• Title/Summary/Keyword: classification of seismic stations

Search Result 8, Processing Time 0.025 seconds

Investigation on site conditions for seismic stations in Romania using H/V spectral ratio

  • Pavel, Florin;Vacareanu, Radu
    • Earthquakes and Structures
    • /
    • v.9 no.5
    • /
    • pp.983-997
    • /
    • 2015
  • This research evaluates the soil conditions for seismic stations situated in Romania using the horizontal-to-vertical spectral ratio (HVSR). The strong ground motion database assembled for this study consists of 179 analogue and digital strong ground motion recordings from four intermediate-depth Vrancea seismic events with $M_w{\geq}6.0$. In the first step of the analysis, the influence of the earthquake magnitude and source-to-site distance on the H/V curves is evaluated. Significant influences from both the earthquake magnitude and hypocentral distance are found especially for soil class A sites. Next, a site classification method proposed in the literature is applied for each seismic station and the soil classes are compared with those obtained from borehole data and from the topographic slope method. In addition, the success and error rates of this method are computed and compared with other studies from the literature. A more in-depth analysis of the H/V results is performed using data from seismic stations in Bucharest and a comparison of the free-field and borehole H/V curves is done for three seismic stations. The results show large differences between the free-field and the borehole curves. As a conclusion, the results from this study represent an intermediary step in the evaluation of the soil conditions for seismic stations in Romania and the need to perform more detailed soil classification analysis is highly emphasized.

Site characteristics and classification of seismic stations based on observed earthquake data (지진관측 자료를 이용한 국내 지진관측소의 지반특성 분류)

  • 박동희;연관희;장천중
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2003.03a
    • /
    • pp.61-68
    • /
    • 2003
  • The H/V ratio (Horizontal to Vertical spectral ratio) has been used to infer site amplification without previous knowledge of near-surface geology and in fact may provide useful general site condition information. This method is used to classify the site characteristics of seismic stations in Korea by comparison with known H/V ratios representative of various sites all over the world. In addition, differences between horizontal and vertical kappa values were evaluated for each seismic stations by comparing WV ratio and Weak Motion amplification derived from inversion of stochastic ground motion parameters and were used as index to quantitatively classify the site characteristics.

  • PDF

Multi-site based earthquake event classification using graph convolution networks (그래프 합성곱 신경망을 이용한 다중 관측소 기반 지진 이벤트 분류)

  • Kim, Gwantae;Ku, Bonhwa;Ko, Hanseok
    • The Journal of the Acoustical Society of Korea
    • /
    • v.39 no.6
    • /
    • pp.615-621
    • /
    • 2020
  • In this paper, we propose a multi-site based earthquake event classification method using graph convolution networks. In the traditional earthquake event classification methods using deep learning, they used single-site observation to estimate seismic event class. However, to achieve robust and accurate earthquake event classification on the seismic observation network, the method using the information from the multi-site observations is needed, instead of using only single-site data. Firstly, our proposed model employs convolution neural networks to extract informative embedding features from the single-site observation. Secondly, graph convolution networks are used to integrate the features from several stations. To evaluate our model, we explore the model structure and the number of stations for ablation study. Finally, our multi-site based model outperforms up to 10 % accuracy and event recall rate compared to single-site based model.

Case Study of Dynamic Amplification Characteristics of the Seismic Stations Using Observed Seismic Waves (관측지진파를 이용한 지반증폭특성 사례분석)

  • Lee, Jundae;Kim, Junkyoung
    • Journal of the Korean GEO-environmental Society
    • /
    • v.10 no.1
    • /
    • pp.35-41
    • /
    • 2009
  • It is necessary to consider the site amplification for estimating SSI (soil structure interaction) and seismic source with more confidence. The horizontal to vertical (H/V) ratio technique in spectral domain is one of several techniques to estimate empirical site transfer function. The technique, originally proposed by Nakamura (1989), is applied to analyze the surface waves in the microtremor records. However, the application of this technique has been widened to the shear wave energy of strong motions for estimating site amplification. The purpose of this paper is to estimate spectral ratio using observed data at the seismic stations distributed within Southern Korean Peninsula from the Fukuoka earthquake including 11 aftershocks. The results show that each station has the its own characteristics of the specific resonance, high-band, and low-band frequency. The characteristics of the resonance frequency is more important because the quality of the seismic records are dependent on the resonance frequency. The result can be used for the study of site classification and removal of the site amplification effects from observed records can give us more reliable seismic source parameters.

  • PDF

Classification of Seismic Stations Based on the Simultaneous Inversion Result of the Ground-motion Model Parameters (지진동모델 파라미터 동시역산을 이용한 지진관측소 분류)

  • Yun, Kwan-Hee;Suh, Jung-Hee
    • Geophysics and Geophysical Exploration
    • /
    • v.10 no.3
    • /
    • pp.183-190
    • /
    • 2007
  • The site effects of seismic stations were evaluated by conducting a simultaneous inversion of the stochastic point-source ground-motion model (STGM model; Boore, 2003) parameters based on the accumulated dataset of horizontal shear-wave Fourier spectra. A model parameter $K_0$ and frequency-dependent site amplification function A(f) were used to express the site effects. Once after a H/V ratio of the Fourier spectra was used as an initial estimate of A(f) for the inversion, the final A(f) which is considered to be the result of combined effect of the crustal amplification and loca lsite effects was calculated by averaging the log residuals at the site from the inversion and adding the mean log residual to the H/V ratio. The seismic stations were classified into five classes according to $logA_{1-10}^{max}$(f), the maximum level of the site amplification function in the range of 1 Hz < f < 10 Hz, i.e., A: $logA_{1-10}^{max}$(f) < 0.2, B: 0.2 $\leq$ $logA_{1-10}^{max}$(f) < 0.4, C: 0.4 $\leq$ $logA_{1-10}^{max}$(f) < 0.6, D: 0.6 $\leq$ $logA_{1-10}^{max}$(f) < 0.8, E: 0.8 $\leq$ $logA_{1-10}^{max}$(f). Implication of the classified result was supported by observing a shift of the dominant frequency of average A(f) for each classified stations as the class changes. Change of site classes after moving seismic stations to a better site condition was successfully described by the result of the station classification. In addition, the observed PGA (Peak Ground Acceleration)-values for two recent moderate earthquakes were well classified according to the proposed station classes.

A Comparison Study of the Amplification Characteristics of the Seismic Observation Sites using Coda wave, Background Noise, and S-wave Energy from Fukuoka Earthquakes Series (후쿠오카 지역 발생 지진의 Coda파, 배경잡음 및 S파 에너지를 이용한 관측소의 증폭특성에 관한 비교 연구)

  • Kim, Jun Kyoung
    • The Journal of Engineering Geology
    • /
    • v.23 no.4
    • /
    • pp.435-445
    • /
    • 2013
  • Since design response spectrum does not reflect local soil characteristics, site specific response spectrum of observed ground motions appears relatively higher than design response spectrum at high frequency range. These problems have been pointed out from the domestic seismic design industry. Among various estimation methods, this study used the method H/V ratio of ground motion for estimating site amplification. This method has been extended to background noise, Coda waves and S waves recently for estimating site amplification. This study applied this method to the background noise and Coda wave energy. This study analysed more than 267 background noises from 15 macro earthquakes including main Fukuoka earthquake (2005/03/20, M=6.5) and then compared to results from S waves, at 8 main domestic seismic stations. The results showed that most of the domestic seismic stations gave similar results to those from S waves. Each station showed its own characteristics of site amplification property in low, high and specific resonance frequency ranges. Comparison of this study to other studies using different method can give us much information about dynamic amplification of domestic sites characteristics and site classification.

Dynamic Amplification Characteristics of Major Domestic Seismic Observation Sites using Ground Motions from Domestic Macro Earthquakes (국내 중규모지진의 자료를 이용한 주요 관측소 지반의 동적 증폭특성에 관한 연구)

  • Kim, Jun Kyoung
    • The Journal of Engineering Geology
    • /
    • v.22 no.4
    • /
    • pp.399-408
    • /
    • 2012
  • To estimate seismic source and soil-structure interaction more reliably, site amplification characteristics should be considered. Among the various estimation methods, we used Nakamura's method (1989) to estimate site amplification. This method was originally applied to background noise; however, it has recently been successfully applied to S-wave and Coda-wave energy, and is applied to S-waves in the present study. We used more than 180 observed ground motions from 23 macro-earthquakes and then analyzed site amplification characteristics at eight seismic stations. Each station showed characteristics of site amplification properties in the low-, high- and resonance-frequency ranges. Comparison of the present results with those of other studies provide successful information regarding the dynamic amplification of domestic site characteristics and site classification.

A Comparison Study of the Site Amplification Characteristics and Seismic Wave Energy Levels at the Sites near Four Electric Substations (4개 변전소시설 부지 인근관측소의 지반증폭 특성 및 파형에너지 수준 비교 연구)

  • Yoo, Seong-Hwa;Kim, Jun-Kyoung;Wee, Soung-Hoon
    • Journal of the Korean earth science society
    • /
    • v.37 no.1
    • /
    • pp.40-51
    • /
    • 2016
  • The problem has been pointed out that the domestic design response spectrum does not reflect site amplification, particularly in the high frequency bands, including the fact that site specific response spectrum from the observed ground motions appears relatively higher than design response spectrum. Among various methods, this study applied H/V spectral ratio of ground motion for estimating site amplification. This method, originated from S waves and Rayleigh waves, recently has been extended to Coda waves and background noise for estimating site amplification. For limited time of periods, 4 electric substation sites had operated seismic stations at two separate locations (bedrock and borehole) within each substation site. H/V spectral ratio of S wave, Coda wave, and background noise, was applied to 36 accelerations of 3 macro earthquakes (Odaesan, Jeju and Gongju earthquakes), larger than magnitude 3.4. observed simultaneously at each bedrock location within 4 electric substation sites. Site amplifications at the bedrock location of 4 sites were compared among S wave, Coda wave energy, and background noise, and then compared to the previous results from the borehole location data. The site classification was also tried using resonancy frequency information at each site and location. The results suggested that all the electric substation sites showed similar site amplification patterns among S wave, Coda wave, and background noise. Each station showed its own characteristics of site amplification property in low, high and specific resonance frequency ranges. Comparison of this study to other results using different method can give us much more information about dynamic amplification of domestic sites characteristics and site classification.