Assessment of historical earthquakes for seismic hazard analysis: Did M6-7 events occur in the Korean Peninsula?
Abstract
The Korean Peninsula is located in the eastern margin of the Eurasian plate with low seismicity. However, recent noticeable increase of moderate-size earthquakes raises public concerns on possible seismic hazards in the Korean Peninsula. Investigation of long-term seismicity is important for proper seismic hazard mitigation. Historical literatures in Korea include well-recorded seismic damage description for more than 500 years, which is useful for assessment of the long-term seismicity. There is inherent uncertainty in the epicenters and magnitudes of historical earthquakes, which causes limitation in full use of the historical earthquakes for assessment of seismic hazard potentials. We propose a novel method to determine the locations and magnitudes of major historical earthquakes in a probabilistic assessment scheme. We analyze the historical seismic records for 1524 earthquakes in 1393-1904 from JoseonWangjoSillok and Seungjeongwon-ilgi. We carefully assign seismic intensities in modified Mercalli intensity (MMI) scale to the historical damage descriptions. The posteriori probabilities for presumed event locations and magnitudes are calculated considering the instrumental seismicity densities, Gutenberg magnitude-frequency relationship, and the fitness between the observed and theoretical seismic intensities. The event locations and magnitudes with maximum probabilities are chosen to be the optimum source parameters. We observe five historical earthquakes with magnitudes larger than or equal to ML6.4. The largest magnitude of historical earthquakes is determined to be ML7.1, which is much larger than that of instrumental events in the Korean Peninsula, ML 5.8. The distribution of historical earthquakes generally agrees with that of instrumental earthquakes, showing high densities in the northwestern and southern Korean Peninsula and low densities in the northeastern and mid-eastern Korean Peninsula. However, the historical seismicity is high in the mid-western Korean Peninsula where the Seoul metropolitan area is located. We find a historical earthquake of ML 6.8 in the Seoul metropolitan area. The historical seismicity is applicable to the seismic hazard analysis, which suggests high potentials of seismic hazards that are not apparent in the instrumental seismicity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH13D0851P
- Keywords:
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- 4302 Geological;
- NATURAL HAZARDS;
- 4343 Preparedness and planning;
- NATURAL HAZARDS;
- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGY