Evaluation of Peak Ground Acceleration and Response Spectra Considering the Local Site Effects

2010 ◽  
Vol 1 (1) ◽  
pp. 25-41 ◽  
Author(s):  
T. G. Sitharam ◽  
K. S. Vipin
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Response Spectra ◽  
Probabilistic Logic ◽  
Site Classification ◽  
Ground Acceleration ◽  
Entire Study ◽  
Local Site Effects ◽  
Local Site

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluated for the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work.

Evaluation of Peak Ground Acceleration and Response Spectra Considering the Local Site Effects

2012 ◽  
pp. 1-17
Author(s):  
Sitharam T. G. ◽  
Vipin K. S.
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Response Spectrum ◽  
Response Spectra ◽  
Site Classification ◽  
Ground Acceleration ◽  
Local Site Effects ◽  
Local Site ◽  
Uniform Hazard Response Spectrum

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluated for the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work.

Seismic Hazard Analysis for an NPP Site

2004 ◽  
Author(s):  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Structural Response ◽  
Response Spectra ◽  
Seismic Fragility ◽  
Material Strength ◽  
Ground Acceleration ◽  
Hazard Response

The various uncertainties and randomness associated with the occurrence of earthquakes and the consequences of their effects on the NPP components and structures call for a probabilistic seismic risk assessment (PSRA). However, traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to be computed for PGA only. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for Kakrapar Atomic Power Station site. Sensitivity of the results to the changes in various parameters has also been presented. These results determine the seismic hazard at the given site and the associated uncertainties. The paper also presents some results of the seismic fragility for an existing containment structure. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study the seismic fragility of the structure is developed. The results are presented as families of conditional probability curves plotted against the peak ground acceleration (PGA). The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.

scholarly journals Seismic hazard assessment and local site effect evaluation in Hanoi, Vietnam

2017 ◽  
Vol 17 (4B) ◽  
pp. 82-95
Author(s):  
Nguyen Anh Duong ◽  
Pham Dinh Nguyen ◽  
Vu Minh Tuan ◽  
Bui Van Duan ◽  
Nguyen Thuy Linh
Keyword(s):  
Seismic Hazard ◽  
Shear Wave ◽  
Ground Motion ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Peak Ground Acceleration ◽  
Site Effect ◽  
Local Site Effect ◽  
Ground Acceleration ◽  
Local Site

In this study, we have carried out the probabilistic seismic hazard analysis in Hanoi based on the latest seismotectonic data. The seismic hazard map shows peak ground acceleration values on rock corresponding to the 10% probability of exceedance in a 50-year time period (approximately return periods of 500 years). The calculated results reveal that the maximum ground acceleration can occur on rock in Hanoi is about 0.13 g corresponding to the shaking intensity level of VIII on the MSK-64 scale. The ground motion values calculated on rock vary according to the local site conditions. We have evaluated and corrected the local site effects on ground motion in Ha Dong district, Hanoi by using microtremor and borehole data. The Nakamura’s H/V spectral ratio method has been applied to establish a map of ground dominant periods in Ha Dong with a TS range of 0.6 - 1.2 seconds. The relatively high values of periods indicate that Ha Dong has soft soil and thick Quaternary sediments. The sediment thickness in Ha Dong is calculated to vary between 30 - 75 m based on ground dominant periods and shear wave velocity VS30 = 171 - 254 m/s. The results of local site effect on ground motion show that the 500-year return period peak ground acceleration in Ha Dong ranges from 0.13 g to 0.17 g. It is once again asserted that the seismic hazard in Hanoi is a matter of great concern, due not only to the relatively high ground acceleration, but also to the seismic characteristics of soil (low shear wave velocity, ground dominant period of approximately 1 second).

scholarly journals Probabilistic seismic hazard assessment of Bishkek, Kyrgyzstan, considering empirically estimated site effects

2015 ◽  
Vol 58 (1) ◽  
Author(s):  
Shahid Ullah ◽  
Dino Bindi ◽  
Marco Pilz ◽  
Stefano Parolai
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Assessment ◽  
Site Effects ◽  
Response Spectrum ◽  
Seismic Hazard Assessment ◽  
Geological Structure ◽  
Probabilistic Seismic Hazard Assessment ◽  
Site Classification ◽  
Ground Acceleration

<p>It is well known that variability in the surface geology potentially leads to the modification of earthquake-induced ground motion over short distances. Although this effect is of major importance when seismic hazard is assessed at the urban level, it is very often not appropriately accounted for. In this paper, we present a first attempt at taking into account the influence of the shallow geological structure on the seismic hazard assessment for Bishkek, Kyrgyzstan, using a proxy (Vs30) that has been estimated from in situ seismic noise array analyses, and considering response spectral ratios calculated by analyzing a series of earthquake recordings of a temporary seismic network. To highlight the spatial variability of the observed ground motion, the obtained results are compared with those estimated assuming a homogeneous Vs30 value over the whole urban area. The seismic hazard is evaluated in terms of peak ground acceleration (PGA) and spectral acceleration (SA) at different periods (frequencies). The presented results consider the values obtained for a 10% probability of exceedance in 50 years. The largest SA estimated considering a rock site classification of the area (0.43 g) is observed for a period of 0.1 s (10 Hz), while the maximum PGA reaches 0.21 g. When site effects are included through the Vs30 proxy in the seismic hazard calculation, the largest SA, 0.67 g, is obtained for a period of 0.3 s (about 3.3 Hz). In terms of PGA, in this case the largest estimated value reaches 0.31 g in the northern part of the town. When the variability of ground motion is accounted for through response spectrum ratios, the largest SA reaches a value as high as 1.39 g at a period of 0.5 s. In general, considering site effects in the seismic hazard assessment of Bishkek leads to an increase of seismic hazard in the north of the city, which is thus identified as the most hazardous part within the study area and which is more far away from the faults.</p>

The power of the little ones: Computed and observed aftershock hazard in Central Italy

2021 ◽  
pp. 875529302110369
Author(s):  
Robin Gee ◽  
Laura Peruzza ◽  
Marco Pagani
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Hazard Analysis ◽  
Central Italy ◽  
Current Approach ◽  
Time Dependent ◽  
Ground Acceleration ◽  
Key Features ◽  
Hazard Curves

Seismic hazard in Central Italy due to the 2016–2017 seismic sequence is modeled using a standard probabilistic aftershock seismic hazard model. Two key features of the model are the consideration of time-dependent aftershock occurrence, modeled by stacking Omori decay curves associated with the three largest ( Mw > 5.5) events, and the incorporation of geologic information by modeling the locations of expected seismicity along realistic fault surfaces. The computed seismic hazard at Amatrice indicates higher hazard values compared to those computed using a conventional time-independent hazard analysis. We then compare the computed hazard curves against empirical hazard curves constructed for 12 individual recording stations in terms of peak ground acceleration, each with at least 35 (and up to 231) recordings. At eight sites, the observed exceedances fall within one standard deviation of the expected mean, while at the remaining sites, the observed exceedances fall outside this range indicating a poorer match. The soil sites are among the stations with the poorest match, suggesting that site effects may not be accurately modeled with the current approach.

Seismic hazard assessment of Chennai city considering local site effects

2008 ◽  
Vol 117 (S2) ◽  
pp. 853-863 ◽  
Author(s):  
A. Boominathan ◽  
G. R. Dodagoudar ◽  
A. Suganthi ◽  
R. Uma Maheswari
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Site Effects ◽  
Seismic Hazard Assessment ◽  
Local Site Effects ◽  
Local Site ◽  
Chennai City

scholarly journals Seismic Hazard Assessment of Shigo Kas Hydro-Power Project (Khyber Pakhtunkhwa, Pakistan)

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 349
Author(s):  
Muhammad Abid ◽  
Haytham F. Isleem ◽  
Khan Shahzada ◽  
Afed Ullah Khan ◽  
Muhammad Kamal Shah ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Peak Ground Acceleration ◽  
Soil Analysis ◽  
Safety Evaluation ◽  
Seismic Hazard Assessment ◽  
Deep Soil ◽  
Ground Acceleration ◽  
Hydro Power ◽  
Local Site

In this paper, a seismic hazard assessment (SHA) of the Shigo Kas hydropower project has been performed by deterministic and probabilistic approaches. The previously developed MATLAB-based code has been used for deterministic SHA, incorporating local site effects through deep soil analysis. On the other hand, for probabilistic SHA, CRISIS 2007 has been used through diffuse areal source zones. The latest updated earthquake instrumental and historical catalogs have been developed. Based on the recommendations of the International Commission on Large Dams, peak ground acceleration (PGA) values for the maximum credible earthquake (MCE), safety evaluation earthquake (SEE), design basis earthquake (DBE) and operating basis earthquake (OBE) have been assessed, which are 0.50 g, 0.68 g, 0.35 g and 0.24 g, respectively, at the intake location, and 0.50 g, 0.61 g, 0.30 g and 0.22 g, respectively, at the powerhouse location. Hazard maps have been developed for scenario-based earthquakes (MCE) and for the peak ground acceleration of 145-, 475- and 2500-year return periods. The de-aggregation process has evaluated the combined effects of magnitude and distance. At a distance of 30 to 70 km from the earthquake source, earthquakes of magnitude 5 Mw to 5.6 Mw and 5.9 Mw to 6.5 Mw are more hazardous for the current project.

scholarly journals Seismic hazard in Australia and New Zealand

1995 ◽  
Vol 28 (4) ◽  
pp. 279-287 ◽  
Author(s):  
D. J. Dowrick ◽  
G. Gibson ◽  
K. McCue
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Return Period ◽  
Peak Ground Acceleration ◽  
Regional Differences ◽  
Response Spectra ◽  
Building Codes ◽  
Hazard Maps ◽  
Ground Acceleration ◽  
Different Response

As a prelude to the planned harmonization of building codes in Australia and New Zealand, this paper illustrates the seismic hazard in the two countries for discussion purposes. Hazard maps for peak ground acceleration for a 475 year return period are presented, and also for 2500 year return period in New Zealand, along with typical response spectra. It is shown that the hazard in the least seismic parts of New Zealand is similar to that of the more seismically active parts of Australia. The eventual harmonized loadings code would accommodate regional differences in hazard by using different response spectra and zone factors appropriate to the different regions of the two countries.

scholarly journals Seismic hazard assessment of Iran

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
B. Tavakoli ◽  
M. Ghafory-Ashtiany
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Grid Point ◽  
Seismic Hazard Assessment ◽  
Earthquake Hazard ◽  
Seismic Source ◽  
Historical Earthquakes ◽  
Earthquake Insurance ◽  
Ground Acceleration ◽  
Seismic Source Models

The development of the new seismic hazard map of Iran is based on probabilistic seismic hazard computation using the historical earthquakes data, geology, tectonics, fault activity and seismic source models in Iran. These maps have been prepared to indicate the earthquake hazard of Iran in the form of iso-acceleration contour lines, and seismic hazard zoning, by using current probabilistic procedures. They display the probabilistic estimates of Peak Ground Acceleration (PGA) for the return periods of 75 and 475 years. The maps have been divided into intervals of 0.25 degrees in both latitudinal and longitudinal directions to calculate the peak ground acceleration values at each grid point and draw the seismic hazard curves. The results presented in this study will provide the basis for the preparation of seismic risk maps, the estimation of earthquake insurance premiums, and the preliminary site evaluation of critical facilities.

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