable and unique scientific opportunity for volcanology, as well as a target for intense media 

and public attention. 

Table 4 also indicates for each threat group the commensurate level of monitoring that should 

be in place before the onset of an unrest crisis or eruptive activity. The most threatening 

volcanoes, those near communities and transportation infrastructure (ground and air) and with a 

history of frequent and violent eruptions, need to be well monitored in real time (Level 4) with an 

extensive suite of instrument types to detect the earliest symptoms of unrest and to reliably 

forecast behavior of the volcano. Waiting until unrest escalates to augment monitoring 

capabilities at these high-threat volcanoes puts people (including scientists in the field) and 

property at undue risk. Remote, isolated, or less frequently erupting volcanoes that 

nevertheless can pose hazards to air-traffic corridors require sufficient ground-based 

instruments to detect and track unrest (Level 3: basic real-time monitoring) so that other 

agencies responsible for enroute flight safety (elements of the Federal Aviation Administration 

and National Oceanic and Atmospheric Administration) can be kept apprised of the potential for 

explosive, ash-cloud-forming eruptions. Volcanoes that are unlikely to erupt in the near future 

and that pose little threat on the ground or in the air can be monitored by sparser networks and 

satellite surveillance (Levels 2 and 1). 

In the next section, we compare the monitoring capability currently in place at each volcano to 

the level of monitoring required by its threat score, with the objective to systematically ascertain 

where there are gaps in monitoring and to identify those volcanoes – in addition to currently 

erupting or restless ones – that are most in need of additional monitoring resources.

19
Table 4. U.S. volcanoes listed alphabetically by state in five threat groups, with required level of 

monitoring indicated. Threat groups are defined in the text using Figures 3 and 4. A fuller 

description of monitoring levels is given in Appendix 4.

THREAT GROUP REQUIRED MONITORING LEVEL 

VERY HIGH THREAT VOLCANOES

Alaska

Akutan, Augustine, Makushin, Redoubt, Spurr,

California

Lassen, Long Valley Caldera, Shasta 

Hawaii

Kilauea, Mauna Loa 

Oregon

Crater Lake, Hood, Newberry, South Sister 

Washington

Baker, Glacier Peak, Rainier, St. Helens 

HIGH THREAT VOLCANOES

Alaska

Aniakchak, Atka, Churchill, Dutton, Gareloi, Great Sitkin, 

Griggs, Hayes, Iliamna, Kaguyak, Kanaga, Katmai, 

Mageik, Martin, Novarupta, Okmok, Pavlof, Pavlof Sister, 

Seguam, Semisopochnoi, Shishaldin, Trident, UgashikPeulik, Veniaminof, Westdahl, Wrangell 

California

Clear Lake, Inyo Craters, Medicine Lake, Mono Craters 

Hawaii

Hualalai 

Mariana Islands

Agrigan, Alamagan, Anatahan, Pagan, 

Washington

Adams 

Wyoming

Yellowstone 

LEVEL 4: WELL MONITORED IN REAL TIME

Monitoring should provide the ability to track 

detailed changes in real-time and to develop, 

test, and apply models of ongoing and 

expected activity. 

• Seismic: 12-20 stations within 20 km of vent, 

including several near-field sites. Network includes 

numerous three-component stations and mix of 

other instrument types, including digital broadband 

stations, acoustic sensors, and accelerometers. 

Borehole instruments where practicable. 

• Deformation: Routine surveys along with sufficient 

continuous stations (GPS, tiltmeters, and/or 

borehole dilatometers) to track closely geodetic 

changes in space and time and do detailed source 

modeling. 

• Gas: Frequent airborne or campaign gas 

measurements. Arrays of continuous sensors and 

other types of gas measurements as appropriate for 

the volcano. 

• Hydrologic: Level-3 coverage along with real-time 

monitoring of hill-slope soil moisture, stream

discharge, etc., as appropriate. AFM systems for 

lahar detection where warranted. 

• Remote sensing: Level 3 coverage along with other 

data from pertinent satellite sensors (e.g., daily 

multi-channel, high-resolution thermal-infrared

images and frequent, high resolution, multi-channel 

visible images). Where practicable, continuous 

ground-based thermal imaging and Doppler radar 

coverage. 

MMMOOODDDEEERRRAAATTTEEETTTHHHRRREEEAAATTTVVVOOOLLLCCCAAANNNOOOEEESSS

Alaska

Adagdak, Amak, Amukta, Black Peak, Bogoslof, 

Chiginigak, Cleveland, Dana, Denison, Douglas, 

Edgecumbe, Emmons Lake, Fisher, Frosty, Kasatochi, 

Kialagvik, Kiska, Kukak, Kupreanof, Little Sitkin, Moffett, 

Recheschnoi, Roundtop, Sanford, Snowy Mountain, 

Steller, Tanaga, Ukinrek Maars, Vsevidof, Yantarni, 

Yunaska, 

Arizona

Sunset Crater 

California

Coso Volc. Field, Mono Lake Volc Field, Red Cones, 

Ubehebe Craters 

Colorado

Dotsero 

Hawaii

Haleakala, Mauna Kea 

Mariana Islands

Asuncion, Farallon de Pajaros, Guguan, Sarigan 

LEVEL 3: BASIC REAL-TIME MONITORING

Monitoring should provide the ability detect 

and track pre-eruptive and eruptive changes in 

real-time, with a basic understanding of what

is occurring. 

• Seismic: Network with 3-4 near-field stations and a 

total of at least six within 20 km of vent. 

• Deformation: Routinely repeated surveys. At least 

six continuous stations (GPS and/or tiltmeters) in 

vicinity of volcano. LIDAR-derived images available 

for active features. 

• Gas: Frequent airborne or campaign measurements 

of gas emissions (annually to monthly, as 

appropriate) along with support of 1-2 telemetered 

continuous sensors. 

• Hydrologic: Level-2 coverage along with 

continuous-sensing probes in features of primary

interest, including water wells. LIDAR-derived DEMs 

for lahar-runout modeling. cont’d.

20
(Moderate threat cont’d.) 

Nevada

Steamboat Springs 

New Mexico

Valles Caldera

Oregon

Bachelor, North Sister Field 

Utah

Black Rock Desert 

• Remote sensing: Level 2 coverage along with

routine use of multi-channel thermal-infrared data 

from ASTER-class satellite. Thermal and/or SAR 

overflights, as indicated by other monitoring data. 

Where practicable, remote video camera in 

operation. 

LOW THREAT VOLCANOES

Alaska

Bobrof, Buldir, Buzzard Creek, Carlisle, Chagulak, 

Davidof, Duncan Canal. Fourpeaked, Herbert, 

Ingakslugwat Hills, Isanotski, Kagamil, Koniuji, Nunivak 

Island, Segula, Sergief, Stepovak, St.Michael, Table 

Top-Wide Bay, Takawangha, Uliaga, Unnamed 

Idaho

Craters of the Moon, Hell’s Half Acre, Shoshone Lava 

Field, Wapi Lava Field 

Mariana Islands

Esmeralda Bank, Maug Islands, Ruby

Oregon

Belknap, Blue Lake Crater 

Utah

Markagunt Plateau 

Washington

Indian Heaven, West Crater 

LEVEL 2: LIMITED MONITORING FOR 

CHANGE DETECTION

Monitoring should provide the ability to detect 

and track activity frequently enough in nearreal time to recognize that anomalous activity

is occurring.

• Seismic: Regional network with 1-2 near-field

stations in place (within ~10 km of volcano). 

• Geodetic: Two or more surveys for establishing 

baseline. InSAR observations possible on summerto-summer basis. At least three continuous stations 

(GPS or tiltmeters) in vicinity of volcano. 

• Gas: Baseline of carbon-dioxide emission rate (or 

other gas as appropriate to the volcano). 

• Hydrologic: Comprehensive database on

temperatures and chemistry of springs and 

fumaroles. 

Remote-Sensing: Regular processing and review of 

near-real-time meteorological satellite images (AVHRR, 

GOES), and/or review of non-real-time research 

satellite images (e.g., MODIS) by an observatory. 

Baseline inventory of air photos and/or satellite images 

with high spatial resolution (1 m). 

VERY LOW THREAT VOLCANOES

Alaska

Behm Canal-Rudyerd Bay, Gordon, Imuruk Lake, 

Kookooligit Mountains, St. Paul Island, Tlevak StraitSuemez Island

Arizona

Uinkaret Field 

California

Amboy, Big Cave, Brushy Butte, Eagle Lake Field, 

Golden Trout Creek, Lavic Lake, Tumble Buttes, Twin 

Buttes 

Mariana Islands

Ahyi, Supply Reef 

New Mexico

Carrizozo, Zuni-Bandera 

Oregon

Cinnamon Butte, Davis Lake, Devils Garden, Diamond 

Craters, Four Craters Lava Field, Jackies Butte, 

Jefferson, Jordan Craters, Lava Mountain, Sand 

Mountain Field, Washington 

Utah

Bald Knoll, Santa Clara

LEVEL 1: MINIMAL MONITORING

Monitoring should provide the ability to detect 

that an eruption is occurring or that gross 

changes are occurring/have occurred near a 

volcano. 

• Seismic –Volcano lies within a regional network; 

no near-field stations are in place but at least one 

station is within 50 km of the volcano. Or, a single 

near-field station is present, but no regional

network exists. 

• Remote sensing - Baseline inventory exists of 

Landsat-class satellite images. Routine scans for 

eruption clouds are conducted by meteorological 

agencies. 

21
GAP ANALYSIS FOR A NATIONAL VOLCANO EARLY WARNING SYSTEM 

The NVEWS gap analysis – the method for determining the difference between the current level 

of monitoring at a volcano and the level called for by its threat score – is intended to be a tool for 

prioritizing monitoring targets in advance of the onset of unrest or eruption so that future 

instances of playing high-stakes catch up with a restless volcano are minimized. 

Current monitoring capabilities at U.S. volcanoes are rated on our ability to characterize ongoing

and expected activity during a potential unrest crisis based on the types, numbers, and 

proximity of monitoring instrumentation now in place at each volcano. Each of the primary 

monitoring methods – seismic, deformation, gas, hydrologic, and remote-sensing – is rated for 

each volcano using a scale from 0 to 4 (details of the scale are given in Appendix 4). Based on 

those ratings (which are tabulated in Appendix 5), an overall current monitoring level for each 

volcano also is assigned, again using a scale from 0 for no real-time ground-based monitoring 

to 4 for well monitored in real time. 

A breakdown of current overall monitoring levels by threat group (Table 5) gives a general 

indication that inadequacies in monitoring capabilities exist. Only three U.S. volcanoes (17% of

the 18 very-high-threat volcanoes) are well-monitored in real-time at Level 4: Mount St. Helens, 

Washington, which erupted catastrophically in 1980 and began a new eruptive phase in 2004; 

Kilauea, which has been erupting since 1983; and Long Valley caldera, California, which is a 

site of recurring unrest and also is the focus of many topical research studies utilizing instrument 

arrays. Nearly one quarter of the 37 high-threat volcanoes have minimal to no ground-based 

monitoring (11% at Level 1; 13% at Level 0). Moderate-threat volcanoes also have a significant 

proportion (33%) with no ground-based monitoring. The high percentages of low- and very-lowthreat volcanoes with Level 1 and Level 0 monitoring (85% and 100%, respectively) is 

reasonable, given their negligible threat potential. 

Table 5. Summary of current overall monitoring levels at U.S. volcanoes by 

threat groups. Percentages based on the number of volcanoes (N) in 

each threat group. 

Level 4

Well 

monitored 

Level 3

Basic real 

time 

Level 2

Limited 

Level 1

Minimal 

Level 0

No ground 

based 

Very High Threat 

(N=18) 

17% 33% 39% 11% 0% 

High Threat 

(N=37) 

0% 54% 22% 11% 13% 

Moderate Threat 

(N=48) 

0% 11% 29% 27% 33% 

Low Threat 

(N=34) 

0% 6% 9% 32% 53% 

Very Low Threat 

(N=32) 

0% 0% 0% 69% 31% 

22
To pinpoint which volcanoes are most in need of additional monitoring resources, the existing 

monitoring capability at each volcano is compared to the level of monitoring called for by its 

threat score. For each volcano, the value of the current overall monitoring level is subtracted 

from the value of the required level indicated in Table 4; the resulting number is a measure of 

the monitoring gap at that volcano. For example, the current overall monitoring level at Lassen 

Volcanic Center is at 2 but the needed level for such a high-threat volcano is 4, giving a 

monitoring gap of 2. Results of this monitoring-gap analysis for all U.S. volcanoes are given in 

Table 6. 

It should be noted again that the gap analysis is a tool for prioritizing monitoring targets in 

advance of the onset of unrest crisis or eruption. Accordingly, activity at the volcanoes that 

currently are erupting (Mount St. Helens, Kilauea, and Anatahan) or exhibiting heightened 

unrest (e.g., Mauna Loa, Mount Spurr) supersedes their particular monitoring gap analysis. An 

erupting or highly restless volcano will require a heightened monitoring response regardless of 

its ranking in the gap analysis; even a volcano with a low overall threat score may warrant a 

strong response to address a specific local threat or because scientific investigations there may 

reveal insights about eruptive behavior and hazards elsewhere. Moreover, as demonstrated by 

intense public and media interest in the recent reawakening of Mount St. Helens, eruptions are 

undeniably fascinating events that compel the attention of scientists and the public alike. 

Eruptions, particularly those in accessible locations, will not be ignored. 

Table 6: Results of NVEWS gap analysis. The monitoring gap for each volcano is determined by 

subtracting the value of the current monitoring level from the required monitoring level. 

Threat groups are color coded: very high threat is red, high is orange, moderate is yellow, 

low is blue, and very low is green. Gray highlighting indicates volcanoes that currently are 

erupting or showing heightened unrest (as of April 2005). 

Volcano State 

AviationThreat

Score 

Threat

Score 

Required 

Monitoring

Level 

Current 

Monitoring

Level 

Monitoring

Gap 

Kilauea HI 48 324 4 4 Eruption 

St. Helens WA 56 267 4 4 Eruption 

Rainier WA 35 244 4 2 2 

Hood OR 28 213 4 2 2 

Shasta CA 37 210 4 2 2 

South Sister OR 28 194 4 2 2 

Lassen Volcanic Center CA 31 186 4 2 2 

Mauna Loa HI 4 170 4 3 Unrest 

Redoubt AK 44 164 4 3 1 

Crater Lake OR 35 161 4 1 3 

Baker WA 14 156 4 2 2 

Glacier Peak WA 35 155 4 1 3 

Makushin AK 34 152 4 3 1 

Akutan AK 42 140 4 3 1 

Spurr AK 44 130 4 3 Unrest 

Long Valley Caldera CA 29 128 4 4 0 

Newberry Volcano OR 28 126 4 2 2 

Augustine AK 44 123 4 3 1 

23
Adams WA 14 113 4 2 2 

Veniaminof AK 42 109 4 3 1 

Yellowstone WY 24 107 4 3 1 

Iliamna AK 32 106 4 3 1 

Inyo Craters CA 29 106 4 2 2 

Shishaldin AK 37 104 4 3 1 

Kanaga AK 37 102 4 3 1 Wrangell AK 32 100 4 2 2 

Mono Craters CA 29 98 4 1 3 

Pavlof AK 32 95 4 3 1 

Ugashik-Peulik AK 37 93 4 3 1 

Hualalai HI 21 92 4 2 2 

Medicine Lake CA 18 92 4 2 2 

Pagan CNMI 28 91 4 0 4 Trident AK 27 90 4 3 1 

Katmai AK 27 90 4 3 1 

Great Sitkin AK 37 90 4 3 1 

Clear Lake CA 14 89 4 1 3 

Aniakchak AK 37 88 4 3 1 

Churchill AK 27 83 4 1 3 

Gareloi AK 37 82 4 3 1 

Anatahan CNMI 18 81 4 2 Eruption 

Agrigan CNMI 24 77 4 0 4 

Martin AK 21 75 4 3 1 

Mageik AK 21 75 4 3 1 

Novarupta AK 32 75 4 3 1 

Griggs AK 21 75 4 3 1 

Hayes AK 32 75 4 1 3 

Dutton AK 11 74 4 2 2 Westdahl AK 42 74 4 3 1 

Alamagan CNMI 24 72 4 0 4 

Atka AK 32 71 4 3 1 

Semisopochnoi AK 37 69 4 0 4 

Okmok AK 34 69 4 3 1 

Kaguyak AK 27 68 4 2 2 

Pavlof Sister AK 21 66 4 3 1 

Seguam AK 42 64 4 0 4 

Chiginagak AK 21 63 3 1 2 

Steamboat Springs NV 7 62 3 2 1 

Snowy Mountain AK 11 60 3 3 0 

Dana AK 27 59 3 1 2 

Kiska AK 30 58 3 0 3 

Roundtop AK 11 58 3 1 2 

Tanaga AK 21 57 3 3 0 

Vsevidof AK 30 56 3 0 3 

Mono Lake Volcanic Field CA 21 55 3 1 2 

Valles Caldera NM 18 55 3 2 1 

Kupreanof AK 16 55 3 1 2 

24
North Sister F

ield OR 21 54 3 1 2 

Edgecumbe AK 21 53 3 1 2 

Coso Volcanic Field CA 14 53 3 2 1 

Douglas AK 16 53 3 1 2 

Yantarni AK 27 52 3 0 3 

Frosty AK 11 52 3 2 1 

Ukinrek Maars AK 21 52 3 3 0 

Guguan CNMI 24 48 3 0 3 

Sarigan CNMI 18 48 3 1 2 

Little Sitkin AK 22 48 3 0 3 Fisher AK 32 48 3 3 0 

Recheschnoi AK 17 47 3 0 3 

Ubehebe Craters CA 14 46 3 1 2 

Black Peak AK 27 45 3 1 2 

Dotsero CO 12 45 3 0 3 

Kukak AK 11 45 3 2 1 

Haleakala HI 3 44 3 2 1 

Cleveland AK 26 43 3 0 3 

Emmons Lake AK 16 43 3 2 1 

Bachelor OR 7 42 3 2 1 

Moffett AK 5 38 3 2 1 

Adagdak AK 5 38 3 2 1 

Denison AK 11 38 3 2 1 

Steller AK 11 38 3 2 1 

Red Cones CA 1 36 3 3 0 

Amukta AK 26 34 3 0 3 

Bogoslof AK 26 34 3 0 3 

Kialagvik AK 11 34 3 0 3 

Amak AK 16 33 3 0 3 

Sanford AK 5 33 3 1 2 

Mauna Kea HI 2 33 3 2 1 Farallon de Pajaros CNMI 16 32 3 0 3 

Asuncion CNMI 16 32 3 0 3 

Sunset Crater AZ 15 32 3 2 1 

Kasatochi AK 21 32 3 0 3 

Black Rock Desert UT 14 32 3 1 2 

Yunaska AK 26 30 3 0 3 

Carlisle AK 17 30 2 0 2 Fourpeaked AK 5 30 2 2 0 

Isanotski AK 5 29 2 3 -1 

Kagamil AK 13 26 2 0 2 Takawangha AK 5 25 2 3 -1 

Bobrof AK 5 24 2 2 0 

St. Michael AK 11 23 2 0 2 

Segula AK 9 21 2 0 2 

Blue Lake Crater OR 7 21 2 1 1 

Ingakslugwat Hills AK 9 18 2 0 2 

Nunivak Island AK 9 18 2 0 2 

25
Maug Islands CNMI 8 16 2 0 2 

Koniuji AK 5 16 2 0 2 

Sergief AK 5 16 2 0 2 

Hell's Half Acre ID 1 14 2 1 1 

Stepovak AK 2 14 2 0 2 

Buldir AK 4 13 2 0 2 

Chagulak AK 4 13 2 0 2 

Herbert AK 4 13 2 0 2 

Uliaga AK 4 13 2 0 2 

Craters of the Moon ID 0 12 2 2 0 

Unnamed AK 5 12 2 0 2 

Indian Heaven WA 0 11 2 1 1 

Davidof AK 4 11 2 0 2 

West Crater WA 1 10 2 1 1 

Markagunt Plateau UT 7 10 2 1 1 

Shoshone Lava Field ID 1 10 2 1 1 

Belknap OR 0 9 2 1 1 Table Top-Wide Bay AK 1 8 2 0 2 Wapi Lava Field ID 0 8 2 1 1 

Duncan Canal AK 1 7 2 0 2 

Buzzard Creek AK 2 7 2 1 1 

Ruby CNMI 0 6 2 1 1 

Esmeralda Bank CNMI 0 6 2 1 1 

Carrizozo NM 0 6 1 0 1 

Zuni-Bandera NM 0 6 1 0 1 

Santa Clara UT 0 5 1 1 0 

Jordan Craters OR 0 4 1 0 1 

Gordon AK 0 4 1 0 1 

Eagle Lake Field CA 0 4 1 1 0 

Big Cave CA 0 4 1 1 0 

Twin Buttes CA 0 4 1 1 0 

Davis Lake OR 0 4 1 1 0 Tumble Buttes CA 0 4 1 1 0 

Lavic Lake CA 0 4 1 1 0 

Brushy Butte CA 0 4 1 1 0 Washington OR 0 3 1 1 0 

Amboy CA 0 3 1 0 1 

Sand Mountain Field OR 0 3 1 1 0 

Jefferson OR 0 3 1 1 0 

Bald Knoll UT 0 3 1 1 0 

Cinnamon Butte OR 0 3 1 1 0 

Uinkaret Field AZ 0 3 1 1 0 

St. Paul Island AK 0 3 1 1 0 Tlevak Strait-Suemez Is. AK 0 3 1 1 0 Four Craters Lava Field OR 0 3 1 1 0 

Imuruk Lake AK 0 3 1 1 0 

Lava Mountain OR 0 3 1 1 0 

Devils Garden OR 0 3 1 1 0 

26
Diamond Craters OR 0 2 1 1 0 

Jackies Butte OR 0 2 1 0 1 

Golden Trout Creek CA 0 2 1 1 0 

Kookooligit Mountains AK 0 2 1 0 1 

Behm Canal-Rudyerd Bay AK 0 0 1 0 1 

Ahyi CNMI 0 0 1 0 1 

Supply Reef CNMI 0 0 1 0 1 

Based on the NVEWS analysis summarized in Table 6 and volcanic activity as of April 2005, the 

HIGHEST PRIORITY TARGETS for monitoring improvements are: 

• 5 volcanoes that currently are erupting (Mount St. Helens, Anatahan, Kilauea) or 

exhibiting heightened unrest (Mauna Loa, Mount Spurr). 

• 13 very-high-threat volcanoes with some but inadequate monitoring: This group 

includes 9 volcanoes in the Cascade Range that are significantly under-monitored (gaps 

of 2 or 3; viz. Rainier, Hood, Shasta, South Sister, Lassen, Crater Lake, Baker, Glacier 

Peak, Newberry). Cascade volcanoes do not erupt frequently, but they threaten major 

populations and development. Winter is harsh at the elevations of these volcanoes, 

making an unplanned response to unrest very difficult much of the year. Also in this 

group are 4 volcanoes in Alaska with monitoring gaps of 1 (viz. Redoubt, Makushin, 

Akutan, Augustine). 

• 19 high- and moderate-threat volcanoes in Alaska and the CNMI that have high aviationthreat scores (>15) and no real-time ground-based monitoring at the present time: 

USGS notices of escalating unrest or eruption are part of an international system to 

avert encounters of aircraft with dangerous volcanic-ash clouds (Miller and Casadevall, 

2000). With no real-time ground sensors at a volcano, timely evidence of a volcano’s 

precursory unrest will be lacking. Depending on the remoteness of the volcano, even 

eruption reports may be delayed, as was the case with the surprise eruption in 2003 of 

Anatahan volcano in the Mariana Islands. Hours elapsed from the eruption’s onset to 

the issuance of the first warning to aviation of ash in the atmosphere; luckily, no 

damaging encounters of aircraft occurred during that dangerous period. The 19 targeted 

volcanoes are Semisopochnoi, Seguam, Kiska, Vsevidof, Yantarni, Little Sitkin, 

Recheschnoi, Cleveland, Amukta, Bogoslof, Amak, Kasatochi, and Yunaska in Alaska, 

and Pagan, Agrigan, Alamagan, Guguan, Farallon de Pajaros, and Asuncion in the 

CNMI. 

Additional HIGH PRIORITY TARGETS include: 

• 11 high-threat volcanoes with that are significantly under-monitored (gaps of 2 and 3). 

This group includes Mount Adams in Washington; Inyo Craters and Mono Craters in 

California; Hualalai in Hawaii; Medicine Lake and Clear Lake in California; Wrangell, 

Churchill, Hayes, Dutton and Kaguyak in Alaska. 

• 9 moderate-threat volcanoes that have high aviation-threat scores and minimal groundbased monitoring (gaps of 2 in Table 6). These are Dana, Black Peak, Chiginigak, 

Edgecumbe, Kupreanof, and Douglas in Alaska, Mono Lake Volcanic Field in California, 

North Sister Field in Oregon, and Sarigan in the CNMI. 

• 1 under-monitored high-threat caldera system that also experiences large tectonic 

earthquakes, specifically Yellowstone caldera. The magnitude 7.5 Hebgen Lake 

earthquake occurred on the periphery of the Yellowstone volcanic system in 1959. The 

fact that this system also hosts earthquake hazards not strictly of volcanic origin 

indicates the need for close collaboration between NVEWS and the Advanced National 

27
Seismic System. (Another caldera with large tectonic earthquakes is Long Valley 

caldera in California; four magnitude 6 earthquakes occurred on its periphery as recently 

as 1980. Long Valley caldera is a very-high-threat center but currently is considered to

be well monitored.) 

Low- and very-low-threat volcanoes are not NVEWS priorities at this time. Such volcanoes 

should at least be covered by a regional seismic network (28 are not; monitoring level of 0 in 

Table 6), but given that the threats posed are minor and resources are limited, response to any 

signs of reawakening would be on a case-by-case basis. 

NVEWS priority volcanic targets are dispersed throughout the United States and the Mariana 

Islands (Figure 5). The requisite monitoring improvements would be achieved most efficiently 

by proceeding on multiple regional fronts each year, thus spreading the work out among the 

various volcano observatories. On an annual basis, specific work plans must be developed that 

take into account various factors. Technological constraints (e.g., telemetry infrastructure in 

remote locations) may limit monitoring options or require considerable advance planning. 

Permits for access to Wilderness Areas and National Parks must be obtained in advance from 

land managers. Physical terrain and weather (e.g., on high, glacier-clad stratovolcanoes) can 

alter scheduled instrument installation and maintenance. A cluster of volcanoes may be 

efficiently monitored as a unit, even if some of the individual volcanoes are of lower threat. 

Occasionally, opportunities arise to partner efficiently with another group (e.g., NSF-funded 

scientists) working at a particular volcano. Certainly, volcanoes showing new/escalating unrest 

or eruptive activity would become high-priority targets. And it is important to note that some 

volcanoes not listed as priorities nevertheless still require an investment of monitoring resources 

for routine maintenance and upgrades. 

28
Figure 5. Locations of volcanoes that are NVEWS priority targets for monitoring improvements. 

See text for volcano names. 

29
IMPLEMENTATION FRAMEWORK 

A proposed framework is outlined here to give an overview of the issues related to future 

implementation of a National Volcano Early Warning System. 

Products and Outcomes of NVEWS 

The physical aspects of NVEWS involve installation of modern monitoring arrays with data links 

to observatory facilities of the USGS and CUSVO partners. In addition, NVEWS would create a 

common information technology (IT) infrastructure for coordinating the collection and 

dissemination of data among all relevant federal agencies, academic partners, and the general 

public. 

A fully implemented NVEWS, when combined with current monitoring capabilities, would 

provide: 

• A much richer body of observations and data on volcanic activity, as the basis for more 

reliable eruption forecasts and a range of derived information products from real-time 

graphical and map depictions of data to peer-reviewed research papers. 

• Minimized risk of a surprise eruption at a dangerous volcano. 

• Real-time hazard analysis and rapid event notification during periods of escalating

unrest and eruption at well-monitored volcanoes, aiming for 5-minute notification by 

volcano observatories to the FAA of major explosive eruptions. 

• The hardware, software, and networking infrastructure to enable observatory and 

affiliated scientists to view and analyze all data streams from monitored volcanoes in

real time at multiple locations. 

• A National 24X7 Volcano Watch Office for full alerting capabilities and authoritative 

information about unrest and eruptive activity throughout the U.S. and more general 

situational awareness of volcanic activity globally. 

• A National Volcano Data Center to archive all the diverse kinds of data produced by 

NVEWS. 

• An NVEWS web site with a daily status report covering all monitored volcanoes, with

graphics and plots of monitoring data and links to other related sites. 

• Efficient coordination of volcano-monitoring resources across agencies and institutions. 

NVEWS Organizational Structure 

NVEWS would be implemented under the existing observatory-based structure of the USGS 

Volcano Hazards Program and affiliated CUSVO partners. The observatories would continue to 

be the focal points for data gathering and analysis, information dissemination, and forecasting 

activity, just as they are now. The strength of the current system is that observatory staff meets 

directly with local emergency-response officials to explain the pertinent data and ensure that all 

parties understand the significance of hazard assessments and forecasts; the importance of 

face-to-face professional relationships for such matters cannot be overestimated. 

NVEWS is an opportunity to develop a higher degree of inter-operability between scientific 

groups than currently exists. Using recent advances in IT and high-speed data transmission, 

NVEWS would institute the hardware, software, and networking infrastructure to permit data 

streams from monitored volcanoes to be accessed with a common suite of data-analysis tools in

real time at multiple locations. We propose that development of data-analysis and datamanagement tools be guided by a CUSVO IT working group under a broader NVEWS 

coordinating committee. Enhanced inter-operability will greatly aid both crisis response and 

30
research as scientists from different locations and specialties will be able to collaborate more 

easily on projects or form small teams to address larger issues.

General Equipment Needs of NVEWS 

Volcanoes are complex systems that are monitored with a variety of geophysical, geochemical, 

and geospatial sensor systems (such as seismometers, GPS stations, tiltmeters, borehole 

strainmeters, microbarometers, gas sensors, lahar detectors, Doppler RADAR, stream and 

precipitation gauges, weather satellites, etc.). Addressing inadequacies and gaps in monitoring 

would require a substantial investment over the next decade beyond the current resources of 

the USGS Volcano Hazards Program and its affiliated partners. The needed monitoring 

improvements would entail new capital costs for equipment and recurring expenses for 

operation and maintenance and take several years to implement. 

Some equipment needs of NVEWS can be met by instrument arrays funded by the National 

Science Foundation as part of its Earthscope Program. As part of Earthscope’s Plate Boundary 

Observatory (PBO) projects, installation of strain-measuring instruments (GPS stations, 

tiltmeters, borehole strainmeters, and borehole seismometers) is planned at a few volcanoes 

that are also NVEWS targets. Already, PBO accelerated the planned deployment of GPS 

stations to augment the monitoring effort at Mount St. Helens when the volcano resumed activity 

in 2004. Wherever there are joint interests, NVEWS plans will be closely coordinated with plans 

of PBO (or similar groups) to eliminate duplication and ensure efficient use of governmentfunded resources. 

Improvements to telemetry infrastructure also must occur along with an increase in monitoring 

instrumentation. Robust, broadband data transmission infrastructure is necessary to reliably 

carry data from the various instrument types at the volcanoes to the observatories and partner 

institutions. For example, in areas without straightforward terrestrial radio telemetry or access 

to telephone lines, more use of Very Small Aperture Terminal (VSAT) satellite communications 

systems will be needed to carry large volumes of data generated by seismic and other sensors. 

Over the next few years, we can expect to see new technological developments in telemetry 

systems that should be exploited for volcano monitoring. 

In the event that an under-monitored volcano becomes restless before NVEWS can be fully 

implemented, or an eruption occurs at an unlikely volcano, a cache of instruments needs to be 

available for immediate deployment. A limited cache of instruments was used to help with the 

recent monitoring response at Mount St. Helens, but a much more extensive cache is needed to 

deal with volcanoes that reawaken but lack adequate monitoring infrastructure. Some 

equipment in the cache would be rotated into permanent installations and then directly replaced; 

other items in the cache would be one-of-a-kind instruments to be deployed as needed then 

returned to the cache (e.g., portable Doppler RADAR, certain kinds of airborne gas sensors). 

Deploying instruments from a cache wastes time and does not fulfill the basic NVEWS goal of 

optimal data collection and earliest warning, but it does serve as a critical safeguard for 

monitoring capability when needed. 

NVEWS Information Technology

The advances in Information Technology (IT) over the past 10 years are staggering. Raw 

computing power and storage capabilities combined with lower costs provide, what were until 

recently, improbable amounts of data and analytical computational power to a scientist. Equally

impressive are the advances in data transmission that make it possible to view data in almost 

real-time, almost anywhere on the planet. 

31
NVEWS proposes to take advantage of these IT advances by implementing a framework to 

store and access NVEWS data, which will require enhancing efforts to establish common data 

formats and common database schemas, as well as acquiring the hardware and software for 

the system. As this framework is established, software programmers will work with scientists to 

develop the next generation of visualization and analysis tools. These tools will encompass 

tasks from the routine (displaying simple time-series data from a seismometer, for instance) to 

the complex (real-time modeling of deformation data). NVEWS data come from a wide variety 

of sources including field instruments operated by the volcano observatories, field instruments 

operated by groups outside the observatories, maps compiled by a variety of sources over 

decades, existing reports and photographs, and remote sensing data collected by satellites, to

name just a few sources. NVEWS would organize these disparate data in such a way that they 

are readily and reliably available for scientific analysis. 

With the implementation of standard formats, techniques, and tools – as recommended by the 

National Research Council review in 2000 of the USGS Volcano Hazards Program – the 

observatories would become the basis of a national system of inter-operating nodes such that 

resources can be quickly focused where needed during crises and teams of scientists can easily 

create formal or informal work groups no matter where they are geographically located. A 

conceptual model of the proposed NVEWS IT system is presented in Figure 6. 

Data storage – in terms of both the quantity and the diversity of data collected – is a major issue 

for NVEWS. Each observatory-related data center now collects on the order of 10 gigabytes of 

data each day, and under NVEWS this number would increase 5 to 10 times. The bulk of the 

data is from the real-time geophysical networks and from a variety of satellite-based sensors. In 

addition to the real-time data is a skyrocketing amount of video and digital photography. At the 

present time, the amount of data is swamping the existing IT infrastructure. 

The NVEWS model recognizes the need for greater computational power at each observatory 

data center and broadband connections for rapid data transmission between them. To address 

this, NVEWS would establish the necessary online data servers where the data are collected. 

Rather than fight the natural flow of information to an observatory from its networks, each 

observatory data center would maintain several servers capable of holding 10’s of terabytes of 

data and the ability to add more. NVEWS would establish standard technologies for these 

servers to acquire, store, and serve data to scientists. Standard interfaces and databases will 

enable developers to produce tools that can be used at all observatories. This degree of interoperability will permit the efficient operation of a 24X7 Volcano Watch Office (see below). 

For long-term data archiving, NVEWS would take advantage of the several existing centers that 

have been set up by the various scientific communities for specific data where staff are 

dedicated to tracking data storage in a systematic manner. For example, GPS data can be 

archived through UNAVCO, seismic data at one of several data centers (e.g., IRIS or UCBerkeley), and satellite data at the USGS Eros Data Center among other groups. However, 

there is no existing institution that is set up to archive all of the diverse kinds of data that the 

NVEWS will produce. Such a volcano data archive (a National Volcano Data Center) could be 

established within one of the CUSVO member institutions to provide a single portal to volcanic 

data rather than requiring researchers to go the different archives to assemble the data set they 

need. The volcano-data archive may still draw on data stored at the other discipline-specific 

archive centers, but it will simplify retrieval and integration of those data with other data sets. 

32
24X7 National Volcano Watch Office 

NVEWS proposes to institute a National 24X7 Volcano Watch Office to improve alerting 

capabilities and provide authoritative information on U.S. volcanic activity and greater situational

awareness of volcanic activity globally. A Volcano Watch Office does not supersede or replace

existing observatories but instead complements them by providing a true 24X7 capability,

replacing the system of alarms, pagers, answering services, assigned checks of data from

home during nonbusiness hours, etc. currently used by the observatories. The Watch Office

cannot be detached from the observatories as a stand-alone entity. It is to be an arm of each

observatory in order to insure that significant changes in volcanic activity are detected quickly

and appropriate action taken. However, the Volcano Watch Office can take advantage of the

enhanced inter-operability of observatories possible under NVEWS by sharing watch duties 

among all the observatories in a distributed fashion. Watch Office staff also should be able to 

contribute to other tasks related to expansion of monitoring networks and development of IT 

systems. The National Volcano Watch Office would complement the National Earthquake 

Information Center (NEIC), NOAA’s Pacific and Alaska Tsunami Warning Centers, and pertinent 

DoD operations. 

Figure 6A. Proposed model for data and information flow through an observatory under NVEWS. Data 

collected locally and from non-observatory collaborators flow into the observatory data servers. NVEWS 

staff, both inside and outside the observatory, accesses the data using common tools and protocols. 

 

33
Figure 6B. Proposed model of NVEWS data and information flow to data centers and general research 

community. Individual volcano observatories and the Volcano Watch Office maintain data holdings at 

their facilities for their own use. Copies of the data are sent to national centers where they are archived 

and available for public use. For data with no suitable national center, NVEWS proposes to establish a 

National Volcano Data Center (NVDC) to hold and distribute these data. Additionally, the NVDC would 

provide portals to all data, whether on NVDC servers or elsewhere, for users interested in acquiring 

integerated data sets specific to volcanology. 

NVEWS Coordination Mechanisms 

We propose that an NVEWS coordinating committee be established under CUSVO to develop a 

full implementation plan. Coordination with NSF-funded projects will take place primarily 

through EarthScope committees, in particular the Science and Education Committee, Facilities 

Executive Committee, EarthScope/PBO Standing Committee, and PBO Magmatic Systems Site 

Selection Committee. Some CUSVO members already serve on or advise these committees, 

and a PBO representative is a member of CUSVO. 

Regional seismic networks that are operated to track earthquake hazards also provide data 

about volcano seismicity in some areas, and vice versa. Accordingly, NVEWS will coordinate 

development of its seismic networks with the Advanced National Seismic System (ANSS). The 

administration of ANSS is along regional lines – Alaska, Hawaii, Washington/Oregon, California, 

and Yellowstone – that can mesh sensibly with the volcano-observatory structure of NVEWS. 

34
NVEWS also will rely on ongoing activities that use Synthetic Aperture Radar (SAR) 

interferometry to monitor deformation at volcanoes. USGS scientists have access to data from 

European Space Agency SAR satellites and, in collaboration with NASA and with the Alaska 

Satellite Facility at the University of Alaska, have access to SAR data from the Canadian 

Radarsat satellite. Access to future Japanese SAR data will also be coordinated through the 

Alaska Satellite Facility. 

Major interagency coordination is necessary to issue real-time hazard warnings about volcanicash clouds to the aviation sector. Much of that coordination is done through the NOAA’s Office 

of the Federal Coordinator for Meteorology (OFCM), specifically the Volcanic Ash Working 

Group which has representation from the USGS, NOAA, FAA, NASA, DOD, and Smithsonian 

Institution. NVEWS will continue to use that venue for coordination of its relevant activities. 

Role of Research in NVEWS 

Research on volcanic processes is integral to volcano-monitoring activities and is conducted by 

the USGS, as well as by the academic community. Observations from monitoring networks are 

used to formulate and test models of volcanic behavior so that unrest can be interpreted more 

definitively and forecasts improved. Monitoring without research into the driving physicochemical processes becomes mechanistic pattern recognition, an inadequate approach to 

phenomena as complex as volcanoes. Research and experience in the 25 years since the 

1980 eruption of Mount St. Helens has brought volcanology to a point where, with adequate 

monitoring systems in place, the timing of volcanic eruptions can be forecast with some 

confidence hours to days in advance. The next first-order scientific goal for volcanology is to be 

able to accurately forecast the style and magnitude of eruptions. NVEWS will help achieve this 

goal by creating a much richer body of observations and data on volcanic activity and 

eliminating barriers that impede the use of monitoring data for innovative and multi-disciplinary 

scientific research. 

External Grants Program

To augment its knowledge base, NVEWS proposes a competitive, peer-reviewed program to 

award research grants to entities in academia and the private sector for investigations 

coordinated with and complementary to NVEWS activities. This initiative would more directly 

incorporate the Nation’s volcanological expertise in academia. NSF does not have a program 

devoted specifically to volcanology, nor are the practical aspects of monitoring and volcanohazard assessment the main focus of NSF-funded projects. The USGS Volcano Hazards 

Program could administer such a grants program. We propose that 10-15% of new funding for 

NVEWS be devoted to an external grants program. 

Next Steps for NVEWS 

As a next step, the USGS Volcano Hazards Program will convene workshops to review and 

refine the implementation framework proposed here. A workshop will be held with the full 

CUSVO membership and other scientific stakeholders to establish data and operational policies 

and launch topical working groups. At another workshop, a broader group including

representatives from other Federal agencies (such as the National Oceanic and Atmospheric 

Administration, Federal Aviation Administration, National Park Service, Department of 

Homeland Security, and National Science Foundation), State and County emergency 

management agencies, and business and private organizations, will be consulted about their 

specific information requirements. 

35
REFERENCES CITED 

Ewert, J.W. and Harpel, C.J., 2004, In harms way: population and volcanic risk, Geotimes, v. 49 

n.4, p. 14-17. 

Guffanti, M., Ewert, J. W., Swanson, G., Gallina, G., and Bluth, G., 2005, The volcanic-ash 

hazard to aviation during the 2003-2004 eruptive activity of Anatahan Volcano, 

Commonwealth of the Northern Mariana Islands: Journal of Volcanology and Geothermal 

Research, special issue on the 2003-2004 eruption of Anatahan Volcano, in press. 

Miller, T.P. and Casadevall, T.J., 2000, Volcanic ash hazards to aviation in Sigurdsson, H. (ed.), 

Encyclopedia of Volcanoes, New York, Academic Press, p. 915-930. 

National Research Council, 2000, Review of the U.S. Geological Survey’s Volcano Hazards 

Program: National Academy Press, Washington, D.C., 138 p. 

Salinas, L.J., and Watt, D.J., 2004, Volcanic ash impact on aviation safety: Second 

International Conference on Volcanic Ash and Aviation Safety, 21-24 June 2004, Alexandria 

Virginia (oral presentation) 

Simkin, T., and Siebert, L., 1994, Volcanoes of the world: Geoscience Press, Tucson, 349 p. 

Voight, B., 1996, The management of volcano emergencies – Nevado del Ruiz: in, Scarpa, R. 

And Tilling, R.I., editors, Monitoring and management of volcano hazards, Springer Verlag 

Berlin Heidelberg, p. 719-769. 

36
APPENDIX 1 

C U S V O 

CONSORTIUM OF U.S. VOLCANO OBSERVATORIES 

Alaska, Cascades, Hawaii, Long Valley, Yellowstone 

CHARTER

23 January 2002 

CUSVO is established to strengthen interaction and communication among Federal, state, and 

academic representatives of the five U.S. volcano observatories supported by the USGS 

Volcano Hazards Program – the Alaska Volcano Observatory (AVO), the Cascades Volcano 

Observatory (CVO), the Hawaiian Volcano Observatory (HVO), the Long Valley Observatory 

(LVO), and the Yellowstone Volcano Observatory (YVO). The purpose of the consortium is to 

enhance scientific and technical coordination on operational and research matters that are of 

broad mutual concern among the observatories, with the goal of generating consensus, where 

appropriate, for common operating procedures and uniform data standards and products. The 

consortium will meet periodically as a group to discuss specific pertinent matters and also may 

convene scientific workshops on specialized topics, prepare technical white papers and 

planning documents, undertake educational outreach to promote understanding of observatory 

activities, and interact with other groups involved with volcano monitoring and related research. 

CUSVO is a voluntary scientific working group. It is not administered as a bureaucratic unit of 

any single institution or entity. The objectives and undertakings of CUSVO are aligned with the 

Federal monitoring, research, and mitigation mission of the USGS Volcano Hazards Program, 

which provides the primary funding and overall scientific direction for observatory activities. 

Recommendations, decisions, and policies espoused by the consortium will be based on 

inclusive, open discussion and solid consensus among its members. 

Membership in CUSVO is ex-officio and consists of the: USGS Volcano Hazards Team Chief 

Scientist, USGS Volcano Hazards Program Coordinator, USGS Scientist-in-Charge of AVO, 

Coordinating Scientist of AVO at the University of Alaska Fairbanks Geophysical Institute, AVO 

state representative at the Alaska Division of Geological and Geophysical Surveys, USGS 

Scientist-in-Charge of CVO, Director of the Pacific Northwest Seismic Network at the University 

of Washington, USGS Scientist-in-Charge of HVO, Director of the Center for the Study of Active 

Volcanoes at the University of Hawaii, USGS Scientist-in-Charge of LVO, USGS Scientist-inCharge of YVO, Coordinating Scientist of YVO at the University of Utah, Coordinating Scientist 

of YVO at Yellowstone National Park, USGS Chief of the Volcano Disaster Assistance Program 

for the VHP, seismic-network manager for the USGS Earthquake Hazards Program, and an 

executive secretary who can be from any participating agency or institution. Members may be 

added or removed to reflect changes in the scientific offices of the participating groups. There is 

no standing chairperson of CUSVO; each meeting is to be chaired by a member(s) appropriate 

for the topic of the meeting and agreeable to the majority of other members. 

37
LIST OF PARTICIPANTS IN MEETINGS TO FORMULATE NVEWS 

Meetings were held on:

25-26 Feb. 2004, Cascades Volcano Observatory, Vancouver WA 

13-14 May 2004, Cascades Volcano Observatory, Vancouver WA 

10 Aug. 2004, Cascades Volcano Observatory, Vancouver WA 

11 Dec. 2004, American Geophysical Union Annaul Meeting, San Francisco CA 

Attendees, in alphabetical order:

David Applegate, USGS 

Steven Brantley, USGS 

Peter Cervelli, USGS 

Daniel Dzurisin, USGS 

John Eichelberger, University of Alaska Fairbanks 

Elliot Endo, USGS 

William Evans, USGS 

John Ewert, USGS 

Marianne Guffanti, USGS (meetings chair) 

Christopher Harpel, USGS 

Rosalind Helz, USGS 

David Hill, USGS 

Shaul Hurwitz, USGS 

Michael Jackson, UNAVCO 

Michael Lisowski, USGS 

Jacob Lowenstern, USGS 

Steven Malone, University of Washington 

Kenneth McGee, USGS 

C. Dan Miller, USGS 

Seth Moran, USGS 

Thomas Murray, USGS 

Manuel Nathenson, USGS 

Christopher Nye, Alaska Division of Geological and Geophysical Surveys 

John Power, USGS 

David Oppenheimer, USGS 

James Quick, USGS 

David Schmidt, University of Oregon

Robert Smith, University of Utah 

Donald Swanson, USGS 

Donald Thomas, Universtiy of Hawaii 

Jeffrey Wynn, USGS

38
APPENDIX 2 

EXPLANATION OF HAZARD AND EXPOSURE FACTORS FOR NVEWS THREAT 

ASSESSMENT 

Hazard factors 

The hazards-ranking schema relies heavily on the Smithsonian’s Global Volcanism Program

(GVP) volcano reference file as the principal source of the volcano coordinate, volcano type, 

eruption frequency, and eruption magnitude data. Other references used as general information 

sources are Wood and Kienle (1990), and Miller and others (1998) supplemented as necessary 

with other maps, reports or journal articles. There are a number of “not determined” (nd) 

entries, particularly for the unrest fields for Alaskan volcanoes. These uncertainties reflect the 

state of monitoring capabilities at this writing. 

Volcano Type (0,1): The GVP classification of volcano type is used to help score other factors. 

Type 0 volcanoes are cinder cones, basaltic volcanic fields, shields, tuff rings, and fissure vents. 

Type 1 volcanoes are the generally more explosive stratovolcanoes, lava domes, complex 

volcanoes, maars, or calderas. The score given for volcano type is the most basic breakout of less 

dangerous (Type 0) versus more dangerous (Type 1). The Type assigned in the GVP system

does not always accurately reflect the behavior of the volcanic system. For instance, both 

Newberry and Medicine Lake are listed as shield volcanoes, but both have produced moderatesized explosive silicic eruptions. In cases where the assigned type does not accurately reflect 

known behavior, the volcano was scored as appropriate. Volcanoes modified were Yanuska, 

Okmok, Nunivak Island, Ingakslugwat Hills, St. Micheal, and Wrangell, Alaska; Newberry and 

Medicine Lake, Oregon; Clear Lake and Mono Lake, California; Black Rock Desert, Utah; and 

Kilauea, Hawaii; which received a score of 1. Mt. Jefferson, Oregon, a stratovolcano whose only 

Holocene activity has come from basaltic flank vents, received a score of 0. 

Maximum VEI (scored 0-3 in this scheme): The Volcano Explosivity Index (VEI), defined by 

Newhall and Self (1982), is a simple 0-8 index of increasing eruptive explosivity, each interval 

representing an increase of approximately a factor of 10. Owing to uncertainties in assigning 

VEI estimates to prehistoric or early historic eruptions, and the gradational transition from one 

VEI level to the next, this system codes VEI designations into 4 scoring categories based mainly 

on the GVP catalog listings. VEI ≤ 2 receive a 0 because they tend to be short lived and/or not 

particularly dangerous except in areas close to the vent. VEI 2 is also the GVP’s default 

designation for historical explosive eruptions for which there are no additional descriptive 

information (Simkin and Siebert, 1994) and as such includes many smaller magnitude eruptions 

as well. Larger eruptions are more reliably reported historically and usually leave clear evidence 

of their prehistoric occurrence in the geologic record, giving us greater confidence that the larger

eruptions are more accurately captured. VEI 3-4 receive a 1, VEI 5-6 receive a score of 2, and 

VEI 7-8 receive a score of 3. If no eruption magnitudes are reported in the literature, Volcano 

type is used to assign a default score of 0 (for Type 0 volcanoes) or 1 (for Type 1 volcanoes). In 

the United States, the score of 3 is limited to the few large Pleistocene-age silicic caldera 

systems—Long Valley, Yellowstone, and Valles—none of which have had Holocene-age 

39
magmatic eruptions. In these cases, the score of 3 is based on the estimated volume of the 

ignimbrite rather than a formal VEI designation. 

Explosive Activity and Major Explosive Activity (0-1): These two factors are meant to emphasize 

particularly active, explosive systems, and de-emphasize systems that may have had major 

explosive activity at some point in the Holocene, but have changed their eruptive style or have 

quieted down since (e.g., Crater Lake, Oregon). 

Eruption Recurrence (0,1): This factor is meant to capture the average time between eruptions, 

irrespective of explosivity. Eruption recurrence intervals are often bimodal, with clusters of 

frequent eruptions separated by longer times of quiet (Nathenson, 2001). Because only a limited 

number of volcanoes have had extensive radiometric dating of eruption products, we employ 

only 4 broad groupings of recurrence intervals. Although volcanoes with longer eruption 

recurrence intervals tend to produce more powerful eruptions, this behavior is accounted for in 

the Explosive activity codes. Large Pleistocene-age silicic caldera systems receive a score of 1 

for this factor only if they have demonstrable seismic, deformation and fumarolic unrest. The 

Eruption Recurrence code factor recognizes large basaltic systems like Kilauea and Mauna Loa 

for non-explosive but frequently occurring hazards. 

Holocene Pyroclastic Flows (0,1): Pyroclastic flows are one of the most destructive and lethal

of volcano hazards. If a system has generated pyroclastic flows in past eruptions, it is deemed 

capable of producing them again. 

Holocene Lahar (0,1): This factor is meant to account for large lahars (volcanic debris flows), 

that traveled beyond the immediate eruption site, beyond the volcanic edifice, and reached nowpopulated, or potentially-populated areas. As with pyroclastic flows, if a system has generated 

lahars in past eruptions, it is deemed capable of producing them again. 

Holocene Lava Flows (0,1): This factor flags volcanoes that have produced a lava flow that 

traveled to populated or potentially populated areas, i.e. some distance beyond the immediate 

vicinity of the vent. 

Holocene Tsunami (0,1): Volcanogenic tsunamis can be generated by several causes. If a 

tsunami was generated by a sector collapse, and collapses are no longer a factor, then a score of 0 

is given. Otherwise, if the tsunami was caused by factors such as explosions through water, 

dome collapse, or pyroclastic flows, then more may be deemed possible, and a score of 1 is 

given. 

Hydrothermal Explosion Potential (0,1): This factor is meant to capture those systems that have 

evidence of significant Holocene phreatic explosive activity, and/or those systems whose thermal 

features are extensive enough to pose a potential for explosive activity. 

Sector Collapse Potential (0,1): This factor is probably the most ambiguous in its application. It 

is limited to stratovolcanoes, and large oceanic shield volcanoes (Kilauea and Mauna Loa, 

Hawaii). In general if the volcano has more than about 1000 m relief, has active fumaroles, or 

has large altered areas and/or has a permanent snow and ice cover, and appears steep sided, it 

40
was scored positively. If a volcano has a history of sector collapses and has rebuilt its edifice it 

also received a score of 1. For instance, Mount Shasta got a score, but Mount St. Helens did not. 

The Alaska Volcano Observatory considers all Aleutian stratovolcanoes that form the bulk of 

islands or are near the coastlines of islands to have significant collapse potential and these were 

scored accordingly. This factor can be more rigorously evaluated on a case by case basis if 

detailed geological and topographical data are available, such as was done for Mount Rainier 

(Reid and others, 2001). 

Primary Lahar Source (0,1): Not all volcanoes have been mapped well enough to determine 

whether or not lahars are part of their history, so this factor considers the key ingredient, water in 

the form of lakes, rivers and ice on the volcanic edifice. Approximately 106

 m3 is the threshold 

water volume to filter out volcanoes with small lakes and marginal permanent snow cover. 

Historical unrest factors 

Unrest is taken to mean abnormal geophysical activity since the last eruption. The unrest factors 

apply if the unrest occurred since the last eruption and is ongoing or occurs in fits and starts. 

Fumarolic activity and the presence of magmatic gas isotopes in cold springs or vents provide 

the most persistent signal of unrest or latent magmatic activity. Fumarolic or hot spring activity 

is easily observed and these phenomena have been widely catalogued through time providing 

greater confidence that this form of unrest is accurately captured in this study. Seismic and 

deformation unrest nearly always require instrumental detection, and thus, the number of 

volcanoes scoring positively for this factor is small because the sample time frame is short. 

Globally, there are exceptions where long historical records include reports of persistent felt 

seismicity near volcanoes in the Mediterranean, Latin America, and Asia, and where deformation 

that can be tracked by evidence left by apparent changes in sea level on natural and man-made 

features, but these are rare. Owing to the short time (approximately 30 years) over which we 

have instrumental observations in the U.S., seismic and deformation unrest at numerous 

volcanoes is scored as ‘not determined’ (nd).

Seismic Unrest (0,1): The criterion for scoring this factor is any seismic activity within about 20 

km of a volcano. Some volcanoes are larger than 40 km in diameter so some flexibility in the 

distance is necessary. The only type of seismicity excluded from this code comprises tectonic 

earthquakes that occur on regional faults not directly related to the volcanic system. 

Deformation Unrest (0,1): This factor is meant to capture those systems that are deforming in 

response to magma intrusion or that exhibit gross changes in the existing hydrothermal system. 

Not included are those systems that are only subsiding (e.g., Medicine Lake). Most of the 

examples of deformation come from either USGS leveling campaigns or InSar surveys, and more 

systems are likely to be found actively deforming as InSAR data become more extensive and 

more instruments are deployed globally. Lu and others (2003, and references therein) was the 

principal source of information for Alaskan volcanoes. 

Fumarolic or Other Magmatic Degassing (0,1): Any fumaroles or thermal features associated 

with a volcanic system result in a score. Cold degassing of magmatic gases is also included as a 

positive factor (e.g. carbon dioxide at Long Valley, sulfur/chloride anomalies at South Sister). 

41
Exposure factors rationale 

Population potentially at risk on the ground can now be easily estimated through the use of the 

LandScan population database (Ewert and Harpel, 2004). Infrastructure potentially at risk was 

coded using map data at various scales (e.g., Federal lands at 1:2M, 

http://nationalatlas.gov/atlasftp.html), and Heiken and others (1995) for power 

generation/transmission. A volcano’s proximity to airports was determined using a U.S. 

Department of Transportation Master Coordinate Table for airports 

(http://www.transtats.bts.gov). Regional aviation risk is based primarily on passenger counts and 

does not take into account the significant amount of freight traffic flying the North Pacific or 

other air routes. Much more work needs to be done to better quantify the number of planes and 

passengers traversing volcanic regions and the aviation numbers reported here are minimums. 

Exposure to tephra fall hazards beyond the immediate vicinity of the volcano are not considered 

here though more people are adversely affected by airfall tephra than any other volcanic 

phenomena. Where tephra falls beyond the immediate vicinity of the volcanic edifice is 

determined by the vicissitudes of wind velocity and direction, and estimating the numbers of 

persons that would be potentially affected by this phenomena is beyond the scope of this study. 

VPI30 (0 to x): This code is the log10 of the population within 30 km radius circle of a volcano. 

The LandScan 2002 database (http://www.ornl.gov/sci/gist/landscan/) produced by the Oak 

Ridge National Laboratory is used in conjunction with coordinate data from the GVP reference 

file to calculate the number of people within 30 km. The 30 km distance was chosen for several 

reasons: 1) population distributions near volcanoes vary greatly with latitude and 30 km appears 

to catch proximal population in all regions, 2) data in Newhall and Hoblitt (2002) show that for 

VEI 4-5 (for many systems the likely worst case) eruptions, a pyroclastic flow has a small but 

significant (approximately 5 percent) chance of exceeding 30 km distance from the vent, 3) data 

from Newhall and Hoblitt (2002) also indicate an that the probability of tephra accumulations 

exceeding 10 cm at 30 km downwind are about 10 percent for a VEI 3 eruption, and about 80% 

for VEI ≥4. Pyroclastic flows are a lethal hazard, and accumulation of several centimeters of 

tephra has adverse effects on surface transportation, electric power distribution, surface water 

supplies, etc. A 10 cm accumulation volcanic ash, particularly if it is wet, is the threshold beyond 

which structural damage to buildings begins. Thus, this index estimates how many persons on 

the ground may be subject to serious (life-threatening) effects. 

 

Yellowstone and other volcanoes with decidedly seasonal populations did not score 

appropriately with this metric. For instance, the Landscan data base indicates that there are no 

people within 30 km of the coordinate given for Yellowstone (not far from Old Faithful), yet 

visitation to the park is close to 3 million people per year, most of it in the summer months. 

Similar situations exist for most other National Park and National Monument volcanoes. Where 

annual visitor statistics are available, those numbers were divided by 365 to produce a nominal 

average population whose activities would potentially be affected by volcanic activity and the 

log10 of this number was added to the LandScan-derived number and the result entered as the 

VPI30. Visitor statistics were available for National Parks and Monuments administered by the 

National Park Service. This procedure was also followed for the town of Mammoth Lakes which 

lies within 30 km of three volcanoes and has a transient recreational population that is double the 

42
permanent population in both winter and summer. Visitor statistics for popular volcanorecreation sites on U.S. Forest Service land (e.g., Mount Hood, Newberry Volcano, Mount 

Shasta, etc.) were not readily available for this study. 

In volcanic fields which consist of numerous vents dispersed over large areas, the VPI30 estimate 

is taken from the single GVP coordinate for the field, which approximates the geometric center 

of the entire field (Simkin and Siebert, 1994). 

Log10 of Approximate Population Downstream or Downslope, outside the 30 km VPI circle (0-x):

This factor is used only with volcanoes that have a primary lahar hazard (e.g., Cascade or 

Alaskan stratovolcanoes) or significant lava flow hazard (e.g., Mauna Loa) that extends farther 

than 30 km from vent areas. Where digital volcano hazards maps exist as Geographic 

Information System (GIS) layers, the flowage hazard zones outside the 30 km VPI circle were 

overlain on the LandScan 2002 to estimate this factor. These calculations were made for 

Kilauea, Mauna Loa, Mauna Kea, Hualalai, Mount Baker, Glacier Peak, Mount Rainer, Mount 

St. Helens, Mount Adams, Mount Hood, South Sister, Crater Lake, and Newberry Volcano. 

Estimates were made for Mount Shasta and Lassen Peak by USGS volcanologists familiar with 

the hazards and geography of these areas (Michael A. Clynne, oral communication, 2004). This 

methodology has not yet been applied to Alaskan volcanoes, though given the generally sparse 

population in the volcanic regions of Alaska, this factor will probably not change the overall 

threat rankings significantly. 

Historical Fatalities (0,1): If there were fatalities at a volcano in the past and a permanent, 

population is still present, chances are good that fatalities may happen again. 

Historical Evacuations (0,1): If there were evacuations at a volcano in the past and a permanent, 

population is still present, chances are good that evacuations may be imposed again.

Local aviation exposure (0-2): Local threats to aviation by volcanoes are principally to airports. 

We reviewed a database on effects of volcanic activity on airports (Guffanti and others, 2003) 

and found that 75 percent of airports adversely affected by volcanic activity were all within 300 

km of the erupting volcano, while those affected solely by basaltic-type eruptions were generally 

within 50 km. To quantify airport exposure the following scoring criteria are used: If any type 

volcano is within 50 km of a jet-service airport it gets a score of 1; if a Type 1 volcano (generally 

explosive potential) is within 300 km of a jet-service airport it gets a score of 1; if a Type 1 

volcano is within 300 km of a major international airport it gets a score of 2; if none of these 

criteria are met the volcano gets a score of 0. Jet service airports used were: Adak, Cold Bay, 

Sitka, Petersburg/Wrangel, Ketchikan, Sun Valley, Idaho Falls, Jackson Hole, Reno, Mammoth, 

Albuquerque, Klamath Falls, Medford, Bend-Redmond, Salt Lake City, Phoenix, Sacramento, 

and Aspen. All Type 1 volcanoes in the conterminous U.S. are within 300 km of a jet service 

airport. Major international airports used were: Anchorage, Fairbanks, Seattle/Tacoma, Portland, 

San Francisco-Oakland, Las Vegas, Honolulu, Kona, and Saipan. 

Regional Aviation exposure = log10 of daily passenger count (0-x): This is one of the more 

difficult exposure factors to quantify. Information on how many jet aircraft and passengers 

traverse a volcanic area in a given time period are not easily available. As a starting point, we 

43
used the airport statistics available from the US D.O.T. (2001) for the principal airports located 

in or near volcanic areas (Anchorage, Fairbanks, Seattle-Tacoma, Portland, Sacramento, San Francisco,

Honolulu, Hilo, Kona, Maui, Guam, and Saipan). These statistics give the number of enplaned 

(departing) passengers per year. Checking statistics in individual port annual reports generally 

confirms the DOT statistics and indicates that the approximate numbers of departing and arriving 

passengers can be obtained by multiplying the enplaned passengers by two. Air cargo flights are 

not included in this factor, though for the North Pacific routes these are an important part of the 

aviation exposure. 

 

Passengers per day for US volcanic regions were estimated in the following manner: For the 

Washington and Oregon Cascades, the daily number of passengers reported for Seattle-Tacoma

and Portland airports were added. For the California Cascades and Long Valley area the daily 

number of passengers at Sacramento and San Francisco/Oakland were added. For Hawaii the 

daily number of passengers from Honolulu, Kona, Hilo, and Maui were added. The 

intermountain portion of the conterminous U.S., Alaska and the Mariana Islands are a little more 

of a challenge to quantify owing to the greater proportion of overflight traffic in these regions. 

In the intermountain west, four volcanoes, Yellowstone, Dotsero, Valles, and Sunset Crater have 

potential regional aviation exposure, but there are few major airports in the region to provide 

passenger statistics. A factor of 5 was given to these four volcanoes, slightly less than for the 

volcanoes in the Pacific states, but in keeping with the overall high level of air traffic in the 

conterminous U.S. For the Marianas, an estimate of about 25,000 flights per year (about 67 per 

day) for a narrowly drawn box around the Northern Mariana Islands (including Guam) was 

received from Air Services Australia in 2003 (Christopher Bruce, written communication 2003). 

Airport statistics for Saipan and Guam indicate about 2.5 M passengers go to and from the 

Marianas each year (~6800 per day), but there are many flights each day between northern and 

southern Asia/Australia that transit the downwind area to the west which are not accounted for 

by the airport statistics or the Air Services Australia data. A conservative estimate of another 

3200 passengers/per day was made to account for these giving the round number of 10,000 

passengers/day potentially affected by eruptions in the Mariana Islands. Similarly for Alaska, 

the airport statistics for Anchorage and Fairbanks show about 11,100 passengers/day, but the 

data do not account for non-stop transits of the region. Miller and Casadevall (2000) estimate 

200 flights and 20,000 passengers/day on the North Pacific air routes and their figure is used. 

In all cases the log10 of the daily passenger counts was used as the regional aviation risk code. 

For the different regions, this code varies between 4 in the Mariana Islands and 5.15 in the 

California Cascades and Long Valley region. The regional code is applied only to Type 1

volcanoes and those Type 0 volcanoes that have a history of producing explosive eruptions. The 

numbers are minimums, but the relative scores appear appropriate relative to one another. 

Power Infrastructure (0,1): Power generation, transmission, or distribution within 30 km or 

within flowage hazard zone (e.g., power generation/transmission for electricity, oil, or gas), or a 

generation facility in the area typically downwind of the volcano get a score of 1 for this factor. 

Heiken and others (1995) are the main data source for this factor. Small distribution lines to a 

few cabins were not counted as “infrastructure”, but distribution lines within a town or city 

downwind were. 

44
Transportation Infrastructure (0,1): Port facilities, rail lines, and major roads are included, and 

for this study state highways and interstate highways were considered major roads. In addition, 

as civil aviation is a critical mode of transportation in Alaska, Type 1 volcanoes near heavily 

used air traffic corridors received a point. Alaskan volcanoes that received this score were 

Mount Spurr, Mount Redoubt, and Augustine Volcano. 

Major Development or Sensitive Area (0,1): This factor is meant to cover economically and 

symbolically important places, things, and activities. If a volcano is within a developed national 

park, it got a point. A volcano in a national park may also threaten developed areas outside park 

boundaries. Other examples that were counted as positives for this factor are ski areas on 

Cascade volcanoes and the fish packing plant at Akutan in the Aleutians.

Volcanic Island (0,1): Experience with eruptions on small populated islands over the past 100 

years demonstrates the particular difficulty in mitigating volcano hazards in such situations. A 

volcano making up a significant portion of an island poses higher risk because islands are 

difficult to evacuate. This factor is only applied to islands with a permanent population. 

References Cited 

Ewert, J.W. and Harpel, C.J., 2004, In harm’s way: population and volcanic risk, Geotimes, v. 49 n.4, p. 

14-17. 

Guffanti, M.C., Mayberry, G.C., Wunderman, R., and Casadevall, T.J., 2003, Impact of volcanic activity

on airports, Abstract Volume, Cities on Volcanoes 3, Hilo, Hawaii, July 14-18, 2003, p. 51. 

Heiken, G., Murphy, M., Hackett, W., and Scott, W., 1995, Volcanic hazards and energy infrastructure, 

United States: U.S. Department of Energy Report LA-UR 95-1087, 45 p.

Lu, Z., Wicks, C., Dzurisin, D., Power, J., Thatcher, W., and Masterlark, T., 2003, Interferometric 

synthetic aperture radar studies of Alaska volcanoes, Earth Observation Magazine, v.12, n.3, p 8-18. 

Miller, T.P. and Casadevall, T.J., 2000, Volcanic ash hazards to aviation in Sigurdsson, H.(ed.), 

Encyclopedia of Volcanoes, New York, Academic Press, p. 915-930. 

Miller, T.P., McGimsey, R.G., Richter, D.H., Riehle, J.R., Nye, C.J., Yount, M.E., and Dumoulin, J.A., 

1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-file 

Report 98-582, 104 p. 

Nathenson, M., 2001, Probabilities of volcanic eruptions and application to the recent history of Medicine 

Lake Volcano in Vecchia, A.V., (compiler), A unified approach to probabilistic risk assessments for 

earthquakes, floods, landslides, and volcanoes, U.S. Geological Survey Open-File Report 01-324, p.

71-74. 

Newhall, C.G. and Hoblitt, R.P., 2002, Constructing event trees for volcanic crises: Bulletin of 

Volcanology, v. 64, p. 3-20. 

Newhall, C.G. and Self, S., 1982, The volcanic explosivity index (VEI): an estimate of explosive 

magnitude for historical volcanism: Journal of Geophysical Research, v. 87, p. 1231-1238. 

Reid, M.E., Sisson, T.W., and Brien, D.L., 2001, Volcano collapse promoted by hydrothermal alteration 

and edifice shape, Mount Rainier, Washington, Geology, v.29, n.9, p.779-782. 

Simkin, T., and Siebert, L., 1994, Volcanoes of the world: Geoscience Press, Tucson, 349 p. 

U.S. Department of Transportation-Bureau of Transportation Statistics, 2001, Airport activity statistics of 

certificated air carriers, summary tables: twelve months ending December 31, 2000, BTS01-05, 28 p. 

Wood, C. A. and Kienle J., (eds.), 1990, Volcanoes of North America, New York, Cambridge University

Press, 354 p. 

45
Hazard and exposure factors used in threat assessment of U.S. volcanoes for the 

National Volcano Early Warning System. 

See appendix text for discussion and explanation of abbreviations. 

Hazards Factors Score 

Volcano type

If volcano type is cinder cone, basaltic field, small shield, or fissure vents: Score = 0 

If volcano type is stratocone, lava domes, complex volcano, maar or caldera: Score = 1 

Maximum Volcano Explosivity Index (VEI)

If maximum known VEI ≤ 2: Score = 0 

If maximum known VEI = 3 or 4: Score = 1

If maximum known VEI = 5 or 6: Score = 2 

If maximum known VEI ≥ 7: Score = 3 

If no maximum VEI is listed by GVP and if volcano type = 0: Score = 0 

If no maximum VEI is listed by GVP but volcano type = 1: Score = 1 

If no known Holocene eruptions and the volcano is not a silicic caldera system: Score = 0 

Explosive activity 

If explosive activity (VEI ≥ 3) within the last 500 years: Score = 1 

Major explosive activity

If major explosive activity (VEI ≥ 4) within last 5000 years: Score = 1 

Eruption recurrence 

If eruption interval is 1-99 years: Score = 4 

If eruption interval is 100 – 1,000 years: Score = 3 

If eruption interval is 1,000 to several thousand years: Score =2 

If eruption interval is 5,000-10,000 years, or if no Holocene eruptions but it is a large-volume 

restless silicic system that has erupted in the last 100,000 years: Score = 1 

If no known Holocene eruption: Score = 0 

Holocene pyroclastic flows?

If yes: Score = 1 

Holocene lava flows?

If Holocene lava flows have traveled beyond the immediate eruption site or flanks and 

reached populated areas: Score =1 

Holocene lahars?

If Holocene lahars have traveled beyond the flanks and reached populated areas: Score =1 

Holocene tsunami(s)?

Has it produced a tsunami within the Holocene? If yes: Score = 1 

Hydrothermal explosion potential?

If the volcano has had Holocene phreatic explosive activity, and/or the volcano has thermal 

features that are extensive enough to pose a potential for explosive activity: Score =1 

Sector collapse potential?

If the volcano has produced a sector collapse in Quaternary-Holocene time and has re-built 

its edifice, or, has high relief, steep flanks and demonstrated or inferred alteration: Score = 1

Primary lahar source?

If volcano has a source of permanent water/ice on edifice, water volume > 106

 m3: Score = 1

 Cont’d. 

46
Historical Unrest Factors 

Observed seismic unrest

Since the last eruption, in the absence of eruptive activity, within 20 km of the volcanic 

edifice? If yes: Score = 1 

Observed ground deformation

Since the last eruption, in the absence of eruptive activity, inflation or other evidence of 

magma injection? If yes: Score = 1 

Observed fumarolic or magmatic degassing

Since the last eruption, in the absence of eruptive activity, either heat source or magmatic

gases? If yes: Score = 1 

Total of Hazard Factors 

Exposure Factors 

Log10 of Volcano Population Index (VPI) at 30 km

Calculated with LandScan population database. Visitor statistics for volcanoes in National 

Parks and other destination recreation areas are added to the VPI factor where available. 

Log10 of approximate population downstream or downslope

Population outside the 30 km VPI circle included within the extent of Holocene flow

deposits or reasonable inundation modeling. This factor to be used only with volcanoes 

that have a primary lahar hazard (e.g. Cascade stratovolcanoes) or significant lava flow 

hazard (e.g. Mauna Loa). 

Historical fatalities? 

If yes, and a permanent population is still present: Score = 1 

Historical evacuations? 

If yes, and a permanent population is still present: Score = 1 

Local aviation exposure

If any type volcano is within 50 km of a jet-service airport, score = 1; if a Type 1 volcano is 

within 300 km of a jet-service airport, score = 1; if a Type 1 volcano is within 300 km of a 

major international airport, score = 2; if none of these criteria are met, score = 0.

Regional aviation exposure

This score is based on the log10 of approximate daily passenger traffic in each region. At 

present, in the U.S., this score ranges from 4 to 5.15. The regional risk code is applied 

only to type 1 volcanoes and those type 0 volcanoes that have produced explosive 

eruptions. 

Power infrastructure 

Is there power infrastructure (e.g., power generation/transmission/distribution for electricity, 

oil, or gas) within flowage hazard zones, or in an area frequently downwind of the volcano 

and close enough to considered at some risk? If yes, score =1 

Transportation infrastructure 

Is there transportation infrastructure (e.g. port facilities, rail lines, major roads) within 

flowage hazard zones, or in an area frequently downwind of the volcano and close enough 

to considered at some risk? If yes, score = 1 

Major development or sensitive areas

Are there major developments or sensitive areas threatened (e.g., National Park facilities, 

flood control projects, government facilities, developed tourist/recreation facilities, 

manufacturing or other significant economic activity)? If yes, score =1 

Volcano is a significant part of a populated island

Holocene volcanic deposits cover >25% of land mass. If yes, score = 1 

Total of Exposure Factors 

Sum of all hazard factors x Sum of all exposure factors = Relative Threat Ranking

47
APPENDIX 3 

Scoring of NVEWS Hazard Factors at U.S. Volcanoes. 

See Appendix 2 for explanation of factors. NUMBER NAME LATITUDE LON

GITUDE 

TYPE CODE 

MAXIMUM VEI CODE 

VEI≥3 IN LAST 500 YRS? 

VEI≥4 IN LAST 5000 YRS? 

ERUPTION RECURRENCE CODE

HOL

OCENE PFS? 

HOL

OCENE LAHARS? 

HOL

OCENE LAVA FLOWS? 

HOL

OCENE TSUNAMI? 

HYDROTHERM

AL EXPLO

SION 

POTEN

TIAL? 

SECTOR COLLAPSE POTENTI

AL? 

PRIMARY LAHAR POTENTIAL? 

SEISMIC SOURCE? 

GROUN

D DEF

ORMATION? 

FUMAROLIC,

O

THER EGASSING? 

HAZARD SCORE 

1101-01- Buldir 52.35 175.91 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-02- Kiska 52.10 177.60 1 1 1 1 4 0 0 0 0 0 1 1 nd nd 1 11

1101-03- Segula 52.02 178.14 1 1 0 0 1 0 0 0 0 0 1 0 nd nd 0 4

1101-04- Davidof 51.97 178.33 1 1 0 0 0 0 0 0 0 0 0 0 nd nd 0 2

1101-05- Little Sitkin 51.95 178.54 1 1 0 0 4 1 0 0 0 0 1 0 nd nd 1 9

1101-06- Semisopochnoi 51.93 179.581 2 0 1 4 1 0 0 0 0 1 0 nd nd 1 11

1101-07- Gareloi 51.79 -178.79 1 1 1 1 4 1 0 0 0 0 1 1 1 nd 1 13

1101-08- Tanaga 51.89 -178.15 1 1 0 0 3 0 0 0 0 0 1 1 1 nd 1 9

1101-09- Takawangha 51.87 -178.01 1 1 0 0 0 0 0 0 0 0 1 1 nd nd 0 4

1101-10- Bobrof 51.91 -177.44 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-11- Kanaga 51.92 -177.17 1 1 1 1 4 1 0 0 0 0 1 1 1 nd 1 13

1101-111 Moffett 51.94 -176.75 1 1 0 0 0 0 0 0 0 0 1 1 0 nd 1 5

1101-112 Adagdak 51.99 -176.59 1 1 0 0 0 0 0 0 0 0 1 1 0 nd 1 5

1101-12- Great Sitkin 52.08 -176.13 1 1 1 1 4 1 0 0 0 0 1 1 1 nd 1 13

1101-13- Kasatochi 52.18 -175.51 1 1 0 0 3 0 0 0 0 0 1 0 nd nd 0 6

1101-14- Koniuji 52.22 -175.13 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-15- Sergief 52.03 -174.93 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-16- Atka (Korovin) 52.38 -174.15 1 1 1 0 4 0 0 0 0 0 1 1 nd nd 1 10

1101-18- Seguam 52.32 -172.51 1 2 1 1 4 1 0 0 0 0 0 0 nd 1 1 12

1101-19- Amukta 52.50 -171.25 1 1 1 0 4 0 0 0 0 0 1 0 0 0 0 8

1101-20- Chagulak 52.58 -171.13 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 3

1101-21- Yunaska 52.64 -170.63 1 1 1 1 3 0 0 0 0 0 0 0 nd nd 0 7

1101-22- Herbert 52.74 -170.11 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-23- Carlisle 52.89 -170.05 1 1 0 0 3 0 0 0 0 0 1 1 nd nd 0 7

1101-24- Cleveland 52.83 -169.94 1 1 1 0 4 0 0 0 0 0 1 1 nd nd 1 10

1101-25- Uliaga 53.07 -169.77 1 1 0 0 0 0 0 0 0 0 1 0 nd nd 0 3

1101-26- Kagamil 52.97 -169.72 1 1 0 0 2 0 0 0 0 0 1 0 nd nd 1 6

1101-27- Vsevidof 53.13 -168.69 1 1 1 1 4 0 0 0 0 0 1 1 nd nd 0 10

1101-28- Recheschnoi 53.16 -168.54 1 1 0 1 2 0 0 0 0 0 1 1 nd nd 1 8

1101-29- Okmok 53.43 -168.13 1 2 1 1 4 1 1 0 1 0 0 1 1 1 1 16

1101-30- Bogoslof 53.93 -168.03 1 1 1 0 4 0 0 0 0 0 0 0 nd nd 1 8

1101-31- Makushin 53.89 -166.92 1 2 1 1 4 1 1 0 0 0 1 1 1 1 1 16

1101-311 Table TopWide Bay 53.97 -166.68 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2

48
1101-32

-Akutan

54.13-165.99

12114110001111116

1101-34-Westdahl

54.52-164.65

12114100000111114

1101-35-Fisher

54.65-164.43

1211210000000nd19

1101-36-Shishaldin

54.76-163.97

1210411000111nd114

1101-37-Isanotski

54.77-163.72

1100000000110nd04

1101-38-Roundtop

54.80-163.59

110011100011ndnd18

1101-39-Amak

55.42-163.15

110020000010ndnd05

1102-01-Frosty

55.08-162.81

110011100011ndnd07

1102-011Dutton

55.17-162.27

1100111000111nd19

1102-02-EmmonsLake

55.34-162.08

1200110000000nd16

1102-03-Pavlof

55.42-161.89

1110411000111nd113

1102-04-PavlofSister

55.45-161.84

110120100011ndnd19

1102-05-Dana

55.64-161.21

120121000000ndnd18

1102-051Stepovak

55.93-160.00

110010100011ndnd06

1102-06-Kupreanof

56.01-159.80

110020100011ndnd18

1102-07-Veniaminof

56.17-159.38

1211411000011nd114

1102-08-BlackPeak

56.55-158.79

1201210000000nd07

1102-09-Aniakchak

56.88-158.17

1211311010001nd113

1102-10-Yantarni

57.02-157.19

120121000011ndnd09

1102-11-Chiginagak

57.14-156.99

110121100011ndnd110

1102-12-Kialagvik

57.20-156.75

110011000001ndnd05

1102-13-Ugashik-

Peulik57.75-156.37

121131100011nd1114

1102-131UkinrekMaars

57.83-156.51

1110210000001018

1102-132Unnamed

57.87-155.42

1100000000000nd02

1102-14-Martin

58.17-155.36

11012100001110110

1102-15-Mageik

58.20-155.25

11012100001110110

1102-16-Trident

58.24-155.10

11112100001111112

1102-17-Katmai

58.28-154.96

11112110001110112

1102-18-Novarupta

58.27-155.16

12112100000010110

1102-19-Griggs

58.35-155.09

11012110001100110

1102-20-SnowyMtn

58.34-154.68

1100110000111018

1102-21-Denison

58.42-154.45

110010000011ndnd05

1102-22-Steller

58.43-154.40

110010000011ndnd05

1102-23-Kukak

58.45-154.36

110010000011ndnd16

1102-25-Kaguyak

58.61-154.03

120121?00001ndnd19

1102-26-Fourpeaked

58.77-153.67

110000000011ndnd04

1102-27-Douglas

58.86-153.54

110020000011ndnd17

1103-01-Augustine

59.36-153.43

1111411010101nd114

1103-02-Iliamna

60.03-153.09

1111211000111nd112

1103-03-Redoubt

60.49-152.74

11114110001110114

1103-04-Spurr

61.30-152.25

1111411000111nd114

1103-05-Hayes

61.64-152.41

1201211000010nd09

1104-01- St. Paul Is. 

57.18-170.30

000010000000ndnd01

1104-02-NunivakIs.

60.02-166.33

110010000000ndnd03

1104-03- Ing

akslugwat 

Hills 

61.43-164.47

110010000000ndnd03

1104-04-St.Michael

63.45-162.12

110010000000ndnd03

1104-05-Kookooligit

Mtns63.60-170.43

000010000000ndnd01

1104-06-ImurukLake

65.60-163.92

000020000000ndnd02

1105-001Buzzard

Creek 

64.07-148.42

110010000000ndnd03

1105-01-Sanford

62.22-144.13

110000000011ndnd04

49
50

1105-02-Wrangell

62.00-144.02

1201310000111nd112

1105-021Gordon

62.13-143.08

000000000011ndnd02

1105-03-Churchill

61.38-141.75

120121100011ndnd010

1105-04-Edgecumbe

57.05-135.75

120020100000ndnd06

1105-05-DuncanCanal

56.50-133.10

000010100000ndnd02

1105-06-Tlevak StraitSuemez Is. 55.25 -133.30 000010000000ndnd01

1105-07-Behm CanalRudyerd Bay 55.32 -131.05 000000000000ndnd00

1201-01=Baker

48.78-121.81

1100111001110019

1201-02-GlacierPeak

48.11-121.11

11013110001100111

1201-03-Rainier

46.87-121.76

11013110011110113

1201-04-Adams

46.21-121.49

1000201000110017

1201-05-St.Helens

46.20-122.18

12114110000111115

1201-06-WestCrater

45.88-122.08

0000100000001002

1201-07-IndianHeaven

45.93-121.82

0000100100000002

1202-01-Hood

45.37-121.69

11003110011110112

1202-02-Jefferson

44.69-121.80

0000100000000001

1202-03-BlueLake

Crater 

44.42-121.77

1000100000000002

1202-04-SandMtn

Field44.38-121.93

0000100000000001

1202-05-Washington

44.33-121.84

0000100000000001

1202-06-Belknap

44.29-121.84

0000200000000002

1202-07- N. Sister Field 

44.17-121.77

1100200000000004

1202-08-SouthSister

44.10-121.77

11012110001111112

1202-09-Bachelor

43.98-121.69

1000100000010003

1202-10-DavisLake

43.57-121.82

0000100000000001

1202-11-Newberry

43.72-121.23

1101211100000019

1202-12-DevilsGarden

43.51-120.86

0000100000000001

1202-13-Lava

Mountain43.47-120.75

000010000000ndnd01

1202-14-FourCraters

Lava Field 

43.36-120.67

000010000000ndnd01

1202-15-Cinnamon

Butte 

43.24-122.11

000010000000ndnd01

1202-16-CraterLake

42.93-122.12

130021100001ndnd110

1202-17-Diamond

Craters 

43.10-118.75

000010000000ndnd01

1202-19-Jordan

Craters 

43.15-117.47

000010010000ndnd02

1202-20-JackiesButte

42.61-117.59

000010000000ndnd01

1203-01-Shasta

41.42-122.20

11113110001110113

1203-02-MedicineLake

41.58-121.57

1100200100001017

1203-03-BrushyButte

41.18-121.44

0000100000000001

1203-04-BigCave

40.96-121.37

0000100000000001

1203-05-Twin Buttes

40.78-121.60

0000100000000001

1203-06-TumbleButtes

40.68-121.55

0000100000000001

1203-08-Lassen

40.49-121.51

11103110011110113

1203-09-EagleLake

Field40.63-120.83

0000100000000001

1203-10-ClearLake

38.97-122.77

1100100001001016

1203-11-MonoLake

Volc Field 38.00 -119.03 

1100200000000015

1203-12-Mono Craters

37.88-119.00

1101211000000018

1203-13-InyoCraters

37.69-119.02

1101211000000018

1203-14-Long Valley

37.70-118.87

1300100001001119
1203-15- Red Cones 37.58 -119.05 0 0 0 0 1 0 0 0 0 1 0 0 1 1 1 5

1203-16- Ubehebe

Craters 37.02 -117.45

1 1 0 0 1 1 0 0 0 0 0 0 0 0 0 4

1203-17- Golden Trout

Creek 36.36 -118.32

0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1

1203-18- Coso Volc

Field 36.03 -117.82

1 1 0 0 1 0 0 0 0 0 0 0 1 0 1 5

1203-19- Lavic Lake 34.75 -116.63 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1

1203-20- Amboy 34.55 -115.78 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1

1204-01- Shoshone

Lava Field 43.18 -114.35

0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2

1204-02- Craters of the 

Moon 43.42 -113.50

0 0 0 0 2 0 0 1 0 0 0 0 0 0 0 3

1204-03- Wapi Lava

Field 42.88 -113.22

0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2

1204-04- Hell's Half

Acre 43.50 -112.45

0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2

1205-01- Yellowstone 44.43 -110.67 1 3 0 0 1 0 0 0 0 1 0 0 1 1 1 9 

1206-01- Steamboat 

Springs 39.38 -119.72 

1 1 0 0 0 0 0 0 0 1 0 0 0 0 1 4 

1207-01- Santa Clara 37.26 -113.63 0 0 0 0 1 0 0 0 0 0 0 0 nd 0 0 1 

1207-03- Bald Knoll 37.33 -112.41 0 0 0 0 1 0 0 0 0 0 0 0 nd 0 0 1 

1207-04- Markagunt 

Plateau 37.58 -112.67 

0 0 0 0 1 0 0 0 0 0 0 0 nd 0 0 1 

1207-05- Black Rock 

Desert 38.97 -112.50 

1 1 0 0 1 0 0 0 0 0 0 0 nd 0 0 3 

1208-01- Dotsero 39.65 -107.03 1 1 0 0 1 0 1 0 0 0 0 0 nd 0 0 4 

1209-01- Uinkaret Field 36.38 -113.13 0 0 0 0 1 0 0 0 0 0 0 0 nd 0 0 1 

1209-02- Sunset Crater 35.37 -111.50 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 3 

1210-01- Carrizozo 33.78 -105.93 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2 

1210-02- Zuni-Bandera 34.80 -108.00 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2 

1210-03- Valles Caldera 35.87 -106.57 1 3 0 0 0 0 0 0 0 0 0 0 0 0 1 5 

1302-01- Kilauea 19.43 -155.29 1 1 1 1 4 1 0 1 1 1 1 0 1 1 1 16 

1302-02= Mauna Loa 19.48 -155.61 0 0 0 0 4 0 1 1 1 0 1 0 1 1 1 11 

1302-03- Mauna Kea 19.82 -155.47 0 0 0 0 2 0 0 1 0 0 0 0 0 0 0 3 

1302-04- Hualalai 19.69 -155.87 1 0 0 0 3 0 0 1 0 0 0 0 1 0 0 6 

1302-06- Haleakala 20.71 -156.25 0 0 0 0 3 0 0 1 0 0 0 0 0 0 1 5 

0804-14= Farallon de 

Pajaros 20.53 144.90 

1 0 0 0 4 0 0 0 0 0 1 0 1 0 1 8 

0804-141 Ahyi 20.42 145.03 0 0 0 0 3 0 0 0 0 0 1 0 nd 0 0 4 

0804-142 Supply Reef 20.13 145.10 0 0 0 0 3 0 0 0 0 0 1 0 nd 0 0 4 

0804-143 Maug Islands 20.02 145.22 1 1 0 0 1 0 0 0 0 0 0 0 nd nd 1 4 

0804-15= Asuncion 19.67 145.40 1 1 0 0 3 0 0 0 0 0 1 0 1 nd 1 8 

0804-16= Agrigan 18.77 145.67 1 1 1 1 3 1 0 0 0 0 1 0 1 0 1 11 

0804-17= Pagan 18.13 145.80 1 1 1 1 4 1 1 0 0 0 1 0 1 ? 1 13 

0804-18= Alamagan 17.60 145.83 1 1 0 0 3 1 0 0 0 0 1 0 1 0 1 9 

0804-19= Guguan 17.32 145.85 1 1 0 0 3 0 0 0 0 0 1 0 1 0 1 8 

0804-191 Sarigan 16.71 145.78 1 1 0 0 2 0 0 0 0 0 1 0 1 0 0 6 

0804-20= Anatahan 16.35 145.67 1 1 0 0 2 1 0 0 0 0 1 0 1 1 1 9 

0804-201 Ruby 15.62 145.57 0 0 0 0 4 0 0 0 0 0 1 0 1 nd 0 6 

0804-21= Esmeralda 

Bank 15.00 145.25 

0 0 0 0 4 0 0 0 0 0 1 0 1 nd 0 6 

 

51
Scoring of NVEWS Exposure Factors at U.S. Volcanoes.

See Appendix 2 for explanation of factors. NUMBER NAME LATITUDE

LONGITUDE

LOG VPI30

LOG APPX.

DOWNSTREAM/SLOPE

POPULATION

HISTORICAL FATALITIES?

HISTORICAL EVACUATIONS?

LOCAL AVIATION EXPOSURE?

REGIONAL AVIATION

EXPOSURE?

POWER INFRASTRUCTURE?

TRANSPORTATION

INFRASTRUCTURE?

MAJOR DEVELOPMENT OR

SENSITIVE AREA?

>25% OF A POPULATED ISLAND?

Exposure Score

1101-01- Buldir 52.35 175.91 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-02- Kiska 52.10 177.60 0.00 0.00 0 0 0 4.3 0 0 1 0 5.3

1101-03- Segula 52.02 178.14 0.00 0.00 0 0 0 4.3 0 0 1 0 5.3

1101-04- Davidof 51.97 178.33 0.00 0.00 0 0 0 4.3 0 0 1 0 5.3

1101-05- Little Sitkin 51.95 178.54 0.00 0.00 0 0 0 4.3 0 0 1 0 5.3

1101-06- Semisopochnoi 51.93 179.58 0.00 0.00 0 0 1 4.3 0 0 1 0 6.3

1101-07- Gareloi 51.79 -178.79 0.00 0.00 0 0 1 4.3 0 0 1 0 6.3

1101-08- Tanaga 51.89 -178.15 0.00 0.00 0 0 1 4.3 0 0 1 0 6.3

1101-09- Takawangha 51.87 -178.01 0.00 0.00 0 0 1 4.3 0 0 1 0 6.3

1101-10- Bobrof 51.91 -177.44 1.66 0.00 0 0 1 4.3 0 0 1 0 8.0

1101-11- Kanaga 51.92 -177.17 1.58 0.00 0 0 1 4.3 0 0 1 0 7.9

1101-111 Moffett 51.94 -176.75 1.38 0.00 0 0 1 4.3 0 0 1 0 7.7

1101-112 Adagdak 51.99 -176.59 1.36 0.00 0 0 1 4.3 0 0 1 0 7.7

1101-12- Great Sitkin 52.08 -176.13 0.60 0.00 0 0 1 4.3 0 0 1 0 6.9

1101-13- Kasatochi 52.18 -175.51 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3

1101-14- Koniuji 52.22 -175.13 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3

1101-15- Sergief 52.03 -174.93 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3

1101-16- Atka (Korovin) 52.38 -174.15 0.85 0.00 0 0 1 4.3 0 0 0 1 7.1

1101-18- Seguam 52.32 -172.51 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3

1101-19- Amukta 52.50 -171.25 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-20- Chagulak 52.58 -171.13 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-21- Yunaska 52.64 -170.63 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-22- Herbert 52.74 -170.11 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-23- Carlisle 52.89 -170.05 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-24- Cleveland 52.83 -169.94 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-25- Uliaga 53.07 -169.77 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-26- Kagamil 52.97 -169.72 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-27- Vsevidof 53.13 -168.69 1.26 0.00 0 0 0 4.3 0 0 0 0 5.6

1101-28- Recheschnoi 53.16 -168.54 1.57 0.00 0 0 0 4.3 0 0 0 0 5.9

1101-29- Okmok 53.43 -168.13 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-30- Bogoslof 53.93 -168.03 0.00 0.00 0 0 0 4.3 0 0 0 0 4.3

1101-31- Makushin 53.89 -166.92 3.19 0.00 0 0 0 4.3 0 1 1 0 9.5

1101-311 Table Top-Wide Bay 53.97 -166.68 3.02 0.00 0 0 1 0 0 0 0 0 4.0

1101-32- Akutan 54.13 -165.99 1.46 0.00 0 0 1 4.3 0 0 1 1 8.8

1101-34- Westdahl 54.52 -164.65 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3

1101-35- Fisher 54.65 -164.43 0.00 0.00 0 0 1 4.3 0 0 0 0 5.3
1101-36- Shishaldin 54.76 -163.97 2.15 0.00

001 4.30000 7.4

1101-37- Isanotski 54.77 -163.72 1.88 0.00001 4.30000 7.2

1101-38- Roundtop 54.80 -163.59 1.95 0.00001 4.30000 7.3

1101-39- Amak 55.42 -163.15 1.38 0.00001 4.30000 6.7

1102-01- Frosty 55.08 -162.81 2.12 0.00001 4.30000 7.4

1102-011 Dutton 55.17 -162.27 1.97 0.00001 4.30010 8.3

1102-02- Emmons Lake 55.34 -162.08 1.83 0.00001 4.30000 7.1

1102-03- Pavlof 55.42 -161.89 1.99 0.00001 4.30000 7.3

1102-04- Pavlof Sister 55.45 -161.84 2.06 0.00001 4.30000 7.4

1102-05- Dana 55.64 -161.21 2.10 0.00001 4.30000 7.4

1102-051 Stepovak 55.93 -160.00 1.26 0.0000100000 2.3

1102-06- Kupreanof 56.01 -159.80 1.54 0.00001 4.30000 6.8

1102-07- Veniaminof 56.17 -159.38 1.51 0.00011 4.30000 7.8

1102-08- Black Peak 56.55 -158.79 1.18 0.00001 4.30000 6.5

1102-09- Aniakchak 56.88 -158.17 1.45 0.00001 4.30000 6.7

1102-10- Yantarni 57.02 -157.19 0.48 0.00001 4.30000 5.8

1102-11- Chiginagak 57.14 -156.99 1.00 0.00001 4.30000 6.3

1102-12- Kialagvik 57.20 -156.75 1.46 0.00001 4.30000 6.8

1102-13- Ugashik-Peulik 57.75 -156.37 1.34 0.00001 4.30000 6.6

1102-131 Ukinrek Maars 57.83 -156.51 1.18 0.00001 4.30000 6.5

1102-132 Unnamed 57.87 -155.42 0.60 0.00001 4.30000 5.9

1102-14- Martin 58.17 -155.36 2.21 0.00001 4.30000 7.5

1102-15- Mageik 58.20 -155.25 2.21 0.00001 4.30000 7.5

1102-16- Trident 58.24 -155.10 2.21 0.00001 4.30000 7.5

1102-17- Katmai 58.28 -154.96 2.21 0.00001 4.30000 7.5

1102-18- Novarupta 58.27 -155.16 2.21 0.00001 4.30000 7.5

1102-19- Griggs 58.35 -155.09 2.20 0.00001 4.30000 7.5

1102-20- Snowy Mountain 58.34 -154.68 2.20 0.00001 4.30000 7.5

1102-21- Denison 58.42 -154.45 2.20 0.00001 4.30000 7.5

1102-22- Steller 58.43 -154.40 2.20 0.00001 4.30000 7.5

1102-23- Kukak 58.45 -154.36 2.21 0.00001 4.30000 7.5

1102-25- Kaguyak 58.61 -154.03 2.21 0.00001 4.30000 7.5

1102-26- Fourpeaked 58.77 -153.67 2.22 0.00001 4.30000 7.5

1102-27- Douglas 58.86 -153.54 2.22 0.00001 4.30000 7.5

1103-01- Augustine 59.36 -153.43 0.48 0.00002 4.30110 8.8

1103-02- Iliamna 60.03 -153.09 1.54 0.00002 4.30010 8.8

1103-03- Redoubt 60.49 -152.74 1.42 0.00012 4.31110 11.7

1103-04- Spurr 61.30 -152.25 0.00 0.00002 4.31110 9.3

1103-05- Hayes 61.64 -152.41 0.00 0.00002 4.31010 8.3

1104-01- St. Paul Island 57.18 -170.30 1.89 0.0000000001 2.9

1104-02- Nunivak Island 60.02 -166.33 1.63 0.00000 4.30000 5.9

1104-03- Ingakslugwat Hills 61.43 -164.47 1.65 0.00000 4.30000 6.0

1104-04- St. Michael 63.45 -162.12 2.41 0.00001 4.30000 7.7

1104-05- Kookooligit Mountains 63.60 -170.43 2.12 0.0000000000 2.1

1104-06- Imuruk Lake 65.60 -163.92 1.36 0.0000000000 1.4

1105-001 Buzzard Creek 64.07 -148.42 1.30 0.0000100000 2.3

1105-01- Sanford 62.22 -144.13 2.00 0.00001 4.30010 8.3

1105-02- Wrangell 62.00 -144.02 2.00 0.00001 4.30010 8.3

1105-021 Gordon 62.13 -143.08 2.00 0.0000000000 2.0

1105-03- Churchill 61.38 -141.75 2.00 0.00001 4.30010 8.3

1105-04- Edgecumbe 57.05 -135.75 3.56 0.00001 4.30000 8.9

1105-05- Duncan Canal 56.50 -133.10 2.54 0.0000100000 3.5
1105-06- Tlevak Strait-Suemez Is. 55.25 -133.30 2.85 0.00

00000000 2.8

1105-07- Behm Canal-Rudyerd Bay 55.32 -131.05 0.00 0.0000100000 1.0

1201-01= Baker 48.78 -121.81 3.65 4.69002 5.041100 17.4

1201-02- Glacier Peak 48.11 -121.11 2.42 4.66002 5.040000 14.1

1201-03- Rainier 46.87 -121.76 3.69 5.07002 5.041110 18.8

1201-04- Adams 46.21 -121.49 2.93 4.13002 5.041100 16.1

1201-05- St. Helens 46.20 -122.18 2.84 3.93112 5.040110 17.8

1201-06- West Crater 45.88 -122.08 3.95 0.0000100000 5.0

1201-07- Indian Heaven 45.93 -121.82 3.69 0.0000001100 5.7

1202-01- Hood 45.37 -121.69 3.75 3.98002 5.041110 17.8

1202-02- Jefferson 44.69 -121.80 3.03 0.0000000000 3.0

1202-03- Blue Lake Crater 44.42 -121.77 3.48 0.00002 5.040000 10.5

1202-04- Sand Mountain Field 44.38 -121.93 3.18 0.0000000000 3.2

1202-05- Washington 44.33 -121.84 3.43 0.0000000000 3.4

1202-06- Belknap 44.29 -121.84 3.42 0.0000000100 4.4

1202-07- North Sister Field 44.17 -121.77 3.50 2.00002 5.040100 13.5

1202-08- South Sister 44.10 -121.77 3.32 3.83002 5.041010 16.2

1202-09- Bachelor 43.98 -121.69 4.06 2.00002 5.040010 14.1

1202-10- Davis Lake 43.57 -121.82 3.67 0.0000000000 3.7

1202-11- Newberry Volcano 43.72 -121.23 4.01 0.00002 5.041110 14.0

1202-12- Devils Garden 43.51 -120.86 2.52 0.0000000000 2.5

1202-13- Lava Mountain 43.47 -120.75 2.65 0.0000000000 2.7

1202-14- Four Craters Lava Field 43.36 -120.67 2.74 0.0000000000 2.7

1202-15- Cinnamon Butte 43.24 -122.11 2.96 0.0000000000 3.0

1202-16- Crater Lake 42.93 -122.12 3.36 3.70002 5.041010 16.1

1202-17- Diamond Craters 43.10 -118.75 2.18 0.0000000000 2.2

1202-19- Jordan Craters 43.15 -117.47 2.22 0.0000000000 2.2

1202-20- Jackies Butte 42.61 -117.59 2.18 0.0000000000 2.2

1203-01- Shasta 41.42 -122.20 4.03 3.00001 5.151110 16.2

1203-02- Medicine Lake 41.58 -121.57 2.99 2.00001 5.151010 13.1

1203-03- Brushy Butte 41.18 -121.44 3.54 0.0000000000 3.5

1203-04- Big Cave 40.96 -121.37 3.79 0.0000000000 3.8

1203-05- Twin Buttes 40.78 -121.60 3.71 0.0000000000 3.7

1203-06- Tumble Buttes 40.68 -121.55 3.67 0.0000000000 3.7

1203-08- Lassen Volc Center 40.49 -121.51 3.46 3.70001 5.150010 14.3

1203-09- Eagle Lake Field 40.63 -120.83 3.83 0.0000000000 3.8

1203-10- Clear Lake 38.97 -122.77 4.64 0.00002 5.151110 14.8

1203-11- Mono Lake Volc Field 38.00 -119.03 2.87 0.00002 5.150100 11.0

1203-12- Mono Craters 37.88 -119.00 4.09 0.00002 5.150100 12.2

1203-13- Inyo Craters 37.69 -119.02 4.11 0.00002 5.150110 13.3

1203-14- Long Valley 37.70 -118.87 4.11 0.00002 5.151110 14.3

1203-15- Red Cones 37.58 -119.05 4.10 0.0010100010 7.1

1203-16- Ubehebe Craters 37.02 -117.45 3.47 0.00002 5.150010 11.6

1203-17- Golden Trout Creek 36.36 -118.32 2.18 0.0000000000 2.2

1203-18- Coso Volc Field 36.03 -117.82 2.43 0.00002 5.151000 10.6

1203-19- Lavic Lake 34.75 -116.63 3.61 0.0000000000 3.6

1203-20- Amboy 34.55 -115.78 3.36 0.0000000000 3.4

1204-01- Shoshone Lava Field 43.18 -114.35 3.82 0.0000100000 4.8

1204-02- Craters of the Moon 43.42 -113.50 3.09 0.0000000010 4.1

1204-03- Wapi Lava Field 42.88 -113.22 3.01 0.0000000010 4.0

1204-04- Hell's Half Acre 43.50 -112.45 3.80 0.0000100110 6.8

1205-01- Yellowstone 44.43 -110.67 3.91 0.0000150110 11.9
1206-01- Steamboat Springs 39.38 -119.72 5.41 0.00

002 5.151110 15.6

1207-01- Santa Clara 37.26 -113.63 4.69 0.0000000000 4.7

1207-03- Bald Knoll 37.33 -112.41 2.98 0.0000000000 3.0

1207-04- Markagunt Plateau 37.58 -112.67 2.79 0.0000250000 9.8

1207-05- Black Rock Desert 38.97 -112.50 3.53 0.0000250000 10.5

1208-01- Dotsero 39.65 -107.03 4.29 0.0000150100 11.3

1209-01- Uinkaret Field 36.38 -113.13 1.95 0.0000000010 3.0

1209-02- Sunset Crater 35.37 -111.50 4.65 0.0000051000 10.7

1210-01- Carrizozo 33.78 -105.93 2.82 0.0000000000 2.8

1210-02- Zuni-Bandera 34.80 -108.00 2.79 0.0000000000 2.8

1210-03- Valles Caldera 35.87 -106.57 3.97 0.0000150010 11.0

1302-01- Kilauea 19.43 -155.29 4.09 4.29112 4.871110 20.3

1302-02= Mauna Loa 19.48 -155.61 3.68 4.7511101111 15.4

1302-03- Mauna Kea 19.82 -155.47 3.86 4.2000100110 11.1

1302-04- Hualalai 19.69 -155.87 4.51 0.00012 4.871110 15.4

1302-06- Haleakala 20.71 -156.25 4.83 0.0000100111 8.8

0804-14= Farallon de Pajaros 20.53 144.90 0.00 0.0000040000 4.0

0804-141 Ahyi 20.42 145.03 0.00 0.0000000000 0.0

0804-142 Supply Reef 20.13 145.10 0.00 0.0000000000 0.0

0804-143 Maug Islands 20.02 145.22 0.00 0.0000040000 4.0

0804-15= Asuncion 19.67 145.40 0.00 0.0000040000 4.0

0804-16= Agrigan 18.77 145.67 1.00 0.0001040001 7.0

0804-17= Pagan 18.13 145.80 1.00 0.0001040001 7.0

0804-18= Alamagan 17.60 145.83 1.00 0.0000240001 8.0

0804-19= Guguan 17.32 145.85 0.00 0.0000240000 6.0

0804-191 Sarigan 16.71 145.78 1.00 0.0000240001 8.0

0804-20= Anatahan 16.35 145.67 1.00 0.0001240001 9.0

0804-201 Ruby 15.62 145.57 0.00 0.0000000100 1.0

0804-21= Esmeralda Bank 15.00 145.25 0.00 0.0000000100 1.0
APPENDIX 4

GUIDELINES FOR RATING THE LEVEL OF MONITORING AT U.S. VOLCANOES. 

These guidelines are used to characterize both current and future (desired) monitoring levels. 

For each volcano, the main monitoring methods (seismic, deformation, gas, hydrologic, remotesensing) are rated on a scale of 0-4. Then an overall rating is given, also using a 0-4 scale. 

Seismic pertains to real-time stations. Remote sensing pertains to airborne, satellite, and/or 

ground based instruments that are independent of airborne gas measurements and satellitebased InSAR. The seismic rating strongly influences the overall rating; for any volcano, the 

overall rating cannot be higher than its seismic rating. For each volcano, six numbers are 

assigned (see Appendix 5): a number for the level of each of the five monitoring techniques 

(seismic, deformation, gas, hydrologic, and remote-sensing) and a number for the overall level 

of monitoring. 

LEVEL 0: No ground-based monitoring

No real-time data from ground-based sensors are available. Eruption confirmation (up to hours 

after the fact) is provided only by remote-sensing data or from people observing the event.

LEVEL 1: Minimal monitoring

Monitoring provides the ability to detect that an eruption is occurring or that gross changes are 

occurring/have occurred near a volcano. Data are not collected systematically or at very long 

intervals (e.g., >5 years). 

Seismic –Volcano lies within a regional network; no near-field stations are in place but at least one 

station is within 50 km of the volcano. (Example: Crater Lake). Or, a single near-field station is

present, but no regional network exists. (Example, Sarigan). 

Deformation – Geodetic benchmarks and baseline measurements exist for detection of deformation 

via repeated surveys at multiple-year intervals. (Example: Shasta). Or, coherent InSAR 

interferogram(s) exist(s). 

Gas – Airborne or campaign gas measurements are done rarely as an infrequent reconnaissance 

check for anomalous degassing. 

Hydrologic - Inventory exists of temperature and major chemistry of fumaroles, thermal, and slightly 

thermal springs and wells. Where lahar potential exists, study of past lahars and debris flows has 

been conducted, including as appropriate, estimation of extent of hydrothermal alteration and 

estimates of slope stability.

Remote sensing - Baseline inventory exists of Landsat-class (15-30 m resolution) satellite images. 

Routine scans for eruption clouds are conducted by meteorological agencies. 

LEVEL 2: Limited monitoring for change detection

Monitoring provides the ability to detect and track activity frequently enough in near-real time to 

recognize that something anomalous is occurring. 

Seismic – Volcano lies within a regional network and 1-2 near-field (within ~10 km of volcano) 

stations are in place. (Examples: Hood, Lassen). 

Deformation - Geodetic network exists, with baseline established by two or more surveys. InSAR 

observations are possible on a summer-to-summer basis. At least three continuous stations (GPS 

56
or tiltmeters are operating in the vicinity of the volcano. The combination of techniques enables 

tracking of geodetic unrest in space and time at a minimal level. (Example: Three Sisters). 

Gas – Repeated airborne or campaign gas measurements have been conducted to establish a 

baseline of carbon dioxide emission rate (or other gas as appropriate to the volcano) for 

identification of significant changes in degassing. 

Hydrologic - Comprehensive temperature, chemical, and isotopic database exists on gases and 

waters, with scheduled re-sampling of selected features. Scheduled measurements are taken of

stream discharge, sediment transport, if appropriate, along with annual max-min estimates of snow

and ice cover. Water levels in wells that respond to strain events are recorded. 

Remote sensing - Regular processing and review of near-real-time meteorological satellite images 

(AVHRR, GOES), and/or review of non-real-time research satellite images (e.g., MODIS) is done by 

an observatory. Baseline inventory exists of air photos and/or satellite images with high spatial 

resolution (1 m). 

LEVEL 3: Basic real-time monitoring

Monitoring provides the ability detect and track pre-eruptive and eruptive changes in real-time, 

with a basic understanding of what is occurring. 

Seismic – Volcano network includes 3-4 near-field stations and a total of at least six within 20 km of 

vent. The volcano may or may not be within regional network. Network may or may not have a 

single three-component instrument. (Examples: Rainier, Redoubt) 

Deformation - Geodetic network exists, and surveys are routinely repeated. At least six continuous 

stations (GPS and/or tiltmeters) are operating in the vicinity of the volcano. This enables tracking of 

geodetic unrest in space and time and source modeling at a basic level. LIDAR-derived images are 

available for active features. (Example: St. Helens). 

Gas – Airborne or campaign measurements of gas emissions are done frequently (annually to 

monthly, as appropriate), with support of 1-2 telemetered continuous monitoring installations. Less 

frequent plume measurements are supplemented by ground-based instruments. 

Hydrologic - Level-2 coverage is available along with continuous-sensing probes deployed in

features of primary interest, including water wells. LIDAR-derived DEMs are available for laharrunout modeling. 

Remote sensing – Level 2 capability plus routine use of multi-channel thermal-infrared data from an 

ASTER-class satellite. Airborne thermal and/or SAR overflights, are conducted as indicated by 

other monitoring data. Where practicable, remote video camera is in operation. 

LEVEL 4: Well-monitored

Monitoring provides the ability to track detailed changes in real-time and to develop, test, and 

apply models of ongoing and expected activity. 

Seismic – 12-20 stations are in place within 20 km of vent; including several near-field sites. 

Network includes numerous three-component instruments and a mix of other instrument types, 

including several digital broadband stations, acoustic sensors, and accelerometers. Borehole 

instruments are used where practicable. (Examples: Long Valley, Kilauea) 

Deformation - Geodetic surveys are routine, and sufficient continuous stations (GPS, tiltmeters, 

and/or dilatometers) are installed to track closely geodetic unrest in space and time and do detailed 

57
source modeling to help distinguish among alternative mechanisms. (Examples: Long Valley, 

Kilauea) 

Gas – Airborne or campaign gas measurements done frequently. A continuous monitoring array of 

several stations and other types of gas measurements (including DOAS) is deployed as appropriate 

for the volcano to enable quick identification of key geochemical changes. 

Hydrologic - Level-3 coverage is available along with real-time monitoring of hill-slope soil moisture, 

stream discharge, etc. as appropriate. AFM systems are installed, where warranted, and supported 

by models predicting lahar size and area of impact. 

Remote sensing – Level 3 coverage is available along with other data from all pertinent satellite

sensors (e.g., daily multi-channel, high-resolution thermal-infrared images and frequent, high 

resolution, multi-channel visible images). Where practical, continuous ground-based thermal 

imaging and Doppler radar coverage is available for ash detection and eruption-rate estimates. 

58
APPENDIX 5 

RATINGS OF CURRENT MONITORING CAPABILITIES AT U.S. VOLCANOES.

See Appendix 4 for criteria of rating levels 0-4.

Vnum Volcano Name

Current 

Seismic 

Rating 

Current 

Deformation 

Rating. 

Current 

Gas 

Rating 

Current 

HydroLogic

rating 

Current 

RemoteSensing 

Current 

Overall 

Monitoring

Rating 

1101-01- Buldir 0 0 0 0 2 0

1101-02- Kiska 0 1 0 0 2 0

1101-03- Segula 0 0 0 0 2 0

1101-04- Davidof 0 0 0 0 2 0

1101-05- Little Sitkin 0 0 0 0 2 0

1101-06- Semisopochnoi 0 0 0 0 2 0

1101-07- Gareloi 3 0 0 0 2 3

1101-08- Tanaga 3 0 0 0 2 3

1101-09- Takawangha 3 0 0 0 2 3

1101-10- Bobrof 2 0 0 0 2 2

1101-11- Kanaga 3 1 0 0 2 3

1101-111 Moffett 2 0 0 0 2 2

1101-112 Adagdak 2 0 0 0 2 2

1101-12- Great Sitkin 3 1 0 0 2 3

1101-13- Kasatochi 0 0 0 0 2 0

1101-14- Koniuji 0 0 0 0 2 0

1101-15- Sergief 0 0 0 0 2 0

1101-16- Atka (Korovin) 3 1 0 0 2 3

1101-18- Seguam 0 1 0 0 2 0

1101-19- Amukta 0 0 0 0 2 0

1101-20- Chagulak 0 0 0 0 2 0

1101-21- Yunaska 0 0 0 0 2 0

1101-22- Herbert 0 0 0 0 2 0

1101-23- Carlisle 0 0 0 0 2 0

1101-24- Cleveland 0 0 0 0 2 0

1101-25- Uliaga 0 0 0 0 2 0

1101-26- Kagamil 0 0 0 0 2 0

1101-27- Vsevidof 0 0 0 0 2 0

1101-28- Recheschnoi 0 0 0 0 2 0

1101-29- Okmok 3 3 0 0 2 3

1101-30- Bogoslof 0 0 0 0 2 0

1101-31- Makushin 3 1 0 0 2 3

1101-311 Table Top-Wide Bay 0 0 0 0 2 0

1101-32- Akutan 3 3 0 0 2 3

1101-34- Westdahl 3 1 0 0 2 3

1101-35- Fisher 3 0 0 0 2 3

1101-36- Shishaldin 3 1 0 0 2 3

1101-37- Isanotski 3 0 0 0 2 3

1101-38- Roundtop 1 0 0 0 2 1

59
1101-39

- Amak 0 0 0 0 2 

0

1102-01- Frosty 2 0 0 0 2 

2

1102-011 Dutton 2 0 0 0 2 

2

1102-02- Emmons Lake 2 0 0 0 2 

2

1102-03- Pavlof 3 1 0 0 2 

3

1102-04- Pavlof Sister 3 1 0 0 2 

3

1102-05- Dana 1 0 0 0 2 

1

1102-051 Stepovak 0 0 0 0 2 

0

1102-06- Kupreanof 1 0 0 0 2 

1

1102-07- Veniaminof 3 1 1 0 2 

3

1102-08- Black Peak 1 0 0 0 2 

1

1102-09- Aniakchak 3 1 0 0 2 

3

1102-10- Yantarni 0 0 0 0 2 

0

1102-11- Chiginagak 1 0 0 0 2 

1

1102-12- Kialagvik 0 0 0 0 2 

0

1102-13- Ugashik-Peulik 3 1 1 0 2 

3

1102-131 Ukinrek Maars 3 0 1 0 2 

3

1102-132 Unnamed 0 0 0 0 2 

0

1102-14- Martin 3 0 2 0 2 

3

1102-15- Mageik 3 0 2 0 2 

3

1102-16- Trident 3 1 0 0 2 

3

1102-17- Katmai 3 1 0 0 2 

3

1102-18- Novarupta 3 1 0 0 2 

3

1102-19- Griggs 3 0 1 0 2 

3

1102-20- Snowy Mountain 3 0 0 0 2 

3

1102-21- Denison 2 0 0 0 2 

2

1102-22- Steller 2 0 0 0 2 

2

1102-23- Kukak 2 0 0 0 2 

2

1102-25- Kaguyak 2 0 0 0 2 

2

1102-26- Fourpeaked 2 0 0 0 2 

2

1102-27- Douglas 1 0 1 0 2 

1

1103-01- Augustine 3 3 2 0 2 

3

1103-02- Iliamna 3 0 2 0 2 

3

1103-03- Redoubt 3 1 2 0 2 

3

1103-04- Spurr 3 2 2 0 2 

3

1103-05- Hayes 1 0 0 0 2 

1

1104-01- St. Paul Island 1 0 0 0 2 

1

1104-02- Nunivak Island 0 0 0 0 2 

0

1104-03- Ingakslugwat Hills 0 0 0 0 2 

0

1104-04- St. Michael 0 0 0 0 2 

0

1104-05- Kookooligit Mountains 0 0 0 0 2 

0

1104-06- Imuruk Lake 1 0 0 0 2 

1

1105-001 Buzzard Creek 1 0 0 0 2 

1

1105-01- Sanford 1 0 0 0 2 

1

1105-02- Wrangell 2 1 0 0 2 

2

1105-021 Gordon 0 0 0 0 2 

0

1105-03- Churchill 1 0 0 0 2 

1

60
1105-04

- Edgecumbe 1 0 0 0 2 

1

1105-05- Duncan Canal 0 0 0 0 2 

0

1105-06- Tlevak Strait-Suemez Is. 1 0 0 0 2 

1

1105-07- Behm CanalRudyerd Bay 0 0 0 0 2 

0

1201-01= Baker 2 1 2 1 1 

2

1201-02- Glacier Peak 1 0 0 1 1 

1

1201-03- Rainier 3 1 1 1 1 

2

1201-04- Adams 2 1 1 0 1 

2

1201-05- St. Helens 4 3 3 3 3 

4

1201-06- West Crater 1 0 0 0 1 

1

1201-07- Indian Heaven 1 0 0 0 1 

1

1202-01- Hood 2 2 1 2 1 

2

1202-02- Jefferson 2 0 1 1 1 

1

1202-03- Blue Lake Crater 1 0 0 0 1 

1

1202-04- Sand Mountain Field 1 0 0 1 1 

1

1202-05- Washington 1 0 0 0 1 

1

1202-06- Belknap 1 0 0 1 1 

1

1202-07- North Sister Field 2 1 0 1 1 

1

1202-08- South Sister 2 2 1 2 2 

2

1202-09- Bachelor 2 1 0 1 1 

2

1202-10- Davis Lake 1 0 0 0 1 

1

1202-11- Newberry Volcano 2 2 1 1 1 

2

1202-12- Devils Garden 1 0 0 0 1 

1

1202-13- Lava Mountain 1 0 0 0 1 

1

1202-14- Four Craters Lava Field 1 0 0 0 1 

1

1202-15- Cinnamon Butte 1 0 0 0 1 

1

1202-16- Crater Lake 1 1 0 1 0 

1

1202-17- Diamond Craters 1 0 0 0 1 

1

1202-19- Jordan Craters 0 0 0 0 1 

0

1202-20- Jackies Butte 0 0 0 0 1 

0

1203-01- Shasta 2 1 1 1 1 

2

1203-02- Medicine Lake 2 1 1 1 1 

2

1203-03- Brushy Butte 2 0 0 0 1 

1

1203-04- Big Cave 1 0 0 0 1 

1

1203-05- Twin Buttes 2 0 0 0 1 

1

1203-06- Tumble Buttes 1 0 0 0 1 

1

1203-08- Lassen Volc Center 3 1 1 2 1 

2

1203-09- Eagle Lake Field 1 0 0 0 1 

1

1203-10- Clear Lake 2 0 0 1 1 

1

1203-11- Mono Lake Volc Field 1 1 1 1 1 

1

1203-12- Mono Craters 1 1 1 1 1 

1

1203-13- Inyo Craters 2 2 1 1 1 

2

1203-14- Long Valley 4 4 3 3 2 

4

1203-15- Red Cones 3 3 3 2 2 

3

1203-16- Ubehebe Craters 2 0 0 0 1 

1

1203-17- Golden Trout Creek 1 0 0 0 1 

1

1203-18- Coso Volc Field 2 1 0 1 1 

2

61
1203-19- Lavic Lake 1 1 0 0 1 1

1203-20- Amboy 0 1 0 0 1 0

1204-01- Shoshone Lava Field 1 0 0 0 1 1

1204-02- Craters of the Moon 2 1 0 0 1 2

1204-03- Wapi Lava Field 1 1 0 0 1 1

1204-04- Hell's Half Acre 2 0 0 0 1 1

1205-01- Yellowstone 3 3 2 2 1 3

1206-01- Steamboat Springs 2 0 0 2 1 2

1207-01- Santa Clara 1 0 0 0 1 1

1207-03- Bald Knoll 1 0 0 0 1 1

1207-04- Markagunt Plateau 1 0 0 0 1 1

1207-05- Black Rock Desert 1 0 0 0 1 1

1208-01- Dotsero 0 0 0 0 1 0

1209-01- Uinkaret Field 1 0 0 0 1 1

1209-02- Sunset Crater 2 0 0 0 1 2

1210-01- Carrizozo 0 0 0 0 1 0

1210-02- Zuni-Bandera 0 0 0 0 1 0

1210-03- Valles Caldera 2 0 0 1 1 2

1302-01- Kilauea 4 4 4 2 3 4

1302-02= Mauna Loa 3 3 2 1 2 3

1302-03- Mauna Kea 2 1 0 1 1 2

1302-04- Hualalai 2 1 0 1 1 2

1302-06- Haleakala 2 1 0 1 1 2

0804-14= Farallon de Pajaros 0 0 0 0 1 0

0804-141 Ahyi 0 0 0 0 1 0

0804-142 Supply Reef 0 0 0 0 1 0

0804-143 Maug Islands 0 0 0 0 1 0

0804-15= Asuncion 0 0 0 0 1 0

0804-16= Agrigan 0 0 0 0 1 0

0804-17= Pagan 0 0 0 0 1 0

0804-18= Alamagan 0 0 0 0 1 0

0804-19= Guguan 0 0 0 0 1 0

0804-191 Sarigan 1 0 0 0 1 1

0804-20= Anatahan 2 0 0 0 1 2

0804-201 Ruby 1 0 0 0 1 1

0804-21= Esmeralda Bank 1 0 0 0 1 1

62