The Environmental Seismic Intensity scale (ESI2007) is a new earthquake intensity scale only based on the effects triggered by the earthquake in the natural environment. The coseismic effects considered more diagnostic for intensity evaluation are surface faulting and tectonic uplift/subsidence (primary effects), landslides, ground cracks, liquefactions, displaced boulders, tsunamis and hydrological anomalies (secondary effects). The ESI 2007 scale follows the same basic structure as any other XII degree scale, such as the MCS, MM, MSK and EMS scales (Fig.1. table of intensity degreeS).
This type of intensity scale was proposed to the scientific community, since the beginning of '90s. The idea was definitely accepted in 1999, when a first version of the scale was developed by a Working Group of geologists, seismologists and engineers sponsored by the International Union for Quaternary Research (INQUA). In the following years, this version has been revised and updated. The ESI 2007 scale is the result of the revision of the previous versions after its application to a large number of earthquakes worldwide. In the frame of the INQUA SubCommission on Paleoseismicity, this activity was conducted by academic and research institutes coordinated by the Geological Survey of Italy - APAT, with CNR and INSUBRIA University (for further details, s e e http://www.apat.gov.it/site/en-GB/Projects/INQUA_Scale/default.html/ )
For the intensity levels lower than IX, the main goal of this new scale is to bring the environmental effects in line with the damage indicators. In this range, the ESI 2007 scale should be used along with the other scales. In the range between X and XII the distribution and size of environmental effects, specially primary tectonic features, becomes the most diagnostic tool to assess the intensity level. Documentary report and/or field observations on fault rupture length and surface displacement should be consistently implemented in the macroseismic study of past and future earthquakes. Therefore, the use of the ESI 2007 alone is recommended only when effects on humans and on manmade structures 1) are absent, or too scarce (i.e. in sparsely populated or desert areas), and 2) saturate (i.e., for intensity X to XII) loosing their diagnostic value.
Further information: Eliana Esposito Sabina Porfido