Authors—Wald, D.J.,

Jaiswal, K., Marano, K.D., 

Bausch, D., and Hearne, M.

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1 − 9

10 − 99

100 − 999

1,000 − 9,999

10,000 or more

High : 115,000

Low : 0

Shaking deaths

EXPLANATION

Population

Alert level and color Estimated fatalities Estimated losses (U.S. $$)

Red 1,000+ $1 billion+

Orange 100 – 999 $100 million – $1 billion

Yellow 1 – 99 $1 million – $100 million

Green 0 < $1 million

For more information, contact: David Wald (wald@usgs.gov) or Kristin Marano (kmarano@usgs.gov) 

Earthquake Hazards Program, U.S. Geological Survey, Golden, CO 80401

The PAGER Earthquake Impact Scale

PAGER uses a new Earthquake Impact Scale (EIS) that is based 

on two complementary criteria. The first criterion is the estimated 

cost of damage; this is most suitable for domestic events and those in 

earthquake-resistant communities. The second criterion, representing estimated ranges of fatalities, is generally more appropriate for 

global events, particularly in developing countries. Simple thresholds, 

derived from the systematic analysis of past earthquake impact and 

associated response levels, turn out to be quite effective in communicating predicted impact and response needed after an event, characterized by alerts of green (little or no impact), yellow (regional impact 

and response), orange (national-scale impact and response), and red 

(international response). Corresponding fatality thresholds for yellow, 

orange, and red alert levels are 1, 100, and 1,000, respectively. For 

damage impact, yellow, orange, and red thresholds are triggered by 

estimated losses reaching $1 million, $100 million, and $1 billion, 

respectively. The rationale for this dual approach to earthquake alerting 

stems from the recognition that relatively high fatalities, injuries, and 

homelessness dominate in countries where local building practices 

typically lend themselves to high collapse and casualty rates, and it 

is these impacts that drive prioritization for international response. In 

contrast, it is often financial and overall societal impacts that trigger the 

level of response in regions or countries where prevalent earthquakeresistant construction practices greatly reduce building collapse and 

resulting fatalities. 

Since PAGER calculations are available well in advance of 

ground-truth observations or news accounts, PAGER information 

can be a primary alerting tool for domestic as well as international 

earthquake disasters. An example of the PAGER summary product, 

or onePAGER, is shown on the preceding pages for a recent destructive earthquake in early 2010 near central Chile that killed 547 people. 

This earthquake reached a red-alert level based on projected economic 

losses and an orange-alert for estimated fatalities. 

Though PAGER uses simple and intuitive color-coded alerting 

criteria, it preserves the necessary uncertainty measures by which one 

can gauge the likelihood for the alert to be over- or underestimated. 

Using the earthquake impact scale, PAGER’s rapid loss estimates can 

be used to adequately recommend alert levels and suggest appropriate 

response protocols, despite their uncertainties. Demanding or awaiting 

observations or loss estimates with a high level of accuracy may delay 

response and increase the losses.

Frequency of PAGER Alerts

Over the past 38 years there would have been approximately 

17,792 green, 568 yellow, 52 orange, and 49 red alerts. This frequency 

equates to approximately 15 yellow, 1–2 orange, and 1–2 red alerts per 

year. The map below shows the spatial distribution of earthquakes and 

the fatality-based alerts that would have been produced over the past 

38 years (1970 through mid-2008). The spatial distribution reflects 

relative hazard, population exposure, and building vulnerability. In 

the United States, high-fatality alert levels are, as expected, much 

less frequent due to improved building codes and practices in areas of 

high seismicity. 

Ongoing PAGER Developments

The USGS is improving the PAGER system to include more 

comprehensive loss-estimate methodologies that take into account 

more detailed building inventories representing sub-country-level 

regional variations, more complete population demographics (including time of day population shifts), and better tools to compute building damage. Such datasets are very difficult and time consuming to 

acquire and are not available for many areas of the globe. In particular, 

more detailed country-level building inventories are key for describing the dominant vulnerable structures that contribute to casualties 

in the region. Knowledge of the main collapse “culprits” is vital for 

response, public safety, recovery, and long-term mitigation. Related 

USGS developments under the auspices of the PAGER Project include 

rapid determination of fault geometry, size, and rupture characteristics; 

refined global estimates of seismic soil-amplification patterns; ShakeMap enhancements; ground-motion and loss-uncertainty analyses; and 

earthquake-induced landslide and liquefaction probability mapping.

Acknowledgments

PAGER development and 

maintenance are supported by 

the USGS under the Advanced 

National Seismic System (ANSS), 

with additional funding from 

the Global Earthquake Model 

(GEM) project, and a grant from 

the U.S. Agency for International Development/Office of 

Foreign Disaster Assistance 

(USAID/OFDA). Landscan 

population data from Oak Ridge 

National Laboratory, and data 

from Munich Reinsurance, 

EM-DAT, and NOAA were vital 

for developing and calibrating 

PAGER loss models.

Earthquake Impact Scale with Alert Level thresholds.

Spatial distribution of earthquakes and their fatality-based alerts, 1970–2008.
PAGER report on damaging earthquake in Chile 

M 8.8, OFFSHORE MAULE, CHILE

Origin Time: Sat 2010-02-27 06:34:14 UTC (01:34:14 local)

Location: 35.85o

S 72.72oW Depth: 35 km

PAGER

Version 3

Estimated Fatalities Estimated Economic Losses

Created: 3 hours, 10 minutes after earthquake

Estimated Population Exposed to Earthquake Shaking

ESTIMATED POPULATION

EXPOSURE (k = x1000) - -* - -* 488k* 2,150k* 3,654k 6,407k 3,074k 0 0

ESTIMATED MODIFIED

MERCALLI INTENSITY

PERCEIVED SHAKING Not felt Weak Light Moderate Strong Very Strong Severe Violent Extreme

POTENTIAL

DAMAGE

Resistant

Structures

Vulnerable

Structures

none

none

none

none

none

none

V. Light

Light

Light

Moderate

Moderate

Moderate/Heavy

Moderate/Heavy

Heavy

Heavy

V. Heavy

V. Heavy

V. Heavy

*Estimated exposure only includes population within the map area.

Population Exposure population per ~1 sq. km from Landscan

Red alert level for economic losses. Extensive

damage is probable and the disaster is likely

widespread. Estimated economic losses are

3-20% GDP of Chile. Past events with this alert

level have required a national or international

level response.

Orange alert level for shaking-related fatalities.

Significant casualties are likely.

Structures:

Overall, the population in this region resides

in structures that are resistant to earthquake

shaking, though some vulnerable structures

exist. The two model building types that

contribute most to fatalities are partially

confined masonry and unreinforced masonry.

Historical Earthquakes (with MMI levels):

Date

(UTC)

Dist.

(km)

Mag. Max

MMI(#)

Shaking

Deaths

1975-05-10 264 7.8 VIII(69k) 0

2004-08-28 229 6.5 IX(346) 0

1985-03-03 313 7.9 VII(7,023k) 177

Recent earthquakes in this area have caused

secondary hazards such as tsunamis,

landslides, and liquefaction that might have

contributed to losses.

PAGER content is automatically generated, and only considers losses due to structural damage.

Limitations of input data, shaking estimates, and loss models may add uncertainty.

http://earthquake.usgs.gov/pager

FOR TSUNAMI INFORMATION, SEE: tsunami.noaa.gov

Event ID: us2010tfan

Selected City Exposure

from GeoNames.org

MMI City Population

VIII Arauco 25k

VIII Lota 50k

VIII Concepcion 215k

VIII Constitucion 38k

VIII Bulnes 13k

VIII Cabrero 18k

VII Temuco 238k

VI Valparaiso 282k

VI Santiago 4,837k

V Mendoza 877k

IV Neuquen 242k

bold cities appear on map (k = x1000)
PAGER report on damaging earthquake in Chile 

M 8.8, OFFSHORE MAULE, CHILE

Origin Time: Sat 2010-02-27 06:34:14 UTC (01:34:14 local)

Location: 35.85o

S 72.72oW Depth: 35 km

PAGER

Version 3

Estimated Fatalities Estimated Economic Losses

Created: 3 hours, 10 minutes after earthquake

Estimated Population Exposed to Earthquake Shaking

ESTIMATED POPULATION

EXPOSURE (k = x1000) - -* - -* 488k* 2,150k* 3,654k 6,407k 3,074k 0 0

ESTIMATED MODIFIED

MERCALLI INTENSITY

PERCEIVED SHAKING Not felt Weak Light Moderate Strong Very Strong Severe Violent Extreme

POTENTIAL

DAMAGE

Resistant

Structures

Vulnerable

Structures

none

none

none

none

none

none

V. Light

Light

Light

Moderate

Moderate

Moderate/Heavy

Moderate/Heavy

Heavy

Heavy

V. Heavy

V. Heavy

V. Heavy

*Estimated exposure only includes population within the map area.

Population Exposure population per ~1 sq. km from Landscan

Red alert level for economic losses. Extensive

damage is probable and the disaster is likely

widespread. Estimated economic losses are

3-20% GDP of Chile. Past events with this alert

level have required a national or international

level response.

Orange alert level for shaking-related fatalities.

Significant casualties are likely.

Structures:

Overall, the population in this region resides

in structures that are resistant to earthquake

shaking, though some vulnerable structures

exist. The two model building types that

contribute most to fatalities are partially

confined masonry and unreinforced masonry.

Historical Earthquakes (with MMI levels):

Date

(UTC)

Dist.

(km)

Mag. Max

MMI(#)

Shaking

Deaths

1975-05-10 264 7.8 VIII(69k) 0

2004-08-28 229 6.5 IX(346) 0

1985-03-03 313 7.9 VII(7,023k) 177

Recent earthquakes in this area have caused

secondary hazards such as tsunamis,

landslides, and liquefaction that might have

contributed to losses.

PAGER content is automatically generated, and only considers losses due to structural damage.

Limitations of input data, shaking estimates, and loss models may add uncertainty.

http://earthquake.usgs.gov/pager

FOR TSUNAMI INFORMATION, SEE: tsunami.noaa.gov

Event ID: us2010tfan

Selected City Exposure

from GeoNames.org

MMI City Population

VIII Arauco 25k

VIII Lota 50k

VIII Concepcion 215k

VIII Constitucion 38k

VIII Bulnes 13k

VIII Cabrero 18k

VII Temuco 238k

VI Valparaiso 282k

VI Santiago 4,837k

V Mendoza 877k

IV Neuquen 242k

bold cities appear on map (k = x1000)
Authors—Wald, D.J.,

Jaiswal, K., Marano, K.D., 

Bausch, D., and Hearne, M.

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1 − 9

10 − 99

100 − 999

1,000 − 9,999

10,000 or more

High : 115,000

Low : 0

Shaking deaths

EXPLANATION

Population

Alert level and color Estimated fatalities Estimated losses (U.S. $$)

Red 1,000+ $1 billion+

Orange 100 – 999 $100 million – $1 billion

Yellow 1 – 99 $1 million – $100 million

Green 0 < $1 million

For more information, contact: David Wald (wald@usgs.gov) or Kristin Marano (kmarano@usgs.gov) 

Earthquake Hazards Program, U.S. Geological Survey, Golden, CO 80401

The PAGER Earthquake Impact Scale

PAGER uses a new Earthquake Impact Scale (EIS) that is based 

on two complementary criteria. The first criterion is the estimated 

cost of damage; this is most suitable for domestic events and those in 

earthquake-resistant communities. The second criterion, representing estimated ranges of fatalities, is generally more appropriate for 

global events, particularly in developing countries. Simple thresholds, 

derived from the systematic analysis of past earthquake impact and 

associated response levels, turn out to be quite effective in communicating predicted impact and response needed after an event, characterized by alerts of green (little or no impact), yellow (regional impact 

and response), orange (national-scale impact and response), and red 

(international response). Corresponding fatality thresholds for yellow, 

orange, and red alert levels are 1, 100, and 1,000, respectively. For 

damage impact, yellow, orange, and red thresholds are triggered by 

estimated losses reaching $1 million, $100 million, and $1 billion, 

respectively. The rationale for this dual approach to earthquake alerting 

stems from the recognition that relatively high fatalities, injuries, and 

homelessness dominate in countries where local building practices 

typically lend themselves to high collapse and casualty rates, and it 

is these impacts that drive prioritization for international response. In 

contrast, it is often financial and overall societal impacts that trigger the 

level of response in regions or countries where prevalent earthquakeresistant construction practices greatly reduce building collapse and 

resulting fatalities. 

Since PAGER calculations are available well in advance of 

ground-truth observations or news accounts, PAGER information 

can be a primary alerting tool for domestic as well as international 

earthquake disasters. An example of the PAGER summary product, 

or onePAGER, is shown on the preceding pages for a recent destructive earthquake in early 2010 near central Chile that killed 547 people. 

This earthquake reached a red-alert level based on projected economic 

losses and an orange-alert for estimated fatalities. 

Though PAGER uses simple and intuitive color-coded alerting 

criteria, it preserves the necessary uncertainty measures by which one 

can gauge the likelihood for the alert to be over- or underestimated. 

Using the earthquake impact scale, PAGER’s rapid loss estimates can 

be used to adequately recommend alert levels and suggest appropriate 

response protocols, despite their uncertainties. Demanding or awaiting 

observations or loss estimates with a high level of accuracy may delay 

response and increase the losses.

Frequency of PAGER Alerts

Over the past 38 years there would have been approximately 

17,792 green, 568 yellow, 52 orange, and 49 red alerts. This frequency 

equates to approximately 15 yellow, 1–2 orange, and 1–2 red alerts per 

year. The map below shows the spatial distribution of earthquakes and 

the fatality-based alerts that would have been produced over the past 

38 years (1970 through mid-2008). The spatial distribution reflects 

relative hazard, population exposure, and building vulnerability. In 

the United States, high-fatality alert levels are, as expected, much 

less frequent due to improved building codes and practices in areas of 

high seismicity. 

Ongoing PAGER Developments

The USGS is improving the PAGER system to include more 

comprehensive loss-estimate methodologies that take into account 

more detailed building inventories representing sub-country-level 

regional variations, more complete population demographics (including time of day population shifts), and better tools to compute building damage. Such datasets are very difficult and time consuming to 

acquire and are not available for many areas of the globe. In particular, 

more detailed country-level building inventories are key for describing the dominant vulnerable structures that contribute to casualties 

in the region. Knowledge of the main collapse “culprits” is vital for 

response, public safety, recovery, and long-term mitigation. Related 

USGS developments under the auspices of the PAGER Project include 

rapid determination of fault geometry, size, and rupture characteristics; 

refined global estimates of seismic soil-amplification patterns; ShakeMap enhancements; ground-motion and loss-uncertainty analyses; and 

earthquake-induced landslide and liquefaction probability mapping.

Acknowledgments

PAGER development and 

maintenance are supported by 

the USGS under the Advanced 

National Seismic System (ANSS), 

with additional funding from 

the Global Earthquake Model 

(GEM) project, and a grant from 

the U.S. Agency for International Development/Office of 

Foreign Disaster Assistance 

(USAID/OFDA). Landscan 

population data from Oak Ridge 

National Laboratory, and data 

from Munich Reinsurance, 

EM-DAT, and NOAA were vital 

for developing and calibrating 

PAGER loss models.

Earthquake Impact Scale with Alert Level thresholds.

Spatial distribution of earthquakes and their fatality-based alerts, 1970–2008.