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We carried out a vibration study experiment on a masonry building in the town of Ariano Irpino, southern Italy, using six-channel stations equipped with three-component velocity-transducers and accelerometers and running in continuous modality from January 2006 to December 2007. The analysis of weak motions from several local earthquakes, together with the 3D numerical modelling of the structure, allowed us to identify the first three vibration modes of the target building. Therefore, we checked the validity of ambient noise data to determine the vibration frequencies of buildings. The analysis tools based on earthquake and ambient noise data were conventional, i.e. spectral ratios between homologous components of stations at high floors in the building with respect to a station installed at the basement, and single-station spectral ratios between horizontal and vertical components. The indications derived from earthquakes and ambient noise result in a satisfactory agreement for frequencies between 1 and 20 Hz when using recordings characterized by low levels of amplitude, both for cultural and meteorological noise. In contrast, when the wind speed increases (above 20 km/h, approximately) seismic noise shows an excess of horizontal vibrations at low frequencies (below 2 Hz). These extra-amplitudes are not related to the seismic input vertically incident to the basement, but are probably due to the lateral action of the wind on the building. In contrast anthropic activities do not affect considerably the trend of spectral ratios in the range of frequencies that include the first modes of vibration of the building, even at high noise level.

For several years, the Istituto Nazionale di Geofisica e Vulcanologia (INGV, National Institute of Geophysics and Volcanology) uses ArcGIS Online (www.arcgis.com), to share information about the real-time seismicity in Italy with other geographical data, geological and seismological, through the development of different WebGIS applications with various customized functionalities. During the earthquake emergency in Central Italy in August 2016, WebGIS applications have been widely used. They derive from a common platform developed a few months earlier by the LABGIS of INGV-Irpinia. This platform has enabled the management and updating of the seismic data of the sequence in real time and their integration with the leading INGV databases seismological and seismotectonic and those of other Institutes. Moreover, these applications have permission to manage and share information and even data from the activities of the INGV Emergency Groups , such as the location and characteristics of seismic and accelerometric temporary stations installed by the teams of SISMIKO and EMERSITO and the geological observations from the EMERGEO Group.

At 01:36 UTC (03:36 local time) on August 24th 2016, an earthquake Mw 6.0 struck an extensive sector of the central Apennines (coordinates: latitude 42.70° N, longitude 13.23° E, 8.0 km depth). The earthquake caused about 300 casualties and severe damage to the historical buildings and economic activity in an area located near the borders of the Umbria, Lazio, Abruzzo and Marche regions. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) located in few minutes the hypocenter near Accumoli, a small town in the province of Rieti. In the hours after the quake, dozens of events were recorded by the National Seismic Network (Rete Sismica Nazionale, RSN) of the INGV, many of which had a ML > 3.0. The density and coverage of the RSN in the epicentral area meant the epicenter and magnitude of the main event and subsequent shocks that followed it in the early hours of the seismic sequence were well constrained. However, in order to better constrain the localizations of the aftershock hypocenters, especially the depths, a denser seismic monitoring network was needed. Just after the mainshock, SISMIKO, the coordinating body of the emergency seismic network at INGV, was activated in order to install a temporary seismic network integrated with the existing permanent network in the epicentral area. From August the 24th to the 30th, SISMIKO deployed eighteen seismic stations, generally six components (equipped with both velocimeter and accelerometer), with thirteen of the seismic station transmitting in real-time to the INGV seismic monitoring room in Rome. The design and geometry of the temporary network was decided in consolation with other groups who were deploying seismic stations in the region, namely EMERSITO (a group studying site-effects), and the emergency Italian strong motion network (RAN) managed by the National Civil Protection Department (DPC). Further 25 BB temporary seismic stations were deployed by colleagues of the British Geological Survey (BGS) and the School of Geosciences, University of Edinburgh in collaboration with INGV. All data acquired from SISMIKO stations, are quickly available at the European Integrated Data Archive (EIDA). The data acquired by the SISMIKO stations were included in the preliminary analysis that was performed by the Bollettino Sismico Italiano (BSI), the Centro Nazionale Terremoti (CNT) staff working in Ancona, and the INGV-MI, described below.

On August 24, 2016, at 01:36 UTC a MW 6.0 earthquake struck an extensive area of the central Apennines (Italy). It was followed by a large aftershock (MW 5.3, August 24, 02:33 UTC) and about 20 earthquakes with magnitude greater than 4.0, located between the towns of Norcia and Amatrice. Due to the mainshock magnitude and the widespread damaging level of buildings in the epicentral area, the Emersito task force has been mobilized by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The aim of Emersito is to carry out and coordinate the monitoring of local site effects, caused by geological and geomorphological settings. During the first days of the seismic emergency, Emersito installed a temporary seismic network for site effect studies at 4 municipalities close to the epicentral area (Amandola, Civitella del Tronto, Montereale and Capitignano), using 22 stations equipped with both velocimetric and accelerometric sensors. The selection of the sites where stations have been installed was mainly driven by the proximity to the epicentral area (without interfere with the rescue operation) and by peculiar geologic and geomorphologic settings (topographic irregularities, fault zones, alluvial plains).

On May 20, 2012, at 02:03 UTC, a Ml 5.9 reverse-fault earthquake occurred in the Emilia-Romagna region, northern Italy, at a hypocentral depth of 6.3 km (http://iside.rm.ingv.it/), close to the cities of Modena and Ferrara in the plain of the Po River. The epicenter was near the village of Finale Emilia where macroseismic intensity was assessed at 7 EMS98 [Tertulliani et al. 2012, this issue], while the closest accelerometric station, MRN, located less than 20 km west-ward at Mirandola (Figure 1) recorded peaks of ground accelerations of about 300 cm/s2 (www.protezionecivile.gov.it/resources/cms/documents/Report_DPC_1_Emilia_EQSd.pdf). The mainshock triggered liquefaction phenomena a few kilometers eastwards of the epicenter, around the village of San Carlo. On the same day, two other shocks of Ml 5.1 followed (02:07, 13:18 GMT; http://iside.rm.ingv.it/). On May 29, 2012, at 07:00 UTC another Ml 5.8 earthquake hit the region (http://iside.rm.ingv.it/), with the epicenter close to the village of Mirandola (Figure 1). Three other strong aftershocks occurred afterwards, of Ml 5.3 (May 29, at 10:55), Ml 5.2 (May 29, at 11:00) and Ml 5.1 (June 3, at 19:20). For a detailed description of the seismic sequence, see Moretti et al. [2012], Scognamiglio et al. [2012], and Massa et al. [2012], in this issue. The Emilia seismic sequence resulted in 25 casualties, several of whom were among the workers in the many factories that collapsed during working hours, and there was extensive damage to monuments, public buildings, industrial sites, and private homes. […]