Proposal of an empirical site classification method based on target simulated horizontal over vertical spectral ratio

2018 ◽  
Vol 16 (12) ◽  
pp. 5843-5874 ◽  
Author(s):  
Nasser Laouami ◽  
Mohamed Hadid ◽  
Noureddine Mezouar
Keyword(s):  
Spectral Ratio ◽  
Classification Method ◽  
Site Classification

A Method to Directly Estimate S-Wave Site Amplification Factor from Horizontal-to-Vertical Spectral Ratio of Earthquakes (eHVSRs)

2020 ◽  
Vol 110 (6) ◽  
pp. 2892-2911
Author(s):  
Eri Ito ◽  
Kenichi Nakano ◽  
Fumiaki Nagashima ◽  
Hiroshi Kawase
Keyword(s):  
Amplification Factor ◽  
Strong Motion ◽  
Spectral Ratio ◽  
Site Amplification ◽  
Body Waves ◽  
Correction Function ◽  
Site Classification ◽  
Frequency Range ◽  
S Wave ◽  
Site Amplification Factor

ABSTRACT The main purpose of the site classification or velocity determination at a target site is to obtain or estimate the horizontal site amplification factor (HSAF) at that site during future earthquakes because HSAF would have significant effects on the strong-motion characteristics. We have been investigating various kinds of methods to delineate the S-wave velocity structures and the subsequent HSAF, as precisely as possible. After the advent of the diffuse field concept, we have derived a simple formula based on the equipartitioned energy density observed in the layered half-space for incident body waves. In this study, based on the diffuse field concept, together with the generalized spectral inversion technique (GIT), we propose a method to directly estimate the HSAF of the S-wave portion from the horizontal-to-vertical spectral ratio of earthquakes (eHVSRs). Because the vertical amplification is included in the denominator of eHVSR, it cannot be viewed as HSAF without correction. We used GIT to determine both the HSAF and the vertical site amplification factor (VSAF) simultaneously from strong-motion data observed by the networks in Japan and then deduced the log-averaged vertical amplification correction function (VACF) from VSAFs at a total of 1678 sites in which 10 or more earthquakes have been observed. The VACF without a category has a constant amplitude of about 2 in the frequency range from 1 to 15 Hz. By multiplying eHVSR by VACF, we obtained the simulated HSAF. We verified the effectiveness of this correction method using data from observation sites not used in the aforementioned averaging in the frequency range from 0.12 to 15 Hz.

scholarly journals The horizontal-to-vertical spectral ratio and its applications

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Rong Xu ◽  
Lanmin Wang
Keyword(s):  
Shear Wave ◽  
Velocity Structure ◽  
Site Response ◽  
Mineral Exploration ◽  
Spectral Ratio ◽  
Site Effect ◽  
Research Area ◽  
Site Classification ◽  
S Wave ◽  
Borehole Data

AbstractThe horizontal-to-vertical spectral ratio (HVSR) has been extensively used in site characterization utilizing recordings from microtremor and earthquake in recent years. This method is proposed based on ground pulsation, and then it has been applied to both S-wave and ambient noise, accordingly, in practical application also different. The main applications of HVSR are site classification, site effect study, mineral exploration, and acquisition of underground average shear-wave velocity structure. In site response estimates, the use of microtremors has been introduced long ago in Japan, while it has long been very controversial in this research area, as there are several studies reporting difficulties in recognizing the source effects from the pure site effects in noise recordings, as well as discrepancies between noise and earthquake recordings. In practice, the most reliable way is the borehole data, and the theoretical site response results were compared with the HVSR using shear wave to describe site response. This paper summarizes the applications of the HVSR method and draws conclusions that HVSR has been well applied in many fields at present, and it is expected to have a wider application in more fields according to its advantages.

scholarly journals A Quantitative Site-Specific Classification Approach Based on Affinity Propagation Clustering

2020 ◽  
Author(s):  
Sayed Moustafa ◽  
Farhan Khan ◽  
Mohamed Metwaly ◽  
Eslam A.Elawadi ◽  
Nassir Al-Arifi
Keyword(s):  
Urban Areas ◽  
Clustering Algorithm ◽  
Site Response ◽  
Seismic Hazard Assessment ◽  
Spectral Ratio ◽  
Site Effect ◽  
Affinity Propagation ◽  
Site Classification ◽  
Site Specific ◽  
Affinity Propagation Clustering

Abstract Investigations made to evaluate the site effect characteristics and develop a reliable site classification scheme have received the paramount importance for the planning of urban areas and for a reliable site-specific seismic hazard assessment. This paper presents a new approach for site classification based on affinity propagation (AP) along with a selected set of representative horizontal to vertical spectral ratio (HVSR) curves inside King Saud University (KSU) campus. Measurements of the ambient vibrations were performed to cover the entire campus area by about 307 stations with 20 minutes recording length and sample rate of 128 Hz for each station to satisfy the criteria for reliable and unambiguous HVSR results. Predominant period values were used for identifying of site response and subsequent site classification. Empirical equations from the literature relating frequency of HVSR peak to average shear wave velocity in the upper 30m, commonly used as a proxy for site classification, were found to be unreliable, making site classification difficult. To overcome this problem, Affinity propagation clustering algorithm is used. The obtained results illustrated that microtremors spectral ratios can be remarkably robust tool in determining site effects. The survey results concluded to the preliminary seismic site classification map for the mapped area, which would be useful for future safe design of structures. Finally, the results presented in this study are encouraging prolongation of this type of study in other parts of Saudi Arabia using the microtremors data and site response functions.

Site Classification Method Based on Geomorphological and Geological Characteristics and Its Application in China

2019 ◽  
Vol 109 (5) ◽  
pp. 1843-1854 ◽  
Author(s):  
Xiaojun Li ◽  
Bingbing Jing ◽  
Chen Liu ◽  
Jianming Yin
Keyword(s):  
Large Scale ◽  
Classification Method ◽  
Insurance Companies ◽  
Site Classification ◽  
Site Condition ◽  
Borehole Data ◽  
Earthquake Insurance ◽  
Geological Characteristics ◽  
Slope Method ◽  
Topographic Slope

Abstract Earthquake insurance has become a topic of major importance in mainland China ever since the Mw 7.9 Wenchuan earthquake in 2008. Site‐condition amplification is one of the essential factors that influences the prediction of strong ground motion and the assessment of damages of buildings and structures. The site effects should hence be included in calculating earthquake damage and determining the insurance rate for insurance companies. In particular, large‐scale site classification is required for the implementation of earthquake insurance. This study first used a slope method for site classification in China through the VS30 values from the topographic slope data and the correlation between VS30 and the topographic slope. A novel site classification method, called the slope–geological method, was then proposed in this study to improve the slope method by combining geological characteristics, including geological age, the depositional environment, and soil properties. Four hundred and fifty three pieces of borehole data in Northern Plain and Sichuan of China were used to verify the effectiveness and difference of the slope method and the slope–geological method proposed in this study. Site‐condition classification maps of China were drawn using the slope method and slope–geological method, respectively.

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