Evaluation of earthquake ground motion and site effects in the Thessaloniki urban area by 3D finite-fault numerical simulations

2016 ◽  
Vol 15 (3) ◽  
pp. 787-812 ◽  
Author(s):  
Chiara Smerzini ◽  
Kyriazis Pitilakis ◽  
Kiana Hashemi
Keyword(s):  
Numerical Simulations ◽  
Urban Area ◽  
Ground Motion ◽  
Site Effects ◽  
Earthquake Ground Motion ◽  
Finite Fault

scholarly journals ER3D: a structural and geophysical 3-D model of central Emilia-Romagna (northern Italy) for numerical simulation of earthquake ground motion

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 931-949 ◽  
Author(s):  
Peter Klin ◽  
Giovanna Laurenzano ◽  
Maria Adelaide Romano ◽  
Enrico Priolo ◽  
Luca Martelli
Keyword(s):  
Numerical Simulations ◽  
Ground Motion ◽  
Northern Italy ◽  
Peak Ground Velocity ◽  
Earthquake Ground Motion ◽  
Po River ◽  
Epicentral Area ◽  
River Bank ◽  
Local Seismic Response ◽  
D Model

Abstract. During the 2012 seismic sequence of the Emilia region (northern Italy), the earthquake ground motion in the epicentral area featured longer duration and higher velocity than those estimated by empirical-based prediction equations typically adopted in Italy. In order to explain these anomalies, we (1) build up a structural and geophysical 3-D digital model of the crustal sector involved in the sequence, (2) reproduce the earthquake ground motion at some seismological stations through physics-based numerical simulations and (3) compare the observed recordings with the simulated ones. In this way, we investigate how the earthquake ground motion in the epicentral area is influenced by local stratigraphy and geological structure buried under the Po Plain alluvium. Our study area covers approximately 5000 km2 and extends from the right Po River bank to the Northern Apennine morphological margin in the N–S direction, and between the two chief towns of Reggio Emilia and Ferrara in the W–E direction, involving a crustal volume of 20 km thickness. We set up the 3-D model by using already-published geological and geophysical data, with details corresponding to a map at scale of 1:250 000. The model depicts the stratigraphic and tectonic relationships of the main geological formations, the known faults and the spatial pattern of the seismic properties. Being a digital vector structure, the 3-D model can be easily modified or refined locally for future improvements or applications. We exploit high-performance computing to perform numerical simulations of the seismic wave propagation in the frequency range up to 2 Hz. In order to get rid of the finite source effects and validate the model response, we choose to reproduce the ground motion related to two moderate-size aftershocks of the 2012 Emilia sequence that were recorded by a large number of stations. The obtained solutions compare very well to the recordings available at about 30 stations in terms of peak ground velocity and signal duration. Snapshots of the simulated wavefield allow us to attribute the exceptional length of the observed ground motion to surface wave overtones that are excited in the alluvial basin by the buried ridge of the Mirandola anticline. Physics-based simulations using realistic 3-D geomodels show eventually to be effective for assessing the local seismic response and the seismic hazard in geologically complex areas.

scholarly journals ER3D: a structural and geophysical 3D model of central Emilia-Romagna (Northern Italy) for numerical simulation of earthquake ground motion

2019 ◽  
Author(s):  
Peter Klin ◽  
Giovanna Laurenzano ◽  
M. Adelaide Romano ◽  
Enrico Priolo ◽  
Luca Martelli
Keyword(s):  
Numerical Simulations ◽  
Ground Motion ◽  
High Performance ◽  
3D Model ◽  
Northern Italy ◽  
Peak Ground Velocity ◽  
Earthquake Ground Motion ◽  
Po River ◽  
Epicentral Area ◽  
Local Seismic Response

Abstract. During the 2012 seismic sequence of Emilia region (Northern Italy), the earthquake ground motion in the epicentral area featured longer duration and higher velocity than those estimated by empirical-based prediction equations typically adopted in Italy. In order to explain these anomalies, we (1) build up a structural and geophysical 3D digital model of the crustal sector involved in the sequence, (2) reproduce the earthquake ground motion at some seismological stations through physics-based numerical simulations and (3) compare the observed recordings with the simulated ones. In this way we investigate how the earthquake ground motion in the epicentral area is influenced by local stratigraphy and geological structure buried under the Po Plain alluvium. Our study area covers approximately 5000 km2 and extends from the Po river right bank to the Northern Apennines morphological margin in N-S direction, and between the two chief towns of Reggio Emilia and Ferrara in W-E direction, involving a crustal volume with 20 km of thickness. We set up the 3D model by using already published geological and geophysical data, with a detail corresponding to a map at scale 1:250 000. The model depicts the stratigraphic and tectonic relationships of the main geological formations, the known faults and the spatial pattern of the seismic properties. Being a digital vector structure, the 3D model can be easily modified or refined locally for future improvements or applications. We exploited high performance computing to perform numerical simulations of the seismic wave propagation in the frequency range up to 2 Hz. In order to get rid of the finite source effects and validate the model response, we choose to reproduce the ground motion related to two moderate-size aftershocks of the 2012 Emilia sequence that were recorded by a large number of stations. The obtained solutions compare very well to the recordings available at about 30 stations, in terms of peak ground velocity and signal duration. Snapshots of the simulated wavefield allow us to explain the exceptional length of the observed ground motion as due to surface waves overtones that are excited in the alluvial basin by the buried ridge of the Mirandola anticline. Physics-based simulations using realistic 3D geo-models show eventually to be effective for assessing the local seismic response and the seismic hazard in geologically complex areas.

Spatial Geotechnical Information-Based Assessment of Seismic Structural Vulnerability Related to Site Effects at Daegu Metropolitan City

2011 ◽  
Vol 82 ◽  
pp. 790-795
Author(s):  
Chang Guk Sun
Keyword(s):  
Urban Area ◽  
Site Effects ◽  
Earthquake Ground Motion ◽  
Seismic Zoning ◽  
Structural Vulnerability ◽  
Entire Region ◽  
Soil Thickness ◽  
Metropolitan City ◽  
Area Of Interest ◽  
Geotechnical Information

Site effects inducing the amplification of earthquake ground motion are strongly influenced by the local geologic conditions such as soil thickness and stiffness. Most of major cities in the world are located across wide area where there are various surface topographies and corresponding subsurface geotechnical conditions. To prepare earthquake-induced structural damages and corresponding casualties in an urban area, hence, the spatial prediction of geotechnical information in the entire region is not only important but fundamental. In this study, to predict reliably spatial geotechnical information based on restricted number of boring data, a procedural methodology is introduced and applied into GIS tool. Particularly, an inland metropolitan city, Daegu, in Korea, was selected for implementing an integrated GIS-based geotechnical information system. Based on the various data combined over the area of interest, geotechnical layers information was reliably predicted in the entire region of Daegu with three-dimensional feature. For practical application of geotechnical information to assessing the site effects in the target urban area, seismic zoning maps of bedrock depth and site period were created and presented as regional basic information on seismic disasters. Spatial distribution on seismic structural vulnerability potential in the area of interest was intuitively examined from the seismic zoning maps. Furthermore, seismic zonations were also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation of structures in the Daegu area.

2D numerical simulations of earthquake ground motion: examples from the Marche Region, Italy

2008 ◽  
Vol 12 (3) ◽  
pp. 395-412 ◽  
Author(s):  
Giovanna Laurenzano ◽  
Enrico Priolo ◽  
Emanuele Tondi
Keyword(s):  
Numerical Simulations ◽  
Ground Motion ◽  
Earthquake Ground Motion ◽  
Marche Region

scholarly journals 3-D numerical simulations of earthquake ground motion in sedimentary basins: testing accuracy through stringent models

2015 ◽  
Vol 201 (1) ◽  
pp. 90-111 ◽  
Author(s):  
Emmanuel Chaljub ◽  
Emeline Maufroy ◽  
Peter Moczo ◽  
Jozef Kristek ◽  
Fabrice Hollender ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Ground Motion ◽  
Sedimentary Basins ◽  
Earthquake Ground Motion ◽  
Testing Accuracy

scholarly journals 3D NUMERICAL MODELLING OF THE SEISMIC RESPONSE OF THE THESSALONIKI URBAN AREA: THE CASE OF THE 1978 VOLVI EARTHQUAKE

2017 ◽  
Vol 50 (3) ◽  
pp. 1433
Author(s):  
C. Smerzini ◽  
K. Pitilakis ◽  
K. Hashemi
Keyword(s):  
Numerical Modelling ◽  
Urban Area ◽  
Ground Motion ◽  
Large Scale ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Earthquake Ground Motion ◽  
Ground Shaking ◽  
3D Numerical Modelling ◽  
Wide Scale

This study aims at showing the numerical modelling of earthquake ground motion in the Thessaloniki urban area, using a 3D spectral element approach. The availability of detailed geotechnical/geophysical data together with the seismological information regarding the relevant fault sources allowed us to construct a large-scale 3D numerical model suitable for generating physics based ground shaking scenarios within the city of Thessaloniki up to maximum frequencies of about 2 Hz. Results of the numerical simulation of the destructive MW6.5 1978 Volvi earthquake are addressed, showing that realistic estimates can be obtained. Shaking maps in terms of ground motion parameters such as PGV are used to discuss the main seismic wave propagation effects at a wide scale.

scholarly journals Modelling of pulse-like velocity ground motion during the 2018 Mw 6.3 Hualien earthquake, Taiwan

2020 ◽  
Vol 223 (1) ◽  
pp. 348-365 ◽  
Author(s):  
Yen-Yu Lin ◽  
Hiroo Kanamori ◽  
Zhongwen Zhan ◽  
Kuo-Fong Ma ◽  
Te-Yang Yeh
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Strong Motion ◽  
S Wave ◽  
Finite Fault ◽  
Peak Ground Motion ◽  
Large Velocity ◽  
Reversed Polarity ◽  
Local Slip ◽  
Strong Motion Network

SUMMARY The 2018 February 6 Mw 6.3 Hualien earthquake caused severe localized damage in Hualien City, located 20 km away from the epicentre. The damage was due to strong (>70 cm s−1) and sharp (duration ∼2.5 s) velocity pulses. The observed peak ground-motion velocity in Hualien City symmetrically decays with distance from the nearby Milun fault. Waveforms observed on the opposite sides of the fault show reversed polarity on the vertical and N–S components while the E–W component is almost identical. None of the published finite-fault slip models can explain the spatially highly localized large velocity pulses. In this study, we show that an Mw 5.9 strike-slip subevent on the Milun fault at 2.5 km depth, rupturing from north to south at ∼0.9Vs speed, combined with site effects caused by surficial layers with low S-wave speed, can explain the velocity pulses observed at the dense strong-motion network stations. This subevent contributes only 25 per cent of the total moment of the 2018 Hualien earthquake, suggesting that a small local slip patch near a metropolis can dominate the local hazard. Our result strongly suggests that seismic hazard assessments should consider large ground-motion variabilities caused by directivity and site effects, as observed in the 2018 Hualien earthquake.

National Mitigation Strategy against Earthquakes in Central Asia

2020 ◽  
Author(s):  
Sung-Woo Moon ◽  
Farkhod Hakimov ◽  
Jong Kim ◽  
Klaus Reicherter ◽  
Hans-Balder Havenith ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Central Asia ◽  
Ground Motion ◽  
Urban Areas ◽  
Site Effects ◽  
Site Response ◽  
Engineering Properties ◽  
Response Analysis ◽  
Earthquake Scenarios ◽  
Geological Conditions

<p>Throughout history, earthquakes have caused extensive damages in urban areas with important infrastructures and high population density. Especially, earthquakes have extensively damaged many regions of Central Asia (e.g., Tashkent in 1966, and Almaty in 1911). Hence, the estimation of the seismic hazard of the urban areas in Central Asia is very important due to the high level of seismicity in Central Asia and the rapid construction of new buildings. The high earthquake-induced damages in the cities often result from the local geological conditions and engineering properties of the soils that can produce significant site effects. Such seismic effects combined with the high vulnerability of buildings can result in extreme disasters during earthquakes. Therefore, geotechnical engineers/seismologists should decide to divide the city into specific microzones depending on their site effects and soil properties. However, conventional approaches in Central Asia have been proposed, based on (1) general engineering geological information; (2) the building code based on the estimates of the ground motions in terms of MSK-64 scale developed in 1978; and (3) the quantitative assessment only mapping and overlaying the data.</p><p>By characterizing the soft layers of their nature, thickness, and structure, and assessing the numerical model developed for the high-seismicity area of Central Asia, we can better assess specific site effects in each region of Central Asia. In addition, to predict the essential consequences of earthquakes, physically-based ground motion simulations should be developed by numerical simulations considering all possible processes of seismic wave propagation. Compared to empirical ground-motion predictions, numerical simulations of earthquake scenarios will provide much more flexible and better-suited solutions for most applications – especially those involving complex city environments. The ground-motion prediction equations or stochastic ground-motion estimates integrate characteristics of the earthquake source, path, attenuation, and site effects via approximate or statistical approaches. This method will provide rapid solutions that may be valid for a well-known context and would also be applied in Central Asia, for comparison with the numerical simulations. Finally, the quantitative approach for microzoning map incorporated with numerical simulation/site response analysis, for infrastructures (e.g., buildings, bridges, and dams) will be significantly useful in the future.</p>

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