What is the Earthquake Impact Scale that is used in PAGER?
PAGER employs 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, proved 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 1000, respectively. For damage impact, yellow, orange, and red thresholds are triggered by estimated losses reaching $1M, $100M, and $1B (USD), 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 earthquake resistant construction practices greatly reduce building collapse and resulting fatalities.