2012): Preliminary results of ground-motion characteristics (original) (raw)
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Could large vertical ground motions occur in NE Italy
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Introduction. Recent earthquakes, among which also that of May 20, 2012 in the Ferrara region (northern Italy), highlighted unexpected large vertical ground motions in the near field and specific-related damage, particularly on masonry and precast buildings (Grimaz, 2012). These aspects have caused criticism to the estimates obtained by probabilistic seismic hazard analyses represented by the national seismic hazard maps considered in the building code of various countries [see for a detailed discussion Slejko (2012)], where the main focus is on the horizontal component of seismic ground motion. In the Ferrara area, instead, the most severe damage suffered by the industrial buildings was caused by a vertical peak ground acceleration (PGA) around 1 g, not expected in that area according to the present Italian seismic code. More examples can be found worldwide, see, e.g. Papazoglou and Elnashai (1996), Yang and Sato (2000), Elgamal and He (2004), and Aghabarati and Tehranizadeh (2009)...
CHARACTERISTICS OF GROUND MOTION IN NORTHERN APENNINES (LUNIGIANA-GARFAGNANA, TUSCANY, ITALY)
In this study, predictive relationships for earthquake-induced ground motion have been calibrated over the Northern Apennines. The data set used in this study consists of 605 earthquake with moment magnitudes up to 4.7, recorded by the regional seismic network, RSLG, operating in Lunigiana-Garfagnana. Regressions have been carried out using 6000 three-component short-period seismograms, all recorded within a hypocentral distance r max =200 km, to empirically obtain the scaling relationships for the high-frequency S-wave motion. The dataset were used to parameterize source-spectral models, regional attenuation functions, and empirical functions of the dispersioninduced ground-motion duration. In order to obtain the regional ground-motion parameters, first of all, we regressed the logarithms of the peak values and Fourier amplitudes at a set of sampling frequencies between 0.5 and 15.0 Hz. Then, we modeled our results in terms of geometrical spreading, g(r), frequency dependent Q(f), and distance-independent average κ 0. In order to minimize the trade-off between the stress parameter and κ 0 , the best value of κ 0 is searched by fitting the high frequency spectra of the small events. After obtaining κ 0 , the stress parameter was calibrated on a Brune spectrum with single corner frequency on the largest events.
Characteristics of the Ground Motion in Northeastern Italy
Bulletin of the Seismological Society of America, 2002
A large data set of ground-velocity time histories from earthquakes that occurred in Friuli-Venezia Giulia (northeastern Italy) was used to define regional predictive relationships for ground motion, in the 0.25-to 14.0-Hz frequency band. The bulk of the data set was provided by the seismic network run by Centro Ricerche Sismologiche (CRS), a department of the Istituto Nazionale di Oceanografia e Geofisica (OGS). A collection of 17,238 selected recordings from 1753 earthquakes was compiled for the years 1995-1998, with magnitudes ranging from M w ϳ1 to 5.6. Ninety-six three-component strong-motion waveforms belonging to the largest events of the 1976-1977 Friuli seismic sequence were also taken from the ENEA-ENEL accelerogram database and included in our data set. For the strongest event, which occurred on 6 May 1976 at 20:00 local time, an average local magnitude M L 6.6 was computed by . The inclusion of a large number of acceleration time histories from this earthquake and six others, from magnitudes from M w 5.2 to magnitude M s 6.1 (three of them of M s ϳ6.0), extends the validity of the predictive relationships proposed in this study up to the highest magnitude ever recorded in the region.
Bulletin of Earthquake Engineering, 2014
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A Report on the 2012 seismic sequence in Emilia (northern Italy)
Since mid-May 2012, an energetic seismic sequence has affected the northern part of Italy and specifically a wide sector of the Po River Plain. The sequence has been dominated by two main events: a) Mw = 5.9 occurred near Finale Emilia on May 20th at a depth of 6.3 km, and b) Mw=5.8 occurred near Cavezzo on May 29th at a depth of 10.2 km (earthquake location are obtained Istituto Nazionale di Geofisica e Vulcanologia, http://iside.rm.ingv.it/). The effects of the two main shocks can be summarized as follows:
Ground motion models for the Molise region (Southern Italy)
Soil Dynamics and Earthquake Engineering, 2008
On October 31 st and November 1 st , 2002 two moderate earthquakes of moment magnitude M w =5.7 (INGV-Harvard European-Mediterranean Regional Centroid-Moment tensor project) occurred in southern Italy. After the mainshocks, felt in many municipalities of the Molise and Puglia region, a strong motion and a seismic temporary network were installed in the epicentral area and surrounding regions. The strong motion network was composed by 9 stations, integrating the accelerometers of the permanent Rete Accelerometrica Nazionale (RAN network), and operated until December 2003. The strong motion data set is composed by 195 recordings from 51 earthquakes (2.5<M l <5.4) recorded by 29 accelerometers (Dipartimento della Protezione Civile et al., 2004). In addition to the strong motion network, several Italian research institutions (Istituto .Te.Ris) installed a temporary regional network, composed by 35 seismic stations. This network aimed at monitoring and studying the evolution in time and space of the seismic sequence. More than 1900 aftershocks were recorded in the period November 1st -December 5th, 2002 (Chiarabba et al., 2005. The unified velocity-acceleration data set has been considered to derive ground motion models for peak ground acceleration and peak ground velocity for both maximum horizontal and vertical components. The results obtained for the Molise area have been compared with the attenuation pattern of the Umbria-Marche region (central Italy), that was recently investigated by Bindi et al. (2006). The remarkable differences observed indicate the need of a regional attenuation relation for the area and the need of further investigations, to better identify the role of source characteristics, anelastic and geometric attenuation and site effects in the evaluation of peak ground motion values.
Ground motion models for Molise region (southern Italy)
On October 31 st and November 1 st , 2002 two moderate earthquakes of moment magnitude M w =5.7 (INGV-Harvard European-Mediterranean Regional Centroid-Moment tensor project) occurred in southern Italy. After the mainshocks, felt in many municipalities of the Molise and Puglia region, a strong motion and a seismic temporary network were installed in the epicentral area and surrounding regions. The strong motion network was composed by 9 stations, integrating the accelerometers of the permanent Rete Accelerometrica Nazionale (RAN network), and operated until December 2003. The strong motion data set is composed by 195 recordings from 51 earthquakes (2.5<M l <5.4) recorded by 29 accelerometers (Dipartimento della Protezione Civile et al., 2004). In addition to the strong motion network, several Italian research institutions (Istituto .Te.Ris) installed a temporary regional network, composed by 35 seismic stations. This network aimed at monitoring and studying the evolution in time and space of the seismic sequence. More than 1900 aftershocks were recorded in the period November 1st -December 5th, 2002 (Chiarabba et al., 2005. The unified velocity-acceleration data set has been considered to derive ground motion models for peak ground acceleration and peak ground velocity for both maximum horizontal and vertical components. The results obtained for the Molise area have been compared with the attenuation pattern of the Umbria-Marche region (central Italy), that was recently investigated by Bindi et al. (2006). The remarkable differences observed indicate the need of a regional attenuation relation for the area and the need of further investigations, to better identify the role of source characteristics, anelastic and geometric attenuation and site effects in the evaluation of peak ground motion values.