Towards a catalogue of earthquake environmental effects
|Location||International Geological Congress,oslo 2008|
|Author||Michetti, Alessandro Maria۱; Comerci, Valerio۲; Esposito, Eliana۳; Guerrieri, Luca۲; Porfido, Sabina۳; Silva, Pablo G.۴; Vittori, Eutizio۲|
|Holding Date||29 September 2008|
Earthquake environmental effects are any effects produced by a seismic event on natural environment. Several decades of research on earthquake geology and paleoseismology have pointed out their crucial role in seismic hazard assessment, due to their relations with the earthquake size and with the location of seismogenic sources.
The recently published ESI 2007 intensity scale (Michetti et al., 2007) is a tool for intensity assessment based only on environmental effects which conveniently integrates the traditional damage-based intensity assessments. Preliminary applications of the ESI 2007 to case studies have evidenced the need of a systematic revision, mapping and classification of environmental effects induced by recent, historical and paleo earthquakes. In other words, similarly to historical seismic catalogues, a global catalogue of earthquake environmental effects is necessary, aimed at collecting in a standardized format the characteristics of environmental effects in selected regions worldwide. It will be a product of the activities of the INQUA TERPRO Focus Area on Active Tectonics and Paleoseismology in the period 2007-2011.
A successful catalogue of environmental effects has to be combined with historical catalogues. In fact, seismic hazard assessment takes advantage from this integrated approach, due to the availability of i) two independent intensity assessments (MM or MSK, and ESI), and ii) more reliable spatial and temporary (i.e. recent, historical and paleo earthquakes) comparisons among earthquake intensities.
Preliminary available inventories are the EEE database (http://www.apat.gov.it/INQUA/) and the Spanish Catalogue of Earthquake Ground Effects (Silva et al., 2007). The first one is structured in three different levels of generalization (earthquake, locality and site) and currently collects environmental effects data from 51 earthquakes in 9 countries. The second one is structured in five temporal sections which display an increasing quality of data source, from geological and archeological data, up to historical documents, contemporary reports and newspapers and finally to instrumental data. At present, 32 seismic events have been compiled.
Starting from these pioneer examples, the structure of the global catalogue is expected to be adaptable in order to collect information from very different data sources and diverse geological countries in a homogeneous format.
Peculiar attention must be paid to the most diagnostic features for intensity assessment. To this end, primary effects (i.e., the surface expression of the seismogenic tectonic source) and secondary effects have to be clearly differentiated. Furthermore, special emphasis has to be devoted to the classification of tsunami effects.
Additionally, a GIS interface is indispensable for the evaluation of ESI epicentral intensities (based on total coseismic rupture length as well as on total area of secondary effects) and for spatial representation of local intensities.