The cartography in seismic hazard assessment and communication: the case study of the 2012 Po Plain earthquakes (northern Italy)

Περίληψη

In this article, the use of cartography and geographical information system are discussed within hazard and risk communication approaches. It aims to examine the seismic risk cartography related to the area struck by the 2012 seismic sequence in the Po Plain which was related to the activity of buried Apennines faulted folds. It has consisted of seven M>5 quakes from 20th May to 3rd June 2012 and more than 2500 aftershocks of lower magnitude during almost one year. The most relevant geological effect caused by the two stronger earthquakes (ML = 5.9 and ML = 5.8) was the 10-15 cm uplift of the epicentral area. Moreover several hundreds of earthquake-induced environmental effects (EEE) were detected (soil liquefaction phenomena, ground ruptures, sand boils, etc.). By the comparison of the location of the EEE with the Geomorphological Map of the Po Plain, it appeared that they were aligned and concentrated along the courses of abandoned riverbeds mainly characterized by the presence of superficial sandy texture highlighting the importance the geomorphological maps for seismic hazard assessment. As concerns macroseismic intensity maps, an intensity field that integrates the ESI scale, which considers the EEE and the MCS intensity evaluations, based on the pattern of buildings damage, represents a better tool for characterizing the 2012 event in the framework of the seismic-hazard assessment of the Po Plain. In spite of the unpredictability of earthquakes the population has given credit to various groundless alarms on the basis of gas emission, bubbling water and ground fractures. Therefore the Emilia-Romagna Region established a group of experts that throughout a dedicated website communicates correct information on particular geological phenomena that are observed and usually misunderstood by the population. The role of communication is essential in order to enhance awareness on seismic hazard and environmental effects comprehension among civil society.