In an attempt to develop a diffuse culture of prevention against earthquakes, the Italian government has issued an Act (June 24 2009 n. 77) and subsequent ordinances which regulate the distribution of resources to those regions that promote studies of seismic microzoning (SM). As a result, during the last years the number of Ital ian SM studies has been increasing and posing many new problems and challenges to administrators and scientists. The aim of this paper is to illustrate, through some salient examples of recent SM cases in Italy, the emerging philosophy of a new current of SM studies that can be called ordinary, namely projects devoted to seismic risk reduction through the usual preventive activities that can be carried out by local governments with the contribution of local officials and professionals, to the maximum extent possible. While the SM studies are generally elaborate, slow and costly, the logic of ordinary SM projects is that they have to be performed smoothly, rather quickly and cheaply. The aim is not to obtain the best SM product at any price but the best SM project consistent with efficient administrators who really want to reduce seismic risk in their regions.
In order to reach this objective and to guarantee the quality of the products, local governments (regions, provinces and municipalities) now have new duties; that is, they must undertake, in conjunction with scientists and researchers, positive actions to improve the state of knowledge and of practice in seismic risk reduction in the region, to increase the number and technical capacities of local professionals and public officials, to reduce time and investigation costs through drawing up basic geological maps also in digital format at an appropriate scale for SM, issuing specific valuable SM guidelines, implementing digital models of the territory, creating regional seismological, geological and geotechnical data banks, controlling the accuracy of the obtained SM maps and so on.
The paper focuses on unprecedented problems posed by the new legislation also to scientists and researchers, who are now called by administrators and public officials to play different scientific roles than in the past in order to contribute to advancing the frontiers of knowledge as well as the state of practice through experience transfer and applications.
soil liquefaction
SOIL LIQUEFACTION PHENOMENA OBSERVED IN RECENT SEISMIC EVENTS IN EMILIA-ROMAGNA REGION, ITALY
Significant and widespread liquefaction effects, which caused panic of inhabitants and damage to buildings and infrastructures, were observed in various areas of Emilia-Romagna region, Italy, during the seismic events of May 20 and 29, 2012, with magnitude respectively of Ml 5.9 and Ml. 5.8. In Italian seismic literature these phenomena represent an interesting case study for a number of reasons: for the exceptional impacts, for the size of the area in which liquefaction effects were observed, for the amount of damage produced, for the rarity of soil liquefaction Italian case histories. Immediately after the earthquake of 20 May an extensive field reconnaissance was conducted through the natural and built environment to capture as quickly as possible surface evidences of liquefaction and to document the extent and the severity of damage. The most significant and widespread liquefaction impacts were found in the two settlements of San Carlo and Mirabello. With the aim of a better understanding of the observed scenarios, a detailed investigation program, including geophysical surveys and geotechnical testing (soundings, cone penetration tests, seismic cone penetration tests, cross-hole and down-hole tests as well as many cyclic laboratory tests), was planned. These investigations are now in progress and will be object of forecoming technical notes. This paper summarizes the observation of soil liquefaction effects made during field investigations and presents a first interpretation, based on available information on ground shaking and soil conditions, of the factors that may have contributed to determine the low liquefaction resistance of soils.