Issues in Choosing the References to Use for Spectral Ratios from Observations and Modeling at Cavola Landslide in Northern Italy

Bordoni, Paola; Giulio, Giuseppe Di; Haines, A. J.; Cara, F.; Milana, Giuliano; Rovelli, A.

doi:10.1785/0120090116

Cited by 12 publications

(7 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reason for this choice is twofold: (1) it is located on the same valley side as the site of reference AQ12 used in the experimental approach (Milana et al 2011); (2) a reference site at the southwestern end of the model is better suited for incoming wave-fronts from that direction, which is consistent with most . A reference site located on the opposite side of the valley with respect to the incoming wave fronts introduces changes in the frequency content during propagation through the sediment filled valley resulting in Fourier amplitude spectra amplified or de-amplified at the opposite bedrock site (AQ18 in the L'Aquila setting), as described by the modeling result of Bordoni et al (2010). We have confirmed this effect also in the L'Aquila modeling setting, though we are not showing it for space reasons.…”

Section: Spectral Ratios From Modelingsupporting

confidence: 67%

Seismic response of L’Aquila downtown from comparison between 2D synthetics spectral ratios of SH, P-SV and Rayleigh waves and observations of the 2009 earthquake sequence

Bordoni

Haines

Milana

et al. 2011

Bull Earthquake Eng

View full text Add to dashboard Cite

This is the first part of a study on the seismic response of the L'Aquila city using 2D simulation and experimental data. We have studied two velocity-depth models with the aim of outlining the behavior of a velocity reversal in the top layer, which is associated with the stiff Brecce de L'Aquila unit (BrA). In this setting, the SMTH model is topped by a layer with about 2:1 impedance contrast with the underlying layer while the NORV model has no velocity reversal. We have simulated the propagation of SH and P-SV wavefields in the range 0-10 Hz for incidence 0 • -90 • . Earthquake spectral ratios of the horizontal and vertical components at six sites in L'Aquila downtown are compared to corresponding synthetics spectral ratios. The vertical component of P-SV synthetics enables us to investigate a remarkable amplification effect seen in the vertical component of the recorded strong motion. Sites AQ04 and AQ05 are best matched by synthetics from the NORV model while FAQ5 and AQ06 have a better match with synthetics spectral ratios from the SMTH model. All simulations show this behavior systematically, with horizontal and near-horizontal incident waves predicting the overall pattern of matches more clearly than vertical and near-vertical incidence. The model inferences are in agreement with new geological data reporting lateral passages in the top layer from the stiff BrA to softer sediments. Matches are good in terms of frequency of the first amplification peak and of spectral amplitude: the horizontal compo-P. Bordoni (B) 123 762 Bull Earthquake Eng (2011) 9:761-781 nents have spectral ratio peaks predominantly at 0.5 Hz in the simulations and at 0.7 Hz in the data, both with amplitudes of 4, while the vertical component spectral ratios reach values of 6 at frequencies of about 1 Hz in both data and simulations. The vertical component spectral ratios are very well matched using Rayleigh waves with incidence at 90 • . The NORV model without the velocity reversal predicts spectral ratio peaks for the horizontal components at frequencies up to 6 Hz. The reversal of velocity acts as a low-pass frequency filter on the horizontal components reducing the amplification effect of the sediment filled valley.

show abstract

Section: Spectral Ratios From Modelingsupporting

confidence: 67%

Seismic response of L’Aquila downtown from comparison between 2D synthetics spectral ratios of SH, P-SV and Rayleigh waves and observations of the 2009 earthquake sequence

Bordoni

Haines

Milana

et al. 2011

Bull Earthquake Eng

View full text Add to dashboard Cite

show abstract

“…The choice of the reference sites is a very delicate task for the reliability of SSR technique (Steidl et al 1996;Bordoni et al 2010). In general, the reference site should be properly located with respect to the investigated sites and the sources, and should not exhibit amplification effects.…”

Section: On the Choice Of The Reference Sitementioning

confidence: 99%

Seismic characterization and monitoring of Fucino Basin (Central Italy)

Cara

Giulio

Cavinato

et al. 2011

Bull Earthquake Eng

Self Cite

View full text Add to dashboard Cite

The Fucino basin (Central Italy) is one of the largest intramountain alluvial plain in the Apennines range. It has a tectonic origin related to the presence of important systems of faults located in its northern and eastern edges. Some of these faults are still active and capable of generating strong seismic events. Site effects related to the soft soils filling the basin can be very important. In this paper we show the preliminary results of a seismic network installed in the Fucino area in order to collect information about site amplification effects and geometry of the basin. We analyze ambient seismic vibrations and recordings of about 150 local earthquakes mainly related to the seismic sequence of the April 6th 2009 Mw 6.3 L'Aquila event. Moreover the strongest events of L'Aquila sequence were analyzed at the three permanent strong-motion stations operating in the area. Using standard spectral techniques we investigate the variation of resonance frequencies within the basin. The ground motion recorded in the Fucino plain is mainly characterized by strong energy at low-frequencies ( f < 1 Hz) affecting both horizontal and vertical components. This is particularly evident for stations deployed in correspondence of very thick deposits of sedimentary filling, where a significant increase of ground-motion amplitude and duration is likely caused by locally generated surface waves. The amplification at low-frequencies (<1 Hz) on the horizontal components can reach up a factor of 10 in comparison to nearby stiff sites. However, we found evidences of seismic amplification phenomena also for stiff sites surrounding the basin, including stations of the Italian strong motion network. The independent geological information and the shallow shear-velocity profiles available for the basin can be combined with resonance frequencies 123 1962 Bull Earthquake Eng (2011Eng ( ) 9:1961Eng ( -1985 for deriving representative geological sections to be used as base for future numerical 2D-3D modeling of the basin.

show abstract

“…In particular, the effect of steplike slope topography (i.e. a sketched slope profile constituted of flat top and bottom and of a constant dip face) on seismic ground motions has been studied by using numerical modeling Bouckovalas and Papadimitriou, 2005;Nguyen and Gatmiri, 2007;Papadimitriou and Chaloulos, 2010;Lenti and Martino, 2011), as reliable field measurements are difficult to obtain because wave scattering due to step-like slope geometries require an unrealistically dense distribution of recording stations. These studies have demonstrated that (i) step-like slope topographies may lead to intense amplification and de-amplification irregularly along the slope, depending on the slope geometry; and (ii) the possible interactions among the seismic input, the slope and preexisting landslide masses depend on seismic properties such as frequency content, directivity and the peak of ground acceleration (Bozzano et al, 2008(Bozzano et al, , 2011aMartino and Scarascia Mugnozza, 2005;Del Gaudio and Wasowsky, 2010;Lenti and Martino, 2011).…”

Section: P Alfaro Et Al: the Role Of Near-field Interaction Betweenmentioning

confidence: 99%

“…Nevertheless, the maximum distance of occurrence of landslides may significantly change as an effect of local site conditions (Gallipoli et al, 2000;Wasowsky and Del Gaudio, 2000;Havenith et al, 2002Havenith et al, , 2003aMartino and Scarascia Mugnozza, 2005;Meric et al, 2007;Bourdeau and Havenith, 2008;Bozzano et al, 2008;Bordoni et al, 2010;Bozzano et al, 2011b;Havenith et al, 2003a, b). In particular, seismically-induced disrupted landslides can be strongly influenced by the orientation of local discontinuities and the topographic amplification of the ground motion (Crawford and Curran, 1981;Harp and Jibson, 2002;Moore et al, 2011;Lovati et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

The role of near-field interaction between seismic waves and slope on the triggering of a rockslide at Lorca (SE Spain)

Alfaro

Delgado²,

García-Tortosa³

et al. 2012

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. A ∼1000 m 3 rockslide occurred close to Lorca (SE Spain) during the main shock (M w = 5.1) of the May 2011 seismic sequence. The location of the rockslide, within 10 km of the earthquake epicenter and along the southern slope of a valley in which similar geological conditions occur on both slopes of the valley, suggests a significant near-field effect due to local seismic response. This could be related to the specific interaction between the topography and the obliquely propagating seismic waves.A dynamic stress strain numerical model was constructed using the FLAC 7.0 finite difference code to back analyze the Lorca rockslide event and relate its occurrence to both the local seismic amplification and the interaction between seismic waves and local topography. The results indicate that only for seismic waves with incidence angles in the range 0 • -50 • are the occurred slope instabilities expected. These results do not significantly change when varying the values for either stiffness or strength parameters within the range of the experimental data.

show abstract

Issues in Choosing the References to Use for Spectral Ratios from Observations and Modeling at Cavola Landslide in Northern Italy

Cited by 12 publications

References 16 publications

Seismic response of L’Aquila downtown from comparison between 2D synthetics spectral ratios of SH, P-SV and Rayleigh waves and observations of the 2009 earthquake sequence

Seismic response of L’Aquila downtown from comparison between 2D synthetics spectral ratios of SH, P-SV and Rayleigh waves and observations of the 2009 earthquake sequence

Seismic characterization and monitoring of Fucino Basin (Central Italy)

The role of near-field interaction between seismic waves and slope on the triggering of a rockslide at Lorca (SE Spain)

Contact Info

Product

Resources

About