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.

Modification of seismograph records for effects of local soil conditions

1972 ◽  
Vol 62 (6) ◽  
pp. 1649-1664 ◽  
Author(s):  
P. Schnabel ◽  
H. Bolton Seed ◽  
J. Lysmer
Keyword(s):  
San Francisco ◽  
Ground Surface ◽  
Soil Conditions ◽  
Local Soil ◽  
Geological Conditions ◽  
Soil Deposits ◽  
Time Histories ◽  
Seismic Records ◽  
Local Soil Conditions ◽  
Good Agreement

abstract A procedure for modifying the time histories of seismic records for the effect of local soil conditions is presented. The method is based on a conventional one-dimensional wave-propagation approach with equivalent linear soil properties, extended to practical use for transient motions through the Fast Fourier technique. The validity of the approach is tested against the motions recorded at four soil sites and one rock site during the 1957 San Francisco earthquake. The good agreement between the computed and recorded values indicates that rock motions can be computed from motions recorded on soil deposits, and that the computed rock motions in turn can be used to predict the motion that would have been recorded under different soil and geological conditions. The method is also used to evaluate the probable rock motions in the vicinity of El Centro in the earthquake of 1940 and the ground surface motions that could have been developed on various soil conditions in the same general area.

Effect of Parameters on Equivalent Number of Cycles Using ‎Nonlinear Seismic Site Response Analysis

2011 ◽  
Vol 255-260 ◽  
pp. 2365-2369
Author(s):  
Emad Gheibi ◽  
Mohammad Hosein Bagheripour
Keyword(s):  
Site Response ◽  
Time History ◽  
Current Approach ◽  
Earthquake Magnitude ◽  
Soil Liquefaction ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Nonlinear Site Response ◽  
Equivalent Number ◽  
Number Of Cycles

The concept of equivalent number of uniform stress cycles, is essential for assessment of soil liquefaction potential. In this regard, various procedures are used to convert random acceleration time history to uniform cycles having amplitude of 0.65 of peak acceleration. Equivalent number of cycles (Neq) defines equivalent energy generated by harmonic loading as that imposed by irregular motion during an earthquake. Neq is assumed to be a function of earthquake magnitude. Over the past years, in accordance with development in methods of soil liquefaction evaluation, various methods have been proposed to determinate equivalent number of cycles. In particular, parameters like site to source distance (r), have been related directly to Neq. In this study, more than 80 earthquake records have been investigated and their Neqs are assessed using energy approach and nonlinear site response analysis. It is shown that equivalent number of cycles is related to earthquake magnitude (M), r and depth of originated signals. Unlike previous methods which result in scatter in output data, current approach has led to more uniform and consistent results for each earthquake.

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.

Evaluation of the effect of depth to bedrock on seismic amplification phenomena

2020 ◽  
Author(s):  
gaetano falcone ◽  
giuseppe naso ◽  
stefania fabozzi ◽  
federico mori ◽  
massimiliano moscatelli ◽  
...  
Keyword(s):  
Seismic Waves ◽  
Site Response ◽  
Soft Soil ◽  
Free Field ◽  
Response Spectra ◽  
Maximum Depth ◽  
Response Analysis ◽  
Local Conditions ◽  
Seismic Amplification ◽  
Bedrock Depth

<p>When an earthquake occurs, the propagation of the seismic waves is conditioned by local conditions, e.g., depth to seismic bedrock and impedance ratio between soft soil and seismic bedrock. Bearing in mind that the maximum depth of site prospections generally does not extend up to seismic bedrock depth, a parametric study was carried out with reference to ideal case studies in order to investigate the effect on local seismic amplification of the depth to bedrock.</p><p>The results are presented in terms of charts of amplification factors (i.e., ratio of integral quantities referred to free-field and reference response spectra) and minimum depth to investigate vs building type. These charts will allow defining the thickness of the cover deposit that should be characterised in terms of geophysical and geotechnical parameters in order to perform seismic site response analysis according to a precautionary approach, in areas where depth to seismic bedrock is higher than conventional maximum depth of site surveys.</p>

Site Response Analysis of the Monte Po Hill in the City of Catania

2008 ◽  
Author(s):  
A. Cavallaro ◽  
A. Ferraro ◽  
S. Grasso ◽  
M. Maugeri ◽  
Adolfo Santini ◽  
...  
Keyword(s):  
Site Response ◽  
Site Response Analysis ◽  
Response Analysis ◽  
The City

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 Soil Classification and Seismic Site Response Analysis for Some Areas in Hanoi City

2018 ◽  
Vol 34 (1) ◽  
Author(s):  
Giang Kien Trung ◽  
Nguyen Duc Vinh ◽  
Dang Thi Men
Keyword(s):  
Site Response ◽  
Ground Vibration ◽  
Soil Classification ◽  
Response Analysis ◽  
Borehole Data ◽  
Local Site Effects ◽  
Local Site ◽  
Seismic Site Response ◽  
Geological Conditions ◽  
Geological Factors

Abstract: Along with the development of urban and modern life, Hanoi Capital has been constructing more and more sky buildings, big bridges and huge underground constructions. According to historical studies, Hanoi is a region located on the weak soil ground which has a rather thick sedimentary layer, complicated geology structure and shallow ground water aged in the Holocene and Pleistocene. Hanoi city is cut through by a Red River fault which has been considered to be a strong active fault zone. As a consequence, it is able to cause earthquakes with magnitude M = 6.1 corresponding to the 7th ground vibration level in intensity. In order to predict the casualty of this severe earthquake being able to happen, it is surely essential to assess both seismic site response and geological conditions in Hanoi. In the paper, we will analyze the soil ground data and borehole data obtained in this region to find the specific geological factors which are put into the DeepSoil Program to evaluate local site effects.

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>

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.

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