Synthetic seismograms in laterally heterogeneous, anelastic media by modal summation of P-SV-waves

Vaccari, Franco; Gregersen, Søren; Furlan, Michela; Panza, G. F.

doi:10.1111/j.1365-246x.1989.tb01688.x

Cited by 54 publications

(46 citation statements)

References 5 publications

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“…The modal summation method is practically free from approximations in the relatively simple one-dimensional case and can be eciently extended, introducing approximations of variable and to some extent quanti®able size, to two-and threedimensional cases (VACCARI et al, 1989), while it can also be applied for a quantitative and realistic earthquake hazard assessment (PANZA et al, 1996).…”

Section: Methods Usedmentioning

confidence: 99%

1-D Theoretical Modeling for Site Effect Estimations in Thessaloniki: Comparison with Observations

Triantafyllidis¹,

Hatzidimitriou²,

Suhadolc³

2001

Pure appl. geophys.

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Ð We apply an algorithm based on the modal summation method to theoretically estimate the site eect at selected locations underlain by dierent geological formations within the city of Thessaloniki (Greece). Complete strong motion synthetics are constructed for all components of motion at each site, for a maximum frequency of 10 Hz. The anelastic, local 1-D velocity models are based on crosshole data. Four point sources with dierent azimuths and distances from the city are used to compute the input signals. The theoretical ampli®cation is estimated through spectral ratios of accelerograms obtained by the local 1-D over those obtained by the regional 1-D velocity model. The results from the numerical modeling are compared with those derived from experimental techniques, such as of Standard Spectral Ratio and Horizontal-to-Vertical Spectral Ratio, which had been applied to acceleration data recorded at the same sites. The comparison demonstrates that the theoretical ampli®cations based on known and simple subsurface geology can be used as a ®rst-order estimate, while for cases of more complex geometries the use of at least 2-D modeling in site eects estimation is mandatory.

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Section: Methods Usedmentioning

confidence: 99%

1-D Theoretical Modeling for Site Effect Estimations in Thessaloniki: Comparison with Observations

Triantafyllidis¹,

Hatzidimitriou²,

Suhadolc³

2001

Pure appl. geophys.

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“…The simulation of the ground motion is performed using the hybrid method (Fah 1991;Fah and Panza, 1994;Fah et ai, 1994), that combines the modal summation technique (Panza, 1985;Vaccari et al, 1989;Florsch et aI., 1991;Romanelli et aI., 1996), used to describe the SH and P-SV-wave propagation in the anelastic bedrock structure, with the finite difference technique (Alterman and Karal, 1968;Boore, 1972;Kelly et ai, 1976) used for computation of wave propagation in the anelastic, laterally varying sedimentary area of Bucharest, located about 170 km away from the epicentral area.…”

Section: Ground Motion Modellingmentioning

confidence: 99%

Modelling, for Microzonation Purposes, of the Seismic Ground Motion in Bucharest, Due to the Vrancea Earthquake of May 30, 1990

Moldoveanu

Panza

1999

Vrancea Earthquakes: Tectonics, Hazard and Risk Mitigation

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The Vrancea seismoactive region, characterized by intermediate-depth earthquakes, is the quake source that has to be taken into account for microzonation purposes of Bucharest that could suffer serious damage also because of the severe local site effects. The strong seismic events originating in Vrancea have caused the most destructive damage experienced on the Romanian territory and may seriously affect vulnerable high risk constructions (such as nuclear power plants, chemical plants, large dams, pipelines etc.) located on a wide area, from Central Europe to Moscow.Realistic numerical simulation, describing the propagation of the seismic wavefield generate'd by a given quake in a complex geological structure, is a powerful tool, that may be efficiently used to estimate the ground motion for microzonation of the whole Bucharest area.The realistic modelling of ground motion is canied out by means of a sophisticated hybrid technique that combines modal summation (Panza, 1985; Vaccari et aI., 1989; Florsch et aI., 1991;Panza, 1993; Romanelli et aI., 1996) and finite difference (Fiih 1991;Fah and Panza, 1994; Fah et aI., 1994). The input data necessary for computations are the laterally variable anelastic structural model and the focal mechanism of the seismic source.The medium is modelled with a regional layered structure (bedrock structure), containing the seismic source and assumed to be representative of the path from the source to Bucharest, and a local structure, that is a NE20 0 SW oriented cross section, describing the local structure of Bucharest, along the studied path. The seismic source is described by a double-couple, buried in a layered medium, and corresponds to the focal mechanism of the May 30, 1990 Vrancea earthquake. The upper frequency limit considered in the computations is 1.0 Hz, and this allows us the modelling of seismic input appropriate for ten storeys and higher buildings.The simulated signals are satisfactorily compared with the available instrumental records from Magurele station (44.347 0 N, 26.030 0 E), and stability tests are performed with respect to the variation of focal mechanism, regional and local structure.

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“…The methods used for the modeling of the ground motion are described in detail by PANZA (1985), VACCARI et al (1989), FA È H (1991), FLORSCH et al (1991), FA È H et al (1993, PANZA (1993), FA È H and PANZA (1994) and ROMANELLI et al (1996) and these methods permit realistic consideration of source, path and local soil eects on the entire wavetrain.…”

Section: Four Detailed Examplesmentioning

confidence: 99%

“…The area is formed by deep deposits ± mainly alluvium sands and clays poorly consolidated and with high water content ± that have been trapped by the Xiadian fault. The realistic modeling of ground motion is carried out by means of a sophisticated hybrid technique that combines modal summation (PANZA, 1985, 1993VACCARI et al, 1989FLORSCH et al, 1991;ROMANELLI et al, 1996) and ®nite dierences (FA È H, 1991;. The input data necessary for computations are the laterally variable anelastic structural model and the focal mechanism of the seismic source.…”

Section: Seismic Ground Motion In the Beijing Areamentioning

confidence: 99%

Realistic Modeling of Seismic Input in Urban Areas: A UNESCO-IUGS-IGCP Project

Panza¹,

Vaccari²,

Romanelli³

2001

Pure appl. geophys.

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Ð The estimation of realistic seismic input can be obtained from the computation of a wide set of time histories and spectral information, corresponding to possible seismotectonic scenarios for dierent source and structural models. Such a data set can be very constructively used by civil engineers in the design of new seismo-resistant structures and in the reinforcement of the existing built environment, therefore supplying a particularly powerful tool to the prevention eorts of Civil Defense. The availability of realistic numerical simulations enables us to estimate the ampli®cation eects in complex geological structures exploiting the available geotechnical, lithological, geophysical parameters, topography of the medium, tectonic, historical, paleoseismological data, and seismotectonic models. The realistic modeling of the ground motion is a very important source of knowledge for the preparation of groundshaking scenarios which represent a valid and economical tool in seismic microzonation.

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Synthetic seismograms in laterally heterogeneous, anelastic media by modal summation of P-SV-waves

Cited by 54 publications

References 5 publications

1-D Theoretical Modeling for Site Effect Estimations in Thessaloniki: Comparison with Observations

1-D Theoretical Modeling for Site Effect Estimations in Thessaloniki: Comparison with Observations

Modelling, for Microzonation Purposes, of the Seismic Ground Motion in Bucharest, Due to the Vrancea Earthquake of May 30, 1990

Realistic Modeling of Seismic Input in Urban Areas: A UNESCO-IUGS-IGCP Project

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