The Temporary Seismometric Network at Perugia (Italy)

SCIENTIFIC STAFF: Enrico Priolo1, Roberto De Franco2, Carla Barnaba1, Giovanna Laurenzano1, Marco Romanelli1, Monica Sugan1, Alessandro Vuan1, Grazia Caielli2, Adelmo Corsi2, Antonio Morrone2, Alberto Tento2
1Centro Ricerche Sismologiche, Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Cussignacco (UD) e Sgonico (TS)
2Istituto per le Dinamiche dei Processi Ambientali, Consiglio Nazionale delle Ricerche, Milano

In 2008-2009, OGS was charged by the Perugia Municipality with the task of performing a geophysical study in view of the microzonation of the city. This study encompassed the registration of earthquakes through a temporary seismic network, the acquisition of environmental seismic noise, and the estimation of the shear wave velocity through active seismic methods.

The temporary network of Perugia was implemented in two successive phases using 18 and 11 seismological stations in synchronous acquisition, respectively. The instrumentation included two different kinds of acquisition units, i.e. Reftek 130, Nanometrics Orion, all equipped with Lennartz 3D-Lite 1s short-period seismometer. A total of 28 sites, including two reference sites, was monitored (Fig. 1). Sites were chosen within or close to public or historical buildings (e.g. schools, hospitals, churches, ancient buildings, ...), according to the italian regulations and the indications provided by the Umbria Region (Table 1). The reference sites were located on rock at distance of some kilometres from the historical centre.

The temporary network ---whose sites and data have been include into the OASIS database--- was deployed in September 2008 and remained effective till June 2009. Among other regional earthquakes, the network recorded the ML5.1 earthquake occurred on December 23, 2008 in the the Norhtern Apennnines as well as the ML5.8 earthquake occurred in L'Aquila on April 6, 2009 together with its aftershock sequence (Fig. 2).

Figure 1. Maps of the temporary seismometric network of Perugia. Top: general overview; bottom: progressive detail of the area.

Figure 2. Map of the earthquakes recorded and used for the site response estimation in Perugia. Left: all earthquakes; right: earthquakes of the Central Apennines.

Table 1. Summary of the sites of the temporary network deployed in Perugia