scholarly journals Realistic modelling of observed seismic motion in compIex sedimentary basins

1994 ◽  
Vol 37 (6) ◽  
Author(s):  
D. Fah ◽  
G. F. Panza
Keyword(s):  
Ground Motion ◽  
Mexico City ◽  
Sedimentary Basin ◽  
Numerical Technique ◽  
Sedimentary Basins ◽  
Space Distribution ◽  
Soil Conditions ◽  
Macroseismic Data ◽  
Resonance Effects ◽  
Local Soil

Three applications of a numerical technique are illustrated to model realistically the seismic ground motion for complex two-dimensional structures. First we consider a sedimentary basin in the Friuli region, and we model strong motion records from an aftershock of the 1976 earthquake. Then we simulate the ground motion caused in Rome by the 1915, Fucino (Italy) earthquake, and we compare our modelling with the damage distribution observed in the town. Finally we deal with the interpretation of ground motion recorded in Mexico City, as a consequence of earthquakes in the Mexican subduction zone. The synthetic signals explain the major characteristics (relative amplitudes, spectral amplification, frequency content) of the considered seismograms, and the space distribution of the available macroseismic data. For the sedimentary basin in the Friuli area, parametric studies demonstrate the relevant sensitivity of the computed ground motion to small changes in the subsurface topography of the sedimentary basin, and in the velocity and quality factor of the sediments. The relative Arias Intensity, determined from our numerical simulation in Rome, is in very good agreoment with the distribution of damage observed during the Fucino earthquake. For epicentral distances in the range 50 km-100 km, the source location and not only the local soil conditions control the local effects. For Mexico City, the observed ground motion can be explained as resonance effects and as excitation of local surface waves, and the theoretical and the observed maximum spectral amplifications are very similar. In general, our numerical simulations estimate the maximum and average spectral amplification for specific sites, i.e. they are a very powerful tool for accurate micro-zonation

scholarly journals Investigating the influence of topographic irregularities and two-dimensional effects on surface ground motion intensity with one- and two-dimensional analyses

2014 ◽  
Vol 14 (7) ◽  
pp. 1773-1788 ◽  
Author(s):  
G. Ç. İnce ◽  
L. Yılmazoğlu
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Soil Conditions ◽  
Response Analysis ◽  
Two Dimensional ◽  
Ground Acceleration ◽  
Equivalent Linear ◽  
Local Soil ◽  
Different Depths ◽  
Earthquake Response Analysis

Abstract. In this work, the surface ground motion that occurs during an earthquake in ground sections having different topographic forms has been examined with one and two dynamic site response analyses. One-dimensional analyses were undertaken using the Equivalent-Linear Earthquake Response Analysis (EERA) program based on the equivalent linear analysis principle and the Deepsoil program which is able to make both equivalent linear and nonlinear analyses and two-dimensional analyses using the Plaxis 8.2 software. The viscous damping parameters used in the dynamic site response analyses undertaken with the Plaxis 8.2 software were obtained using the DeepSoil program. In the dynamic site response analyses, the synthetic acceleration over a 475-year return period representing the earthquakes in Istanbul was used as the basis of the bedrock ground motion. The peak ground acceleration obtained different depths of soils and acceleration spectrum values have been compared. The surface topography and layer boundaries in the 5-5' cross section which cuts across the study area west to east were selected in order to examine the effect of the land topography and layer boundaries on the analysis results, and were flattened and compared with the actual status. The analysis results showed that the characteristics of the surface ground motion change in relation to the varying local soil conditions and land topography.

scholarly journals SEISMIC DAMAGE SCENARIOS IN KALAMATA (S. GREECE)

2017 ◽  
Vol 50 (3) ◽  
pp. 1495
Author(s):  
D. Kazantzidou-Firtinidou ◽  
I. Kassaras ◽  
A. Ganas ◽  
C. Tsimi ◽  
N. Sakellariou ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Fragility Curves ◽  
Site Amplification ◽  
Soil Conditions ◽  
Damage Scenarios ◽  
Local Soil ◽  
Protection Strategies ◽  
The Impact ◽  
The City

Damage scenarios are necessary tools for stakeholders, in order to prepare protection strategies and a total emergency post-earthquake plan. To this aim, four seismic hazard models were developed for the city of Kalamata, according to stochastic simulation of the ground motion, using site amplification functions derived from ambient noise HVSR measurements. The structural vulnerability of the city was assessed following an empirical macroseismic model, developed for the European urban environment (EMS-98). The impact of the vulnerability due to the seismic hazard potential is also investigated by means of synthetic response spectral ratios at 108 sites of the city. The expected damage grade per building block, is calculated by combining vulnerability with the respective seismic intensities, derived for the four seismic sources. The importance of the followed methodology for implementing microzonation studies is emphasized, since the expected influence of the ground motion amplification due to local soil conditions has been approximated in detail. Moreover, new fragility curves for the main structural types in Kalamata are proposed for each seismic scenario.

scholarly journals Towards preparation of design spectra for Serbian National Annex to Eurocode 8: Part I: spectral shapes and regional empirical equations for scaling pseudo-acceleration spectra

2012 ◽  
Vol 10 (2) ◽  
pp. 131-154
Author(s):  
Borko Bulajic ◽  
Miodrag Manic ◽  
Djordje Ladjinovic
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Strong Motion ◽  
Soil Conditions ◽  
Eurocode 8 ◽  
Empirical Equations ◽  
Strong Motion Data ◽  
Motion Data ◽  
Local Soil ◽  
Spectral Shapes

Eurocode 8 allows that any country can use its own shape of the elastic response spectrum after it defines it in the National Annex. Having in mind that such country-specific spectra are to be derived through analysis of the strong motion data recorded in the considered seismo-tectonic region, in this Paper we discuss the existing and a set of new empirical equations for scaling pseudo-acceleration spectra in Serbia and the whole region of north-western Balkans. We then compare the presented spectra to those proposed by Eurocode 8. Results show that the indiscriminate use of the strong motion data from different seismo-tectonic regions, improper classification of the local soil conditions, and neglect of the effects of deep geology, may all lead to unreliable scaling equations and to extremely biased ground motion estimates. Moreover, only two spectral shapes that are defined for wide magnitude ranges and scaled by a single PGA value, are not able to adequately represent all important features of real strong ground motion, and instead of using such normalized spectra one should rather employ the direct scaling of spectral amplitudes that is based on the analysis of regionally gathered and processed strong motion data.

The basin effect and liquefaction in the catastrophe models: Case study – Vancouver region, Canada

2020 ◽  
Author(s):  
Svetlana Stripajova ◽  
Peter Pazak ◽  
Jan Vodicka ◽  
Goran Trendafiloski
Keyword(s):  
Ground Motion ◽  
Sedimentary Basin ◽  
Water Saturation ◽  
Site Response ◽  
Earthquake Ground Motion ◽  
Soil Conditions ◽  
Liquefaction Hazard ◽  
Geological Conditions ◽  
Catastrophe Models

<p>The presence of thick soft alluvial sediment-filled basins, like in river’s deltas, can significantly amplify and prolongate the earthquake ground motion. Moreover, the high-water saturation of such soft sediments and cyclic earthquake loading can lead to liquefaction. The basin and liquefaction effect can contribute to substantial modification of the seismic motion and increase of the potential losses at a particular location. Well-known examples of such high financial losses during earthquakes for basin effect is Mw 8.1 Mexico City 1985 and for liquefaction is Darfield and Christchurch earthquakes series in 2010 and 2011. Thus, the quantification of these effects is particularly important for the current underwriting products and the industry requires their further detailed consideration in the catastrophe models and pricing approaches. Impact Forecasting, Aon’s catastrophe model development center of excellence, has been committed to help (re)insurers on that matter.</p><p>This paper presents case study of the quantification of the basin effect and liquefaction for Vancouver region, Canada for specific scenario Mw 7.5 Strait of Georgia crustal earthquake. The southern part of the Vancouver region is located on a deep sedimentary basin created in the Fraser River delta. In case of deep Vancouver sedimentary basin considering amplification only due to shallow site response Vs30-dependent site term is not sufficient. Therefore, we derived (de)amplification function for different periods to quantify basin effect. We used NGA – West 2 ground motion prediction equations (GMPEs) for crustal events which include basin depth term. Amplification function was derived with respect to standard GMPEs for crustal events in western Canada. Amplification, considering site response including Vs30 and basin depth term at period 0.5 s can reach values as high as 3 at the softest and deepest sediments. The liquefaction potential was based on HAZUS and Zhu et al. (2017) methodologies calibrated to better reflect local geological conditions and liquefaction observations (Monahan et al. 2010, Clague 2002). We used USGS Vs30 data, enhanced by local seismic and geologic measurements, to characterize soil conditions, and topographical data and IF proprietary flow accumulation data to characterize water saturation. Liquefaction hazard is calculated in terms of probability of liquefaction occurrence and permanent ground deformation. For the chosen scenario the potential contribution to mean loss due to basin effect could be in the range 15% - 30% and 35% - 75% due to liquefaction depending on structural types of the buildings.</p>

A New Method for the Realistic Estimation of Seismic Ground Motion in Megacities: The Case of Rome

1993 ◽  
Vol 9 (4) ◽  
pp. 643-668 ◽  
Author(s):  
Donat Fäh ◽  
Claudio Iodice ◽  
Peter Suhadolc ◽  
Guilano F. Panza
Keyword(s):  
Total Energy ◽  
Ground Motion ◽  
Sedimentary Basins ◽  
Radial Component ◽  
Hybrid Technique ◽  
Ground Acceleration ◽  
Near Surface ◽  
Local Soil ◽  
Soil Effects ◽  
Rigid Material

A hybrid technique, based on mode summation and finite differences, is used to simulate the ground motion induced in the city of Rome by the January 13, 1915, Fucino (Italy) earthquake (ML=6.8). The technique allows us to take into consideration source, path, and local soil effects. The results of the numerical simulations are used for a comparison between the observed distribution of damage in Rome, and the computed peak ground acceleration, the maximum response of simple oscillators, and the so-called “total energy of ground motion”. The total energy of ground motion is in good agreement with the observed distribution of damage. From the computation of spectral ratios, it has been recognized that the presence of a near-surface layer of rigid material is not sufficient to classify a location as a “hard-rock site” when the rigid material has a sedimentary complex below it. This is because the underlying sedimentary complex causes amplifications due to resonances. Within sedimentary basins, incident energy in certain frequency bands can also be shifted from the vertical, into the radial component of motion. This phenomenon is very localized, both in frequency and space, and closely neighboring sites can be characterized by large differences in the seismic response.

Strong ground motions recorded during earthquakes of May the 11th and 19th, 1962 in Mexico City

1964 ◽  
Vol 54 (1) ◽  
pp. 209-231
Author(s):  
Leonardo Zeevaert
Keyword(s):  
Mexico City ◽  
Ground Motions ◽  
Soft Clay ◽  
Response Spectra ◽  
The Other ◽  
Soil Conditions ◽  
Strong Ground Motions ◽  
Multistory Building ◽  
Local Soil ◽  
Strong Ground

abstract The ground accelerations during the earthquakes of May 11 and 19, 1962 were recorded in Mexico City on a soft clay bed that was formerly the floor of an old lake. Records were obtained from two accelerometers, one instrument was located in the basement of a multistory building and the other was located in a nearby park. Response spectra of the ground motions are presented and analysis is made of the local soil conditions with the view to explaining the characteristics of the spectrums.

Using Aftershocks to Help Locate Historical Earthquakes

2020 ◽  
Vol 91 (5) ◽  
pp. 2695-2703 ◽  
Author(s):  
John E. Ebel
Keyword(s):  
Historical Earthquakes ◽  
Seismic Intensity ◽  
Soil Conditions ◽  
Macroseismic Data ◽  
Aftershock Activity ◽  
Earthquake Locations ◽  
Local Soil ◽  
Macroseismic Intensities ◽  
Historical Accounts ◽  
Directivity Effects

Abstract For historical earthquakes, the spatial distributions of macroseismic intensity reports are commonly used to estimate the event locations. The methods to locate historical earthquakes assume that the highest seismic intensity shows the best estimate of the location of the earthquake. Uncertainties in the locations estimated from macroseismic data can be due to an uneven geographic distribution of sites with intensity reports, variations in intensities due to local soil conditions, ambiguous historical reports, and earthquake directivity effects. Additional constraint on the location of a historical earthquake can come from places where most aftershocks were felt, because these localities may have been closest to the fault on which the mainshock took place. Examples of estimated earthquake locations based on aftershocks are those of the 1727 MLg 5.6 earthquake in northeastern Massachusetts, the MLg 5.7 earthquake in Maine, and the 1755 MLg 6.2 earthquake offshore of Cape Ann, Massachusetts. In all of these cases, the earthquake locations based on the aftershock data are somewhat different from previous locations derived from the macroseismic intensities alone. Uncertainties with this method include identifying aftershocks in historical accounts and the possibility that smaller events that are reported following a strong earthquake are not on or near the mainshock rupture. Even so, evidence of possible aftershock activity may help constrain the location of that mainshock. Because aftershocks of strong earthquakes (M≥7) can last months to years, archival research for aftershocks must be carried out with a somewhat different mindset than that for a mainshock.

scholarly journals Variations of strong earthquake ground shaking in the Los Angeles area

1974 ◽  
Vol 64 (5) ◽  
pp. 1429-1454
Author(s):  
M. D. Trifunac ◽  
F. E. Udwadia
Keyword(s):  
Los Angeles ◽  
Ground Motion ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Soil Conditions ◽  
Minor Role ◽  
Ground Shaking ◽  
Local Soil ◽  
Recording Station ◽  
A Minor

Abstract Accelerograms recorded at six stations in the metropolitan Los Angeles area during the Borrego Mountain, 1968, the Lytle Creek, 1970, and the San Fernando, 1971, earthquakes in southern California have been studied. In comparing the ground motions recorded during different earthquakes at each of the six stations and in correlations of these motions recorded at different stations during the same earthquake, those aspects of the analysis which emerge from this study and are relevant for seismic zoning have been emphasized. It has been found that the patterns of strong ground shaking in this area depend predominantly on the mechanism and the distance of an earthquake source from a recording station and that the local soil conditions played only a minor role in modifying the ground motion at this particular area. It has been shown that gross spectral characteristics of ground motion recorded at various stations can be approximately related by the seismic moment at the low-frequency end and by the stress drop at the high-frequency end.

scholarly journals Investigation of the influence of topographic irregularities and two dimensional effects on the intensity of surface ground motion with one- and two-dimensional analyses

2013 ◽  
Vol 1 (6) ◽  
pp. 7193-7238
Author(s):  
L. Yılmazoğlu ◽  
G. Ç. İnce
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Soil Conditions ◽  
Response Analysis ◽  
Two Dimensional ◽  
Ground Acceleration ◽  
Equivalent Linear ◽  
Local Soil ◽  
Different Depths ◽  
Earthquake Response Analysis

Abstract. In this work, the surface ground motion that occurs during an earthquake in ground sections having different topographic forms has been examined with one and two dynamic site response analyses. One-dimensional analyses were undertaken using the Equivalent-Linear Earthquake Response Analysis program based on the equivalent linear analysis principle and the Deepsoil program which is able to make both equivalent linear and nonlinear analyses and two-dimensional analyses using the Plaxis software. The viscous damping parameters used in the dynamic site response analyses undertaken with the Plaxis software were obtained using the DeepSoil program. In the dynamic site response analyses, the synthetic acceleration over a 475 yr replication period representing the earthquakes in Istanbul was used as the basis of the bedrock ground motion. The peak ground acceleration obtained different depths of soils and acceleration spectrum values have been compared. The surface topography and layer boundaries in the 5-5' section were selected in order to examine the effect of the land topography and layer boundaries on the analysis results were flattened and compared with the actual status. The analysis results showed that the characteristics of the surface ground motion changes in relation to the varying local soil conditions and land topography.

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