• The Journal of Engineering Geology
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• v.10 no.2
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• pp.79-97
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• 2000

Trend of earthquake occurrence of Korea represents that the term from 1978 to 1982 may be called as "active period", the term from 1983 to 1991 is rather tranquil, and from 1992, the occurrence number is increasing greatly. Instrumental earthquake observation of Korea started in 1905 by Japan. It continued until 1943 and ceased then through social disorders such as the independence from Japan Empire and the civil war. After that the observation restarted in 1963 by the establishment the World Wide Standard Seismograph Network. And the fundamental earthquake observation period started in 1978 with the Hongsung earthquake event. KMA(Korea Meteorological Administration) has constructed and operated the 24-hour earthquake and tsunami monitoring system and it propels new construction project of the national seismographic network system. In the result of this project, KMA operates 27 seismic networks, 42 accelerator networks, seismic analyzing system, and sea level monitoring system now. It has the plan to enlarge these systems that 31 seismic networks and 75 accelerator networks until 2001.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.7-11
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• 2008

기상청은 2008년 현재 전국에 107개의 디지털 지진관측망을 운영하고 있다. 또한 지진관측 유관기관인 한국지질자원연구원, 한국원자력안전기술원, 한전전력연구원에서 각 기관의 목적에 맞게 지진관측소를 운영하고 있으며, 이들 지진관측자료의 공유를 목적으로 실시간으로 통합하는 통합지진과측망(KISS)을 2000년에 구축하여 지진분석에 쓰이고 있다. 한반도의 지진발생 현황은 1978년부터 2007년까지 776회로 약 26회/년 정도가 발생하였다. 최근 중국의 쓰촨성과 일본 이와테 지진으로 지진 및 지진예지에 대한 국민적 관심이 대두되고 있다. 한반도에서도 큰 규모의 지진이 발생할 가능성에 대비해 기상청에서는 지진관측망과 지진예지 목적의 지구물리관측망을 구축 중에 있다. 지구물리관측망은 INTERMAGNET에서 등록할 수 있는 수준의 관측소를 목표로 인위적인 자기장의 교란이 적은 지질학적인 요소들을 고려한 후보지 선정을 위하여 지구자기업무에 관한 기획연구(서만철 2007)를 수행 하였다. 그 결과 국가 중심 지구자기관측소의 위치는 충남 공주시와 청양군 사이에 있는 칠갑산 지역이 가장 좋은 후보지라고 제안하여 청양지역을 주변으로 국유림 및 군유지를 조사하여 충남 청양군 장평면 화산리 산 36-2번지에 후보지를 선정하여 최적의 입지 조건을 검증하기 위해 인천교육대학교의 이휘순 교수 MT탐사를 수행 주변의 배경잡음을 측정하여 양호한 조건을 갖춘 것으로 확인되었다. 지구자기관측소에는 Fluxgate Magnetometer 1대, Total field Magnetometer 1대, Theodolite 1대, SP(Self Potential) Monitoring system 1대와 장비들을 보호 할 수 있는 관측소가 설치될 예정이다

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.54-59
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• 2009

Seismic station of high noise level has difficulties detecting relatively weak ground motions due to small earthquakes or teleseismic events because earthquake detectability of seismic station depends on seismic noise level. To figure out the capability of earthquake detection of a seismic network, therefore, seismic noise level of each station also needs to be considered, including the distribution of seismic stations. Recently, it has been known that most of broadband seismic stations in South Korea have affected by cultural noise in the frequencies higher than 1 Hz and show diurnal variations of noise level. In order to analyze the effect of diurnal variation of seismic noise level on earthquake detectability, we used the result of background seismic noise level analysis of seismograms of 30 broadband stations of KIGAM and KMA from 2005 to 2007. This study shows that earthquakes greater than magnitude 2.4 occurring within the Korean Peninsula can be detected at night while those greater than magnitude 2.6 can be detected in the daytime.

• Geophysics and Geophysical Exploration
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• v.13 no.3
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• pp.219-226
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• 2010

Current earthquake alert notification for immediate post-earthquake procedures for the critical facilities is exclusively dependent on the ground-motion intensity measures observed at the seismic station located within the site. This practice is prune to false notification due to a noise and problems of missing and poor quality records of the seismic station. The credibility of the earthquake alert notification can be enhanced by utilizing the multiple transformed records of the nearby seismic stations at other sites interconnected to the same earthquake monitoring system by a network. The time-domain transformation of the site-response between the seismic stations is implemented by convoluting the nearby records with a pair of forward and inverse FIR filters designed for the site response relative to a seismic basement. The transformed records from the nearby seismic stations can be used to estimate the ground-motion intensity measures missing at the site or to evaluate the data quality along with other various possible applications in the area of geoscience and earthquake engineering.

• Proceedings of the KSEG Conference
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• 2005.04a
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• pp.107-110
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• 2005

The seismological observation of Korea began in 1905, and has been run with continuous earthquake network of observation, expanding to the advanced country, but still has some problems in accuracy and speed for report. There are many problems to issue the early warning system for earthquakes and Tsunami in the East Sea because most events in the East Sea occur outside the seismic network. Therefore multi-waveform data conversion and composition from the surrounding countries such as Korea, Japan and Far East Russia are requested in order to more accurate determination of earthquake parameters. We used FESNET(Far East Seismic Network) technology to analyze 2004 May 29th Uljin Earthquake and 2005 March 20th Japanese Fukuoka Earthquake in this research, using the data of KMA, Japan stations and IRIS(4 station).

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.171-178
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• 2006

The seismological observation of Korea began in 1905, and has been run with continuous earthquake network of observation, expanding to the advanced country, but still has some problems in accuracy and speed for report. There are many problems to announce the early warning system for earthquakes and tsunami in the East Sea because most events in the East Sea occur outside the seismic network. Therefore multi-waveform data conversion and composition from the surrounding countries such as Korea, Japan and Far East Russia are requested in order to improve more accurate determination of the earthquake parameters. We used FESNET(Far East Seismic Network) technology to analyze the May 29 and June 1 Earthquakes, and the March 20, 2005 Fukuoka Earthquake in this research, using the data sets of KMA, Japan(JMA/MIED) and IRIS stations. It was found out that use of FESNET resulted in more better outputs than that of a single network, either KMA or JMA stations.

• The Journal of Engineering Geology
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• v.5 no.1
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• pp.59-74
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• 1995

It is well known that the hypocentral parameters inside the seismic array are well determined using HYPO71PC Programs. These programs, however, do not woik well for the non-evenly distribution of the seismic stations and/or the seismic events outside the seismic array. Furthermore it is very difficult to determine the exact locations of small events in North Korea since there is no seismological data exchange between South and North Koreas. We used the polarization method of the single-station with 3-component in addition to HYPO71PC(IASPEI's Program) in order to determine the source parameters of shallow-focus earthquakes outside the seismic array. First of all, we tested the interior events of the Uisung earthquake, April 14, 1991 and the Mt. Keyryong earthquakes, Feorirary 12, 1994, and two exterior events of W. Pyoungyang earthquake, Noventer 12, 1992, and Yellow Sea earthquake, July 26, 1994 to investigate the convergence and divergence to calculate the source parameters. We have found that the source determination outside the seismic array never converges to the exact location whereas the any events inside the array quickly converge to the exact location. The seismic events outside the array such as two events Vladivostok and East Sea, and the Yellow Sea event are more accurately determined using the polarization method. Estimating the source azimuth is carried out by estimating the polarization direction of the interesting phases and the range estimate is made frum the relative timing of different phases. The polarization method is verified by fmding that the estimates of azimuths and incidence angles by the polarization method are identical with those of the synthetic seismograms of the modellings using the generator program.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.79-86
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• 2005

The apparent source spectrum of the Fukuoka earthquake is estimated at the seismic basement by removing from the observed spectra at Korean seismic stations the path and site responses that were previously revealed through inversion process applied to large spectral D/B accumulated until 2004. The approximate source spectrum is also estimated by using data recorded near the epicenter from various Japanese seismic networks and compared with the Korean source spectrum. The comparison result shows that there is good agreement among source spectra estimated based on the data from seismic networks of Korea at large distances (190km

• Journal of the Korean Geophysical Society
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• v.8 no.1
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• pp.15-21
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• 2005

The apparent source spectrum of the Fukuoka earthquake is estimated at the seismic basement by removing from the observed spectra at Korean seismic stations the path and site responses that were previously revealed through inversion process applied to large spectral D/B accumulated until 2004. The approximate source spectrum is also estimated by using data recorded near the epicenter from various Japanese seismic networks and compared with the Korean source spectrum. The comparison result shows that there is good agreement among source spectra estimated based on the data from seismic networks of Korea at large distances (190 km

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.615-621
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• 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.