By Paige Cross           

 

 

National Volcano Early Warning System

From PDF by John Ewert, USGS Open-File Report 2005-1164

 

What is NVEWS?

http://pubs.usgs.gov/fs/2006/3142/2006-3142.pdf



Proving that you can quantify a quality!


Assessment of the Threat of Volcán de Colima19

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

1

Maximum Volcanic Explosivity Index

1

Explosive activity in past 500 years?

1

Major explosive activity in past 5000 years?

0

Eruption recurrence

4

Holocene pyroclastic flows?

1

Holocene lahars?

1

Holocene lava flow?

1

Hydrothermal explosion potential?

1

Holocene tsunami?

0

Sector collapse potential?

1

Primary lahar source?

0

Observed seismic activity

1

Observed ground deformation

0

Observed fumarolic or magmatic degassing

1

Total of Hazard Factors

14

Exposure Factors

Log10 of Volcano Population Index (VPI) at 30 km

5.1

Log10 of approximate population downstream or downslope

0

Historical fatalities?

1

Historical evacuations?

1

Local aviation exposure

1

Regional aviation exposure

2

Power infrastructure

0

Transportation infrastructure

0

Major development or sensitive areas

0

Volcano is a significant part of a populated island

0

Total of Exposure Factors

9.3

Sum of all hazard factors X Sum of all exposure factors = Relative Threat Ranking

130.2

 


 

 Appendix 2 Table19

For in-depth explanation of factors, click here and continue to Appendix 2

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

 

     

 continued... 

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

 


If a volcano is well-monitored, however, the threat presented to the population can be slightly offset by observing the behavior and gathering the data necessary to warn of or even predict eruptions and/or potentially hazardous conditions.

So what exactly does it mean to be well-monitored?

Excerpted from the full PDF....19

"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, remote-sensing) 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 satellite-based 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 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 lahar runout 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 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."  

How well do we know Volcán de Colima?

Monitoring at Volcán de Colima:

 

Name

Current Seismic Rating

Current Deformation Rating

Current Gas Rating

Current Hydrologic Rating

Current Remote Sensing

Current Overall Monitoring Rating

Volcán de Colima

3

3

 3

 3

 2

 3

  

What are the figures based on? Click here to see.