Site Response in Singapore to Long-Distance Sumatra Earthquakes

2002 ◽  
Vol 18 (2) ◽  
pp. 347-367 ◽  
Author(s):  
Tso-Chien Pan ◽  
Chin Long Lee
Keyword(s):  
Site Response ◽  
Seismic Station ◽  
Ground Surface ◽  
Middle Level ◽  
Response Analysis ◽  
Sumatra Earthquake ◽  
Long Distance ◽  
National Network ◽  
Response Characteristics ◽  
Sumatra Earthquakes

Tremors caused by distant Sumatra earthquakes have reportedly been felt in Singapore for many years. The national network of seismic stations consisting of seven stations was therefore set up in 1996 to locate regional earthquake epicenters and investigate the site response characteristics when subjected to long distance Sumatra earthquakes. During the Sumatra earthquake on 1 April 1998, the downhole seismic array at the KAP seismic station successfully captured the first set of instrumental acceleration records in Singapore. The earthquake ground accelerations were recorded at three levels: ground surface, −32 m, and −50 m. Studies of the downhole data show that the soil layers within the 50-m depth at the KAP site of marine clay (locally called Kallang Formation) have a fundamental frequency around 1 Hz. This supports the observation that medium- and high-rise Singapore buildings located in Kallang Formation have been more responsive to long-distance Sumatra earthquakes. Based on the linear site response analysis for vertically propagating shear waves, numerical simulation has successfully reproduced the acceleration waveforms recorded at the ground surface and the middle level (−32 m) of KAP site for the Sumatra earthquake on 1 April 1998.

Site response analysis of liquefiable soil employing continuous wavelet transform

2022 ◽  
Vol 12 (1) ◽  
pp. 1-33
Author(s):  
D. Chavan ◽  
T.G. Sitharam ◽  
P. Anbazhagan
Keyword(s):  
Wavelet Transform ◽  
Site Response ◽  
Amplitude Spectrum ◽  
Ground Surface ◽  
Time History ◽  
Response Analysis ◽  
Fourier Amplitude ◽  
Acceleration Time ◽  
Liquefiable Soil ◽  
Fourier Amplitude Spectrum

Propagation of the earthquake motion towards the ground surface alters both the acceleration and frequency content of the motion. Acceleration time record and Fourier amplitude spectrum of the motion reveal changes in the acceleration and frequency content. However, Fourier amplitude spectrum fails to give frequency-time variation. Wavelet transform overcomes this difficulty. In the present study, site response analysis of a liquefiable soil domain has been investigated employing wavelet transform. Three earthquake motions with distinct predominant frequencies are considered. It is revealed that the moment soil undergoes initial liquefaction, it causes a spike in the acceleration time history. Frequency of the spikes is found to be greater than the predominant frequency of the acceleration-time history recorded at the ground surface from the analysis. Interestingly, the spikes belong to the sharp tips of the shear stress-shear strain curve. Immediately after the spike, acceleration deamplification is observed. Post-liquefaction deamplification (filtering) of the frequency components is also observed.

scholarly journals Seismically Induced Soil Liquefaction and Geological Conditions in the City of Jama due to the M7.8 Pedernales Earthquake in 2016, NW Ecuador

Geosciences ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Diego Avilés-Campoverde ◽  
Kervin Chunga ◽  
Eduardo Ortiz-Hernández ◽  
Eduardo Vivas-Espinoza ◽  
Theofilos Toulkeridis ◽  
...  
Keyword(s):  
Site Response ◽  
Ground Surface ◽  
Soil Liquefaction ◽  
Response Analysis ◽  
Potential Index ◽  
Geological Conditions ◽  
Seismic Amplification ◽  
Seismic Records ◽  
Floodplain Deposits ◽  
The City

Seismically induced soil liquefaction has been documented after the M7.8, 2016 Pedernales earthquake. In the city of Jama, the acceleration recorded by soil amplification yielded 1.05 g with an intensity of VIII to IXESI-07. The current study combines geological, geophysical, and geotechnical data in order to establish a geological characterization of the subsoil of the city of Jama in the Manabi province of Ecuador. Then, the liquefaction potential index (LPI) has been evaluated considering the PGA-rock values calculated from deterministic methods applied to nearby geological faults, as well as the soil acceleration records for the city of Jama since the Pedernales megathrust earthquake. The importance of conducting geotechnical evaluations of particular colluvial, alluvial, and floodplain deposits, for which the liquefaction probability profiles have been additionally obtained, may serve as a useful tool for edifices foundations or earthquake resistant designs. Finally, the site response analysis is presented using a linear equivalent analysis, where previously seismic records compatible with the target spectrum have been selected. Hereby, the results of ground surface effects have been compared with the spectra of the Ecuadorian Regulation of Construction (NEC) in the context of local seismic amplification.

SEISMIC TIME-HISTORY GROUND-MOTIONS FOR A SPECIFIC SITE IN JAKARTA

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
I Wayan Sengara ◽  
Muhammad Addifa Yulman ◽  
Andri Mulia
Keyword(s):  
Seismic Hazard ◽  
Linear Time ◽  
Site Response ◽  
Ground Motions ◽  
Ground Surface ◽  
Time History ◽  
Response Analysis ◽  
Building Collapse ◽  
Surface Development ◽  
Time Histories

Indonesia has developed new seismic building code based on risk-targeted ground-motions adopting 1 % probability of building collapse in 50 years. The new seismic design criterion, which is presented in the code, have combined both seismic hazard and building fragility. For performance-based analysis of high-rise buildings, a complex non-linear time-history analysis is needed. This paper presents results of study on development of the time-history with emphasing on procedure of developing pairs of time-history at ground surface for spesific site in Jakarta with reference to 2012 International Building Codes and ASCE-SEI-7-10. The study involves generation of time-history from reference base-rock through site-response analysis to ground surface. Development of time-history at ground surface with a procedure involving Square Root of the Sum of the Square method (SRSS) in order to reasonably scaled time-histories through spectral matching technique is presented herein. The matched time-histories are developed from various strong-motion records representing different earthquake sources dominant to control the site evaluated from de-aggregation within seismic hazard analysis. This work also adopts baseline corrections in which velocity and displacement components of matched time-histories can be drifted to zero at the end of recorded seismic time.

scholarly journals SEISMIC MICROZONATION OF SEMARANG, INDONESIA BASED ON SITE RESPONSE ANALYSIS USING 30 M SOIL DEPOSIT MODEL

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Windu Partono ◽  
Sri Prabandiyani Retno Wardani ◽  
Masyhur Irsyam ◽  
Syamsul Maarif
Keyword(s):  
Amplification Factor ◽  
Site Response ◽  
Ground Surface ◽  
Seismic Microzonation ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Acceleration Time Histories ◽  
Single Station ◽  
Time Histories ◽  
Deposit Model

Seismic microzonation study of Semarang is still on-going following the recommendations from the Team for Revision of Seismic Hazard Maps of Indonesia 2010 (TRSHMI-2010). The study was performed by carrying one-dimensional site response analysis at 190 locations and implementing Lasem fault as a closest seimic source that significantly influence the hazard of the city. The analysis was performed using two soil deposit models, 30 m and real soil deposit models, to get ground surface peak acceleration (PGA) and amplification factor of PGA. The results obtained using the first model are then compared with the results obtained using the second model. To perform the analysis bedrock elevation and acceleration time histories data are needed. The bedrock elevation was estimated based on 218 single station seismometer measurements. Five different time histories representing different earthquakes with magnitude 6.5 MW and maximum distance 20 km are collected from worldwide historical earthquake records. The results of this study includes the distribution of surface PGA and amplification factor of PGA. The PGA and amplification factor calculated using 30 meter soil deposit model are greater than the same values calculated using real soil deposit model.  

Preliminary microzonation of the Memphis, Tennessee, area

1982 ◽  
Vol 72 (3) ◽  
pp. 1011-1024
Author(s):  
Sunil Sharma ◽  
William D. Kovacs
Keyword(s):  
United States ◽  
Soil Properties ◽  
Damping Ratio ◽  
Ground Surface ◽  
Strong Motion ◽  
Response Analysis ◽  
Borehole Data ◽  
Central United States ◽  
Hazardous Zone ◽  
High Level

abstract The city of Memphis, which is situated very close to the inferred epicenter of one of the three major 1811 to 1812 earthquakes, is in a potentially hazardous zone which will be susceptible to the usual seismic hazards. By recognizing the high level of seismicity in the New Madrid area, this study attempts to microzone the potential hazards by considering the following subjects: (i) the seismicity of the central United States; (ii) design earthquakes; and (iii) response analysis which allows construction of the necessary microzonation maps. The seismicity of the region is evaluated from state-of-the-art literature as there is no recorded strong-motion data available for the central United States. Synthetically generated accelerograms, simulating the design earthquakes, were used to represent the ground motions which were applied at a depth of 45 m, below ground surface, at numerous sites in Memphis. The soil stratigraphy was conceptualized from borehole data, made available by local sources, and dynamic soil properties estimated from available empirical correlations. The results of the response analysis were transformed into microzonation maps depicting: (i) zones showing qualitative estimates of ground response; (ii) zones showing the natural frequency of the soils; (iii) zones showing the peak spectral acceleration for 2 per cent damping ratio; and (iv) zones of liquefaction potential. These maps are useful for preliminary design and are not intended to be used on a quantitative basis. Further investigation is necessary in determining the stratigraphy and soil properties for a site-specific design and analysis.

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