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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!
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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.
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Hazard Factors |
Scoring Ranges |
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Volcano type |
1 |
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Maximum Volcanic Explosivity Index
|
1 |
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Explosive activity in past 500 years?
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1 |
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Major explosive activity in past 5000 years?
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0 |
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Eruption recurrence |
4 |
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Holocene pyroclastic flows? |
1 |
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Holocene lahars? |
1 |
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Holocene lava flow? |
1 |
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Hydrothermal explosion potential?
|
1 |
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Holocene tsunami? |
0 |
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Sector collapse potential? |
1 |
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Primary lahar source? |
0 |
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Observed seismic activity |
1 |
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Observed ground deformation |
0 |
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Observed fumarolic or magmatic degassing
|
1 |
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Total of Hazard Factors
14 |
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Exposure Factors |
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Log10
of Volcano Population Index (VPI)
at 30 km |
5.1 |
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Log10
of approximate population
downstream or downslope |
0 |
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Historical fatalities? |
1 |
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Historical evacuations? |
1 |
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Local aviation exposure |
1 |
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Regional aviation exposure |
2 |
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Power infrastructure |
0 |
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Transportation infrastructure |
0 |
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Major development or sensitive areas |
0 |
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Volcano is a significant part of a populated island |
0 |
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Total of Exposure Factors
9.3 |
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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
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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. |
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Hazards Factors |
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Score |
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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
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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 |
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Explosive activity
If explosive activity (VEI ≥ 3) within the
last 500 years: Score = 1 |
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Major explosive activity
If major explosive activity (VEI ≥ 4) within
last 5000 years: Score = 1 |
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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
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Holocene pyroclastic flows?
If yes: Score = 1 |
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Holocene lava flows?
If Holocene lava flows have traveled beyond
the immediate eruption site or flanks and
reached populated areas: Score =1
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Holocene lahars?
If Holocene lahars have traveled beyond the
flanks and reached populated areas: Score =1
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Holocene tsunami(s)?
Has it produced a tsunami within the
Holocene? If yes: Score = 1 |
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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 |
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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
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Primary lahar source?
If volcano has a source of permanent
water/ice on edifice, water volume > 106
m3:
Score = 1 |
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continued...
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Observed seismic unrest
Since the last eruption, in the absence of
eruptive activity, within 20 km of the
volcanic edifice? If yes: Score = 1
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Observed ground deformation
Since the last eruption, in the absence of
eruptive activity, inflation or other
evidence of magma injection? If yes: Score =
1 |
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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
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Total of Hazard Factors |
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Exposure Factors |
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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. |
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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). |
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Historical fatalities?
If yes, and a permanent population is still
present: Score = 1 |
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Historical evacuations?
If yes, and a permanent population is still
present: Score = 1 |
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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.
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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. |
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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
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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 |
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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 |
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Volcano is a significant part of a populated
island
Holocene volcanic deposits cover >25% of
land mass. If yes, score = 1 |
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Total of Exposure Factors
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Sum of all hazard factors x Sum of all
exposure factors = Relative Threat Ranking
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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:
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Name |
Current Seismic Rating |
Current Deformation Rating |
Current Gas Rating |
Current Hydrologic Rating |
Current Remote Sensing |
Current Overall Monitoring Rating |
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Volcán de Colima |
3 |
3 |
3 |
3 |
2 |
3 |
What are the figures based on?
Click
here to see.
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