• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.119-129
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• 2022

In this paper, we predict the earthquake magnitudes which were recently occurred in Gyeongju and Pohang, using statistical methods based on historical data. For this purpose, we use the five-year block maximum data of 1392~1771 period, which has a relatively high annual density, among the historical earthquake magnitude data of the Chosun Dynasty. Then, we present the prediction and analysis of earthquake magnitudes for the return level over return period in the Chosun Dynasty using the extreme value theory based on the distribution of generalized extreme values (GEV). We use maximum likelihood estimation (MLE) and L-moments estimation for parameters of GEV distribution. In particular, this study also demonstrates via the goodness-of-fit tests that the GEV distribution can be an appropriate analytical model for these historical earthquake magnitude data.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.217-217
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• 2021

우리나라 동해 연안에 영향을 미쳤던 역사지진들과 일본에서 진행된 동해에서의 대규모지진에 관한 조사검토회에서 2014년에 보고된 동해 동연부와 남해 남연부 측에 있는 60개의 지진공백역들에 대한 단층매개변수들이 공개되어있어 수치실험을 통해 지진해일의 재해도를 분석하고 있다. 하지만 이러한 단층매개변수 값들에 대한 불확실성이 존재하기에 이를 대비한 지진해일 대책을 세울 필요가 있다. 단층매개변수의 불확실성을 고려하는 방법 중 한 가지는 해당 변수들을 조정하여 Case 모델들을 다양화하는 것이다. 이 때 매개변수의 변동에 대한 기준이 필요하기에 단층매개변수에 대한 민감도 분석이 진행되어야 한다. 본 연구의 최종목표는 지진해일에 대한 위험성에 대비하기 위해 선정된 연구지역에 대하여 단층매개변수들을 조정한 경우별 모델들을 사용한 수치모형 실험을 실행한 후 도출된 지진해일 처오름높이 및 처내림높이 결과를 분석하여 각 단층매개 변수의 지진해일에 대한 민감도를 결정하는 것이며, 최종적으로 확률론적 지진해일 재해도분석(Probabilistic Tsunami Hazard Analysys : PTHA)을 실시할 때 기준이 되는 로직트리를 작성할 때 명확한 근거를 제시한다. 단층매개변수의 민감도 분석은 일본(Goda et al., 2014), 미국(Sepúlveda and Liu, 2016), 뉴질랜드(D. Burbridge et al., 2015) 등에서 연구가 활발하게 이루어졌으며 현재도 활발한 연구가 진행되고 있다. 민감도 분석 과정은 먼저 역사 지진해일과 우리나라 근해에 영향을 미칠 수 있는 지진해일의 단층매개변수 조사한 후 파향선추적모형(wave ray-tracing)의 결과를 정리하여 대상 지역에 영향을 미치는 단층을 선정하고, 선정한 단층들의 단층매개변수 값을 일정한 기준을 두고 조정하여 실시한 지진해일 수치모형 실험에서 계산한 결과값을 분석하여 민감도를 결정한다.

• Proceedings of the KSEG Conference
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• 2003.04a
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• pp.87-92
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• 2003

한반도는 판 내부지역으로서 지구조적 과정이 느리게 진행된다. 그 결과 지진발생빈도가 낮으며 불규칙한 지진발생특성을 보인다. 우리나라에는 약 1900년 간의 역사지진기록과 약 100년 간의 계기지진자료가 있어 지진발생특성 연구에 중요한 정보를 제공하고 있으나, 이들 지진자료를 이용할 때에는 자료의 신뢰성과 정밀도에 유의할 필요가 있다.

• Journal of the Korean earth science society
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• v.21 no.2
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• pp.159-167
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• 2000

We tested the randomness and estimated the degree of concentration for the earthquake occurrence in the Korean Peninsula by using the statistical methods for spatial data. For the randomness test, we applied both of the test statistics based method and the empirical distribution based method to the both of historical and instrumental seismicity data. It was found that the earthquake occurrences for historical and instrumental seismicity data are not random and clustered rather than scattered. A nonparametric density estimation method was used to estimate the concentration degree in the Peninsula. The earthquake occurrences show relatively high concentration on Seoul, Choongnam, Chonbook and Kyungbook areas for the historical seismicity data. Also,'L" shaped concentrations connecting Whanghaedo -the coast of Choongnam -the inland of Kyungbook area are revealed for the instrumental seismicity data.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.325-334
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• 2016

Both 1900 years of historic literature and recent instrumental seismic records indicate the Korean Peninsula has repeatedly experienced small and large earthquakes. This study has used historical and instrumental records of Korea to investigate the characteristics of earthquakes in the peninsula. Results of GIS spatial analyses indicate Pyongyang, the capital of North Korea, is more vulnerable to the earthquake hazard than that of other regions in the Korean Peninsula. It is also noted that Pyongyang is exposed to high risks of other natural and social disasters because of the high population density and concentrated infra structures. Scenario shake map drawn up assuming a magnitude 6.7 earthquake, which was experienced in A.D. 502 in the area, indicates that 51.1% of the city are exposed to PGA 0.24 g or higher. Recent statistics by the Statistics Korea also indicates the North Korea is far more vulnerable to disasters than those in the South Korea. Results of the preliminary study provide essential information for comprehensive understanding of earthquake hazard estimation in Korea including the North Korea.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.461-467
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• 2001

Shaking table tests were performed with full scale models of stone parapet on the ancient rampart. The objectives of these tests are to study the seismic behavior of the parapet and to obtain quantitative estimation of the intensities of historical earthquakes. Two test models were made based on the structure of the parapet remnant of a mountain fortress in Bukhan-San located in Seoul. Two types of infilling material are considered. The responses to models were tested subjected to three kinds of input motion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.97-102
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• 1988

The strain release associated with historical and instrumental earthquoke data are analyzed. In addition, the relationship between engineering intensity and cumulative frequency of earthquake occurrence is investigated. Based on the study, a seimic zoning map of the Korean peninsula is constructed. For each seismic zone, a peak ground acceleration value is determined for the aseismic designs of two types of structures. First type is general structures like buildings and the second type is special structures like nuclear power plants.

• Journal of the Korean earth science society
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• v.33 no.7
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• pp.637-644
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• 2012

The Seoul metropolitan area is densely populated with 40 percent of Korean people and quite weak to the seismic hazard. According to the analysis of historical documents, the largest earthquake occurred in this area is MMI VIII-IX acompanying with a large shaking, collapse of stone walls, collapse of houses, and many casualties. Two times of damaging earthquakes occurred in the first century (A.D. 27, 89), and there was a long quiet period of about 1430 years. Another big earthquakes re-occurred three times in the 16-17 century (1518, 1613, 1692) and then a quiet period has continued to the present time. Just after Seoul earthquake in 1518, aftershocks occurred almost 19 days consecutively and many triggered earthquakes occurred not only in Seoul metropolitan area but also in Hwanghae province, northern Korea. It indicates that the largest potential earthquake in and around Seoul is MMI VIII-IX with a long occurrence period of about 1400-1500 years.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.369-384
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• 2006

Korean Peninsula, located on the southeastern part of Eurasian plate, belongs to the intraplate region. The characteristics of intraplate earthquake show the low and rare seismicity and the sparse and irregular distribution of epicenters comparing to interplate earthquake. To evaluate the exact seismic activity in intraplate region, long-term seismic data including historical earthquake data should be archived. Fortunately the long-term historical earthquake records about 2,000 years are available in Korea Peninsula. By the analysis of this historical and instrumental earthquake data, seismic activity was very high in 16-18 centuries and is more active at the Yellow sea area than East sea area. Comparing to the high seismic activity of the north-eastern China in 16-18 centuries, it is inferred that seismic activity in two regions shows close relationship. Also general trend of epicenter distribution shows the SE-NW direction. In Korea Peninsula, the first seismic station was installed at Incheon in 1905 and 5 additional seismic stations were installed till 1943. There was no seismic station from 1945 to 1962, but a World Wide Standardized Seismograph was installed at Seoul in 1963. In 1990, Korean Meteorological Adminstration(KMA) had established centralized modem seismic network in real-time, consisted of 12 stations. After that time, many institutes tried to expand their own seismic networks in Korea Peninsula. Now KMA operates 35 velocity-type seismic stations and 75 accelerometers and Korea Institute of Geoscience and Mineral Resources operates 32 and 16 stations, respectively. Korea Institute of Nuclear Safety and Korea Electric Power Research Institute operate 4 and 13 stations, consisted of velocity-type and accelerometer. In and around the Korean Peninsula, 27 intraplate earthquake mechanisms since 1936 were analyzed to understand the regional stress orientation and tectonics. These earthquakes are largest ones in this century and may represent the characteristics of earthquake in this region. Focal mechanism of these earthquakes show predominant strike-slip faulting with small amount of thrust components. The average P-axis is almost horizontal ENE-WSW. In north-eastern China, strike-slip faulting is dominant and nearly horizontal average P-axis in ENE-WSW is very similar with the Korean Peninsula. On the other hand, in the eastern part of East Sea, thrust faulting is dominant and average P-axis is horizontal with ESE-WNW. This indicate that not only the subducting Pacific Plate in east but also the indenting Indian Plate controls earthquake mechanism in the far east of the Eurasian Plate. Crustal velocity model is very important to determine the hypocenters of the local earthquakes. But the crust model in and around Korean Peninsula is not clear till now, because the sufficient seismic data could not accumulated. To solve this problem, reflection and refraction seismic survey and seismic wave analysis method were simultaneously applied to two long cross-section traversing the southern Korean Peninsula since 2002. This survey should be continuously conducted.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.155-168
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• 1999

The paleoseismological importance of the Yangsan fault zone was examined by historical earthquake data, aerial photograph, and trench survey of the area. Occurrences of great earthquakes during the historical time indicate that the Yangsan and/or Ulsan fault have been active during the late Quaternary and generated historical events. Geomorphological evidences of the recent fault activity are clearly shown both in the northern segment (Yugye-ri, Tosung-ri and Naengsu-ri areas) and in the southern segment (Eonyang to Tongdosa areas) of the Yangsan fault. The main Yangsan fault is characterized by fault gouges and NNE-SSW lineaments. The reverse faulting in the Yugye-ri area generated about three-mater displacement of the lower terrace deposits. On the other hand, a major strike-slip movement with a minor component of 5-12 m vertical displacement was identified by the offset of the higher terrace surface in the Eonyang area.