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.

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 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

Site Characterization Using Microtremor Array and Seismic Hazard Assessment for Jakarta, Indonesia

2019 ◽  
Vol 109 (6) ◽  
pp. 2644-2657 ◽  
Author(s):  
Mohamad Ridwan ◽  
Phil R. Cummins ◽  
Sri Widiyantoro ◽  
Masyhur Irsyam
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Soft Soil ◽  
Site Characterization ◽  
Standard Penetration Test ◽  
Alluvial Fan ◽  
Earthquake Hazards ◽  
Ground Acceleration ◽  
Site Class ◽  
Near Surface

Abstract Site characterization is one of the most important components in seismic hazard analysis because it accounts for the important effects of near‐surface geology on ground motion. It is usually quantified based on the time‐averaged S‐wave velocity (VS) for the top 30 m of the profile (VS30). In this study, we estimate the site class in Jakarta based on VS structure estimated using microtremor array observations. The results show that microtremor‐derived VS profiles agree well with standard penetration test‐derived profiles at nine sites. The site‐class estimates in the Jakarta area can be divided into two National Earthquake Hazards Reduction Program classes: (a) site class E (soft soil) located in alluvium, beach ridge, and alluvial fan deposits in northern and western Jakarta, and (b) site class D (stiff soil) found mainly in alluvial fan deposits in southeastern Jakarta. The variation of VS30 in Jakarta leads to different soil amplification factors that will impact the seismic hazard at the surface. We show that the seismic hazard resulting from selected ground‐motion models (GMMs) illustrates a clear influence of site effects at long periods (>1  s). However, the effect on peak ground acceleration and response spectra for short periods (0.2 s) appear to be less pronounced, due to the GMMs’ treatment of basin effects and nonlinear soil behavior. Available GMMs may not accurately account for such effects in the Jakarta basin, and GMMs specific to Indonesia should be developed to accurately assess seismic hazard there.

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.

scholarly journals Application of numerical simulations for a tentative seismic microzonation of the city of Rome

1995 ◽  
Vol 38 (5-6) ◽  
Author(s):  
D. Fah ◽  
C. Iodice ◽  
P. Suhadolc ◽  
G. F. Panza
Keyword(s):  
Numerical Simulations ◽  
Volcanic Rocks ◽  
Cultural Value ◽  
Hybrid Technique ◽  
Central Apennines ◽  
Near Surface ◽  
Resonance Effects ◽  
Rigid Material ◽  
Tiber Basin ◽  
The City

A hybrid technique, based on mode summation and finite differences, was used to silnulate the ground motion induced in the city of Rome by possible earthquakes occurring in the main seisrnogenetic areas surrounding the city: the Central Apennines and the Alban Hills. The results of the numerical simulations are used for a seismic inicrozonation in the city of Rome, which can be used for the retrofitting of buildings of special social and cultural value. On the basis of our analysis Rome can be divided into six main zones: (1) the edges and (2) the central part of the alluvial basin of the River Tiber; (3) the edges and (4) the central part of the Paleotiber basin; the areas outside the large basins of the Tiber and Paleotiber, where we distinguish between (5) areas without, and (6) areas with a layer of volcanic rocks close to the surface. The strongest amplification effects have to be expected at the edges of the Tiber basin, with maximum spectral amplification of the order of 5 to 6, and strong arnplifications occur inside the entire alluvial basin of the Tiber. 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 covers a sedimentary complex. The reason is that the underlying sedimentary complex causes amplifications at the surface due to resonance effects. This phenomenon can be observed in the Paleotiber basin, where spectral amplifications in the frequency range 0.4-1.0 Hz reach values of the order of 3 to 4.

Radiation and Generation of Short- and Long-Period Ground Motions from the 2011 Off Tohoku, Japan,Mw9.0 Earthquake

2014 ◽  
Vol 9 (3) ◽  
pp. 281-293 ◽  
Author(s):  
Takashi Furumura ◽  
◽  
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Tohoku Earthquake ◽  
Sedimentary Basins ◽  
Low Velocity ◽  
Ground Acceleration ◽  
Wooden Frame ◽  
Long Period ◽  
Long Period Ground Motion

Ground motion from theMw9.0 March 11, 2011, Off-Tohoku earthquake recorded by dense seismic networks in Japan, K-NET and KiK-net, clearly demonstrated the high-frequency seismic wavefield radiating from the earthquake source and developing longperiod ground motion in sedimentary basins. The photographic sequence of the visualized wavefield demonstrated the process in which the high-frequency seismic waves radiated from large slips at the top of the subducting Pacific Plate at relatively deeper depth of 25-50 km, which caused multiple large shocks of large (>1000-2000 cm/s2) ground acceleration and several minutes lasting ground motions over a wide area along the Pacific Ocean side of northern Japan. An efficient seismic wave propagation along the subducting Pacific slab and ground motion amplification in a superficial thin low-velocity layer overlying rigid bedrock also enhanced high-frequency (>5 Hz) ground motions very drastically. However, the dominant frequency of the strong ground motion recorded in nearfield station was too high such as to cause serious damage to wooden-frame residences having relatively longer-period resonance period (T= 1-2 s); The velocity response in this frequency band was only about one third to one half of those observed in severely damaged area during the destructiveMw6.9 1995 Kobe earthquake. The 2011 Off-Tohoku earthquake also produced long-period ground motion in sedimentary basins such those at Tokyo’s population center but observation of the long-period ground motion withinT=6-8 s was rather weak and of a level comparable to that of anM7.9 Tonankai earthquake occurring along the Nankai Trough in 1944. This was because the surface wave in this period band was not generated efficiently by the relatively deeper slip over the source fault of the Off-Tohoku earthquake.

Seismic Intensity and Fourier Acceleration Spectra: Revised Relationship

2002 ◽  
Vol 18 (1) ◽  
pp. 161-187 ◽  
Author(s):  
Vladimir Yu Sokolov
Keyword(s):  
Ground Motion ◽  
Seismic Intensity ◽  
Intensity Level ◽  
Ground Acceleration ◽  
Soil Response ◽  
Local Soil ◽  
Spectral Models ◽  
Source Scaling ◽  
Instrumental Intensity ◽  
Comparison Of The Results

This paper presents a revised method for estimating the seismic intensity (MMI or MSK scale) using Fourier amplitude spectra (FAS) of ground acceleration. The improvement of the recently proposed technique (Sokolov and Chernov 1998) has been made on the basis of the data, which were obtained recently during strong earthquakes that occurred throughout the world. The total amount of the used data (horizontal components of ground-motion recordings) is about 1,150 records, while the database of 300 recordings was used in the previous study. The method implies that the seismic intensity is determined by the level of ground motion spectral amplitudes in the frequency range of 0.4–13 Hz. The corresponding empirical relationships between FAS and each intensity level were developed. The method is validated by comparison of the results of the technique application with the empirical data, which have not been included in the database. The Romanian earthquakes (intermediate-depth events of 1977, 1986, and 1990) and the recent 1999 Hector Mine earthquake in southern California were used for this purpose. In general, the FAS intensity shows a good agreement with the reported intensity, and the average residuals do not exceed ±0.3 intensity units and standard deviation is about 0.4-0.6. Evaluation of seismic intensity distribution using region- and site-dependent spectral models, as well as calculation of instrumental intensity map for the recent 1999 Chi-Chi earthquake, Taiwan, show that the FAS intensity clearly reflects the regional (source scaling and attenuation relation) and local (soil response) peculiarities of ground motion.

scholarly journals Acoustic Pressure, Particle Motion, and Induced Ground Motion Signals from a Commercial Seismic Survey Array and Potential Implications for Environmental Monitoring

2021 ◽  
Vol 9 (6) ◽  
pp. 571
Author(s):  
Robert D. McCauley ◽  
Mark G. Meekan ◽  
Miles J. G. Parsons
Keyword(s):  
Ground Motion ◽  
Particle Motion ◽  
Seismic Source ◽  
Propagation Loss ◽  
Seismic Survey ◽  
Ground Acceleration ◽  
Near Surface ◽  
North West ◽  
Northern Site ◽  
Southern Site

An experimental marine seismic source survey off the northwest Australian coast operated a 2600 cubic inch (41.6 l) airgun array, every 5.88 s, along six lines at a northern site and eight lines at a southern site. The airgun array was discharged 27,770 times with 128,313 pressure signals, 38,907 three-axis particle motion signals, and 17,832 ground motion signals recorded. Pressure and ground motion were accurately measured at horizontal ranges from 12 m. Particle motion signals saturated out to 1500 m horizontal range (50% of signals saturated at 230 and 590 m at the northern and southern sites, respectively). For unsaturated signals, sound exposure levels (SEL) correlated with measures of sound pressure level and water particle acceleration (r2= 0.88 to 0.95 at northern site and 0.97 at southern) and ground acceleration (r2= 0.60 and 0.87, northern and southern sites, respectively). The effective array source level was modelled at 247 dB re 1µPa m peak-to-peak, 231 dB re 1 µPa2 m mean-square, and 228 dB re 1 µPa2∙m2 s SEL at 15° below the horizontal. Propagation loss ranged from −29 to −30log10 (range) at the northern site and −29 to −38log10(range) at the southern site, for pressure measures. These high propagation losses are due to near-surface limestone in the seabed of the North West Shelf.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

scholarly journals From scenario-based seismic hazard to scenario-based landslide hazard: fast-forwarding to the future via statistical simulations

2021 ◽  
Author(s):  
Luigi Lombardo ◽  
Hakan Tanyas
Keyword(s):  
Ground Motion ◽  
Landslide Susceptibility ◽  
Additive Model ◽  
Landslide Hazard ◽  
Northridge Earthquake ◽  
Ground Acceleration ◽  
Temporal Dimension ◽  
Earthquake Scenario ◽  
The Mean ◽  
Ground Motion Scenarios

AbstractGround motion scenarios exists for most of the seismically active areas around the globe. They essentially correspond to shaking level maps at given earthquake return times which are used as reference for the likely areas under threat from future ground displacements. Being landslides in seismically actively regions closely controlled by the ground motion, one would expect that landslide susceptibility maps should change as the ground motion patterns change in space and time. However, so far, statistically-based landslide susceptibility assessments have primarily been used as time-invariant.In other words, the vast majority of the statistical models does not include the temporal effect of the main trigger in future landslide scenarios. In this work, we present an approach aimed at filling this gap, bridging current practices in the seismological community to those in the geomorphological and statistical ones. More specifically, we select an earthquake-induced landslide inventory corresponding to the 1994 Northridge earthquake and build a Bayesian Generalized Additive Model of the binomial family, featuring common morphometric and thematic covariates as well as the Peak Ground Acceleration generated by the Northridge earthquake. Once each model component has been estimated, we have run 1000 simulations for each of the 217 possible ground motion scenarios for the study area. From each batch of 1000 simulations, we have estimated the mean and 95% Credible Interval to represent the mean susceptibility pattern under a specific earthquake scenario, together with its uncertainty level. Because each earthquake scenario has a specific return time, our simulations allow to incorporate the temporal dimension into any susceptibility model, therefore driving the results toward the definition of landslide hazard. Ultimately, we also share our results in vector format – a .mif file that can be easily converted into a common shapefile –. There, we report the mean (and uncertainty) susceptibility of each 1000 simulation batch for each of the 217 scenarios.

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