Recorded displacements in a landslide slope due to regional and teleseismic earthquakes

Regional and teleseismic earthquakes can induce displacements along joints in a landslideinvolved rocky slope in Central Italy. The rarity of these effects is due to specific physical properties of the seismic signals associated with: (i) the energy content, (ii) the distribution of relative energy and peak of ground acceleration related to the ground motion components and (iii) the spectral amplitude distribution in the frequency domain; these properties allow the triggering earthquakes to be distinguished from the others. The observed effects are relevant when compared to the direction of the landslide movement and the dimensions of the involved rock mass volume. The landslide movement is less constrained in the direction parallel to the dip of the slope and the landslide dimensions are associated with characteristic periods that control the landslide deformational response in relation to the spectral content of the ground motion. The earthquake-induced displacements are significant because they have the same order of magnitude as the average annual cumulative displacement based on a decade of strain measurements within the slope

Analysis of the seismic site effects along the ancient Via Laurentina (Rome)

This paper presents an evaluation of the Local Seismic Response (LSR) along the route of the ancient Roman road Via Laurentina, which has been exposed in several areas of southwest Rome over the last decade during the construction of new buildings and infrastructures. It is an example of LSR analysis applied to ancient and archaeological sites located in alluvial valleys with some methodological inferences for the design of infrastructure and urban planning. Since the ancient road does not cross the alluvial valley (namely the Fosso di Vallerano Valley) normal to its sides, it was not possible to directly perform 2D numerical modelling to evaluate the LSR along the road route. Therefore, outputs of 2D numerical models, obtained along three cross sections that were normal oriented respect to the valley, were projected along the route of the Via Laurentina within a reliable buffer attributed according to an available high-resolution geological model of the local subsoil. The modelled amplification functions consider physical effects due to both the 2D shape of the valley and the heterogeneities of the alluvial deposits. The 1D and 2D amplification functions were compared to output that non-negligible effects are related to the narrow shape of the fluvial valley and the lateral contacts between the lithotecnical units composing the alluvial fill. The here experienced methodology is suitable for applications to the numerical modelling of seismic response in case of linear infrastructures (i.e., roads, bridges, railways) that do not cross the natural system along physically characteristic directions (i.e. longitudinally or transversally)

Analysis of local seismic response in the historical city centre of Nafplio (Greece)

Local seismic response analysis represents a fundamental tool for assessing the seismic risk of urban areas and Cultural Heritage (CH) sites, nevertheless several open questions remain when complex geological contexts are considered. This study has been carried out in the framework of the research project STABLE (H2020 RISE-Marie Curie Action) which has the aim of evaluating the seismic action on CH sites in the Mediterranean basin. One of them being the city of Nafplio (Greece), a site characterised by a peculiar geological setting and a medium-high regional seismic hazard. Geological and geophysical data have been collected to reconstruct both the subsoil model and the seismotectonic conditions. Several seismic ambient noise measurements were carried out to establish the site resonance frequency and to validate engineering-geological cross-sections for numerical modelling of the seismic wave propagation. Combined engineering-geological, geophysical and numerical modelling allowed evaluating the local seismic response of the urban area of Nafplio, providing a zonation map with homogeneous seismic response zones for which elastic response spectra will be obtained

ask 6 - Gubbio - Deliverable D21: Geological model of the Gubbio basin (Italy) for the characterization of local seismic response

Within the framework of the project S3 “Ground shaking scenarios for some strategic areas in Italy-Task6” the town of Gubbio has been selected as a test site to compute ground motion taking into account finite fault and site effects. Gubbio is located in central Italy, on the northern slopes of one of the many valleys characterising the central Appennines. The historical settlement is located on a rocky slope, while new developments extend on the Quaternary fluvio-lacustrine deposits filling the basin. The Gubbio basin was chosen as a test site for a number of reasons: its geomorphological setting is very common in central and southern Italy, the area is characterised by frequent near events of moderate magnitude (Mmax 6) and large amplifications were observed there for the Colfiorito seismic sequence of the 1997/98. In order to understand the mechanisms controlling the 3D seismic response of the basin, a subsurface model has been constructed. The reconstruction of the model has been done using data coming from different surveys (figure A). Several active and passive seismic measurements have been carried out in the plain, also favoured by the intense seismic activity typical of the area. These investigations mainly consisted of monitoring activities of 4 temporary transects of seismometric stations, operating between June 2005 and May 2006 and described in detail in PS3- Deliverables D22-D23. Two transects have been positioned perpendicularly to the valley axes (GFZ and Ge2 Transects), one parallel (INGV transect) and one near Gubbio (Ge1 transect). More than 300 local and regional earthquakes have been recorded, with maximum magnitude equal to 4. A 2D array was run as well from June to September 2006, to better understand the generation of surface waves. All data are collected in a GIS (Progetto S3 Deliverable D23) Parallel to these activities, ambient noise data have been collected in the field for 90 sites, using the single station technique for the estimation of the fundamental resonance frequencies. Furthermore, 4 noise measurements with a seismic array have been collected to build an S-wave velocity profile of soft sediments, considered representative for the whole plain. The geometry of the basin below 500 m of depth has been investigated through the acquisition of an active seismic line 4.5 km long, in correspondence of one of the transects. This has been used to perform a tomography of arrival times which allowed to recognise the position and shape of the reflecting horizons. As a final step the first 30 metres of deposits have been characterised over a 30 km2 area, using both stratigraphic investigations provided by the Gubbio Municipality and data collected from in-situ surveys and lab tests. In this deliverable we describe the input data for the 3D model of the Gubbio basin and we outline the steps performed to define the geometry, the layers and their seismic properties on the base of the experimental data collected during the project and of the available geological information.Progetto INGV-DPC S3 “Scenari di scuotimento in aree di interesse prioritario e/o strategico” (coord. F.Pacor e M. Mucciarelli)Published4.1. Metodologie sismologiche per l'ingegneria sismicaope

ask 6 - Gubbio - Deliverable D21: Geological model of the Gubbio basin (Italy) for the characterization of local seismic response

Within the framework of the project S3 “Ground shaking scenarios for some strategic areas in Italy-Task6” the town of Gubbio has been selected as a test site to compute ground motion taking into account finite fault and site effects. Gubbio is located in central Italy, on the northern slopes of one of the many valleys characterising the central Appennines. The historical settlement is located on a rocky slope, while new developments extend on the Quaternary fluvio-lacustrine deposits filling the basin. The Gubbio basin was chosen as a test site for a number of reasons: its geomorphological setting is very common in central and southern Italy, the area is characterised by frequent near events of moderate magnitude (Mmax 6) and large amplifications were observed there for the Colfiorito seismic sequence of the 1997/98. In order to understand the mechanisms controlling the 3D seismic response of the basin, a subsurface model has been constructed. The reconstruction of the model has been done using data coming from different surveys (figure A). Several active and passive seismic measurements have been carried out in the plain, also favoured by the intense seismic activity typical of the area. These investigations mainly consisted of monitoring activities of 4 temporary transects of seismometric stations, operating between June 2005 and May 2006 and described in detail in PS3- Deliverables D22-D23. Two transects have been positioned perpendicularly to the valley axes (GFZ and Ge2 Transects), one parallel (INGV transect) and one near Gubbio (Ge1 transect). More than 300 local and regional earthquakes have been recorded, with maximum magnitude equal to 4. A 2D array was run as well from June to September 2006, to better understand the generation of surface waves. All data are collected in a GIS (Progetto S3 Deliverable D23) Parallel to these activities, ambient noise data have been collected in the field for 90 sites, using the single station technique for the estimation of the fundamental resonance frequencies. Furthermore, 4 noise measurements with a seismic array have been collected to build an S-wave velocity profile of soft sediments, considered representative for the whole plain. The geometry of the basin below 500 m of depth has been investigated through the acquisition of an active seismic line 4.5 km long, in correspondence of one of the transects. This has been used to perform a tomography of arrival times which allowed to recognise the position and shape of the reflecting horizons. As a final step the first 30 metres of deposits have been characterised over a 30 km2 area, using both stratigraphic investigations provided by the Gubbio Municipality and data collected from in-situ surveys and lab tests. In this deliverable we describe the input data for the 3D model of the Gubbio basin and we outline the steps performed to define the geometry, the layers and their seismic properties on the base of the experimental data collected during the project and of the available geological information