The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains verified and reliable metadata and intensity measures of manually processed waveforms included in the ESM database. ...The flatfile has been developed within the Seismology Thematic Core Service of EPOS-IP (European Plate Observing System Implementation Phase) and it is disseminated throughout a web portal (
http://esm.mi.ingv.it/flatfile-2018/flatfile.php
) for research and technical purposes. The adopted criteria for flatfile compilation aim to collect strong motion data and related metadata in a uniform, updated, traceable and quality-checked way to develop Ground Motion Models (GMMs) for Probabilistic Seismic Hazard Assessment (PSHA) and engineering applications. In this paper, we present the characteristics of ESM flatfile in terms of recording, event and station distributions, and we discuss the most relevant features of the Intensity Measures (IMs) of engineering interest included in the table. The dataset for flatfile compilation includes 23,014 recordings from 2179 earthquakes and 2080 stations from Europe and Middle-East. The events are characterized by magnitudes in the range 3.5–8.0 and refer to different tectonics regimes, such as shallow active crustal and subduction zones. Intensity measures include peak and integral parameters and duration of each waveform. The spectral amplitudes of the (5% damping) acceleration and displacement response are provided for 36 periods, in the interval 0.01–10 s, as well as the 103 amplitudes of the Fourier spectrum for the frequency range 0.04–50 Hz. Several statistics are shown with reference to the most significant metadata for GMMs calibrations, such as moment magnitude, focal depth, several distance metrics, style of faulting and parameters for site characterization. Furthermore, we also compare and explain the most relevant differences between the metadata of ESM flatfile with those provided by the previous flatfile derived in RESORCE (Reference Database for Seismic Ground Motion in Europe) project.
ABSTRACTThis study focuses on generating a shear-wave velocity averaged within the uppermost 30 m of the ground surface (Vs30) map for the Marche region (central Italy) using two commonly ...acknowledged proxies: topographic slope and lithological classification. The analysis is based on a comprehensive dataset of geophysical tests from the Italian seismic microzonation dataset, employed as a training set. Through regression analysis, Vs30 values are modelled as a function of lithology and topographic slope, with a random effect accounting for the combination of these variables. The resulting Vs30 raster map illustrates the spatial distribution of shear-wave velocities across the region, offering a representation of the subsurface seismic characteristics essential for various applications, including local seismic hazard assessment, prediction of seismic ground motion parameters, microzonation mapping, real-time shakemap generation, and seismic design of engineering structures.
Ground motion model for reference rock sites in Italy Chiara, Felicetta; Giovanni, Lanzano; Maria, D’Amico ...
Soil dynamics and earthquake engineering (1984),
July 2018, 2018-07-00, 20180701, Letnik:
110
Journal Article
Recenzirano
To assess site-specific ground motion it is common practice to calculate seismic hazard at bedrock and then multiply it by a deterministic site-amplification factor typically computed from 1D ...numerical simulation. For this reason, the ground motion at bedrock should be free from amplification phenomena and its site response flat. Ground Motion Prediction Equations are generally calibrated using records at stations classified as rock that, however, can be affected by site-effects, caused by peculiar morphological/stratigraphic features.
In this work, we propose six proxies based on geological, topographical and geophysical data to identify reference rock sites. We apply these proxies to the same set of recording stations used to derive the most recent ground-motion attenuation model for Italy 6 - ITA10. We find that about half of the analyzed sites, classified as rock on the basis of VS,30 or geological conditions, are unaffected by amplifications and can be actually considered as reference rock sites.
Then, we re-calibrate the ITA10 prediction equations for horizontal peak ground acceleration at 20 spectral ordinates in the period range 0.04–2s, accounting for sites that we identify as references rock sites. The resulting reference median values are, on average, 35–40% lower than those calculated by Bindi et al. (2011) model for rock sites. Conversely, the ground motion variability is not significantly changed, even if we introduce a new site soil category to describe the reference rock stations.
•Rock sites can be affected by site amplification.•Identification of reference rock site has implications in the calibration of GMPEs and in site-specific hazard assessment.•VS,30 value is not able to discriminate between reference and generic rock sites.
In this paper, we separate the residuals of ground motion prediction equations into different components, calculating the repeatable site-specific (
δ
S
2
S
s
), location-specific (
δ
L
2
L
r
) and ...path-specific (
δ
P
2
P
e
r
) correction for the median model. In this way, we can reduce the total standard deviation (sigma) of the ground-motion model by Lanzano et al. (Bull Seismol Soc Am 106(1):73–92,
2016
), removing these components and overcome the ergodic assumption. These repeatable terms are empirically estimated using a dataset composed by acceleration waveforms of Italian events mainly occurred in the Po plain and Eastern Alps (Northern Italy), in the time interval 1976–2015. The analysis is carried out on 2241 recordings, from 88 shallow earthquakes recorded by 168 sites. A local model, specifically tailored for Northern Italy, is used as the reference GMPE, which predicts the geometric mean of the horizontal peak ground accelerations and response spectral ordinates in the period range 0.04–4 s. Because most of the propagation paths sampled only once, the path-specific components and the resulting aleatory variability are also calculated from the spatial correlation of residuals, following the approach of Lin et al. (Bull Seismol Soc Am 101(5):2281–2295,
2011
). We find a significant reduction of the overall ground motion variability to an extent comparable to what observed from previous studies on empirical and simulated datasets. The estimated median corrections and variance components can be used in probabilistic seismic hazard assessment for a single site and a single path in Northern Italy. As an example, we compute the hazard curves at some sites by means of three different approaches (ergodic, partially non-ergodic and full non-ergodic), in order to quantify the impact of relaxing the ergodic assumption.
In Italy, earthquakes caused by volcanoes are of primary importance in the evaluation of seismic hazard, since several volcanoes seriously endanger densely populated areas (e.g. Catania and ...surroundings, Campi Flegrei, Vesuvius). On the other hand, there are very few models for the prediction of ground motion induced by volcanic events, mostly because observations are scarce and volcanic earthquakes less frequent than crustal events. Following the recent earthquakes in the Etna area (mainshock 26/12/2018 M
w
= 4.9) and in the island of Ischia (mainshock 21/08/2017 M
w
= 3.9), it was possible to increase the number of recordings for volcanic areas in Italy and, in particular, close to the epicentre. The data available after the recent events revealed the limitations of previous models and especially their inadequacy to predict the ground motion observed in the near source, that can be unexpectedly high. We calibrate a new empirical model to predict the amplitudes of several intensity measures for volcanic areas in Italy. The most relevant aspect in the proposed model is the different attenuation with the distance between shallow and deep events, with discerning focal depth fixed at 5 km. The equations are valid for the geometric mean of horizontal components of PGA, PGV and acceleration response spectra ordinates at 5% damping (in period range T = 0.025–5 s). The range of validity in magnitude is 3.5–4.9 and the hypocentral distance range is 1–200 km.
Earthquakes are a major trigger for instability of natural and man-made slopes. Often the instability of slopes due to an earthquake causes more destruction and kills more people than the actual ...earthquake itself. A comparison is made between different methodologies to analyze the potential stability of slopes during earthquakes. Theoretically, it seems simple to calculate the stability of a slope during an earthquake. In reality, however, the stability is influenced by so many parameters that are either not known or which influence is so poorly known that a decent estimation of stability cannot be made. Offshore the situation is worse because proper data required for stability calculations are even less available than onshore. On- and offshore, erosion and weathering create continuously slopes that may become unstable during a future earthquake, offshore also sedimentation creates continuously new slopes. Another fundamental problem in stability analysis is the complicated and largely unknown behavior of seismic waves in three-dimensions in natural materials. The lack of accurate data and the unknown behavior of seismic waves in three-dimensions make estimations of slope stability during an earthquake unreliable.
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).
The main objective of this work is to provide two zonations of Italy useful to incorporate regional source and path effects in empirical Ground Motion Models (GMMs). To this end, we revise existing ...zonations developed for seismic and tsunami hazard studies, based on the results of a residual analysis between the observations of the ITACAext dataset and the predictions of ITA18, a GMM recently developed for Italy. The analysis consists in the decomposition of the residuals into repeatable terms, according to the well-established approach used for the calibration of non-ergodic models. Based on the spatial trend of the interpolated residuals, and geological and seismological considerations, the zonations are proposed and discussed, in the perspective of supporting regionalization of a future generation of GMMs for Italy.
•The goal is to provide the tools to regionalize seismic motion in Italy.•Zonation for source effects is based on spatial variability of the event residuals.•Zonation for propagation effects is based on spatial variability of random residuals.
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. …
In this study we present a procedure for the topographic classification of Italy, taking advantage of existing high-resolution digital elevation models (DEM), with the support of routines embedded in ...Geographic Information Systems. The proposed method is based on morphometric analyses of a DEM, allowing for hilltop ridge detection, slope computation, identification of reliefs with potential topographic site effects, and topographic classification according to the indications of the current European and Italian seismic codes. The developed procedure can be applied worldwide and has a potential engineering interest for a fast and accurate topographic classification of a site, for both scientific and application purposes. The topographic classification of Italy is tested on several well-known cases of topographic amplification and it is adopted for the topographic classification of Italian accelerometric stations.
•Topographic classification of Italy according to the Italian seismic code.•Novel GIS procedure.•Around one third of the Italian territory has sites with possible topographic amplification.
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